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Sample records for active neutron coincidence

  1. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    SciTech Connect

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

    2002-11-10

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

  2. First principle active neutron coincidence counting measurements of uranium oxide

    NASA Astrophysics Data System (ADS)

    Goddard, Braden; Charlton, William; Peerani, Paolo

    2014-03-01

    Uranium is present in most nuclear fuel cycle facilities ranging from uranium mines, enrichment plants, fuel fabrication facilities, nuclear reactors, and reprocessing plants. The isotopic, chemical, and geometric composition of uranium can vary significantly between these facilities, depending on the application and type of facility. Examples of this variation are: enrichments varying from depleted (~0.2 wt% 235U) to high enriched (>20 wt% 235U); compositions consisting of U3O8, UO2, UF6, metallic, and ceramic forms; geometries ranging from plates, cans, and rods; and masses which can range from a 500 kg fuel assembly down to a few grams fuel pellet. Since 235U is a fissile material, it is routinely safeguarded in these facilities. Current techniques for quantifying the 235U mass in a sample include neutron coincidence counting. One of the main disadvantages of this technique is that it requires a known standard of representative geometry and composition for calibration, which opens up a pathway for potential erroneous declarations by the State and reduces the effectiveness of safeguards. In order to address this weakness, the authors have developed a neutron coincidence counting technique which uses the first principle point-model developed by Boehnel instead of the "known standard" method. This technique was primarily tested through simulations of 1000 g U3O8 samples using the Monte Carlo N-Particle eXtended (MCNPX) code. The results of these simulations showed good agreement between the simulated and exact 235U sample masses.

  3. Analysis of calibration data for the uranium active neutron coincidence counting collar with attention to errors in the measured neutron coincidence rate

    NASA Astrophysics Data System (ADS)

    Croft, Stephen; Burr, Tom; Favalli, Andrea; Nicholson, Andrew

    2016-03-01

    The declared linear density of 238U and 235U in fresh low enriched uranium light water reactor fuel assemblies can be verified for nuclear safeguards purposes using a neutron coincidence counter collar in passive and active mode, respectively. The active mode calibration of the Uranium Neutron Collar - Light water reactor fuel (UNCL) instrument is normally performed using a non-linear fitting technique. The fitting technique relates the measured neutron coincidence rate (the predictor) to the linear density of 235U (the response) in order to estimate model parameters of the nonlinear Padé equation, which traditionally is used to model the calibration data. Alternatively, following a simple data transformation, the fitting can also be performed using standard linear fitting methods. This paper compares performance of the nonlinear technique to the linear technique, using a range of possible error variance magnitudes in the measured neutron coincidence rate. We develop the required formalism and then apply the traditional (nonlinear) and alternative approaches (linear) to the same experimental and corresponding simulated representative datasets. We find that, in this context, because of the magnitude of the errors in the predictor, it is preferable not to transform to a linear model, and it is preferable not to adjust for the errors in the predictor when inferring the model parameters.

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

    NASA Astrophysics Data System (ADS)

    Han, Xiaogang

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

  5. DIVERSE ACTIVE WELL NEUTRON COINCIDENCE COUNTER UTILITY AT THE SAVANNAH RIVER NATIONAL LABORATORY

    SciTech Connect

    Dewberry, R; Saleem Salaymeh, S

    2007-01-08

    In this paper we describe use of the Aquila active well neutron coincidence counter for nuclear material assays of {sup 235}U in multiple analytical techniques at Savannah River Site (SRS), at the Savannah River National Laboratory (SRNL), and at Argonne West National Laboratory (AWNL). The uses include as a portable passive neutron counter for field measurements searching for evidence of {sup 252}Cf deposits and storage; as a portable active neutron counter using an external activation source for field measurements searching for trace {sup 235}U deposits and holdup; for verification measurements of U-Al reactor fuel elements; for verification measurements of uranium metal; and for verification measurements of process waste of impure uranium in a challenging cement matrix. The wide variety of uses described demonstrate utility of the technique for neutron coincidence verification measurements over the dynamic ranges of 100 g-5000 g for U metal, 200 g-1300 g for U-Al, and 8 g-35 g for process waste. In addition to demonstrating use of the instrument in both the passive and active modes, we also demonstrate its use in both the fast and thermal neutron modes.

  6. Estimation of Performance of an Active Well Coincidence Counter Equipped with Boron-Coated Straw Neutron Detectors - 13401

    SciTech Connect

    Young, B.M.; Lacy, J.L.; Athanasiades, A.

    2013-07-01

    He-3, a very rare isotope of natural helium gas, has ideal properties for the detection of thermal neutrons. As such it has become the standard material for neutron detectors and sees ubiquitous use within many radiometric applications that require neutron sensitivity. Until recently, there has been a fairly abundant supply of He-3. However, with the reduction in nuclear weapons, production of tritium ceased decades ago and the stockpile has largely decayed away, reducing the available He-3 supply to a small fraction of that needed for neutron detection. A suitable and rapidly-deployable replacement technology for neutron detectors must be found. Many potential replacement technologies are under active investigation and development. One broad class of technologies utilizes B-10 as a neutron capture medium in coatings on the internal surfaces of proportional detectors. A particular implementation of this sort of technology is the boron-coated 'straw' (BCS) detectors under development by Proportional Technologies, Inc. (PTi). This technology employs a coating of B-10 enriched boron carbide (B{sub 4}C) on the inside of narrow tubes, roughly 4 mm in diameter. A neutron counter (e.g. a slab, a well counter, or a large assay counter designed to accommodate 200 liter drums) could be constructed by distributing these narrow tubes throughout the polyethylene body of the counter. One type of neutron counter that is of particular importance to safeguards applications is the Active Well Coincidence Counter (AWCC), which is a Los Alamos design that traditionally employs 42 He-3 detectors. This is a very flexible design which can accurately assay small samples of uranium- and plutonium-bearing materials. Utilizing the MCNPX code and benchmarking against measurements where possible, the standard AWCC has been redesigned to utilize the BCS technology. Particular aspects of the counter performance include the single-neutron ('singles') detection efficiency and the time constant for

  7. CALIBRATION OF THE HB LINE ACTIVE WELL NEUTRON COINCIDENCE COUNTER FOR MEASUREMENT OF LANL 3013 HIGHLY ENRICHED URANIUM PRODUCT SPLITS

    SciTech Connect

    Dewberry, R; Donald02 Williams, D; Rstephen Lee, R; David-W Roberts, D; Leah Arrigo, L

    2008-01-22

    In this paper we describe set-up, calibration, and testing of the F-Area Analytical Labs active well neutron coincidence counter(HV-221000-NDA-X-1-DK-AWCC-1)in SRNL for use in HB-Line to enable assay of 3013EU/Pu metal product. The instrument was required within a three-month window for availability upon receipt of LANL Category IV uranium oxide samples into the SRS HB-Line facility. We describe calibration of the instrument in the SRNL nuclear nondestructive assay facility in the range 10-400 g HEU for qualification and installation in HB-Line for assay of the initial suite of product samples.

  8. Shift-register coincidence electronics system for thermal neutron counters

    SciTech Connect

    Swansen, J.E.; Collinsworth, P.R.; Krick, M.S.

    1980-04-01

    An improved shift-register, coincidence-counting logic circuit, developed for use with thermal neutron well counters, is described in detail. A distinguishing feature of the circuit is its ability to operate usefully at neutron counting rates of several hundred kHz. A portable electronics package incorporating the new coincidence logic and support circuits is also described.

  9. Uranium Neutron Coincidence Collar Model Utilizing Boron-10 Lined Tubes

    SciTech Connect

    Rogers, Jeremy L.; Ely, James H.; Kouzes, Richard T.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-09-18

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report, providing results for model development of Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) designs, is a deliverable under Task 2 of the project.

  10. Introduction to Neutron Coincidence Counter Design Based on Boron-10

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-01-22

    The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.

  11. Boron-10 Based Neutron Coincidence Counter for Safeguards

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2014-10-01

    The shortage of 3He has triggered the search for effective alternative neutron detection technologies for national security applications, including international nuclear safeguards. Any alternative neutron detection technology must satisfy two basic criteria: it must meet a neutron detection efficiency requirement, and it must be insensitive to gamma-ray interference at a prescribed level while still meeting the neutron detection requirement. For nuclear safeguards, a system must perform measurements in the field with a prescribed precision in a specified time. This paper describes an effort to design, model and test an alternatives-based neutron coincidence counter for nuclear safeguards applications. The technology chosen for use in an alternatives-based uranium neutron coincidence collar was boron-lined proportional counters. Extensive modeling was performed of various system configurations and comparisons were made to measurements on a commercial prototype boron-10 based uranium neutron coincidence collar.

  12. Neutron coincidence detectors employing heterogeneous materials

    DOEpatents

    Czirr, J. Bartley; Jensen, Gary L.

    1993-07-27

    A neutron detector relies upon optical separation of different scintillators to measure the total energy and/or number of neutrons from a neutron source. In pulse mode embodiments of the invention, neutrons are detected in a first detector which surrounds the neutron source and in a second detector surrounding the first detector. An electronic circuit insures that only events are measured which correspond to neutrons first detected in the first detector followed by subsequent detection in the second detector. In spectrometer embodiments of the invention, neutrons are thermalized in the second detector which is formed by a scintillator-moderator and neutron energy is measured from the summed signals from the first and second detectors.

  13. A New Neutron-Capture Detector for Coincidence Counting

    NASA Astrophysics Data System (ADS)

    Browne, Michael C.; Ensslin, Norbert; Geist, William H.; Ianakiev, Kiril; Mayo, Douglas; Russo, Phyllis A.; Sweet, Martin R.

    2000-04-01

    Quantities of special nuclear material (SNM) are measured by counting coincident neutrons. This technique relies on spontaneous fission, in which more than one neutron is released for most events. Neutron coincidence counting (NCC) uses thermal neutron detectors. A problem with measurements of impure materials is that the neutron count rate, which determines the accidental coincidence rate, can be dominated by uncorrelated neutrons. An elevated rate of accidental coincidences can destroy the detection sensitivity. By reducing the detector’s die-away time (t, the time it takes to detect a neutron), true coincidence events are registered more promptly and the accidental rate reduced proportionally. The t of current counters based on 3He proportional detectors is 50 ms. A new detector is being developed with a shorter t of 5 ms for NCC of impure SNM. It uses alternating layers of a scintillator/6Li powder mixture and ribbons of optical fiber for light transport. Neutrons are thermalized and then detected by capture on 6Li. The reaction products deposit energy in the scintillator. The light is transported by the fibers to photomultiplier tubes. However, the detector is sensitive to both gamma rays and neutrons. Separating the two is essential for successful operation. This paper presents a description and evaluation of the new detector. Pulse shape analysis is discussed for discrimination between gamma rays and neutrons.

  14. Self-regulating neutron coincidence counter

    DOEpatents

    Baron, N.

    1980-06-16

    A device for accurately measuring the mass of /sup 240/Pu and /sup 239/Pu in a sample having arbitrary moderation and mixed with various contaminants. The device utilizes a thermal neutron well counter which has two concentric rings of neutron detectors separated by a moderating material surrounding the well. Neutron spectroscopic information derived by the two rings of detectors is used to measure the quantity of /sup 239/Pu and /sup 240/Pu in device which corrects for background radiation, deadtime losses of the detector and electronics and various other constants of the system.

  15. Characteristic evaluation of a Lithium-6 loaded neutron coincidence spectrometer.

    PubMed

    Hayashi, M; Kaku, D; Watanabe, Y; Sagara, K

    2007-01-01

    Characteristics of a (6)Li-loaded neutron coincidence spectrometer were investigated from both measurements and Monte Carlo simulations. The spectrometer consists of three (6)Li-glass scintillators embedded in a liquid organic scintillator BC-501A, which can detect selectively neutrons that deposit the total energy in the BC-501A using a coincidence signal generated from the capture event of thermalised neutrons in the (6)Li-glass scintillators. The relative efficiency and the energy response were measured using 4.7, 7.2 and 9.0 MeV monoenergetic neutrons. The measured ones were compared with the Monte Carlo calculations performed by combining the neutron transport code PHITS and the scintillator response calculation code SCINFUL. The experimental light output spectra were in good agreement with the calculated ones in shape. The energy dependence of the detection efficiency was reproduced by the calculation. The response matrices for 1-10 MeV neutrons were finally obtained.

  16. Computed neutron coincidence counting applied to passive waste assay

    SciTech Connect

    Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R.

    1997-11-01

    Neutron coincidence counting applied for the passive assay of fissile material is generally realised with dedicated electronic circuits. This paper presents a software based neutron coincidence counting method with data acquisition via a commercial PC-based Time Interval Analyser (TIA). The TIA is used to measure and record all time intervals between successive pulses in the pulse train up to count-rates of 2 Mpulses/s. Software modules are then used to compute the coincidence count-rates and multiplicity related data. This computed neutron coincidence counting (CNCC) offers full access to all the time information contained in the pulse train. This paper will mainly concentrate on the application and advantages of CNCC for the non-destructive assay of waste. An advanced multiplicity selective Rossi-alpha method is presented and its implementation via CNCC demonstrated. 13 refs., 4 figs., 2 tabs.

  17. Uranium Neutron Coincidence Collar Model Utilizing 3He

    SciTech Connect

    Siciliano, Edward R.; Rogers, Jeremy L.; Schweppe, John E.; Lintereur, Azaree T.; Kouzes, Richard T.

    2012-07-30

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based alternative system in a configuration typically used for 3He-based coincidence counter applications. The specific application selected for boron-lined tube replacement in this project was one of the Uranium Neutron Coincidence Collar (UNCL) designs. This report, providing results for model development of a UNCL, is a deliverable under Task 2 of the project. The current UNCL instruments utilize 3He tubes. As the first step in developing and optimizing a boron-lined proportional counter based version of the UNCL, models of eight different 3He-based UNCL detectors currently in use were developed and evaluated. A comparison was made between the simulated results and measured efficiencies for those systems with values reported in the literature. The reported experimental measurements for efficiencies and die-away times agree to within 10%.

  18. A new opportunity: coincident spectroscopy in neutron-deficient actinides

    NASA Astrophysics Data System (ADS)

    Gothe, Oliver; Gates, J. M.; Gregorich, K. E.; Baartman, B.; Fallon, P.; Esker, N. E.; Kwarsick, J.; Machiavelli, A. O.; Mudder, P. R.; Olive, D. T.; Pang, G.; Rissanen, J.; Nitsche, H.

    2014-09-01

    Due to high γ-ray background rates heavy element production facilities are usually not sensitive to the electron capture decay of neutron deficient actinides. We have developed new capabilities at the Berkeley Gas Filled Separator (BGS) that allow us to study these isotopes. The highly selective and efficient separation of compound nucleus evaporation residue products using the BGS couple with a rapid delivery to a low-background detector facility, opens up many new possibilities for nuclear decay and structure studies in the neutron deficient actinides. The decay of these actinides produces vacancies in the K-shell resulting in x-rays uniquely identifying the Z of the decay products. We present the first results of this new methodology in studying the nuclear structure of fermium-254 by observing the gamma rays in coincidence with fermium x-rays. Coincident gamma-decay spectroscopy gives us a new tool to study the nuclear structure of previously inaccessible systems.

  19. Active Well Neutron Coincidence Assays for U-235 Content in HB-Line Desicooler Repackage Campaign at the Savannah River Site

    SciTech Connect

    DEWBERRY, RAYMOND

    2004-07-15

    At HB-Line of the Savannah River Site, 4.3 kg of U-235 have been repackaged from FB-Line Desicooler material into a cement matrix in individual one-gallon paint cans for disposition as solid waste. The 4.3 kg of U-235 material were packaged into 172 paint cans with U-235 contents ranging from 8.9 g up to 32 g. Prior to transfer to the Solid Waste Facilities, verification measurements of selected cans were performed to assure valid control of the solid waste. The HB-Line-DOE Sampling Plan designated confirmatory assays, and a total of 67 paint cans were assayed to verify the contents. The Analytical Development Section of the Savannah River National Laboratory selected an active well coincidence neutron counter as the best instrument available to accomplish the assays. The instrument was set up at-line in the thermal excitation mode, and three standard samples that contained 8.9-, 28.5-, and 32.4-g of U-235 were counted for twenty hours of acquisition time each. A linear calibration based on the observed doubles rates was installed in the instrument. Subsequent verification measurements were performed on the selected samples using fifteen one-minute active acquisitions. Of the 67 samples assayed, 53 verification measurements were within the limits greater than or less than 32 per cent prescribed by the sample plan. Eleven samples had results that were biased low by as much as 95 percent, and three samples had results that were biased high and outside of the prescribed range. Because of the extremely variable nature of the cement matrix these results were not unexpected. From the observed data we were able to use the singles rates to develop a correction factor that we could apply to the doubles rates of the eleven negatively biased results that brought each verification measurement back into the prescribed range. The three samples that had large positive biases in the verification measurements were observed in the passive acquisition mode to confirm contributions

  20. High-level neutron coincidence counter maintenance manual

    SciTech Connect

    Swansen, J.; Collinsworth, P.

    1983-05-01

    High-level neutron coincidence counter operational (field) calibration and usage is well known. This manual makes explicit basic (shop) check-out, calibration, and testing of new units and is a guide for repair of failed in-service units. Operational criteria for the major electronic functions are detailed, as are adjustments and calibration procedures, and recurrent mechanical/electromechanical problems are addressed. Some system tests are included for quality assurance. Data on nonstandard large-scale integrated (circuit) components and a schematic set are also included.

  1. Systematic effects in neutron coincidence and multiplicity counting

    SciTech Connect

    Evans, Louise G; Favorite, Jeffrey A; Swinhoe, Martyn T

    2010-01-01

    Correlated neutron counting, including neutron coincidence and multiplicity counting, is an important tool in nuclear material accountancy verification. The accuracy of such measurements is of interest to the safeguards community because as the accuracy of NDA improves, the number of samples that are required to undergo destructive analysis (DA) decreases. The accuracy of a neutron mUltiplicity measurement can be affected by a number of variables. Monte Carlo neutron transport simulations with MCNPX have been performed to understand how the properties of the sample affect the count rate. These resultant count rates have been analyzed with the 'point model' in order to determine the effect on the deduced plutonium mass. The sample properties that have been investigated are density, sample position within the detector cavity, moisture content, isotopic composition, plutonium to total actinide ratio and heavy metal fraction. These parameters affect the Singles, Doubles and Triples count rates in different ways. In addition, different analysis methods use these measured quantities in different combinations, so that the final sensitivity of the {sup 240}Pu mass to each parameter also depends on the analysis method used. For example, the passive calibration curve method only used the Doubles rate to produce the {sup 240}Pu mass and so is not sensitive to changes in the Singles rate (to first order). The analysis methods considered here were passive calibration curve (non-multiplication corrected), known alpha (multiplication corrected) and multiplicity with known efficiency. The effects were studied on both a small mass MOX sample (1 g Pu) and a large MOX sample (6000 g Pu) both measured in high efficiency neutron multiplicity counters. In order to determine the final effect of each parameter it is necessary to know not only the sensitivity of the plutonium mass to that parameter, but also the range over which the parameter can realistically vary. Some estimates are

  2. The optimum choice of gate width for neutron coincidence counting

    NASA Astrophysics Data System (ADS)

    Croft, S.; Henzlova, D.; Favalli, A.; Hauck, D. K.; Santi, P. A.

    2014-11-01

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using 252Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  3. Cosmic ray neutron background reduction using localized coincidence veto neutron counting

    DOEpatents

    Menlove, Howard O.; Bourret, Steven C.; Krick, Merlyn S.

    2002-01-01

    This invention relates to both the apparatus and method for increasing the sensitivity of measuring the amount of radioactive material in waste by reducing the interference caused by cosmic ray generated neutrons. The apparatus includes: (a) a plurality of neutron detectors, each of the detectors including means for generating a pulse in response to the detection of a neutron; and (b) means, coupled to each of the neutrons detectors, for counting only some of the pulses from each of the detectors, whether cosmic ray or fission generated. The means for counting includes a means that, after counting one of the pulses, vetos the counting of additional pulses for a prescribed period of time. The prescribed period of time is between 50 and 200 .mu.s. In the preferred embodiment the prescribed period of time is 128 .mu.s. The veto means can be an electronic circuit which includes a leading edge pulse generator which passes a pulse but blocks any subsequent pulse for a period of between 50 and 200 .mu.s. Alternately, the veto means is a software program which includes means for tagging each of the pulses from each of the detectors for both time and position, means for counting one of the pulses from a particular position, and means for rejecting those of the pulses which originate from the particular position and in a time interval on the order of the neutron die-away time in polyethylene or other shield material. The neutron detectors are grouped in pods, preferably at least 10. The apparatus also includes means for vetoing the counting of coincidence pulses from all of the detectors included in each of the pods which are adjacent to the pod which includes the detector which produced the pulse which was counted.

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

    NASA Astrophysics Data System (ADS)

    Mueller, J. M.; Mattingly, J.

    2016-07-01

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

  5. The effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting

    DOE PAGES

    Croft, Stephen; Favalli, Andrea; Swinhoe, Martyn T.; Goddard, Braden; Stewart, Scott

    2016-01-13

    In neutron coincidence counting using the shift register autocorrelation technique, a predelay is inserted before the opening of the (R+A)-gate. Operationally the purpose of the predelay is to ensure that the (R+A)- and A-gates have matched effectiveness, otherwise a bias will result when the difference between the gates is used to calculate the accidentals corrected net reals coincidence rate. The necessity for the predelay was established experimentally in the early practical development and deployment of the coincidence counting method. The choice of predelay for a given detection system is usually made experimentally, but even today long standing traditional values (e.g.,more » 4.5 µs) are often used. This, at least in part, reflects the fact that a deep understanding of why a finite predelay setting is needed and how to control the underlying influences has not been fully worked out. We attempt, in this paper, to gain some insight into the problem. One aspect we consider is the slowing down, thermalization, and diffusion of neutrons in the detector moderator. The other is the influence of deadtime and electronic transients. These may be classified as non-ideal detector behaviors because they are not included in the conventional model used to interpret measurement data. From improved understanding of the effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting, the performance of both future and current coincidence counters may be improved.« less

  6. The effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting

    NASA Astrophysics Data System (ADS)

    Croft, Stephen; Favalli, Andrea; Swinhoe, Martyn T.; Goddard, Braden; Stewart, Scott

    2016-04-01

    In neutron coincidence counting using the shift register autocorrelation technique, a predelay is inserted before the opening of the (R+A)-gate. Operationally the purpose of the predelay is to ensure that the (R+A)- and A-gates have matched effectiveness, otherwise a bias will result when the difference between the gates is used to calculate the accidentals corrected net reals coincidence rate. The necessity for the predelay was established experimentally in the early practical development and deployment of the coincidence counting method. The choice of predelay for a given detection system is usually made experimentally, but even today long standing traditional values (e.g., 4.5 μs) are often used. This, at least in part, reflects the fact that a deep understanding of why a finite predelay setting is needed and how to control the underlying influences has not been fully worked out. In this paper we attempt to gain some insight into the problem. One aspect we consider is the slowing down, thermalization, and diffusion of neutrons in the detector moderator. The other is the influence of deadtime and electronic transients. These may be classified as non-ideal detector behaviors because they are not included in the conventional model used to interpret measurement data. From improved understanding of the effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting, the performance of both future and current coincidence counters may be improved.

  7. Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel

    SciTech Connect

    Cowles, Christian C.; Kouzes, Richard T.; Siciliano, Edward R.

    2014-10-31

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.

  8. Moisture corrections in neutron coincidence counting of PuO/sub 2/

    SciTech Connect

    Stewart, J.E.; Menlove, H.O.

    1987-01-01

    Passive neutron coincidence counting is capable of 1% assay accuracy for pure, well-characterized PuO/sub 2/ samples that contain plutonium masses from a few tens of grams to several kilograms. Moisture in the sample can significantly bias the assay high by changing the (..cap alpha..,n) neutron production, the sample multiplication, and the detection efficiency. Monte Carlo calculations and an analytical model of coincidence counting have been used to quantify the individual and cumulative effects of moisture biases for two PuO/sub 2/ sample sizes and a range of moisture levels from 0 to 9 wt %. Results of the calculations suggest a simple correction procedure for moisture bias that is effective from 0 to 3 wt % H/sub 2/O. The procedure requires that the moisture level in the sample be known before the coincidence measurement.

  9. Direct fissile assay of enriched uranium using random self-interrogation and neutron coincidence response

    DOEpatents

    Menlove, Howard O.; Stewart, James E.

    1986-01-01

    Apparatus and method for the direct, nondestructive evaluation of the .sup.235 U nuclide content of samples containing UF.sub.6, UF.sub.4, or UO.sub.2 utilizing the passive neutron self-interrogation of the sample resulting from the intrinsic production of neutrons therein. The ratio of the emitted neutron coincidence count rate to the total emitted neutron count rate is determined and yields a measure of the bulk fissile mass. The accuracy of the method is 6.8% (1.sigma.) for cylinders containing UF.sub.6 with enrichments ranging from 6% to 98% with measurement times varying from 3-6 min. The samples contained from below 1 kg to greater than 16 kg. Since the subject invention relies on fast neutron self-interrogation, complete sampling of the UF.sub.6 takes place, reducing difficulties arising from inhomogeneity of the sample which adversely affects other assay procedures.

  10. Direct fissile assay of enriched uranium using random self-interrogation and neutron coincidence response

    DOEpatents

    Menlove, H.O.; Stewart, J.E.

    1985-02-04

    Apparatus and method for the direct, nondestructive evaluation of the /sup 235/U nuclide content of samples containing UF/sub 6/, UF/sub 4/, or UO/sub 2/ utilizing the passive neutron self-interrogation of the sample resulting from the intrinsic production of neutrons therein. The ratio of the emitted neutron coincidence count rate to the total emitted neutron count rate is determined and yields a measure of the bulk fissile mass. The accuracy of the method is 6.8% (1sigma) for cylinders containing UF/sub 6/ with enrichments ranging from 6% to 98% with measurement times varying from 3-6 min. The samples contained from below 1 kg to greater than 16 kg. Since the subject invention relies on fast neutron self-interrogation, complete sampling of the UF/sub 6/ takes place, reducing difficulties arising from inhomogeneity of the sample which adversely affects other assay procedures. 4 figs., 1 tab.

  11. A Coincident Search for Radio and Gravitational Waves from Binary Neutron Star Mergers

    NASA Astrophysics Data System (ADS)

    Cardena, Brett

    2011-05-01

    The merger of neutron star-neutron star binary pairs may be accompanied by the prompt emission of a coherent low-frequency radio pulse. This radio transient is produced as synchrotron radiation caused by the spin and rotation of the surface charge density of a pulsar through the magnetosphere of a larger neutron star, usually referred to as a Magnetar . This type of merger event would also result in the release of a gravitational coalescence wave-form. We will discuss a coincident radio transient and gravitational wave search. This search is being conducted by two radio telescope arrays: The Long Wave Array (LWA) and the Eight-meter-wavelength Transient Array (ETA) in coordination with the Laser Interferometer Gravitational-Wave Observatory (LIGO). We will outline this ongoing coincident search and discuss some preliminary results.

  12. Calibration of a neutron coincidence counter for measurement of the plutonium content of wet oxalate cakes

    SciTech Connect

    Crane, T.W.

    1983-04-01

    A novel calibration procedure has been applied to the dual-ring thermal neutron coincidence counter used at the Los Alamos Plutonium Processing Facility to measure the plutonium content of wet oxalate cakes. The calibration uses the measured content of the plutonium oxide product and the coincidence counter response to estimate the plutonium content in up to four wet plutonium oxalate cakes. These estimated mass values are then used to calibrate the counter. The calibration calculation is iterative in determining the calibration function coefficients and plutonium masses for oxalate material.

  13. Arsenic activation neutron detector

    DOEpatents

    Jacobs, E.L.

    1980-01-28

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

  14. Arsenic activation neutron detector

    DOEpatents

    Jacobs, Eddy L.

    1981-01-01

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

  15. Fast Neutron Dose Evaluation Using CR39 by Coincidence Counting Process

    SciTech Connect

    Vilela, Eudice; Freitas, F. F. de; Brandao, J. O. C.; Santos, J. A. L.

    2008-08-07

    The solid state nuclear tracks detection (SSNTD) technique is widely used in the area of radiation dosimetry. Different materials can be used applying this technique as glass and the most used in the dosimetry field that are the polycarbonates, CR39 and Makrofol-DE. Both are very rich in hydrogenous, that enables the SSNTD to detect fast neutrons through recoils of protons in the own detector material, without need of converters. The low reproducibility of its backgroundhas often been the major drawback in the assessment of low fluences of fast neutrons with SSNTDs. This problem can be effectively solved by counting coincidence of tracks in two detectors foils irradiated in close contact. After processing and counting only tracks produced by the same recoil nuclei on the surfaces of both detectors are considered as a track. This procedure enables the reduction of the background counts in the response of the detectors. In this work a preliminary study on the application of the coincidence technique for neutron dosimetry is presented. The CR39 material was investigated aiming to achieve the personal dose equivalent for fast neutrons. Using this method of analysis a significant reduction on the lower detectable dose was observed resulting even one order of magnitude smaller value. Reading, however, needs to be automated due to the large areas necessary to achieve a satisfactory number of tracks for statistical significance of results.

  16. A new MCNPX PTRAC coincidence capture file capability: a tool for neutron detector design

    SciTech Connect

    Evans, Louise G; Schear, Melissa A; Hendricks, John S; Swinhoe, Martyn T; Tobin, Stephen J; Croft, Stephen

    2011-02-16

    The existing Monte Carlo N-Particle (MCNPX) particle tracking (PTRAC) coincidence capture file allows a full list of neutron capture events to be recorded in any simulated detection medium. The originating event history number (e.g. spontaneous fission events), capture time, location and source particle number are tracked and output to file for post-processing. We have developed a new MCNPX PTRAC coincidence capture file capability to aid detector design studies. New features include the ability to track the nuclides that emitted the detected neutrons as well as induced fission chains in mixed samples before detection (both generation number and nuclide that underwent induced fission). Here, the power of this tool is demonstrated using a detector design developed for the non-destructive assay (NDA) of spent nuclear fuel. Individual capture time distributions have been generated for neutrons originating from Curium-244 source spontaneous fission events and induced fission events in fissile nuclides of interest: namely Plutonium-239, Plutonium-241, and Uranium-235. Through this capability, a full picture for the attribution of neutron capture events in the detector can be simulated.

  17. A new MCNPX PTRAC coincidence capture file capability: a tool for neutron detector design

    SciTech Connect

    Evans, Louise G; Schear, Melissa A; Hendricks, John S; Swinhoe, Martyn T; Tobin, Stephen J; Croft, Stephen

    2010-12-14

    The existing MCNPX{trademark} PTRAC coincidence capture file allows a full list of neutron capture events to be recorded in any simulated detection medium. The originating event history number (e.g. spontaneous fission events), capture time, location and source particle number are tracked and output to file for post-processing. We have developed a new MCNPX PTRAC coincidence capture file capability to aid detector design studies. New features include the ability to track the isotopes that emitted the detected neutrons as well as induced fission chains in mixed samples before detection (both generation number and isotope). Here, the power of this tool is demonstrated using a detector design that has been developed for the non-destructive assay (NDA) of spent nuclear fuel. Individual capture time distributions have been generated for neutrons originating from Curium-244 source spontaneous fission events and induced fission events in fissile isotopes of interest: namely Plutonium-239, Plutonium-241, and Uranium-235. Through this capability, a full picture for the attribution of neutron capture events in the detector can be simulated.

  18. A new NCNPX PTRAC coincidence capture file capability: a tool for neutron detector design

    SciTech Connect

    Evans, Louise G; Schear, Melissa A; Hendricks, John S; Swinhoe, Martyn T; Tobin, Stephen J; Croft, Stephen

    2011-01-13

    The existing Monte Carlo N-Particle (MCNPX) particle tracking (PTRAC) coincidence capture file allows a full list of neutron capture events to be recorded in any simulated detection medium. The originating event history number (e.g. spontaneous fission events), capture time, location and source particle number are tracked and output to file for post-processing. We have developed a new MCNPX PTRAC coincidence capture file capability to aid detector design studies. New features include the ability to track the nuclides that emitted the detected neutrons as well as induced fission chains in mixed samples before detection (both generation number and nuclide that underwent induced fission). Here, the power of this tool is demonstrated using a detector design developed for the non-destructive assay (NDA) of spent nuclear fuel. Individual capture time distributions have been generated for neutrons originating from Curium-244 source spontaneous fission events and induced fission events in fissile nuclides of interest: namely Plutonium-239, Plutonium-241, and Uranium-235. Through this capability, a full picture for the attribution of neutron capture events in the detector can be simulated.

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

    SciTech Connect

    Ji Chuncheng; Kegel, G.H.R.; Egan, J.J.; DeSimone, D.J.; Alimeti, A.; Roldan, C.F.; McKittrick, T.M.; Kim, D.-S.; Chen, X.; Tremblay, S.E.

    2005-05-24

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

  20. Pair neutron transfer in 60Ni+116Sn probed via γ -particle coincidences

    NASA Astrophysics Data System (ADS)

    Montanari, D.; Corradi, L.; Szilner, S.; Pollarolo, G.; Goasduff, A.; Mijatović, T.; Bazzacco, D.; Birkenbach, B.; Bracco, A.; Charles, L.; Courtin, S.; Désesquelles, P.; Fioretto, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Haas, F.; Hess, H.; Jelavić Malenica, D.; Jungclaus, A.; Karolak, M.; Leoni, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Montagnoli, G.; Napoli, D. R.; Pullia, A.; Recchia, F.; Reiter, P.; Rosso, D.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Soić, N.; Stefanini, A. M.; Stezowski, O.; Theisen, Ch.; Ur, C. A.; Valiente-Dobón, J. J.; Varga Pajtler, M.

    2016-05-01

    We performed a γ -particle coincidence experiment for the 60Ni + 116Sn system to investigate whether the population of the two-neutron pickup channel leading to 62Ni is mainly concentrated in the ground-state transition, as has been found in a previous work [D. Montanari et al., Phys. Rev. Lett. 113, 052501 (2014), 10.1103/PhysRevLett.113.052501]. The experiment has been performed by employing the PRISMA magnetic spectrometer coupled to the Advanced Gamma Tracking Array (AGATA) demonstrator. The strength distribution of excited states corresponding to the inelastic, one- and two-neutron transfer channels has been extracted. We found that in the two-neutron transfer channel the strength to excited states corresponds to a fraction (less than 24%) of the total, consistent with the previously obtained results that the 2 n channel is dominated by the ground-state to ground-state transition.

  1. Neutron activation analysis system

    DOEpatents

    Taylor, M.C.; Rhodes, J.R.

    1973-12-25

    A neutron activation analysis system for monitoring a generally fluid media, such as slurries, solutions, and fluidized powders, including two separate conduit loops for circulating fluid samples within the range of radiation sources and detectors is described. Associated with the first loop is a neutron source that emits s high flux of slow and thermal neutrons. The second loop employs a fast neutron source, the flux from which is substantially free of thermal neutrons. Adjacent to both loops are gamma counters for spectrographic determination of the fluid constituents. Other gsmma sources and detectors are arranged across a portion of each loop for deterMining the fluid density. (Official Gazette)

  2. LANL Efforts on Neutron Coincidence Modeling of INL Pulsed Neutron Data

    SciTech Connect

    Stewart, Scott; Thron, Jonathan L.; Swinhoe, Martyn T.; Geist, William H.; Charlton, William S.

    2012-06-25

    Overview of this presentation is: (1) pulsed histogram analysis, (2) creation of SPNS, (3) use of SPNS for modeling pulsed neutron data, (4) creation of MUDI, (5) calculated accidentals correction using GUAM + MUDI, (6) background subtraction analysis, and (7) current/figure work with MCNP.

  3. Feynman variance-to-mean in the context of passive neutron coincidence counting

    NASA Astrophysics Data System (ADS)

    Croft, S.; Favalli, A.; Hauck, D. K.; Henzlova, D.; Santi, P. A.

    2012-09-01

    Passive Neutron Coincidence Counting (PNCC) based on shift register autocorrelation time analysis of the detected neutron pulse train is an important Nondestructive Assay (NDA) method. It is used extensively in the quantification of plutonium and other spontaneously fissile materials for purposes of nuclear materials accountancy. In addition to the totals count rate, which is also referred to as the singles, gross or trigger rate, a quantity known as the reals coincidence rate, also called the pairs or doubles, is obtained from the difference between the measured neutron multiplicities in two measurement gates triggered by the incoming events on the pulse train. The reals rate is a measure of the number of time correlated pairs present on the pulse train and this can be related to the fission rates (and hence material mass) since fissions emit neutrons in bursts which are also detected in characteristic clusters. A closely related measurement objective is the determination of the reactivity of systems as they approach criticality. In this field an alternative autocorrelation signature is popular, the so called Feynman variance-to-mean technique which makes use of the multiplicity histogram formed the periodic, or clock-triggered opening of a coincidence gate. Workers in these two application areas share common challenges and improvement opportunities but are often separated by tradition, problem focus and technical language. The purpose of this paper is to recognize the close link between the Feynman variance-to-mean metric and traditional PNCC using shift register logic applied to correlated pulse trains. We, show using relationships for the late-gate (or accidentals) histogram recorded using a multiplicity shift register, how the Feynman Y-statistic, defined as the excess variance-to-mean ratio, can be expressed in terms of the singles and doubles rates familiar to the safeguards and waste assay communities. These two specialisms now have a direct bridge between

  4. Characterizations of double pulsing in neutron multiplicity and coincidence counting systems

    NASA Astrophysics Data System (ADS)

    Koehler, Katrina E.; Henzl, Vladimir; Croft, Stephen S.; Henzlova, Daniela; Santi, Peter A.

    2016-10-01

    Passive neutron coincidence/multiplicity counters are subject to non-ideal behavior, such as double pulsing and dead time. It has been shown in the past that double-pulsing exhibits a distinct signature in a Rossi-alpha distribution, which is not readily noticed using traditional Multiplicity Shift Register analysis. However, it has been assumed that the use of a pre-delay in shift register analysis removes any effects of double pulsing. In this work, we use high-fidelity simulations accompanied by experimental measurements to study the effects of double pulsing on multiplicity rates. By exploiting the information from the double pulsing signature peak observable in the Rossi-alpha distribution, the double pulsing fraction can be determined. Algebraic correction factors for the multiplicity rates in terms of the double pulsing fraction have been developed. We discuss the role of these corrections across a range of scenarios.

  5. Measurement of Activated Au foils by 2{pi}{beta}+2{pi}{beta}-{gamma} Coincidence Counting and EGS5 Monte Carlo Calculation

    SciTech Connect

    Sato, Yasushi; Harano, Hideki; Matsumoto, Tetsuro; Nishiyama, Jun; Moriyama, Kentaro; Unno, Yasuhiro; Yamada, Takahiro; Yunoki, Akira; Hino, Yoshio; Kudo, Katsuhisa

    2009-03-10

    Neutron activation analysis using Au foil is a common and important method for measurement of thermal neutron fluence. To determine the activity of Au foil experimentally, Kawada et al. proposed 2{pi}{beta}+2{pi}{beta}-{gamma} coincidence counting. This method is based on 4{pi}{beta}-{gamma} coincidence counting but a 4{pi}{beta} detector is divided into two 2{pi}{beta} detectors those are independently operated in the method. In this research the correction factors in 2{pi}{beta}+2{pi}{beta}-{gamma} coincidence counting were obtained by measurement and simulation. The activities obtained by these correction factors were in good agreement.

  6. Performance of a coincidence based blood activity monitor

    SciTech Connect

    Moses, W.W.

    1989-12-01

    A new device has been constructed that measures the positron emitting radio-tracer concentration in arterial blood by extracting blood with a peristaltic pump, then measuring the activity concentration by detecting coincident pairs of 511 keV photons with a pair of heavy inorganic scintillators attached to photomultiplier tubes. The sensitivity of this device is experimentally determined to be 610 counts/second per {mu}Ci/ml, and has a paralyzing dead time of 1.2 {mu}s, so is capable of measuring blood activity concentration as high as 1 mCi/ml. Its performance is compared to two other blood monitoring methods: discrete blood samples counted with a well counter and device that uses a plastic scintillator to directly detect positrons. The positron detection efficiency of this device for {sup 18}F is greater than the plastic scintillation counter, and also eliminates the radioisotope dependent correction factors necessary to convert count rate to absolute concentration. Coincident photon detection also has the potential of reducing the background compared to direct positron detection, thereby increasing the minimum detectable isotope concentration. 10 refs., 6 figs.

  7. European Neutron Activation System.

    2013-01-11

    Version 03 EASY-2010 (European Activation System) consists of a wide range of codes, data and documentation all aimed at satisfying the objective of calculating the response of materials irradiated in a neutron flux. The main difference from the previous version is the upper energy limit, which has increased from 20 to 60 MeV. It is designed to investigate both fusion devices and accelerator based materials test facilities that will act as intense sources of high-energymore » neutrons causing significant activation of the surrounding materials. The very general nature of the calculational method and the data libraries means that it is applicable (with some reservations) to all situations (e.g. fission reactors or neutron sources) where materials are exposed to neutrons below 60 MeV. EASY can be divided into two parts: data and code development tools and user tools and data. The former are required to develop the latter, but EASY users only need to be able to use the inventory code FISPACT and be aware of the contents of the EAF library (the data source). The complete EASY package contains the FISPACT-2007 inventory code, the EAF-2003, EAF-2005, EAF-2007 and EAF-2010 libraries, and the EASY User Interface for the Window version. The activation package EASY-2010 is the result of significant development to extend the upper energy range from 20 to 60 MeV so that it is capable of being used for IFMIF calculations. The EAF-2010 library contains 66,256 reactions, almost five times more than in EAF-2003 (12,617). Deuteron-induced and proton-induced cross section libraries are also included, and can be used with EASY to enable calculations of the activation due to deuterons and proton [2].« less

  8. Application of the coincidence counting technique to DD neutron spectrometry data at the NIF, OMEGA, and Z

    NASA Astrophysics Data System (ADS)

    Lahmann, B.; Milanese, L. M.; Han, W.; Gatu Johnson, M.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D.; Hahn, K. D.; Jones, B.

    2016-11-01

    A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.

  9. Application of the coincidence counting technique to DD neutron spectrometry data at the NIF, OMEGA, and Z

    DOE PAGES

    Lahmann, B.; Milanese, L. M.; Han, W.; Gatu Johnson, M.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D.; Hahn, K. D.; Jones, B.

    2016-07-20

    A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protonsmore » at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. In conclusion, these results are in excellent agreement with previous work applied to DT neutrons.« less

  10. Neutron activation for ITER

    SciTech Connect

    Barnes, C.W.; Loughlin, M.J.; Nishitani, Takeo

    1996-04-29

    There are three primary goals for the Neutron Activation system for ITER: maintain a robust relative measure of fusion power with stability and high dynamic range (7 orders of magnitude); allow an absolute calibration of fusion power (energy); and provide a flexible and reliable system for materials testing. The nature of the activation technique is such that stability and high dynamic range can be intrinsic properties of the system. It has also been the technique that demonstrated (on JET and TFTR) the highest accuracy neutron measurements in DT operation. Since the gamma-ray detectors are not located on the tokamak and are therefore amenable to accurate characterization, and if material foils are placed very close to the ITER plasma with minimum scattering or attenuation, high overall accuracy in the fusion energy production (7--10%) should be achievable on ITER. In the paper, a conceptual design is presented. A system is shown to be capable of meeting these three goals, also detailed design issues remain to be solved.

  11. Determination of the 235U Mass and Enrichment within Small UF6 Cylinders via a Neutron Coincidence Well Counting System

    SciTech Connect

    McElroy, Robert Dennis; Croft, Dr. Stephen; Young, Brian M; Venkataraman, Ram

    2011-01-01

    The construction of three new uranium enrichment facilities in the United States has sparked renewed interest in the development and enhancement of methods to determine the enrichment and fissile mass content of UF6 cylinders. We describe the design and examine the expected performance of a UF6 bottle counter developed for the assay of Type 5A cylinders. The counter, as designed and subsequently constructed, is a tall passive neutron well counter with a clam-shell configuration and graphite end plugs operated in fast neutron mode. Factory performance against expectation is described. The relatively high detection efficiency and effectively 4 detection geometry provide a near-ideal measurement configuration, making the UF6 bottle counter a valuable tool for the evaluation of the neutron coincidence approach to UF6 cylinder assay. The impacts of non-uniform filling, voids, enrichment, and mixed enrichments are examined

  12. Neutron Production in Coincidence with Fragments from the {sup 40}Ca + H Reactions at E{sub lab} = 357 and 565 A MeV

    SciTech Connect

    Tuve, C.; Albergo, S.; Boemi, D.; Caccia, Z.; Chen, C.-X.; Costa, S.; Crawford, H.J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Guzik, T.G.; Insolia, A.; Knott, C.N.; Lindstrom, P.J.; Mitchell, J.W.; Potenza, R.; Russo, G.V.; Soutoul, A.; Testard, O.; Tricomi, A.; Tull, C.E.; Waddington, C.J.; Webber, W.R.; Wefel, J.P.

    2000-12-31

    In the frame of the Transport Collaboration neutrons in coincidence with charged fragments produced in the {sup 40}Ca + H reaction at E{sub lab} = 357 and 565 AMeV have been measured at the Heavy Ion Spectrometer System (HISS) facility of the Lawrence Berkeley National Laboratory, using the multifunctional neutron spectrometer MUFFINS. The detector covered a narrow angular range about the beam in the forward direction (0? - 3.2?). In this contribution we report absolute neutron production cross sections in coincidence with charged fragments (10 {<=} Z {<=} 20). The neutron multiplicities have been estimated from the comparison between the neutron cross sections, in coincidence with the fragments, and the elemental cross sections. We have found evidence for a pre-equilibrium emission of prompt neutrons in superposition to a 'slower' deexcitation of the equilibrated remnant by emission of nucleons and fragments, as already seen in the inclusive rapidity distributions.

  13. Neutron Activation Analysis: Techniques and Applications

    NASA Astrophysics Data System (ADS)

    MacLellan, Ryan

    2011-04-01

    The role of neutron activation analysis in low-energy low-background experimentsis discussed in terms of comparible methods. Radiochemical neutron activation analysis is introduce. The procedure of instrumental neutron activation analysis is detailed especially with respect to the measurement of trace amounts of natural radioactivity. The determination of reactor neutron spectrum parameters required for neutron activation analysis is also presented.

  14. Neutron Activation Analysis: Techniques and Applications

    SciTech Connect

    MacLellan, Ryan

    2011-04-27

    The role of neutron activation analysis in low-energy low-background experimentsis discussed in terms of comparible methods. Radiochemical neutron activation analysis is introduce. The procedure of instrumental neutron activation analysis is detailed especially with respect to the measurement of trace amounts of natural radioactivity. The determination of reactor neutron spectrum parameters required for neutron activation analysis is also presented.

  15. Neutron activated switch

    DOEpatents

    Barton, David M.

    1991-01-01

    A switch for reacting quickly to a neutron emission. A rod consisting of fissionable material is located inside a vacuum tight body. An adjustable contact is located coaxially at an adjustable distance from one end of the rod. Electrical leads are connected to the rod and to the adjustable contact. With a vacuum drawn inside the body, a neutron bombardment striking the rod causes it to heat and expand longitudinally until it comes into contact with the adjustable contact. This circuit closing occurs within a period of a few microseconds.

  16. Enhanced NIF neutron activation diagnostics

    SciTech Connect

    Yeamans, C. B.; Bleuel, D. L.; Bernstein, L. A.

    2012-10-15

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the {sup 89}Zr/{sup 89m}Zr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  17. Enhanced NIF neutron activation diagnostics.

    PubMed

    Yeamans, C B; Bleuel, D L; Bernstein, L A

    2012-10-01

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the (89)Zr/(89 m)Zr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  18. Enhanced NIF neutron activation diagnosticsa)

    NASA Astrophysics Data System (ADS)

    Yeamans, C. B.; Bleuel, D. L.; Bernstein, L. A.

    2012-10-01

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the 89Zr/89mZr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  19. Analysis of initial in-plant active neutron multiplicity measurements

    SciTech Connect

    Ensslin, N.; Krick, M.S.; Harker, W.C.

    1993-08-01

    This paper analyzes initial in-plant measurements made by active neutron multiplicity counting, a new technique currently under development for the assay of bulk uranium containing kilograms of {sup 235}U. The measurements were made at Savannah River and Y-12 using active well coincidence counters and prototype multiplicity electronics and software from Los Alamos. For one of the sets of highly enriched uranium samples measured to data, we improved the assay accuracy by an order-of-magnitude by adding the multiplicity analysis to the conventional coincidence analysis. This paper summarizes our results and describes areas where further work is needed.

  20. Attributes from NMIS Time Coincidence, Fast-Neutron Imaging, Fission Mapping, And Gamma-Ray Spectrometry Data

    SciTech Connect

    Swift, Alicia L; Grogan, Brandon R; Mullens, James Allen; Hayward, J P; Mihalczo, John T

    2012-01-01

    This work tests a systematic procedure for analyzing data acquired by the Nuclear Materials Identification System (NMIS) at Oak Ridge National Laboratory with fast-neutron imaging and high-purity germanium (HPGe) gamma spectrometry capabilities. NMIS has been under development by the US Department of Energy Office of Nuclear Verification since the mid-1990s, and prior to that by the National Nuclear Security Administration Y-12 National Security Complex, with NMIS having been used at Y-12 for template matching to confirm inventory and receipts. In this present work, a complete set of NMIS time coincidence, fast-neutron imaging, fission mapping, and HPGe gamma-ray spectrometry data was obtained from Monte Carlo simulations for a configuration of fissile and nonfissile materials. The data were then presented for analysis to someone who had no prior knowledge of the unknown object to accurately determine the description of the object by applying the previously-mentioned procedure to the simulated data. The best approximation indicated that the unknown object was composed of concentric cylinders: a void inside highly enriched uranium (HEU) (84.7 {+-} 1.9 wt % {sup 235}U), surrounded by depleted uranium, surrounded by polyethylene. The final estimation of the unknown object had the correct materials and geometry, with error in the radius estimates of material regions varying from 1.58% at best and 4.25% at worst; error in the height estimates varied from 2% to 12%. The error in the HEU enrichment estimate was 5.9 wt % (within 2.5{sigma} of the true value). The accuracies of the determinations could be adequate for arms control applications. Future work will apply this iterative reconstructive procedure to other unknown objects to further test and refine it.

  1. Neutron Coincidence Counting Studies

    SciTech Connect

    Rogers, Jeremy L.; Ely, James H.; Kouzes, Richard T.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-08-31

    The efficiency comparison for measured and simulated responses of a 10B-lined proportional counter and a 3He proportional counter in a close, symmetrical geometry are presented. The measurement geometry was modeled in MCNPX to validate the methods used for simulating the response of both the 3He and 10B-lined tubes. The MCNPX models agree within 1% with the 3He tube measurements and within 3% for the 10B-lined tubes when a 0.75-µm boron-metal lining is used.

  2. Neutron Activation Analysis of Water - A Review

    NASA Technical Reports Server (NTRS)

    Buchanan, John D.

    1971-01-01

    Recent developments in this field are emphasized. After a brief review of basic principles, topics discussed include sources of neutrons, pre-irradiation physical and chemical treatment of samples, neutron capture and gamma-ray analysis, and selected applications. Applications of neutron activation analysis of water have increased rapidly within the last few years and may be expected to increase in the future.

  3. Active dendrites mediate stratified gamma-range coincidence detection in hippocampal model neurons

    PubMed Central

    Das, Anindita; Narayanan, Rishikesh

    2015-01-01

    Hippocampal pyramidal neurons exhibit gamma-phase preference in their spikes, selectively route inputs through gamma frequency multiplexing and are considered part of gamma-bound cell assemblies. How do these neurons exhibit gamma-frequency coincidence detection capabilities, a feature that is essential for the expression of these physiological observations, despite their slow membrane time constant? In this conductance-based modelling study, we developed quantitative metrics for the temporal window of integration/coincidence detection based on the spike-triggered average (STA) of the neuronal compartment. We employed these metrics in conjunction with quantitative measures for spike initiation dynamics to assess the emergence and dependence of coincidence detection and STA spectral selectivity on various ion channel combinations. We found that the presence of resonating conductances (hyperpolarization-activated cyclic nucleotide-gated or T-type calcium), either independently or synergistically when expressed together, led to the emergence of spectral selectivity in the spike initiation dynamics and a significant reduction in the coincidence detection window (CDW). The presence of A-type potassium channels, along with resonating conductances, reduced the STA characteristic frequency and broadened the CDW, but persistent sodium channels sharpened the CDW by strengthening the spectral selectivity in the STA. Finally, in a morphologically precise model endowed with experimentally constrained channel gradients, we found that somatodendritic compartments expressed functional maps of strong theta-frequency selectivity in spike initiation dynamics and gamma-range CDW. Our results reveal the heavy expression of resonating and spike-generating conductances as the mechanism underlying the robust emergence of stratified gamma-range coincidence detection in the dendrites of hippocampal and cortical pyramidal neurons. PMID:26018187

  4. The Feynman-Y Statistic in Relation to Shift-Register Neutron Coincidence Counting: Precision and Dead Time

    SciTech Connect

    Croft, Stephen; Santi, Peter A.; Henzlova, Daniela; Hauck, Danielle K.; Favalli, Andrea

    2012-07-13

    The Feynman-Y statistic is a type of autocorrelation analysis. It is defined as the excess variance-to-mean ratio, Y = VMR - 1, of the number count distribution formed by sampling a pulse train using a series of non-overlapping gates. It is a measure of the degree of correlation present on the pulse train with Y = 0 for Poisson data. In the context of neutron coincidence counting we show that the same information can be obtained from the accidentals histogram acquired using the multiplicity shift-register method, which is currently the common autocorrelation technique applied in nuclear safeguards. In the case of multiplicity shift register analysis however, overlapping gates, either triggered by the incoming pulse stream or by a periodic clock, are used. The overlap introduces additional covariance but does not alter the expectation values. In this paper we discuss, for a particular data set, the relative merit of the Feynman and shift-register methods in terms of both precision and dead time correction. Traditionally the Feynman approach is applied with a relatively long gate width compared to the dieaway time. The main reason for this is so that the gate utilization factor can be taken as unity rather than being treated as a system parameter to be determined at characterization/calibration. But because the random trigger interval gate utilization factor is slow to saturate this procedure requires a gate width many times the effective 1/e dieaway time. In the traditional approach this limits the number of gates that can be fitted into a given assay duration. We empirically show that much shorter gates, similar in width to those used in traditional shift register analysis can be used. Because the way in which the correlated information present on the pulse train is extracted is different for the moments based method of Feynman and the various shift register based approaches, the dead time losses are manifested differently for these two approaches. The resulting

  5. Development of a method for activity measurements of 232Th daughters with a multidetector gamma-ray coincidence spectrometer.

    PubMed

    Antovic, N; Svrkota, N

    2009-06-01

    The method for activity measurements of the (232)Th daughters, developed at the six-crystal gamma-ray coincidence spectrometer PRIPYAT-2M and based on coincidence counting of the 583 and 2615 keV photons from cascade transitions which follow beta(-)-decay of (208)Tl, as well as on counting the 911 keV photons which follow beta(-)-decay of (228)Ac in the integral and non-coincidence mode of counting, is presented.

  6. Development of a method for activity measurements of 232Th daughters with a multidetector gamma-ray coincidence spectrometer.

    PubMed

    Antovic, N; Svrkota, N

    2009-06-01

    The method for activity measurements of the (232)Th daughters, developed at the six-crystal gamma-ray coincidence spectrometer PRIPYAT-2M and based on coincidence counting of the 583 and 2615 keV photons from cascade transitions which follow beta(-)-decay of (208)Tl, as well as on counting the 911 keV photons which follow beta(-)-decay of (228)Ac in the integral and non-coincidence mode of counting, is presented. PMID:19299155

  7. Computer-automated neutron activation analysis system

    SciTech Connect

    Minor, M.M.; Garcia, S.R.

    1983-01-01

    An automated delayed neutron counting and instrumental neutron activation analysis system has been developed at Los Alamos National Laboratory's Omega West Reactor (OWR) to analyze samples for uranium and 31 additional elements with a maximum throughput of 400 samples per day. 5 references.

  8. Effects of Calcium Spikes in the Layer 5 Pyramidal Neuron on Coincidence Detection and Activity Propagation.

    PubMed

    Chua, Yansong; Morrison, Abigail

    2016-01-01

    The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon, in which action potentials triggered by stimuli near the soma above a certain frequency trigger a calcium spike at distal dendrites, leading to further somatic depolarization, is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network (FFN) embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be

  9. Effects of Calcium Spikes in the Layer 5 Pyramidal Neuron on Coincidence Detection and Activity Propagation

    PubMed Central

    Chua, Yansong; Morrison, Abigail

    2016-01-01

    The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon, in which action potentials triggered by stimuli near the soma above a certain frequency trigger a calcium spike at distal dendrites, leading to further somatic depolarization, is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network (FFN) embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be

  10. Neutron activation analysis of a penny

    NASA Astrophysics Data System (ADS)

    Stevens, Richard E.

    2000-04-01

    Neutron activation analysis has been used for many years as an analysis tool and as an educational tool to teach students about nuclear properties. This article presents an exercise in the neutron activation analysis of a penny which, due to the simplicity of the resulting gamma-ray spectra, is appropriate for general physics classes. Students express a great deal of interest both in seeing the reactor in use as well as determining the composition of something that is familiar to them.

  11. Neutron counter based on beryllium activation

    SciTech Connect

    Bienkowska, B.; Prokopowicz, R.; Kaczmarczyk, J.; Paducha, M.; Scholz, M.; Igielski, A.; Karpinski, L.; Pytel, K.

    2014-08-21

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

  12. Neutron counter based on beryllium activation

    NASA Astrophysics Data System (ADS)

    Bienkowska, B.; Prokopowicz, R.; Scholz, M.; Kaczmarczyk, J.; Igielski, A.; Karpinski, L.; Paducha, M.; Pytel, K.

    2014-08-01

    The fusion reaction occurring in DD plasma is followed by emission of 2.45 MeV neutrons, which carry out information about fusion reaction rate and plasma parameters and properties as well. Neutron activation of beryllium has been chosen for detection of DD fusion neutrons. The cross-section for reaction 9Be(n, α)6He has a useful threshold near 1 MeV, which means that undesirable multiple-scattered neutrons do not undergo that reaction and therefore are not recorded. The product of the reaction, 6He, decays with half-life T1/2 = 0.807 s emitting β- particles which are easy to detect. Large area gas sealed proportional detector has been chosen as a counter of β-particles leaving activated beryllium plate. The plate with optimized dimensions adjoins the proportional counter entrance window. Such set-up is also equipped with appropriate electronic components and forms beryllium neutron activation counter. The neutron flux density on beryllium plate can be determined from the number of counts. The proper calibration procedure needs to be performed, therefore, to establish such relation. The measurements with the use of known β-source have been done. In order to determine the detector response function such experiment have been modeled by means of MCNP5-the Monte Carlo transport code. It allowed proper application of the results of transport calculations of β- particles emitted from radioactive 6He and reaching proportional detector active volume. In order to test the counter system and measuring procedure a number of experiments have been performed on PF devices. The experimental conditions have been simulated by means of MCNP5. The correctness of simulation outcome have been proved by measurements with known radioactive neutron source. The results of the DD fusion neutron measurements have been compared with other neutron diagnostics.

  13. Evaluation of Am-Li neutron spectra data for active well type neutron multiplicity measurements of uranium

    NASA Astrophysics Data System (ADS)

    Goddard, Braden; Croft, Stephen; Lousteau, Angela; Peerani, Paolo

    2016-09-01

    Safeguarding nuclear material is an important and challenging task for the international community. One particular safeguards technique commonly used for uranium assay is active neutron correlation counting. This technique involves irradiating unused uranium with (α, n) neutrons from an Am-Li source and recording the resultant neutron pulse signal which includes induced fission neutrons. Although this non-destructive technique is widely employed in safeguards applications, the neutron energy spectra from an Am-Li sources is not well known. Several measurements over the past few decades have been made to characterize this spectrum; however, little work has been done comparing the measured and theoretical spectra of various Am-Li sources to each other. This paper examines fourteen different Am-Li spectra, focusing on how these spectra affect simulated neutron multiplicity results using the code Monte Carlo N-Particle eXtended (MCNPX). Two measurement and simulation campaigns were completed using Active Well Coincidence Counter (AWCC) detectors and uranium standards of varying enrichment. The results of this work indicate that for standard AWCC measurements, the fourteen Am-Li spectra produce similar doubles and triples count rates. The singles count rates varied by as much as 20% between the different spectra, although they are usually not used in quantitative analysis, being dominated by scattering which is highly dependent on item placement.

  14. Evaluation of Am–Li neutron spectra data for active well type neutron multiplicity measurements of uranium

    DOE PAGES

    Goddard, Braden; Croft, Stephen; Lousteau, Angela; Peerani, Paolo

    2016-05-25

    Safeguarding nuclear material is an important and challenging task for the international community. One particular safeguards technique commonly used for uranium assay is active neutron correlation counting. This technique involves irradiating unused uranium with ( α,n) neutrons from an Am-Li source and recording the resultant neutron pulse signal which includes induced fission neutrons. Although this non-destructive technique is widely employed in safeguards applications, the neutron energy spectra from an Am-Li sources is not well known. Several measurements over the past few decades have been made to characterize this spectrum; however, little work has been done comparing the measured spectra ofmore » various Am-Li sources to each other. This paper examines fourteen different Am-Li spectra, focusing on how these spectra affect simulated neutron multiplicity results using the code Monte Carlo N-Particle eXtended (MCNPX). Two measurement and simulation campaigns were completed using Active Well Coincidence Counter (AWCC) detectors and uranium standards of varying enrichment. The results of this work indicate that for standard AWCC measurements, the fourteen Am-Li spectra produce similar doubles and triples count rates. Finally, the singles count rates varied by as much as 20% between the different spectra, although they are usually not used in quantitative analysis.« less

  15. Coincidence/Multiplicity Photofission Measurements

    SciTech Connect

    J.L. Jones; M.T. Swinhoe; S.J. Tobin; W. H. Geist; D.R. Norman; R.B. Rothrock; C.R. Freeman; K. J. Haskell

    2009-09-01

    An series of experiments using the Idaho National Laboratory (INL) photonuclear inspection system and a Los Alamos National Laboratory (LANL)-supplied, list-mode data acquisition method have shown enhanced performance utilizing pulsed photofission-induced, neutron coincidence counting between pulses of an up-to-10-MeV electron accelerator for nuclear material detection and identification. The enhanced inspection methodology has applicability to homeland security, treaty-related support, and weapon dismantlement applications. For the latter, this technology can directly support of Department of Energy/NA241 programmatic mission objectives relative to future Rocky Ridge-type testing campaigns for active inspection systems.

  16. Neutron and proton activation measurements from Skylab

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1974-01-01

    Radioactivity induced by high-energy protons and secondary neutrons (from nuclear interactions) in various samples returned from different locations in Skylab was measured directly by gamma-ray spectroscopy measurements of decay gamma rays from the samples. Incident fluxes were derived from the activation measurements, using known nuclear cross-section. Neutron and proton flux values were found to range from 0.2 to 5 particles/sq cm-sec, depending on the energy range and location in Skylab. The thermal neutron flux was less than 0.07 neutrons/sq cm-sec. The results are useful for data analysis and planning of future high-energy astronomy experiments.

  17. Application of active and passive neutron non destructive assay methods to concrete radioactive waste drums

    NASA Astrophysics Data System (ADS)

    Jallu, F.; Passard, C.; Brackx, E.

    2011-09-01

    This paper deals with the application of non-destructive neutron measurement methods to control and characterize 200 l radioactive waste drums filled with a concrete matrix. Due to its composition, and particularly to hydrogen, concrete penalizes the use of such methods to quantify uranium (U) and plutonium (Pu) components, which are mainly responsible of the α-activity of the waste. The determination of the alpha activity is the main objective of neutron measurements, in view to verify acceptance criteria in surface storage. Calibration experiments of the Active Neutron Interrogation (ANI) method lead to Detection Limit Masses (DLM) of about 1 mg of 239Pu eff in the total counting mode, and of about 10 mg of 239Pu eff in the coincidence counting mode, in case of a homogeneous Pu source and measurement times between one and two hours. Monte Carlo calculation results show a very satisfactory agreement between experimental values and calculated ones. Results of the application of passive and active neutron methods to control two real drums are presented in the last part of the paper. They show a good agreement between measured data and values declared by the waste producers. The main difficulties that had to be overcome are the low neutron signal in passive and active coincidence counting modes due to concrete, the analysis of the passive neutron signal in presence of 244Cm in the drum, which is a strong spontaneous fission neutron emitter, the variation of the active background with the concrete composition, and the analysis of the active prompt neutron signal due to the simultaneous presence of U and Pu in the drums.

  18. First satellite measurements of chemical changes in coincidence with sprite activity

    NASA Astrophysics Data System (ADS)

    Arnone, Enrico; São Sabbas, Fernanda; Kero, Antti; Soula, Serge; Carlotti, Massimo; Chanrion, Olivier; Dinelli, Bianca Maria; Papandrea, Enzo; Castelli, Elisa; Neubert, Torsten

    2010-05-01

    The last twenty years have seen the discovery of electric discharges in the Earth's atmosphere above thunderstorms, the so-called sprites and jets. It has been suggested that they impact the atmospheric chemistry and possibly affect the ozone layer through their repeated occurrence. Whereas theoretical studies and laboratory experiments suggest enhancement of such gasses as nitrogen oxides by up to hundreds of percent within sprites, a definitive detection of their chemical effects have to date been unsuccessful. In this paper, we report on the first measurements of atmospheric chemical perturbations recorded in coincidence with sprite activity. A striking event occurred on 25 August 2003 when the MIPAS spectrometer onboard the Envisat satellite recorded spectroscopic measurements soon after a sequence of 11 sprites observed above Corsica (France) by Eurosprite ground facilities (details of the convective system are discussed in a companion paper by São Sabbas et al.). The measurements show an enhancement of ambient nitrous oxide by 80% at 52 km altitude in the region above the parent thunderstorm. The recorded chemical changes imply sprites can exert significant modification of the atmospheric chemistry at a regional scale, confirming model and laboratory predictions of sprite-chemistry, and requiring a new estimate of their global impact. The results of the analysis and their implications are discussed.

  19. Miniature Neutron-Alpha Activation Spectrometer

    NASA Astrophysics Data System (ADS)

    Rhodes, Edgar; Holloway, James Paul; He, Zhong; Goldsten, John

    2002-10-01

    We are developing a miniature neutron-alpha activation spectrometer for in-situ analysis of chem-bio samples, including rocks, fines, ices, and drill cores, suitable for a lander or Rover platform for Mars or outer-planet missions. In the neutron-activation mode, penetrating analysis will be performed of the whole sample using a γ spectrometer and in the α-activation mode, the sample surface will be analyzed using Rutherford-backscatter and x-ray spectrometers. Novel in our approach is the development of a switchable radioactive neutron source and a small high-resolution γ detector. The detectors and electronics will benefit from remote unattended operation capabilities resulting from our NEAR XGRS heritage and recent development of a Ge γ detector for MESSENGER. Much of the technology used in this instrument can be adapted to portable or unattended terrestrial applications for detection of explosives, chemical toxins, nuclear weapons, and contraband.

  20. Nondestructive examination using neutron activated positron annihilation

    DOEpatents

    Akers, Douglas W.; Denison, Arthur B.

    2001-01-01

    A method is provided for performing nondestructive examination of a metal specimen using neutron activated positron annihilation wherein the positron emitter source is formed within the metal specimen. The method permits in situ nondestructive examination and has the advantage of being capable of performing bulk analysis to determine embrittlement, fatigue and dislocation within a metal specimen.

  1. Neutron Yield Measurements via Aluminum Activation

    SciTech Connect

    1999-12-08

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

  2. Neutron Fluence Monitoring by Foil Activation at the NBSR

    SciTech Connect

    Richard M. Lindstrom

    2000-11-12

    In a reactor facility such as the National Institute of Standards and Technology Center for Neutron Research, it is occasionally necessary to measure the intensity and characteristics of neutron fields, inside and outside the reactor vessel. Design of thermal- and cold-neutron beam guides and filters, neutron activation analysis, and health physics calibrations are the most common needs. To meet these requirements, routine procedures have been developed for efficient and transparent measurements of slow neutrons.

  3. A neutron activation spectrometer and neutronic experimental platform for the National Ignition Facility (invited)

    NASA Astrophysics Data System (ADS)

    Yeamans, C. B.; Gharibyan, N.

    2016-11-01

    At the National Ignition Facility, the diagnostic instrument manipulator-based neutron activation spectrometer is used as a diagnostic of implosion performance for inertial confinement fusion experiments. Additionally, it serves as a platform for independent neutronic experiments and may be connected to fast recording systems for neutron effect tests on active electronics. As an implosion diagnostic, the neutron activation spectrometers are used to quantify fluence of primary DT neutrons, downscattered neutrons, and neutrons above the primary DT neutron energy created by reactions of upscattered D and T in flight. At a primary neutron yield of 1015 and a downscattered fraction of neutrons in the 10-12 MeV energy range of 0.04, the downscattered neutron fraction can be measured to a relative uncertainty of 8%. Significant asymmetries in downscattered neutrons have been observed. Spectrometers have been designed and fielded to measure the tritium-tritium and deuterium-tritium neutron outputs simultaneously in experiments using DT/TT fusion ratio as a direct measure of mix of ablator into the gas.

  4. Physical basis for prompt-neutron activation analysis

    SciTech Connect

    Chrien, R.E.

    1982-01-01

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

  5. Neutron Unfolding Code System for Calculating Neutron Flux Spectra from Activation Data of Dosimeter Foils.

    1982-04-30

    Version 00 As a part of the measurement and analysis plan for the Dosimetry Experiment at the "JOYO" experimental fast reactor, neutron flux spectral analysis is performed using the NEUPAC (Neutron Unfolding Code Package) code system. NEUPAC calculates the neutron flux spectra and other integral quantities from the activation data of the dosimeter foils.

  6. Activity determination of a 201Tl solution by 4πβ-γ and sum-peak coincidence methods

    NASA Astrophysics Data System (ADS)

    Ruzzarin, A.; da Silva, M. A. L.; Iwahara, A.; da Silva, R. L.; Filho, O. L. T.; Poledna, R.; Lopes, R. T.

    2016-07-01

    201Tl is used in nuclear medicine in cardiac imaging for evaluating the injury level in cardiac muscle at rest and exercise. In this work the activity concentration of a 201 Tl radioactive solution has been absolutely determined using the 4πβ-γ coincidence and sum-peak coincidence methods. The presence of 202Tl radioactive impurity that imposes some difficult in the activity measurements was taken into account in the measurements. In the sum-peak method a planar germanium detector was used. The half-lives were evaluated by the reference source method and the results obtained were (3.033 ± 0.004) d and (12.320 ± 0.163) d, respectively, for 201Tl and 202Tl.

  7. Active Neutron Shielding R&D for Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Henderson, Shawn; Monroe, Jocelyn; Fisher, Peter; Dmtpc Collaboration

    2011-04-01

    Neutrons are a dangerous background to direct dark matter detection searches because they can mimic exactly the signal signature. For this reason, it is desirable to measure the neutron flux directly at underground sites where dark matter experiments are active. We have developed a liquid scintillator-based neutron detector for this purpose, which is currently underground and taking data at the Waste Isolation Pilot Plant (WIPP) in NM. Before being commissioned underground, the response of this detector to neutrons with kinetic energies from 50 MeV to 800 MeV was determined in a beam test at the Los Alamos Neutron Science Center (LANSCE) in NM. The goal of this R&D is to (i) demonstrate the feasibility of a large scale active and passive neutron shield for dark matter searches and (ii) to measure the neutron energy spectrum underground at WIPP above 50 MeV neutron kinetic energies.

  8. Differential involvement of excitatory and inhibitory neurons of cat motor cortex in coincident spike activity related to behavioral context.

    PubMed

    Putrino, David; Brown, Emery N; Mastaglia, Frank L; Ghosh, Soumya

    2010-06-01

    To assess temporal associations in spike activity between pairs of neurons in the primary motor cortex (MI) related to different behaviors, we compared the incidence of coincident spiking activity of task-related (TR) and non-task-related (NTR) neurons during a skilled motor task and sitting quietly in adult cats (Felis domestica). Chronically implanted microwires were used to record spike activity of MI neurons in four animals (two male and two female) trained to perform a skilled reaching task or sit quietly. Neurons were identified as TR if spike activity was modulated during the task (and NTR if not). Based on spike characteristics, they were also classified as either regular-spiking (RS, putatively excitatory) or fast-spiking (FS, putatively inhibitory) neurons. Temporal associations in the activities of simultaneously recorded neurons were evaluated using shuffle-corrected cross-correlograms. Pairs of NTR and TR neurons showed associations in their firing patterns over wide areas of MI (representing forelimb and hindlimb movements) during quiet sitting, more commonly involving RS neurons. During skilled task performance, however, significantly coincident firing was seen almost exclusively between TR neurons in a smaller part of MI (representing forelimb movements), involving mainly FS neurons. The findings of this study show evidence for widespread interactions in MI when the animal sits quietly, which changes to a more specific and restricted pattern of interactions during task performance. Different populations of excitatory and inhibitory neurons appear to be synchronized during skilled movement and quiet sitting.

  9. Total body nitrogen analysis. [neutron activation analysis

    NASA Technical Reports Server (NTRS)

    Palmer, H. E.

    1975-01-01

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

  10. Neutron activation analysis of Etruscan pottery

    SciTech Connect

    Whitehead, J.; Silverman, A.; Ouellet, C.G.; Clark, D.D.; Hossain, T.Z

    1992-07-01

    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)

  11. Photon and neutron active interrogation of highly enriched uranium.

    SciTech Connect

    Myers, W. L.; Goulding, C. A.; Hollas, C. L.; Moss, C. E.

    2004-01-01

    The physics of photon and neutron active interrogation of highly enriched uranium (HEU) using the delayed neutron reinterrogation method is described in this paper. Two sets of active interrogation experiments were performed using a set of subcritical configurations of cocentric HEU metal hemishells. One set of measurements utilized a pulsed 14-MeV neutron generator as the active source. The second set of measurements utilized a linear accelerator-based bremsstrahlung photon source as an active interrogation source. The neutron responses were measured for both sets of experiments. The operational details and results for both measurement sets are described.

  12. ACTIV87: Fast Neutron Activation Cross Section File

    1993-08-01

    4. HISTORICAL BACKGROUND AND INFORMATION ACTIV87 is a compilation of fast neutron induced activation reaction cross-sections. The compilation covers energies from threshold to 20 MeV and is based on evaluated data taken from other evaluated data libraries and individual evaluations. The majority of these evaluations were performed by using available experimental data. The aforementioned available experimental data were used in the selection of needed parameters for theoretical computations and for normalizing the results of suchmore » computations. Theoretical calculations were also used for interpolation and extrapolation of experimental cross-section data. All of the evaluated data curves were compared with experimental data that had been reported over the four year period preceding 1987. Only those cross-sections not in contradiction with experimental data that was current in 1987 were retained in the activation file, ACTIV87. In cases of several conflicting evaluations, that evaluation was chosen which best corresponded to the experimental data. A few evaluated curves were renormalized in accordance with the results of the latest precision measurements. 5. APPLICATION OF THE DATA 6. SOURCE AND SCOPE OF DATA The following libraries and individual files of evaluated neutron cross-section data were used for the selection of the activation cross-sections: the BOSPOR Library, the Activation File of the Evaluated Nuclear Data Library, the Evaluated Neutron Data File (ENDF/B-V) Activation File, the International Reactor Dosimetry File (IRDF-82), and individual evaluations carried out under various IAEA research contracts. The file of selected reactions contains 206 evaluated cross-section curves of the (n,2n), (n,p) and (n,a) reactions which lead to radioactive products and may be used in many practical applications of neutron activation analysis. Some competing activation reactions, usually with low cross-section values, are given for completeness.« less

  13. Neutron activation analysis in archaeological chemistry

    SciTech Connect

    Harbottle, G.

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  15. Utilization of the intense pulsed neutron source (IPNS) at Argonne National Laboratory for neutron activation analysis

    SciTech Connect

    Heinrich, R.R.; Greenwood, L.R.; Popek, R.J.; Schulke, A.W. Jr.

    1983-01-01

    The Intense Pulsed Neutron Source (IPNS) neutron scattering facility (NSF) has been investigated for its applicability to neutron activation analysis. A polyethylene insert has been added to the vertical hole VT3 which enhances the thermal neutron flux by a factor of two. The neutron spectral distribution at this position has been measured by the multiple-foil technique which utilized 28 activation reactions and the STAYSL computer code. The validity of this spectral measurement was tested by two irradiations of National Bureau of Standards SRM-1571 (orchard leaves), SRM-1575 (pine needles), and SRM-1645 (river sediment). The average thermal neutron flux for these irradiations normalized to 10 ..mu..amp proton beam is 4.0 x 10/sup 11/ n/cm/sup 2/-s. Concentrations of nine trace elements in each of these SRMs have been determined by gamma-ray spectrometry. Agreement of measured values to certified values is demonstrated to be within experiment error.

  16. NEUTRON MULTIPLICITY AND ACTIVE WELL NEUTRON COINCIDENCE VERIFICATION MEASUREMENTS PERFORMED FOR MARCH 2009 SEMI-ANNUAL DOE INVENTORY

    SciTech Connect

    Dewberry, R.; Ayers, J.; Tietze, F.; Klapper, K.

    2010-02-05

    The Analytical Development (AD) Section field nuclear measurement group performed six 'best available technique' verification measurements to satisfy a DOE requirement instituted for the March 2009 semi-annual inventory. The requirement of (1) yielded the need for SRNL Research Operations Department Material Control & Accountability (MC&A) group to measure the Pu content of five items and the highly enrich uranium (HEU) content of two. No 14Q-qualified measurement equipment was available to satisfy the requirement. The AD field nuclear group has routinely performed the required Confirmatory Measurements for the semi-annual inventories for fifteen years using sodium iodide and high purity germanium (HpGe) {gamma}-ray pulse height analysis nondestructive assay (NDA) instruments. With appropriate {gamma}-ray acquisition modeling, the HpGe spectrometers can be used to perform verification-type quantitative assay for Pu-isotopics and HEU content. The AD nuclear NDA group is widely experienced with this type of measurement and reports content for these species in requested process control, MC&A booking, and holdup measurements assays Site-wide. However none of the AD HpGe {gamma}-ray spectrometers have been 14Q-qualified, and the requirement of reference 1 specifically excluded a {gamma}-ray PHA measurement from those it would accept for the required verification measurements. The requirement of reference 1 was a new requirement for which the Savannah River National Laboratory (SRNL) Research Operations Department (ROD) MC&A group was unprepared. The criteria for exemption from verification were: (1) isotope content below 50 grams; (2) intrinsically tamper indicating or TID sealed items which contain a Category IV quantity of material; (3) assembled components; and (4) laboratory samples. Therefore all (SRNL) Material Balance Area (MBA) items with greater than 50 grams total Pu or greater than 50 grams HEU were subject to a verification measurement. The pass/fail criteria of reference 7 stated 'The facility will report measured values, book values, and statistical control limits for the selected items to DOE SR...', and 'The site/facility operator must develop, document, and maintain measurement methods for all nuclear material on inventory'. These new requirements exceeded SRNL's experience with prior semi-annual inventory expectations, but allowed the AD nuclear field measurement group to demonstrate its excellent adaptability and superior flexibility to respond to unpredicted expectations from the DOE customer. The requirements yielded five SRNL items subject to Pu verification and two SRNL items subject to HEU verification. These items are listed and described in Table 1.

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

    SciTech Connect

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

    1996-09-01

    Previous work on active neutron multiplicity measurements and analyses is summarized. New active multiplicity measurements are described for samples of Y-12 skull oxide using an Active Well Coincidence Counter and MSR4 multiplicity electronics. Neutron multiplication values for the samples were determined from triples/doubles ratios. Neutron multiplication values were also obtained from Monte Carlo calculations using the MCNP code and the results compared with the experimental values. A calibration curve of AmLi source-sample coupling vs neutron multiplication was determined and used for active multiplicity assay of the skull oxides. The results are compared with those obtained from assay with the conventional calibration-curve technique, where the doubles rate is calibrated vs the {sup 235}U mass. The coupling-multiplication relationship determined for the skull oxides is compared with that determined earlier for pure high-enrichment uranium metal and pure uranium oxide. Conclusions are drawn about the application of active multiplicity techniques to uranium assay. Additional active multiplicity measurements and calculations are recommended.

  18. Neutron activation of NIF Final Optics Assemblies

    NASA Astrophysics Data System (ADS)

    Sitaraman, S.; Dauffy, L.; Khater, H.; Brereton, S.

    2010-08-01

    Analyses were performed to characterize the radiation field in the vicinity of the Final Optics Assemblies (FOAs) at the National Ignition Facility (NIF) due to neutron activation following Deuterium-Deuterium (DD), Tritium-Hydrogen-Deuterium (THD), and Deuterium-Tritium (DT) shots associated with different phases of the NIF operations. The activation of the structural components of the FOAs produces one of the larger sources of gamma radiation and is a key factor in determining the stay out time between shots to ensure worker protection. This study provides estimates of effective dose rates in the vicinity of a single FOA and concludes that the DD and THD targets produce acceptable dose rates within10 minutes following a shot while about 6-days of stay out time is suggested following DT shots. Studies are ongoing to determine the combined effects of multiple FOAs and other components present in the Target Bay on stay-out time and worker dose.

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

    SciTech Connect

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

    2013-11-06

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

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

    USGS Publications Warehouse

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

    1966-01-01

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

  1. Homocysteine-induced apoptosis in endothelial cells coincides with nuclear NOX2 and peri-nuclear NOX4 activity.

    PubMed

    Sipkens, Jessica A; Hahn, Nynke; van den Brand, Carlien S; Meischl, Christof; Cillessen, Saskia A G M; Smith, Desirée E C; Juffermans, Lynda J M; Musters, René J P; Roos, Dirk; Jakobs, Cornelis; Blom, Henk J; Smulders, Yvo M; Krijnen, Paul A J; Stehouwer, Coen D A; Rauwerda, Jan A; van Hinsbergh, Victor W M; Niessen, Hans W M

    2013-11-01

    Apoptosis of endothelial cells related to homocysteine (Hcy) has been reported in several studies. In this study, we evaluated whether reactive oxygen species (ROS)-producing signaling pathways contribute to Hcy-induced apoptosis induction, with specific emphasis on NADPH oxidases. Human umbilical vein endothelial cells were incubated with 0.01-2.5 mM Hcy. We determined the effect of Hcy on caspase-3 activity, annexin V positivity, intracellular NOX1, NOX2, NOX4, and p47(phox) expression and localization, nuclear nitrotyrosine accumulation, and mitochondrial membrane potential (ΔΨ m). Hcy induced caspase-3 activity and apoptosis; this effect was concentration dependent and maximal after 6-h exposure to 2.5 mM Hcy. It was accompanied by a significant increase in ΔΨ m. Cysteine was inactive on these parameters excluding a reactive thiol group effect. Hcy induced an increase in cellular NOX2, p47(phox), and NOX4, but not that of NOX1. 3D digital imaging microscopy followed by image deconvolution analysis showed nuclear accumulation of NOX2 and p47(phox) in endothelial cells exposed to Hcy, but not in control cells, which coincided with accumulation of nuclear nitrotyrosine residues. Furthermore, Hcy enhanced peri-nuclear localization of NOX4 coinciding with accumulation of peri-nuclear nitrotyrosine residues, a reflection of local ROS production. p47(phox) was also increased in the peri-nuclear region. The Hcy-induced increase in caspase-3 activity was prevented by DPI and apocynin, suggesting involvement of NOX activity. The data presented in this article reveal accumulation of nuclear NOX2 and peri-nuclear NOX4 accumulation as potential source of ROS production in Hcy-induced apoptosis in endothelial cells.

  2. Experimental neutronics tests for a neutron activation system for the European ITER TBM

    SciTech Connect

    Klix, A.; Fischer, U.; Gehre, D.; Kleizer, G.; Raj, P.; Rovni, I.; Ruecker, Tom

    2014-08-21

    We are investigating methods for neutron flux measurement in the ITER TBM. In particular we have tested sets of activation materials leading to induced gamma activities with short half-lives of the order of tens of seconds up to minutes and standard activation materials. Packages of activation foils have been irradiated with the intense neutron generator of Technical University of Dresden in a pure DT neutron field as well as in a neutronics mock-up of the European ITER HCLL TBM. An important aim was to check whether the gamma activity induced in the activation foils in these packages could be measured simultaneously. It was indeed possible to identify gamma lines of interest in gamma-ray measurements immediately after extraction from the irradiation.

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

    SciTech Connect

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

    2012-10-15

    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 {sup 115}In(n,n'){sup 115m} In reaction. Outside the chamber, zirconium and copper are used to measure 14 MeV deuterium-tritium fusion neutrons via {sup 90}Zr(n,2n), {sup 63}Cu(n,2n), and {sup 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.

  4. Development of attenuated baroreflexes in obese Zucker rats coincides with impaired activation of nucleus tractus solitarius

    PubMed Central

    Guimaraes, Priscila S.; Huber, Domitila A.; Campagnole-Santos, Maria J.

    2014-01-01

    Adult obese Zucker rats (OZR; >12 wk) develop elevated sympathetic nerve activity (SNA) and mean arterial pressure (MAP) with impaired baroreflexes compared with adult lean Zucker rats (LZR) and juvenile OZR (6–7 wk). In adult OZR, baroreceptor afferent nerves respond normally to changes in MAP, whereas electrical stimulation of baroreceptor afferent fibers produces smaller reductions in SNA and MAP compared with LZR. We hypothesized that impaired baroreflexes in OZR are linked to reduced activation of brain stem sites that mediate baroreflexes. In conscious adult rats, a hydralazine (HDZ)-induced reduction in MAP evoked tachycardia that was initially blunted in OZR, but equivalent to LZR within 5 min. In agreement, HDZ-induced expression of c-Fos in the rostral ventrolateral medulla (RVLM) was comparable between groups. In contrast, phenylephrine (PE)-induced rise in MAP evoked markedly attenuated bradycardia with dramatically reduced c-Fos expression in the nucleus tractus solitarius (NTS) of adult OZR compared with LZR. However, in juvenile rats, PE-induced hypertension evoked comparable bradycardia in OZR and LZR with similar or augmented c-Fos expression in NTS of the OZR. In urethane-anesthetized rats, microinjections of glutamate into NTS evoked equivalent decreases in SNA, heart rate (HR), and MAP in juvenile OZR and LZR, but attenuated decreases in SNA and MAP in adult OZR. In contrast, microinjections of glutamate into the caudal ventrolateral medulla, a target of barosensitive NTS neurons, evoked comparable decreases in SNA, HR, and MAP in adult OZR and LZR. These data suggest that OZR develop impaired glutamatergic activation of the NTS, which likely contributes to attenuated baroreflexes in adult OZR. PMID:24573182

  5. Development of attenuated baroreflexes in obese Zucker rats coincides with impaired activation of nucleus tractus solitarius.

    PubMed

    Guimaraes, Priscila S; Huber, Domitila A; Campagnole-Santos, Maria J; Schreihofer, Ann M

    2014-05-01

    Adult obese Zucker rats (OZR; >12 wk) develop elevated sympathetic nerve activity (SNA) and mean arterial pressure (MAP) with impaired baroreflexes compared with adult lean Zucker rats (LZR) and juvenile OZR (6-7 wk). In adult OZR, baroreceptor afferent nerves respond normally to changes in MAP, whereas electrical stimulation of baroreceptor afferent fibers produces smaller reductions in SNA and MAP compared with LZR. We hypothesized that impaired baroreflexes in OZR are linked to reduced activation of brain stem sites that mediate baroreflexes. In conscious adult rats, a hydralazine (HDZ)-induced reduction in MAP evoked tachycardia that was initially blunted in OZR, but equivalent to LZR within 5 min. In agreement, HDZ-induced expression of c-Fos in the rostral ventrolateral medulla (RVLM) was comparable between groups. In contrast, phenylephrine (PE)-induced rise in MAP evoked markedly attenuated bradycardia with dramatically reduced c-Fos expression in the nucleus tractus solitarius (NTS) of adult OZR compared with LZR. However, in juvenile rats, PE-induced hypertension evoked comparable bradycardia in OZR and LZR with similar or augmented c-Fos expression in NTS of the OZR. In urethane-anesthetized rats, microinjections of glutamate into NTS evoked equivalent decreases in SNA, heart rate (HR), and MAP in juvenile OZR and LZR, but attenuated decreases in SNA and MAP in adult OZR. In contrast, microinjections of glutamate into the caudal ventrolateral medulla, a target of barosensitive NTS neurons, evoked comparable decreases in SNA, HR, and MAP in adult OZR and LZR. These data suggest that OZR develop impaired glutamatergic activation of the NTS, which likely contributes to attenuated baroreflexes in adult OZR.

  6. Out of control: Diminished prefrontal activity coincides with impaired motor performance due to choking under pressure

    PubMed Central

    Lee, Taraz G.; Grafton, Scott T.

    2014-01-01

    There are three non-exclusive theoretical explanations for the paradoxical collapse of performance due to large financial incentives. It has been proposed that “choking under pressure” is either due to distraction, interference via an increase in top-down control and performance monitoring, or excessive levels of arousal in the face of large losses. Given the known neural architecture involved in executive control and reward, we used fMRI of human participants during incentivized motor performance to provide evidence to support and/or reconcile these competing models in a visuomotor task. We show that the execution of a pre-trained motor task during neuroimaging is impaired by high rewards. BOLD activity occurring prior to movement onset is increased in dorsolateral prefrontal cortex and functional connectivity between this region and motor cortex is likewise increased just prior to choking. However, the extent of this increase in functional connectivity is inversely related to a participant's propensity to choke, suggesting that a failure in exerting top-down influence on motor control underlies choking under pressure due to large incentives. These results are consistent with a distraction account of choking and suggest that frontal influences on motor activity are necessary to protect performance from vulnerability under pressure. PMID:25449744

  7. Layered shielding design for an active neutron interrogation system

    NASA Astrophysics Data System (ADS)

    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.

  8. Determination of multielements in a typical Japanese diet certified reference material by instrumental neutron activation analysis.

    PubMed

    Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji

    2003-08-01

    Multielements in a typical Japanese diet certified reference material prepared at the National Institute for Environmental Studies (NIES) of Japan, in collaboration with the National Institute of Radiological Sciences (NIRS) of Japan were determined by instrumental neutron activation analysis (INAA). Five samples (ca. 510-1000 mg) and comparative standards were irradiated for a short time (10 s) at a thermal neutron flux of 1.5 x 10(12) n cm(-2) s(-1) (pneumatic transfer) and for a long time (6 h) at a thermal neutron flux of 3.7 x 10(12) n cm(-2) s(-1) (central thimble) in the Rikkyo University Research Reactor (TRIGA Mark-II, 100 kW). The irradiated samples were measured by conventional gama-ray spectrometry using a coaxial Ge detector, and by anti-coincidence and coincidence gamma-ray spectrometry with a coaxial Ge detector and a well-type NaI(Tl) detector. The concentrations of 38 elements were determined by these methods. PMID:12945682

  9. Integrated Active Fire Retrievals and Biomass Burning Emissions Using Complementary Near-Coincident Ground, Airborne and Spaceborne Sensor Data

    NASA Technical Reports Server (NTRS)

    Schroeder, Wilfrid; Ellicott, Evan; Ichoku, Charles; Ellison, Luke; Dickinson, Matthew B.; Ottmar, Roger D.; Clements, Craig; Hall, Dianne; Ambrosia, Vincent; Kremens, Robert

    2013-01-01

    Ground, airborne and spaceborne data were collected for a 450 ha prescribed fire implemented on 18 October 2011 at the Henry W. Coe State Park in California. The integration of various data elements allowed near coincident active fire retrievals to be estimated. The Autonomous Modular Sensor-Wildfire (AMS) airborne multispectral imaging system was used as a bridge between ground and spaceborne data sets providing high quality reference information to support satellite fire retrieval error analyses and fire emissions estimates. We found excellent agreement between peak fire radiant heat flux data (less than 1% error) derived from near-coincident ground radiometers and AMS. Both MODIS and GOES imager active fire products were negatively influenced by the presence of thick smoke, which was misclassified as cloud by their algorithms, leading to the omission of fire pixels beneath the smoke, and resulting in the underestimation of their retrieved fire radiative power (FRP) values for the burn plot, compared to the reference airborne data. Agreement between airborne and spaceborne FRP data improved significantly after correction for omission errors and atmospheric attenuation, resulting in as low as 5 difference between AquaMODIS and AMS. Use of in situ fuel and fire energy estimates in combination with a collection of AMS, MODIS, and GOES FRP retrievals provided a fuel consumption factor of 0.261 kg per MJ, total energy release of 14.5 x 10(exp 6) MJ, and total fuel consumption of 3.8 x 10(exp 6) kg. Fire emissions were calculated using two separate techniques, resulting in as low as 15 difference for various species

  10. Active Neutron Interrogation to Detect Shielded Fissionable Material

    SciTech Connect

    D. L. Chichester; E. H. Seabury

    2009-05-01

    Portable electronic neutron generators (ENGs) may be used to interrogate suspicious items to detect, characterize, and quantify the presence fissionable material based upon the measurement of prompt and/or delayed emissions of neutrons and/or photons resulting from fission. The small size (<0.2 m3), light weight (<12 kg), and low power consumption (<50 W) of modern ENGs makes them ideally suited for use in field situations, incorporated into systems carried by 2-3 individuals under rugged conditions. At Idaho National Laboratory we are investigating techniques and portable equipment for performing active neutron interrogation of moderate sized objects less than ~2-4 m3 to detect shielded fissionable material. Our research in this area relies upon the use of pulsed deuterium-tritium ENGs and the measurement of die-away prompt fission neutrons and other neutron signatures in-between neutron pulses from the ENG and after the ENG is turned off.

  11. Enhanced Photofission-based, Coincidence/Multiplicity Inspection Measurements

    SciTech Connect

    J.L. Jones; D.R. Norman; K.J. Haskell; M.T. Swinhoe; S.J. Tobin; W.H. Geist; R.B. Rothrock; C.R. Freeman

    2010-07-01

    An enhanced active interrogation system has been developed that integrates a transportable Idaho National Laboratory (INL) photonuclear inspection system, using a pulsed bremsstrahlung source and a reconfigurable neutron detection system, with a Los Alamos National Laboratory (LANL) list-mode data acquisition system. A series of active interrogation experiments have shown enhanced nuclear material detection and identification utilizing pulsed photofission-induced, neutron coincidence/multiplicity counting between pulses of an up-to-10-MeV electron accelerator. This paper describes the integrated inspection system and presents some key shielded and unshielded nuclear material inspection results. The enhanced inspection methodology has applicability to homeland security and possible nuclear weapon dismantlement treaties.

  12. A Dosimetry Study of Deuterium-Deuterium Neutron Generator-based In Vivo Neutron Activation Analysis.

    PubMed

    Sowers, Daniel; Liu, Yingzi; Mostafaei, Farshad; Blake, Scott; Nie, Linda H

    2015-12-01

    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 that produces neutrons at 2.45 MeV by the fusion reaction 2H(d, n)3He at a calculated flux of 7 × 10(8) ± 30% s(-1). A moderator/reflector/shielding [5 cm high density polyethylene (HDPE), 5.3 cm graphite and 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 dosimeters (EPD). The neutron ambient dose outside the shielding was measured by Fuji NSN3, and the photon dose was measured 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 neutrons and 4.2 ± 0.2 mSv for photons for 10 min; 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. PMID:26509624

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

    NASA Astrophysics Data System (ADS)

    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.

  14. A Dosimetry Study of Deuterium-Deuterium Neutron Generator-based In Vivo Neutron Activation Analysis.

    PubMed

    Sowers, Daniel; Liu, Yingzi; Mostafaei, Farshad; Blake, Scott; Nie, Linda H

    2015-12-01

    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 that produces neutrons at 2.45 MeV by the fusion reaction 2H(d, n)3He at a calculated flux of 7 × 10(8) ± 30% s(-1). A moderator/reflector/shielding [5 cm high density polyethylene (HDPE), 5.3 cm graphite and 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 dosimeters (EPD). The neutron ambient dose outside the shielding was measured by Fuji NSN3, and the photon dose was measured 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 neutrons and 4.2 ± 0.2 mSv for photons for 10 min; 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.

  15. Self-shielding effects in neutron spectra measurements for neutron capture therapy by means of activation foils.

    PubMed

    Pytel, Krzysztof; Józefowicz, Krystyna; Pytel, Beatrycze; Koziel, Alina

    2004-01-01

    The design and optimisation of a neutron beam for neutron capture therapy (NCT) is accompanied by the neutron spectra measurements at the target position. The method of activation detectors was applied for the neutron spectra measurements. Epithermal neutron energy region imposes the resonance structure of activation cross sections resulting in strong self-shielding effects. The neutron self-shielding correction factor was calculated using a simple analytical model of a single absorption event. Such a procedure has been applied to individual cross sections from pointwise ENDF/B-VI library and new corrected activation cross sections were introduced to a spectra unfolding algorithm. The method has been verified experimentally both for isotropic and for parallel neutron beams. Two sets of diluted and non-diluted activation foils covered with cadmium were irradiated in the neutron field. The comparison of activation rates of diluted and non-diluted foils has demonstrated the correctness of the applied self-shielding model.

  16. Neutrons and Granite: Transport and Activation

    SciTech Connect

    Bedrossian, P J

    2004-04-13

    In typical ground materials, both energy deposition and radionuclide production by energetic neutrons vary with the incident particle energy in a non-monotonic way. We describe the overall balance of nuclear reactions involving neutrons impinging on granite to demonstrate these energy-dependencies. While granite is a useful surrogate for a broad range of soil and rock types, the incorporation of small amounts of water (hydrogen) does alter the balance of nuclear reactions.

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

    SciTech Connect

    Harrison, J.E.

    1984-01-01

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

  18. Active and passive mode calibration of the Combined Thermal Epithermal Neutron (CTEN) system

    SciTech Connect

    Veilleux, J. M.

    2002-06-01

    The Combined Thermal/Epithermal Neutron (CTEN) non-destructive assay (NDA) system was designed to assay transuranic waste by employing an induced active neutron interrogation and/or a spontaneous passive neutron measurement. This is the second of two papers, and focuses on the passive mode, relating the net double neutron coincidence measurement to the plutonium mass via the calibration constant. National Institute of Standards and Technology (NIST) calibration standards were used and the results verified with NIST-traceable verification standards. Performance demonstration program (PDP) 'empty' 208-L matrix drum was used for the calibration. The experimentally derived calibration constant was found to be 0.0735 {+-} 0.0059 g {sup 240}Pu effective per unit response. Using this calibration constant, the Waste Isolation Pilot Plant (WIPP) criteria was satisfied with five minute waste assays in the range from 3 to 177g Pu. CTEN also participated in the PDP Cycle 8A blind assay with organic sludge and metal matrices and passed the criteria for accuracy and precision in both assay modes. The WIPP and EPA audit was completed March 1, 2002 and full certification is awaiting the closeout of one finding during the audit. With the successful closeout of the audit, the CTEN system will have shown that it can provide very fast assays (five minutes or less) of waste in the range from the minimum detection limit (about 2 mg Pu) to 177 g Pu.

  19. Thermal neutron imaging in an active interrogation environment

    SciTech Connect

    Vanier,P.E.; Forman, L., and Norman, D.R.

    2009-03-10

    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

  20. Planetary Geochemistry Using Active Neutron and Gamma Ray Instrumentation

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    The Pulsed Neutron Generator-Gamma Ray And Neutron Detector (PNG-GRAND) experiment is an innovative application of the active neutron-gamma ray technology so successfully used in oil field well logging and mineral exploration on Earth, The objective of our active neutron-gamma ray technology program at NASA Goddard Space Flight Center (NASA/GSFC) is to bring the PNG-GRAND instrument to the point where it can be flown on a variety of surface lander or rover missions to the Moon, Mars, Venus, asterOIds, comets and the satellites of the outer planets, Gamma-Ray Spectrometers have been incorporated into numerous orbital planetary science missions and, especially in the case of Mars Odyssey, have contributed detailed maps of the elemental composition over the entire surface of Mars, Neutron detectors have also been placed onboard orbital missions such as the Lunar Reconnaissance Orbiter and Lunar Prospector to measure the hydrogen content of the surface of the moon, The DAN in situ experiment on the Mars Science Laboratory not only includes neutron detectors, but also has its own neutron generator, However, no one has ever combined the three into one instrument PNG-GRAND combines a pulsed neutron generator (PNG) with gamma ray and neutron detectors to produce a landed instrument that can determine subsurface elemental composition without drilling. We are testing PNG-GRAND at a unique outdoor neutron instrumentation test facility recently constructed at NASA/GSFC that consists of a 2 m x 2 m x 1 m granite structure in an empty field, We will present data from the operation of PNG-GRAND in various experimental configurations on a known sample in a geometry that is identical to that which can be achieved on a planetary surface. We will also compare the material composition results inferred from our experiments to both an independent laboratory elemental composition analysis and MCNPX computer modeling results,

  1. Measurements of DT and DD neutron yields by neutron activation on TFTR

    SciTech Connect

    Barnes, C.W.; Larson, A.R.; LeMunyan, G.; Loughlin, M.J.

    1994-05-05

    A variety of elemental foils have been activated by neutron fluence from TFTR under conditions with the DT neutron yield per shot ranging from 10{sup 12} to over 10{sup 18}, and with the DT/(DD+DT) neutron ratio varying from 0.5% (from triton burnup) to unity. Linear response over this large dynamic range is obtained by reducing the mass of the foils and increasing the cooling time, all while accepting greatly improved counting statistics. Effects on background gamma-ray lines from foil-capsule-material contaminants. and the resulting lower limits on activation foil mass, have been determined. DT neutron yields from dosimetry standard reactions on aluminum, chromium, iron, nickel, zirconium, and indium are in agreement within the {plus_minus}9% (one-sigma,) accuracy of the measurements: also agreeing are yields from silicon foils using the ACTL library cross-section. While the ENDF/B-V library has too low a cross-section. Preliminary results from a variety of other threshold reactions are presented. Use of the {sup 115}In(n,n) {sup 115m}In reaction (0.42 times as sensitive to DT neutrons as DD neutrons) in conjunction with pure-DT reactions allows a determination of the DT/(DD+DT) ratio in trace tritium or low-power tritium beam experiments.

  2. In vivo neutron activation facility at Brookhaven National Laboratory

    SciTech Connect

    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.

  3. Mobile neutron/gamma waste assay system for characterization of waste containing transuranics, uranium, and fission/activation products

    SciTech Connect

    Davidson, D.R.; Haggard, D.; Lemons, C.

    1994-12-31

    A new integrated neutron/gamma assay system has been built for measuring 55-gallon drums at Pacific Northwest Laboratory. The system is unique because it allows simultaneous measurement of neutrons and gamma-rays. This technique also allows measurement of transuranics (TRU), uranium, and fission/activation products, screening for shielded Special Nuclear Material prior to disposal, and critically determinations prior to transportation. The new system is positioned on a platform with rollers and installed inside a trailer or large van to allow transportation of the system to the waste site instead of movement of the drums to the scanner. The ability to move the system to the waste drums is particularly useful for drum retrieval programs common to all DOE sites and minimizes transportation problems on the site. For longer campaigns, the system can be moved into a facility. The mobile system consists of two separate subsystems: a passive Segmented Gamma Scanner (SGS) and a {open_quotes}clam-shell{close_quotes} passive neutron counter. The SGS with high purity germanium detector and {sup 75}Se transmission source simultaneously scan the height of the drum allowing identification of unshieled {open_quotes}hot spots{close_quotes} in the drum or segments where the matrix is too dense for the transmission source to penetrate. Dense segments can flag shielding material that could be used to hide plutonium or uranium during the gamma analysis. The passive nuetron counter with JSR-12N Neutron Coincidence Analyzer measures the coincident neutrons from the spontaneous fission of even isotopes of plutonium. Because high-density shielding produces minimal absorption of neutrons, compared to gamma rays, the passive neutron portion of the system can detect shielded SNM. Measurements to evaluate the performance of the system are still underway at Pacific Northwest Laboratory.

  4. Addressing Different Active Neutron Interrogation Signatures from Fissionable Material

    SciTech Connect

    D. L. Chichester; E. H. Seabury

    2009-10-01

    In a continuing effort to examine portable methods for implementing active neutron interrogation for detecting shielded fissionable material research is underway to investigate the utility of analyzing multiple time-correlated signatures. Time correlation refers here to the existence of unique characteristics of the fission interrogation signature related to the start and end of an irradiation, as well as signatures present in between individual pulses of an irradiating source. Traditional measurement approaches in this area have typically worked to detect die-away neutrons after the end of each pulse, neutrons in between pulses related to the decay of neutron emitting fission products, or neutrons or gamma rays related to the decay of neutron emitting fission products after the end of an irradiation exposure. In this paper we discus the potential weaknesses of assessing only one signature versus multiple signatures and make the assertion that multiple complimentary and orthogonal measurements should be used to bolster the performance of active interrogation systems, helping to minimize susceptibility to the weaknesses of individual signatures on their own. Recognizing that the problem of detection is a problem of low count rates, we are exploring methods to integrate commonly used signatures with rarely used signatures to improve detection capabilities for these measurements. In this paper we will discuss initial activity in this area with this approach together with observations of some of the strengths and weaknesses of using these different signatures.

  5. Development of NANA: A Fast-Scintillator, Coincidence Gamma-ray Array for Radioactive Source Characterisation and Absolute Activity Measurements at the UK National Physical Laboratory

    NASA Astrophysics Data System (ADS)

    Regan, P. H.; Shearman, R.; Judge, S. M.; Lorusso, G.; Main, P.; Bell, S.; Collins, S. M.; Ivanov, P.; Jerome, S. M.; Keightley, J. D.; Larijani, C.; Lotay, G.; Pearce, A. K.

    2015-06-01

    A multi-detector modular coincidence gamma-ray spectrometer is being designed and constructed for use at the UK's National Physical Laboratory (NPL) for use in direct measurement and metrological standardisation of nuclear decay activities. In its first generation, the NPL National Nuclear Array (NANA) will consist of twelve individual halide scintillation detectors placed in a high-efficiency geometry around a well-defined central point source position. This brief conference paper provides details of the measured detector module and coincidence energy and timing responses for the LaBr3(Ce) detectors which will be used in the NANA array. Preliminary GEANT4 simulations of the array's full energy peak efficiency and expected gamma-ray coincidence response are also presented.

  6. Measurement of fluorine total concentration in dental enamel using fast-neutron activation

    NASA Astrophysics Data System (ADS)

    Mouadili, A.; Vernois, J.; Isabelle, D. B.

    1989-08-01

    Fluorine which is present in dental enamel, at the level of a few tens to a few hundred ppm, plays an important role in the behaviour of this tissue. Therefore its quantitative determination is of interest for particular studies of the dental system. We present a nuclear nondestructive method to determine the total fluorine content in dental enamel by cyclotron-produced fast-neutron activation. The 19F(n, 2n) reaction leads to 18F which is a β+ emitter with a 109.8 min half-life. The irradiated sample activity is measured by detecting in coincidence the annihilation photons. A fluorine standard is used for calibration. The detection limit is of the order of 1 ppm, while the reproducibility is better than 95%.

  7. Feasibility study of activity measurement of positron emitters based on gamma-gamma coincident detection by two NaI(Tl) detectors.

    PubMed

    Volkovitsky, Peter; Unterweger, Michael

    2012-09-01

    Detection of two and more γ-rays in coincidence by two NaI(Tl) detectors with almost 4π geometry allows absolute characterization of radionuclides emitting coincidence gammas. The method is a generalization of the Eldridge-Crowther method developed originally for x-rays and low energy γ-rays. This method is applied to the case of (94)Nb decay with two coincident gamma-rays emitted in one cascade. The application of this method for the case of coincident positron-gamma emission ((22)Na and (26)Al sources) meets some difficulties. In these decays, two 511 keV gamma quanta produced in positron annihilation are strongly correlated. Despite the fact that the third gamma emitted in (22)Na and (26)Al decays is not correlated with two annihilation quanta, the number of independent observables for (22)Na and (26)Al decays is less than the number of unknowns. The small parameter ω(00), the probability that both annihilation quanta escape detection in both NaI(Tl) detectors, cannot be determined. However, if this parameter is defined from experimental data for one source with known activity ((22)Na), the activity of the other source ((26)Al) can be calculated from experimental data for (26)Al decay.

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

    NASA Technical Reports Server (NTRS)

    1973-01-01

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

  9. Human hair neutron activation analysis: Analysis on population level, mapping

    NASA Astrophysics Data System (ADS)

    Zhuk, L. I.; Kist, A. A.

    1999-01-01

    Neutron activation analysis is an outstanding analytical method having very wide applications in various fields. Analysis of human hair within last decades mostly based on neutron activation analysis is a very attractive illustration of the application of nuclear analytical techniques. Very interesting question is how the elemental composition differs in different areas or cities. In this connection the present paper gives average data and maps of various localities in the vicinity of drying-out Aral Sea and of various industrial cities in Central Asia.

  10. Determination of fission neutron transmission through waste matrix material using neutron signal correlation from active assay of {sup 239}Pu

    SciTech Connect

    Hollas, C.L.; Arnone, G.; Brunson, G.; Coop, K.

    1996-09-01

    The accuracy of TRU (transuranic) waste assay using the differential die-away technique depends upon significant corrections to compensate for the effects of the matrix material in which the TRU waste is located. The authors have used a new instrument, the Combined Thermal/Epithermal Neutron (CTEN) instrument for the assay of TRU waste, to develop methods to improve the accuracy of these corrections. Neutrons from a pulsed 14-MeV neutron generator are moderated in the walls of the CTEN cavity and induce fission in the TRU material. The prompt neutrons from these fission events are detected in cadmium-wrapped {sup 3}He neutron detectors. They report new methods of data acquisition and analysis to extract correlation in the neutron signals resulting form fission during active interrogation. They use the correlation information in conjunction with the total number of neutrons to determine the fraction of fission neutrons transmitted through the matrix material into the {sup 3}He detectors. This determination allows them to cleanly separate the matrix effects into two processes: matrix modification upon the neutron interrogating flux and matrix modification upon the fraction of fission neutrons transmitted to the neutron detectors. This transmission information is also directly applied in a neutron multiplicity analysis in the passive assay of {sup 240}Pu.

  11. Triton burnup measurements in KSTAR using a neutron activation system

    NASA Astrophysics Data System (ADS)

    Jo, Jungmin; Cheon, MunSeong; Kim, Jun Young; Rhee, T.; Kim, Junghee; Shi, Yue-Jiang; Isobe, M.; Ogawa, K.; Chung, Kyoung-Jae; Hwang, Y. S.

    2016-11-01

    Measurements of the time-integrated triton burnup for deuterium plasma in Korea Superconducting Tokamak Advanced Research (KSTAR) have been performed following the simultaneous detection of the d-d and d-t neutrons. The d-d neutrons were measured using a 3He proportional counter, fission chamber, and activated indium sample, whereas the d-t neutrons were detected using activated silicon and copper samples. The triton burnup ratio from KSTAR discharges is found to be in the range 0.01%-0.50% depending on the plasma conditions. The measured burnup ratio is compared with the prompt loss fraction of tritons calculated with the Lorentz orbit code and the classical slowing-down time. The burnup ratio is found to increase as plasma current and classical slowing-down time increase.

  12. BOREHOLE NEUTRON ACTIVATION: THE RARE EARTHS.

    USGS Publications Warehouse

    Mikesell, J.L.; Senftle, F.E.

    1987-01-01

    Neutron-induced borehole gamma-ray spectroscopy has been widely used as a geophysical exploration technique by the petroleum industry, but its use for mineral exploration is not as common. Nuclear methods can be applied to mineral exploration, for determining stratigraphy and bed correlations, for mapping ore deposits, and for studying mineral concentration gradients. High-resolution detectors are essential for mineral exploration, and by using them an analysis of the major element concentrations in a borehole can usually be made. A number of economically important elements can be detected at typical ore-grade concentrations using this method. Because of the application of the rare-earth elements to high-temperature superconductors, these elements are examined in detail as an example of how nuclear techniques can be applied to mineral exploration.

  13. Neutron-activation study of figurines, pottery, and workshop materials from the Athenian Agora, Greece. [Neutron reactions; France, Israel, Cyprus

    SciTech Connect

    Fillieres, D.; Harbottle, G.; Sayre, E.V.

    1983-01-01

    Ceramic specimens from the excavations of the Agora of ancient Athens, Greece, including material from factories, i.e., trial firing pieces, pottery and figurine wasters, datable to the Protogeometric, Subgeometric, and Classical Periods, and stylistically related figurines and pottery were analyzed by neutron activation. The factory material from the three distinct chronological periods separated respectively into three significantly different compositional groups, indicating either that separate sources of clay were used during each of these periods or that some other significant changes in the traditions of fabrication had occurred. Many of the figurines and sherds analyzed coincided in composition with one of these three groups and therefore were shown to be consistent with the output of Athenian workshops. Some specimens of Corinthian style formed a separate compositional group as did some other specimens that agreed in composition with a clay from Aegina. Comparison of these results with previous analyses on file in the Brookhaven Data Bank revealed a number of specimens that corresponded both in style and composition to the Agora material. Most significant was a sizable amount of Classical Greek pottery excavated in southern France, in Israel, and in Cyprus that conformed in composition to the Attic Classical Group. 6 figures, 2 tables.

  14. Well coincidence counting and analysis

    SciTech Connect

    Lu, Ming-Shih; Teichmann, T.; Ceo, R.N.; Collins, L.L.

    1994-03-01

    In several recent papers a physical/mathematical model was developed to describe the nuclear multiplicative processes in samples containing fissile material from a general statistical viewpoint, starting with the basic underlying physical phenomena. The results of this model agreed with the established picture used in ``standard`` HLNCC (High Level Neutron Coincidence Counter) measurements, but considerably extended them, and allowed a more detailed interpretation of the underlying physical mechanisms and of the higher moments of the neutron counts. The present paper examines some recent measurements made at Y-12 (Oak Ridge) using the AWCC, in the light of this model. The results show internal consistency under a variety of conditions, and give good agreement between experiment and theory.

  15. Active Interrogation of Sensitive Nuclear Material Using Laser Driven Neutron Beams

    SciTech Connect

    Favalli, Andrea; Roth, Markus

    2015-05-01

    An investigation of the viability of a laser-driven neutron source for active interrogation is reported. The need is for a fast, movable, operationally safe neutron source which is energy tunable and has high-intensity, directional neutron production. Reasons for the choice of neutrons and lasers are set forth. Results from the interrogation of an enriched U sample are shown.

  16. Status report of CPHS and neutron activities at Tsinghua University

    NASA Astrophysics Data System (ADS)

    Wang, X.; Xing, Q.; Zheng, S.; Yang, Y.; Gong, H.; Xiao, Y.; Wu, H.; Guan, X.; Du, T.

    2016-11-01

    The Compact Pulsed Hadron Source (CPHS) project that was launched in September 2009 at Tsinghua University has reached a first commissioning stage in conjunction with ongoing activities to fulfill the eventual design goal of a ˜ 1013 n/s epithermal-to-cold neutron yield for education, instrumentation development, and industrial applications. Here, we report the latest progress on the commissioning and applications of 3MeV proton and neutron beam lines in the last one and half years, and the design, fabrication, engineering of the 13MeV/16kW proton accelerator system.

  17. Active helium target: Neutron scalar polarizability extraction via Compton scattering

    SciTech Connect

    Morris, Meg Hornidge, David; Annand, John; Strandberg, Bruno

    2015-12-31

    Precise measurement of the neutron scalar polarizabilities has been a lasting challenge because of the lack of a free-neutron target. Led by the University of Glasgow and the Mount Allison University groups of the A2 collaboration in Mainz, Germany, preparations have begun to test a recent theoretical model with an active helium target with the hope of determining these elusive quantities with small statistical, systematic, and model-dependent errors. Apparatus testing and background-event simulations have been carried out, with the full experiment projected to run in 2015. Once determined, these values can be applied to help understand quantum chromodynamics in the nonperturbative region.

  18. Development and testing of an active area neutron dosemeter.

    PubMed

    Brushwood, J M; Gow, J P D; Beeley, P A; Spyrou, N M

    2004-01-01

    This paper describes the design, development and testing of an active area neutron dosemeter (AAND). The classic moderator and central detector is retained but in AAND this arrangement is augmented by small thermal neutron detectors positioned within the moderating body. The outputs from these detectors are combined using an appropriately weighted linear superposition to fit both the ambient dose equivalent and the radiation weighting factor. Experimental verifications of both the modelled detector energy reponses and the overall AAND response are given. In the relatively soft D2O moderated 252Cf spectra, the AAND determined both the H*(10) and mean radiation weighting factor to better than +10%.

  19. BNL Activities in Advanced Neutron Source Development: Past and Present

    SciTech Connect

    Hastings, J.B.; Ludewig, H.; Montanez, P.; Todosow, M.; Smith, G.C.; Larese, J.Z.

    1998-06-14

    Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In this report we discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

  20. BNL ACTIVITIES IN ADVANCED NEUTRON SOURCE DEVELOPMENT: PAST AND PRESENT

    SciTech Connect

    HASTINGS,J.B.; LUDEWIG,H.; MONTANEZ,P.; TODOSOW,M.; SMITH,G.C.; LARESE,J.Z.

    1998-06-14

    Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In the sections below the authors discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

  1. Neutron activation analysis; A sensitive test for trace elements

    SciTech Connect

    Hossain, T.Z. . Ward Lab.)

    1992-01-01

    This paper discusses neutron activation analysis (NAA), an extremely sensitive technique for determining the elemental constituents of an unknown specimen. Currently, there are some twenty-five moderate-power TRIGA reactors scattered across the United States (fourteen of them at universities), and one of their principal uses is for NAA. NAA is procedurally simple. A small amount of the material to be tested (typically between one and one hundred milligrams) is irradiated for a period that varies from a few minutes to several hours in a neutron flux of around 10{sup 12} neutrons per square centimeter per second. A tiny fraction of the nuclei present (about 10{sup {minus}8}) is transmuted by nuclear reactions into radioactive forms. Subsequently, the nuclei decay, and the energy and intensity of the gamma rays that they emit can be measured in a gamma-ray spectrometer.

  2. Prototyping an Active Neutron Veto for SuperCDMS

    SciTech Connect

    Calkins, Robert; Loer, Ben

    2015-08-17

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

  3. Prototyping an active neutron veto for SuperCDMS

    SciTech Connect

    Calkins, Robert; Loer, Ben

    2015-08-17

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

  4. Prototyping an active neutron veto for SuperCDMS

    NASA Astrophysics Data System (ADS)

    Calkins, Robert; Loer, Ben

    2015-08-01

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

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

    PubMed

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

    2014-12-01

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

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

    SciTech Connect

    Chichester, D. L.; Seabury, E. H.

    2009-03-10

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

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

    SciTech Connect

    David L. Chichester; Edward H. Seabury

    2008-08-01

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

  8. Synthesis, characterization, and neutron activation of holmium metallofullerenes

    SciTech Connect

    Cagle, D.W.; Thrash, T.P.; Wilson, L.J.; Alford, M.; Chibante, L.P.F.; Ehrhardt, G.J.

    1996-08-28

    Isolation of the first macroscopic quantities of endohedral holmium metallofullerenes (principally Ho@C{sub 82}, Ho{sub 2}@C{sub 82}, and Ho{sub 3}@C{sub 82} by LD-TOF mass spectrometry) has been accomplished by carbon-arc and preparative HPLC methodologies. The detailed procedure for production and isolation of the metallofullerenes includes a new technique whereby holmium-impregnated electrodes are prepared simply by soaking porous graphite rods in an ethanolic solution of Ho(NO{sub 3}){sub 3}.xH{sub 2}O. Monoisotopic {sup 165}Ho offers a unique combination of advantages for neutron-activation studies of metallofullerenes, and purified samples containing {sup 165}Ho@C{sub 82}, {sup 165}Ho{sub 2}@C{sub 82}, and {sup 165}Ho{sub 3}@C{sub 82} have been activated by high-flux neutron irradiation ({Phi} = 4 x 10{sup 13}n cm{sup -2} s{sup -1}) to generate {sup 166}Ho metallofullerenes, which undergo {beta}{sup -} decay to produce stable {sup 166}Er. Chemical workup of the irradiated samples, followed by re-irradiation, has been used to demonstrate that observed decomposition of holmium metallofullerenes is due mainly to `fast` neutron damage rather than to holmium atom nuclear recoil (E{sub max} = 200 eV). This implies that metallofullerene damage can be minimized by using neutron fluxes with the highest possible thermal component. 60 refs., 4 figs.

  9. A coincidence detection system based on real-time software

    NASA Astrophysics Data System (ADS)

    Ayuso, Sindulfo; José Blanco, Juan; Medina, José; Gómez-Herrero, Raúl; García-Población, Oscar; García Tejedor, Ignacio

    2016-09-01

    Conventional real-time coincidence systems use electronic circuitry to detect coincident pulses (hardware coincidence). In this work, a new concept of coincidence system based on real-time software (software coincidence) is presented. This system is based on the recurrent supervision of the analogue-to-digital converters status, which is described in detail. A prototype has been designed and built using a low-cost development platform. It has been applied to two different experimental sets for cosmic ray muon detection. Experimental muon measurements recorded simultaneously using conventional hardware coincidence and our software coincidence system have been compared, yielding identical results. These measurements have also been validated using simultaneous neutron monitor observations. This new software coincidence system provides remarkable advantages such as higher simplicity of interconnection and adjusting. Thus, our system replaces, at least, three Nuclear Instrument Modules (NIMs) required by conventional coincidence systems, reducing its cost by a factor of 40 and eliminating pulse delay adjustments.

  10. Diagnostic Application of Absolute Neutron Activation Analysis in Hematology

    SciTech Connect

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

    2004-10-03

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

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

    PubMed

    Johansen, O; Steinnes, E

    1966-08-01

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

  12. Neutron Flux Spectra Determination by Multiple Foil Activation - Iterative Method.

    1994-07-08

    Version 00 Neutron energy spectra are determined by an analysis of experimental activation detector data. As with the original CCC-112/SAND-II program, which was developed at Air Force Weapons Laboratory, this code system consists of four modules, CSTAPE, SLACTS, SLATPE, and SANDII. The first three modules pre-process the dosimetry cross sections and the trial function spectrum library. The last module, SANDII, actually performs the iterative spectrum characterization.

  13. Obsidian sources characterized by neutron-activation analysis.

    PubMed

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

    1968-07-26

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

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

    PubMed

    Johansen, O; Steinnes, E

    1966-08-01

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

  15. Coincidence Proportional Counter

    DOEpatents

    Manley, J H

    1950-11-21

    A coincidence proportional counter having a plurality of collecting electrodes so disposed as to measure the range or energy spectrum of an ionizing particle-emitting source such as an alpha source, is disclosed.

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

    SciTech Connect

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

    2006-08-14

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

  17. Mercury mass measurement in fluorescent lamps via neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Viererbl, L.; Vinš, M.; Lahodová, Z.; Fuksa, A.; Kučera, J.; Koleška, M.; Voljanskij, A.

    2015-11-01

    Mercury is an essential component of fluorescent lamps. Not all fluorescent lamps are recycled, resulting in contamination of the environment with toxic mercury, making measurement of the mercury mass used in fluorescent lamps important. Mercury mass measurement of lamps via instrumental neutron activation analysis (NAA) was tested under various conditions in the LVR-15 research reactor. Fluorescent lamps were irradiated in different positions in vertical irradiation channels and a horizontal channel in neutron fields with total fluence rates from 3×108 cm-2 s-1 to 1014 cm-2 s-1. The 202Hg(n,γ)203Hg nuclear reaction was used for mercury mass evaluation. Activities of 203Hg and others induced radionuclides were measured via gamma spectrometry with an HPGe detector at various times after irradiation. Standards containing an Hg2Cl2 compound were used to determine mercury mass. Problems arise from the presence of elements with a large effective cross section in luminescent material (europium, antimony and gadolinium) and glass (boron). The paper describes optimization of the NAA procedure in the LVR-15 research reactor with particular attention to influence of neutron self-absorption in fluorescent lamps.

  18. Identification of a supernova remnant coincident with the soft gamma-ray repeater SGR1806-20

    NASA Technical Reports Server (NTRS)

    Kulkarni, S. R.; Frail, D. A.

    1993-01-01

    It is shown here that the well-localized soft gamma-ray repeater (SGR) SGR1806-20 coincides with an SNR: the amorphous radio nebula G10.0-0.3. Together with the coincident of SGR0526-66 with the SNR N49, this argues strongly in favor of a neutron-star origin for SGRs. It is suggested that all young pulsars pass through a brief phase of SGR activity. The detection of pulsar-powered synchrotron nebulae in, or pulsations from, the two SNRs coincident with SGRs would confirm this model.

  19. On the self-shielding factors in neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Trkov, A.; Žerovnik, G.; Snoj, L.; Ravnik, M.

    2009-11-01

    Whenever the sample size in neutron activation analysis cannot be made small enough, self-shielding effects need to be taken into account. When several resonance absorbers are present in the sample, resonance interference must also be considered. Estimation of the self-shielding factors by the Monte Carlo technique is too cumbersome for routine application. Various simplified approaches were compared to rigorous Monte Carlo calculations, pointing out their potential limitations. Good results are obtained using self-shielding factors calculated from evaluated nuclear data libraries and tabulated as a function of the dilution cross-section. The dilution cross-section depends on the material composition and the sample dimensions through the equivalence principle, which is well known in reactor physics. Resonance interference is calculated by solving the neutron spectrum slowing-down equation from cross-sections in 640-group representation. The MATSSF code was written for the purpose and is available on request.

  20. Fast counting electronics for neutron coincidence counting

    DOEpatents

    Swansen, James E.

    1987-01-01

    An amplifier-discriminator is tailored to output a very short pulse upon an above-threshold input from a detector which may be a .sup.3 He detector. The short pulse output is stretched and energizes a light emitting diode (LED) to provide a visual output of operation and pulse detection. The short pulse is further fed to a digital section for processing and possible ORing with other like generated pulses. Finally, the output (or ORed output ) is fed to a derandomizing buffer which converts the rapidly and randomly occurring pulses into synchronized and periodically spaced-apart pulses for the accurate counting thereof. Provision is also made for the internal and external disabling of each individual channel of amplifier-discriminators in an ORed plurality of same.

  1. Fast counting electronics for neutron coincidence counting

    DOEpatents

    Swansen, J.E.

    1985-03-05

    An amplifier-discriminator is tailored to output a very short pulse upon an above-threshold input from a detector which may be a /sup 3/He detector. The short pulse output is stretched and energizes a light emitting diode (LED) to provide a visual output of operation and pulse detection. The short pulse is further fed to a digital section for processing and possible ORing with other like generated pulses. Finally, the output (or ORed output) is fed to a derandomizing buffer which converts the rapidly and randomly occurring pulses into synchronized and periodically spaced-apart pulses for the accurate counting thereof. Provision is also made for the internal and external disabling of each individual channel of amplifier-discriminators in an ORed plurality of same.

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

    SciTech Connect

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

    2000-07-01

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

  3. Measurements of neutrons at JET by means of the activation methods

    NASA Astrophysics Data System (ADS)

    Prokopowicz, R.; Bienkowska, B.; Drozdowicz, K.; Jednorog, S.; Kowalska-Strzeciwilk, E.; Murari, A.; Popovichev, S.; Pytel, K.; Scholz, M.; Szydlowski, A.; Syme, B.; Tracz, G.; JET-EFDA Contributors

    2011-05-01

    The neutron diagnostics in tokamaks like Joint European Torus (JET) are essential in estimating fusion power. The neutron activation method, supported by neutron transport calculations, is particularly useful for the evaluation of the total neutron yield from a single plasma discharge. This paper presents the results of activation experiments and calculations carried out for JET plasmas, from the selection of the activation materials to their irradiations in the neutron field of JET discharges. Neutron transport calculations were performed, leading to activation coefficients for new materials. The results of the calculations were used to design new composite samples to obtain information on both the yield and the neutron spectrum. The neutron measurements using these new activation materials were performed during the last JET experimental campaigns. The results are compared with neutron transport calculations. Additionally, application of the cadmium difference method allows revelation of the part of thermal neutrons near the tokamak first wall. The advantages of new activation materials and benchmarking the activation method against neutron transport calculations are also discussed.

  4. RADSAT Benchmarks for Prompt Gamma Neutron Activation Analysis Measurements

    SciTech Connect

    Burns, Kimberly A.; Gesh, Christopher J.

    2011-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

    The Canadian Department of National Defence has developed a teleoperated, vehicle-mounted, multi-sensor system to detect anti-tank landmines on roads and tracks in peacekeeping operations. A key part of the system is a thermal neutron activation (TNA) sensor which is placed above a suspect location to within a 30 cm radius and confirms the presence of explosives via detection of the 10.835 MeV gamma ray associated with thermal neutron capture on 14N. The TNA uses a 100 μg252Cf neutron source surrounded by four 7.62 cm×7.62 cm NaI(Tl) detectors. The system, consisting of the TNA sensor head, including source, detectors and shielding, the high-rate, fast pulse processing electronics and the data processing methodology are described. Results of experiments to characterize detection performance are also described. The experiments have shown that anti-tank mines buried 10 cm or less can be detected in roughly a minute or less, but deeper mines and mines significantly displaced horizontally take considerably longer time. Mines as deep as 30 cm can be detected for long count times (1000 s). Four TNA detectors are now in service with the Canadian Forces as part of the four multi-sensor systems, making it the first militarily fielded TNA sensor and the first militarily fielded confirmation sensor for landmines. The ability to function well in adverse climatic conditions has been demonstrated, both in trials and operations.

  6. Neutron activation analysis of an Egyptian monazite ore sample

    NASA Astrophysics Data System (ADS)

    Eissa, E. A.; Rofail, N. B.; Ashmawy, L. S.; Hassan, A. M.

    1999-01-01

    The absolute sensitivity of a gamma-ray line following thermal or epithermal neutron activation is expressed as a product of four terms, namely, the intrinsic, irradiation, decay and measurement factors. The total absolute sensitivity is the sum of the absolute sensitivities due to thermal and epithermal activation. A. FORTRAN computer program was prepared on the TANDY 3000 NL PCA to calculate the total absolute sensitivity of the intensive gamma-ray lines from the thermal and epithermal neutron activation of all the naturally occurring nuclides. Another program was prepared for the determination of the total absolute sensitivity for gammarays emitted by radioactive daughters such as233Pa from233Th and239Np from239U. Long time irradiation periods (about 48 hours) for specimens of the monazite ore sample were carried out at the (ET-RR-1) reactor core periphery. The monazite ore sample was separated from the associating minerals in the sand of Abou-Khashaba of Rashied (Rosetta) area on the Mediterranean (North of Egypt). The separated monazite ore sample was provided by the Nuclear Material Authority of Egypt. The cadmium difference method was applied to thin gold foils for absolute thermal and epithermal neutron flux determination. The gamma-ray spectra were measured using a spectrometer with a HPGe coaxial detector. The evaluated absolute sensitivity tables were helpful in identifying the radioisotopes contributing to the gamma- ray spectra and in evaluating the elemental concentration of the monazite constitutents. Most of the rare earth elements were observed and their concentrations are reported. La, Ce, Nd, Sd and Th were found as major elements, U, Tb, Hf and Eu as minor elements.

  7. Neutron distribution and induced activity inside a Linac treatment room.

    PubMed

    Juste, B; Miró, R; Verdú, G; Díez, S; Campayo, J M

    2015-01-01

    Induced radioactivity and photoneutron contamination inside a radiation therapy bunker of a medical linear accelerator (Linac) is investigated in this work. The Linac studied is an Elekta Precise electron accelerator which maximum treatment photon energy is 15 MeV. This energy exceeds the photonuclear reaction threshold (around 7 MeV for high atomic number metals). The Monte Carlo code MCNP6 has been used for quantifying the neutron contamination inside the treatment room for different gantry rotation configuration. Walls activation processes have also been simulated. The approach described in this paper is useful to prevent the overexposure of patients and medical staff. PMID:26737878

  8. Neutron Activation Analysis and Product Isotope Inventory Code System.

    1990-10-31

    Version 00 NAC was designed to predict the neutron-induced gamma-ray radioactivity for a wide variety of composite materials. The NAC output includes the input data, a list of all reactions for each constituent element, and the end-of-irradiation disintegration rates for each reaction. NAC also compiles a product isotope inventory containing the isotope name, the disintegration rate, the gamma-ray source strength, and the absorbed dose rate at 1 meter from an unshielded point source. The inducedmore » activity is calculated as a function of irradiation and decay times; the effect of cyclic irradiation can also be calculated.« less

  9. Coincident activation of NMDA and dopamine D1 receptors within the nucleus accumbens core is required for appetitive instrumental learning.

    PubMed

    Smith-Roe, S L; Kelley, A E

    2000-10-15

    The nucleus accumbens, a brain structure ideally situated to act as an interface between corticolimbic information-processing regions and motor output systems, is well known to subserve behaviors governed by natural reinforcers. In the accumbens core, glutamatergic input from its corticolimbic afferents and dopaminergic input from the ventral tegmental area converge onto common dendrites of the medium spiny neurons that populate the accumbens. We have previously found that blockade of NMDA receptors in the core with the antagonist 2-amino-5-phosphonopentanoic acid (AP-5; 5 nmol) abolishes acquisition but not performance of an appetitive instrumental learning task (Kelley et al., 1997). Because it is currently hypothesized that concurrent dopamine D(1) and glutamate receptor activation is required for long-term changes associated with plasticity, we wished to examine whether the dopamine system in the accumbens core modulates learning via NMDA receptors. Co-infusion of low doses of the D(1) receptor antagonist SCH-23390 (0.3 nmol) and AP-5 (0.5 nmol) into the accumbens core strongly impaired acquisition of instrumental learning (lever pressing for food), whereas when infused separately, these low doses had no effect. Infusion of the combined low doses had no effect on indices of feeding and motor activity, suggesting a specific effect on learning. We hypothesize that co-activation of NMDA and D(1) receptors in the nucleus accumbens core is a key process for acquisition of appetitive instrumental learning. Such an interaction is likely to promote intracellular events and gene regulation necessary for synaptic plasticity and is supported by a number of cellular models.

  10. Fission measurements with PPAC detectors using a coincidence technique

    SciTech Connect

    Paradela, C.; Duran, I.; Tarrio, D.; Audouin, L.; Tassan-Got, L.; Stephan, C.

    2011-07-01

    A fission detection setup based on Parallel Plate Avalanche Counters (PPAC) has been constructed and used at the CERN n-TOF facility. The setup takes advantage of the coincidence detection of both fission fragments to discriminate the background reactions produced by high energy neutrons and it allows obtaining neutron-induced fission cross section up to 1 GeV. (authors)

  11. Activation of cobalt by neutrons from the Hiroshima bomb

    SciTech Connect

    Kerr, G.D.; Dyer, F.F.; Emery, J.F.; Pace, J.V. III ); Brodzinski, R.L. ); Marcum, J. )

    1990-02-01

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

  12. Assessment of the Fire Radiative Power retrieved by BIRD and the MODIS Active Fire Products from near coincident data acquisitions

    NASA Astrophysics Data System (ADS)

    Ruecker, Gernot; Tiemann, Joachim; Leimbach, David; Lorenz, Eckehard

    2013-04-01

    Due to its spatial resolution and sensor characteristics, the experimental small satellite BIRD (Bispectral InfraRed Detection, active from 2001 through 2003) was superior to any past or current spaceborne instrument in its capacity to detect and characterize fires. Based on a comparison of historical BIRD data with observations from MODIS, we present the first systematic comparison of MODIS FRP retrievals to higher resolution data and provide a first estimate of FRP underestimation due to coarse resolution and variable pixel sizes of the MODIS product. We also highlight differences in FRP retrievals that are due to the usage of different FRP retrieval algorithms, namely the MODIS algorithm adapted to BIRD, the BIRD algorithm and the MIR-radiance algorithm adapted to BIRD. We conclude that the algorithm independent FRP underestimation of MODIS when compared to BIRD may be in the order of 20 %. Since many of the low intensity fires are not detected are smouldering fires - such as peat fires - which release a greater share of methane and carbon monoxide per mass unit burned when compared to flaming fires the FRP underestimation may lead to a larger underestimation of global warming potential by algorithms that derive emissions from fire radiative energy. Prospects for cross validation efforts using the BIRD type sensor on the TET-1 satellite launched in 2012 and on the BIROS satellite to be launched in 2014 with the VIIRS sensor on Suomi NPP as well as geostationary sensors are briefly discussed.

  13. Neutron Activation Analysis for the Demonstration of Amphibolite Rock-Weathering Activity of a Yeast

    PubMed Central

    Rades-Rohkohl, E.; Hirsch, P.; Fränzle, O.

    1979-01-01

    Neutron activation analysis was employed in a survey of weathering abilities of rock surface microorganisms. A yeast isolated from an amphibolite of a megalithic grave was found actively to concentrate, in media and in or on cells, iron and other elements when grown in the presence of ground rock. This was demonstrated by comparing a spectrum of neutron-activated amphibolite powder (particle size, 50 to 100 μm) with the spectra of neutron-activated, lyophilized yeast cells which had grown with or without amphibolite powder added to different media. The most active yeast (IFAM 1171) did not only solubilize Fe from the rock powder, but significant amounts of Co, Eu, Yb, Ca, Ba, Sc, Lu, Cr, Th, and U were also mobilized. The latter two elements occurred as natural radioactive isotopes in this amphibolite. When the yeast cells were grown with neutron-activated amphibolite, the cells contained the same elements. Furthermore, the growth medium contained Fe, Co, and Eu which had been solubilized from the amphibolite. This indicates the presence, in this yeast strain, of active rockweathering abilities as well as of uptake mechanisms for solubilized rock components. PMID:16345472

  14. A systematic overview of the coincidences of river sinuosity changes and tectonically active structures in the Pannonian Basin

    NASA Astrophysics Data System (ADS)

    Petrovszki, Judit; Székely, Balázs; Timár, Gábor

    2012-12-01

    As tectonic movements change the valley slope (low-gradient reaches of valleys, in sedimentary basins), the alluvial rivers, as sensitive indicators, respond to these changes, by varying their courses to accommodate this forcing. In our study sinuosity values, a commonly used characteristic parameter to detect river pattern changes, were studied for the major rivers in the Pannonian Basin in order to reveal neotectonic influence on their planform shape. Our study area comprises the entire Pannonian Basin (330,000 km2) located in eastern Central-Europe, bounded by the Alps, Carpathians and Dinarides. The studied rivers were mostly in their natural meandering state before the main river regulations of the 19th century. The last quasi-natural, non-regulated river planforms were surveyed somewhat earlier, during the Second Military Survey of the Habsburg Empire. Using the digitized river sections of that survey, the sinuosities of the rivers were calculated with different sample section sizes ranging from 5 km to 80 km. Depending on the bank-full discharge, also a 'most representative' section size is given, which can be connected to the neotectonic activity. In total, the meandering reaches of 28 rivers were studied; their combined length is 7406 km. The places where the river sinuosity changed were compared to the structural lines of the "Atlas of the present-day geodynamics of the Pannonian Basin" (Horváth et al., 2006). 36 junctions along 26 structural lines were identified where the fault lines of this neotectonic map crossed the rivers. Across these points the mean sinuosity changed. Depending on the direction of the relative vertical movements, the sinuosity values increased or decreased. There were some points, where the sinuosity changed in an opposite way. Along these sections, the rivers belong to the range of unorganized meandering or there are lithological margins. Assuming that the rivers indicate on-going faulting accurately, some places were found

  15. Epithermal Neutron Activation Analysis of the Asian Herbal Plants

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  16. Epithermal Neutron Activation Analysis of the Asian Herbal Plants

    SciTech Connect

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

    2011-06-28

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

  17. δ-Opioid receptors stimulate the metabolic sensor AMP-activated protein kinase through coincident signaling with G(q/11)-coupled receptors.

    PubMed

    Olianas, Maria C; Dedoni, Simona; Olianas, Alessandra; Onali, Pierluigi

    2012-02-01

    AMP-activated protein kinase (AMPK) and δ-opioid receptors (DORs) are both involved in controlling cell survival, energy metabolism, and food intake, but little is known on the interaction between these two signaling molecules. Here we show that activation of human DORs stably expressed in Chinese hamster ovary (CHO) cells increased AMPK activity and AMPK phosphorylation on Thr172. DOR-induced AMPK phosphorylation was prevented by pertussis toxin, reduced by protein kinase A (PKA) activators, and unaffected by PKA, transforming growth factor-β-activated kinase 1, mitogen-activated protein kinase, and protein kinase C inhibitors. Conversely, the DOR effect was reduced by Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK) inhibition, apyrase treatment, G(q/11) antagonism, and blockade of P2 purinergic receptors. Apyrase treatment also depressed DOR stimulation of intracellular Ca(2+) concentration, whereas P2 receptor antagonism blocked DOR stimulation of inositol phosphate accumulation. In SH-SY5Y neuroblastoma cells and primary olfactory bulb neurons, DOR activation failed to affect AMPK phosphorylation per se but potentiated the stimulation by either muscarinic agonists or 2-methyl-thio-ADP. Sequestration of G protein βγ subunits (Gβγ) blocked the DOR potentiation of AMPK phosphorylation induced by oxotremorine-M. In CHO cells, the AMPK activator 5-aminoimidazole-4-carboxamide1-β-D-ribonucleoside stimulated AMPK phosphorylation and glucose uptake, whereas pharmacological inhibition of AMPK, expression of a dominant-negative mutant of AMPKα1, and P2Y receptor blockade reduced DOR-stimulated glucose uptake. The data indicate that in different cell systems, DOR activation up-regulates AMPK through a Gβγ-dependent synergistic interaction with G(q/11)-coupled receptors, potentiating Ca(2+) release and CaMKKβ-dependent AMPK phosphorylation. In CHO cells, this coincident signaling mechanism is involved in DOR-induced glucose uptake. PMID:22031472

  18. Indirect determination of Mn-BOPP concentrations using neutron activation analysis

    SciTech Connect

    Combs, M.J.; Oveissi, C.; Mulder, R.U.; Berr, S.

    1994-12-31

    ONe aspect of neutron capture therapy (NCT) is the determination of boron levels in tissues as a function of time. The objective of this work was the development of a simple instrumental neutron activation analysis method for the indirect determination of boron. One compound studied for use in NCT was Mn-BOPP because Mn 55 will neutron activate to Mn 56 which could serve as an indicator of boron levels. In addition, it can be used as a magnetic resonance imaging agent.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prompt-gamma neutron activation (PGNA) analysis is used for the non-invasive measurement of human body composition. Advancements in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators are available: D-D with 2.5 MeV and D-T with...

  20. Prompt-gamma neutron activation analysis system design: effects of D-T versus D-D neutron generator source selection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prompt-gamma neutron activation analysis (PGNAA) is used for the non-invasive measurement of human body composition. Advancements in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators are available: D-D with 2.5 MeV, and D-T wi...

  1. Neutron activation analysis of stoney spherules from a marine sediment sample

    NASA Technical Reports Server (NTRS)

    Millar, H. T., Jr.; Englert, P.

    1984-01-01

    The identification of extraterrestrial material in samples collected at the surface of the Earth is discussed. Criteria were established for black magnetic spherules which involve the presence of: Fe, Ni, and Co in iron meteoritic ratios, wustite, and Fe-Ni metal while reliable criteria for stoney spherules are not well established. Neutron activation analysis was performed on eight stony spherules separated from the same marine sediment used by Millard and Finkelman. The 22 elements were determined by Compton suppression and triple coincidence gamma counting. It is found that Fe, Mg, Al, Ni, Cr, Co, Ir, and Sc are the best discriminators between chondritic and terrestrial compositions. Three of the spherules have compositions very close to chondrites and of these, two contain 0.5 and 0.25 ppm Ir. The other five spherules contain much less than chondritic concentrations of Ni but this element may be segregated and lost during ablation of the parent meteorite. One of these five low Ni spherules contains 2.9 ppm Ir while the other four contain less than 0.05 ppm Ir.

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

    PubMed

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

    2016-10-01

    A standard high purity germanium (HPGe) detector was used to determine the previously unknown neutron activity of a weak americium-beryllium (AmBe) neutron source. γ rays were created through (27)Al(n,n'), (27)Al(n,γ) and (1)H(n,γ) reactions induced by the neutrons on aluminum and acrylic disks, respectively. These γ rays were measured using the HPGe detector. Given the unorthodox experimental arrangement, a Monte Carlo simulation was developed to model the efficiency of the detector system to determine the neutron activity from the measured γ rays. The activity of our neutron source was determined to be 307.4±5.0n/s and is consistent for the different neutron-induced γ rays.

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

    PubMed

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

    2016-10-01

    A standard high purity germanium (HPGe) detector was used to determine the previously unknown neutron activity of a weak americium-beryllium (AmBe) neutron source. γ rays were created through (27)Al(n,n'), (27)Al(n,γ) and (1)H(n,γ) reactions induced by the neutrons on aluminum and acrylic disks, respectively. These γ rays were measured using the HPGe detector. Given the unorthodox experimental arrangement, a Monte Carlo simulation was developed to model the efficiency of the detector system to determine the neutron activity from the measured γ rays. The activity of our neutron source was determined to be 307.4±5.0n/s and is consistent for the different neutron-induced γ rays. PMID:27474906

  4. Active detection of shielded SNM with 60-keV neutrons

    SciTech Connect

    Hagmann, C; Dietrich, D; Hall, J; Kerr, P; Nakae, L; Newby, R; Rowland, M; Snyderman, N; Stoeffl, W

    2008-07-08

    Fissile materials, e.g. {sup 235}U and {sup 239}Pu, can be detected non-invasively by active neutron interrogation. A unique characteristic of fissile material exposed to neutrons is the prompt emission of high-energy (fast) fission neutrons. One promising mode of operation subjects the object to a beam of medium-energy (epithermal) neutrons, generated by a proton beam impinging on a Li target. The emergence of fast secondary neutrons then clearly indicates the presence of fissile material. Our interrogation system comprises a low-dose 60-keV neutron generator (5 x 10{sup 6}/s), and a 1 m{sup 2} array of scintillators for fast neutron detection. Preliminary experimental results demonstrate the detectability of small quantities (370 g) of HEU shielded by steel (200 g/cm{sup 2}) or plywood (30 g/cm{sup 2}), with a typical measurement time of 1 min.

  5. CHARACTERIZATION OF A THIN SILICON SENSOR FOR ACTIVE NEUTRON PERSONAL DOSEMETERS.

    PubMed

    Takada, M; Nunomiya, T; Nakamura, T; Matsumoto, T; Masuda, A

    2016-09-01

    A thin silicon sensor has been developed for active neutron personal dosemeters for use by aircrews and first responders. This thin silicon sensor is not affected by the funneling effect, which causes detection of cosmic protons and over-response to cosmic neutrons. There are several advantages to the thin silicon sensor: a decrease in sensitivity to gamma rays, an improvement of the energy detection limit for neutrons down to 0.8 MeV and an increase in the sensitivity to fast neutrons. Neutron response functions were experimentally obtained using 2.5 and 5 MeV monoenergy neutron beams and a (252)Cf neutron source. Simulation results using the Monte Carlo N-Particle transport code agree quite well with the experimental ones when an energy deposition region shaped like a circular truncated cone is used in place of a cylindrical region. PMID:27150515

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

    SciTech Connect

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

    2004-10-07

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

  7. Measurement of residual 60Co activity induced by atomic-bomb neutrons in Nagasaki and background contribution by environmental neutrons.

    PubMed

    Shizuma, Kiyoshi; Endo, Satoru; Hoshi, Masaharu; Takada, Jun; Iwatani, Kazuo; Hasai, Hiromi; Oka, Takamitsu; Shimazaki, Tatsuya; Okumura, Yutaka; Fujita, Shoichiro; Watanabe, Tadaaki; Imanaka, Tetsuji

    2002-12-01

    Residual 60Co activity in five steel samples induced by neutrons from the Nagasaki atomic bomb has been measured within about 1000 m from the hypocenter. The chemical separation of cobalt and nickel from steel samples was performed, and cobalt-enriched samples were prepared for all samples. Gamma-ray measurements were carried out with a low-background well-type germanium detector. The gamma-ray spectra for five samples were compared with the spectrum of a control sample to ensure that the observed 60Co was actually induced by A-bomb neutrons. The activation of cobalt by environmental neutrons was also investigated. It has been shown that the present 60Co data are consistent with earlier Hashizume's data. PMID:12674203

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

    SciTech Connect

    Cohn, S.H.

    1982-01-01

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

  9. Clinical applications of in vivo neutron-activation analysis

    SciTech Connect

    Cohn, S.H.

    1982-01-01

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

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

    USGS Publications Warehouse

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

    1954-01-01

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

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

    SciTech Connect

    Hahn, K. D. Ruiz, C. L.; Fehl, D. L.; Chandler, G. A.; Knapp, P. F.; Smelser, R. M.; Torres, J. A.; Cooper, G. W.; Nelson, A. J.; Leeper, R. J.

    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.

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

    SciTech Connect

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

    2002-11-01

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

  13. Active Neutron Interrogation of Non-Radiological Materials with NMIS

    SciTech Connect

    Walker, Mark E; Mihalczo, John T

    2012-02-01

    The Nuclear Materials Identification System (NMIS) at Oak Ridge National Laboratory (ORNL), although primarily designed for analyzing special nuclear material, is capable of identifying nonradiological materials with a wide range of measurement techniques. This report demonstrates four different measurement methods, complementary to fast-neutron imaging, which can be used for material identification: DT transmission, DT scattering, californium transmission, and active time-tagged gamma spectroscopy. Each of the four techniques was used to evaluate how these methods can be used to identify four materials: aluminum, polyethylene, graphite, and G-10 epoxy. While such measurements have been performed individually in the past, in this project, all four measurements were performed on the same set of materials. The results of these measurements agree well with predicted results. In particular, the results of the active gamma spectroscopy measurements demonstrate the technique's applicability in a future version of NMIS which will incorporate passive and active gamma-ray spectroscopy. This system, designated as a fieldable NMIS (FNMIS), is under development by the US Department of Energy Office of Nuclear Verification.

  14. Characterization of indoor cooking aerosol using neutron activation analysis

    SciTech Connect

    Wu, D.; Landsberger, S.; Larson, S. )

    1993-01-01

    Suspended particles in air are potentially harmful to human health, depending on their sizes and chemical composition. Residential indoor particles mainly come from (a) outdoor sources that are transported indoors, (b) indoor dust that is resuspended, and (c) indoor combustion sources, which include cigarette smoking, cooking, and heating. Jedrychowski stated that chronic phlegm in elderly women was strongly related to the cooking exposure. Kamens et al. indicated that cooking could generate small particles (<0.1 [mu]m), and cooking one meal could contribute [approximately]5 to 18% of total daytime particle volume exposure. Although cooking is a basic human activity, there are not many data available on the properties of particles generated by this activity. Some cooking methods, such as stir-frying and frying, which are the most favored for Chinese and other Far East people, generate a large quantity of aerosols. This research included the following efforts: 1. investigating particle number concentrations, distributions, and their variations with four different cooking methods and ventilation conditions; 2. measuring the chemical composition of cooking aerosol samples by instrumental neutron activation analysis.

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

    SciTech Connect

    Iyengar, V.

    1988-01-01

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

  16. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect

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

    2013-09-01

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

  17. Real-time active cosmic neutron background reduction methods

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  18. Activation of the Carbon Concentrating Mechanism by CO2 Deprivation Coincides with Massive Transcriptional Restructuring in Chlamydomonas reinhardtii[W][OA

    PubMed Central

    Brueggeman, Andrew J.; Gangadharaiah, Dayananda S.; Cserhati, Matyas F.; Casero, David; Weeks, Donald P.; Ladunga, Istvan

    2012-01-01

    A CO2-concentrating mechanism (CCM) is essential for the growth of most eukaryotic algae under ambient (392 ppm) and very low (<100 ppm) CO2 concentrations. In this study, we used replicated deep mRNA sequencing and regulatory network reconstruction to capture a remarkable scope of changes in gene expression that occurs when Chlamydomonas reinhardtii cells are shifted from high to very low levels of CO2 (≤100 ppm). CCM induction 30 to 180 min post-CO2 deprivation coincides with statistically significant changes in the expression of an astonishing 38% (5884) of the 15,501 nonoverlapping C. reinhardtii genes. Of these genes, 1088 genes were induced and 3828 genes were downregulated by a log2 factor of 2. The latter indicate a global reduction in photosynthesis, protein synthesis, and energy-related biochemical pathways. The magnitude of transcriptional rearrangement and its major patterns are robust as analyzed by three different statistical methods. De novo DNA motif discovery revealed new putative binding sites for Myeloid oncogene family transcription factors potentially involved in activating low CO2–induced genes. The (CA)n repeat (9 ≤ n ≤ 25) is present in 29% of upregulated genes but almost absent from promoters of downregulated genes. These discoveries open many avenues for new research. PMID:22634764

  19. Measurements of activation induced by environmental neutrons using ultra low-level gamma-ray spectrometry.

    PubMed

    Martínez Canet, M J; Hult, M; Köhler, M; Johnston, P N

    2000-03-01

    The flux of environmental neutrons is being studied by activation of metal discs of selected elements. Near the earth's surface the total neutron flux is in the order of 10(-2) cm(-2)s(-1), which gives induced activities of a few mBq in the discs. Initial results from this technique, involving activation at ground level for several materials (W, Au, Ta, In, Re, Sm, Dy and Mn) and ultra low-level gamma-ray spectrometry in an underground laboratory located at 500 m.w.e., are presented. Diffusion of environmental neutrons in water is also measured by activation of gold at different depths.

  20. Computer programs for absolute neutron activation analysis on the nuclear data 6620 data acquisition system

    SciTech Connect

    Wade, J.W.; Emery, J.F.

    1982-03-01

    Five computer programs that provide multielement neutron activation analysis are discussed. The software package was designed for use on the Nuclear Data 6620 Data Acquisition System and interacts with existing Nuclear Data Corporation software. The programs were developed to make use of the capabilities of the 6620 system to analyze large numbers of samples and assist in a large sample workload that had begun in the neutron activation analysis facility of the Oak Ridge Research Reactor. Nuclear Data neutron activation software is unable to perform absolute activation analysis and therefore was inefficient and inadequate for our applications.

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

    SciTech Connect

    Williams, R.E.

    1981-10-12

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

  2. Search for reaction-in-flight neutrons using thulium activation at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Grim, Gary; Rundberg, Robert; Tonchev, Anton; Fowler, Malcolm; Wilhelmy, Jerry; Archuleta, Tom; Bionta, Richard; Boswell, Mitzi; Gostic, Julie; Griego, Jeff; Knittel, Kenn; Klein, Andi; Moody, Ken; Shaughnessy, Dawn; Wilde, Carl; Yeamans, Charles

    2013-10-01

    We report on measurements of reaction-in-flight (RIF) neutrons at the National Ignition Facility. RIF neutrons are produced in cryogenically layered implision by up-scattered deuterium, or tritium ions that undergo subsequent fusion reactions. The rate of RIF neutron production is proportional to the fuel areal density (| | R) and ion-stopping length in the dense fuel assembly. Thus, RIF neutrons provide information on charge particle stopping in a strongly coupled plasma, where perturbative modeling breaks down. To measure RIF neutrons, a set of thulium activation foils was placed 50 cm from layered cryogenic implosions at the NIF. The reaction 169Tm(n,3n)167Tm has a neutron kinetic energy threshold of 14.96 MeV. We will present results from initial experiments performed during the spring of 2013. Prepared by LANL under Contract DE-AC-52-06-NA25396, TSPA, LA-UR-13-22085.

  3. Feasibility of culvert IED detection using thermal neutron activation

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  4. A laser-induced repetitive fast neutron source applied for gold activation analysis

    SciTech Connect

    Lee, Sungman; Park, Sangsoon; Lee, Kitae; Cha, Hyungki

    2012-12-15

    A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 Multiplication-Sign 10{sup 5} n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He{sup 4} nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T{sup 3}.

  5. A laser-induced repetitive fast neutron source applied for gold activation analysis.

    PubMed

    Lee, Sungman; Park, Sangsoon; Lee, Kitae; Cha, Hyungki

    2012-12-01

    A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 × 10(5) n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He(4) nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T(3). PMID:23277984

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Source output stability is important for accurate measurement in prompt gamma neutron activation. This is especially true when measuring low-concentration elements such as in vivo nitrogen (~2.5% of body weight). We evaluated the stability of the compact DT neutron generator within an in vivo nitrog...

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

    NASA Astrophysics Data System (ADS)

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

    2001-07-01

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

  8. Measurement of residual 152Eu activity induced by atomic bomb neutrons in Nagasaki and the contribution of environmental neutrons to this activity.

    PubMed

    Shizuma, Kiyoshi; Endo, Satoru; Hoshi, Masaharu; Takada, Jun; Ishikawa, Masayori; Iwatani, Kazuo; Hasai, Hiromi; Oka, Takamitsu; Fujita, Shoichiro; Watanabe, Tadaaki; Yamashita, Tomoaki; Imanaka, Tetsuji

    2003-06-01

    Residual 152Eu activities induced by neutrons from the Nagasaki atomic bomb were measured for nine mineral samples located up to 1,061 m in the slant range and one control sample at 2,850 m from the hypocenter. A chemical separation to prepare europium-enriched samples was performed for all samples, and gamma ray measurements were carried out with a low background well-type germanium detector. In this paper, the measured specific activities of 152Eu are compared with activation calculations based on the DS86 neutron fluence and the 93Rev one. The calculated-to-measured ratios are also compared with those of 60Co and 36Cl. The present results indicate that the measurements agree to the calculation within a factor of three as observed in the nuclear tests at Nevada. The activation level of environmental neutrons and the detection limit for 152Eu are also discussed. PMID:13678342

  9. Development of active environmental and personal neutron dosemeters.

    PubMed

    Nakamura, T; Nunomiya, T; Sasaki, M

    2004-01-01

    For neutron dosimetry in the radiation environment surrounding nuclear facilities, two types of environmental neutron dosemeters, the high-sensitivity rem counter and the high-sensitivity multi-moderator, the so-called Bonner ball, have been developed and the former is commercially available from Fuji Electric Co. By using these detectors, the cosmic ray neutrons at sea level have been sequentially measured for about 3 y to investigate the time variation of neutron spectrum and ambient dose equivalent influenced by cosmic and terrestrial effects. Our Bonner ball has also been selected as the neutron detector in the International Space Station and has already been used to measure neutrons in the US experimental module. The real time wide-range personal neutron dosemeter which uses two silicon semiconductor detectors has been developed for personal dosimetry and is commercially available from Fuji Electric Co. This dosemeter has good characteristics, fitted to the fluence-to-dose conversion factor in the energy range from thermal energies to several tens of mega-electron-volts and is now widely used in various nuclear facilities.

  10. Multielement analysis of human hair and kidney stones by instrumental neutron activation analysis with the k0-standardization method.

    PubMed

    Abugassa, I; Sarmani, S B; Samat, S B

    1999-06-01

    This paper focuses on the evaluation of the k0 method of instrumental neutron activation analysis in biological materials. The method has been applied in multielement analysis of human hair standard reference materials from IAEA, No. 085, No. 086 and from NIES (National Institute for Environmental Sciences) No. 5. Hair samples from people resident in different parts of Malaysia, in addition to a sample from Japan, were analyzed. In addition, human kidney stones from members of the Malaysian population have been analyzed for minor and trace elements. More than 25 elements have been determined. The samples were irradiated in the rotary rack (Lazy Susan) at the TRIGA Mark II reactor of the Malaysian Institute for Nuclear Technology and Research (MINT). The accuracy of the method was ascertained by analysis of other reference materials, including 1573 tomato leaves and 1572 citrus leaves. In this method the deviation of the 1/E1+ alpha epithermal neutron flux distribution from the 1/E law (P/T ratio) for true coincidence effects of the gamma-ray cascade and the HPGe detector efficiency were determined and corrected for.

  11. Multielement analysis of human hair and kidney stones by instrumental neutron activation analysis with the k0-standardization method.

    PubMed

    Abugassa, I; Sarmani, S B; Samat, S B

    1999-06-01

    This paper focuses on the evaluation of the k0 method of instrumental neutron activation analysis in biological materials. The method has been applied in multielement analysis of human hair standard reference materials from IAEA, No. 085, No. 086 and from NIES (National Institute for Environmental Sciences) No. 5. Hair samples from people resident in different parts of Malaysia, in addition to a sample from Japan, were analyzed. In addition, human kidney stones from members of the Malaysian population have been analyzed for minor and trace elements. More than 25 elements have been determined. The samples were irradiated in the rotary rack (Lazy Susan) at the TRIGA Mark II reactor of the Malaysian Institute for Nuclear Technology and Research (MINT). The accuracy of the method was ascertained by analysis of other reference materials, including 1573 tomato leaves and 1572 citrus leaves. In this method the deviation of the 1/E1+ alpha epithermal neutron flux distribution from the 1/E law (P/T ratio) for true coincidence effects of the gamma-ray cascade and the HPGe detector efficiency were determined and corrected for. PMID:10355102

  12. Analysis of 125Xe electron–photon coincidence decay

    DOE PAGES

    Klingberg, Franziska J.; Biegalski, Steven R.; Prinke, Amanda; Haas, Derek A.; Lowrey, Justin D.

    2015-10-26

    In this study, as part of the verification component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), environmental gas samples originating from nuclear fission are analyzed for the presence of 131mXe, 133mXe, 133Xe, and 135Xe. In this work, the non-traditional radioxenon isotope 125Xe was investigated. The isotope was produced as an isotopically pure sample via neutron activation of 124Xe at the University of Texas at Austin Nuclear Engineering Teaching Lab’s TRIGA MARK II Reactor. The sample was then measured using a HPGe detector as well as an ARSA-style β–γ coincidence detector. Potential sources and sensitivities for production of 125Xe are also consideredmore » for relevance to the CTBT verification mission.« less

  13. Neutron Activation Analysis PRognosis and Optimization Code System.

    2004-08-20

    Version 00 NAAPRO predicts the results and main characteristics (detection limits, determination limits, measurement limits and relative precision of the analysis) of neutron activation analysis (instrumental and radiochemical). Gamma-ray dose rates for different points of time after sample irradiation and input count rate of the spectrometry system are also predicted. The code uses standard Windows user interface and extensive graphical tools for the visualization of the spectrometer characteristics (efficiency, response and background) and simulated spectrum.more » Optimization part is not included in the current version of the code. This release is designated NAAPRO, Version 01.beta. The MCNP code was used for generating detector responses. PREPRO-2000 and FCONV programs were used at the preparation of the program nuclear databases. A special program was developed for viewing, editing and updating of the program databases (not included into the present program package). The MCNP, PREPRO-2000 and FCONV software packages are not included in the NAAPRO package.« less

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

    PubMed

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

    2015-01-01

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

  15. An Analysis Technique for Active Neutron Multiplicity Measurements Based on First Principles

    SciTech Connect

    Evans, Louise G; Goddard, Braden; Charlton, William S; Peerani, Paolo

    2012-08-13

    Passive neutron multiplicity counting is commonly used to quantify the total mass of plutonium in a sample, without prior knowledge of the sample geometry. However, passive neutron counting is less applicable to uranium measurements due to the low spontaneous fission rates of uranium. Active neutron multiplicity measurements are therefore used to determine the {sup 235}U mass in a sample. Unfortunately, there are still additional challenges to overcome for uranium measurements, such as the coupling of the active source and the uranium sample. Techniques, such as the coupling method, have been developed to help reduce the dependence of calibration curves for active measurements on uranium samples; although, they still require similar geometry known standards. An advanced active neutron multiplicity measurement method is being developed by Texas A&M University, in collaboration with Los Alamos National Laboratory (LANL) in an attempt to overcome the calibration curve requirements. This method can be used to quantify the {sup 235}U mass in a sample containing uranium without using calibration curves. Furthermore, this method is based on existing detectors and nondestructive assay (NDA) systems, such as the LANL Epithermal Neutron Multiplicity Counter (ENMC). This method uses an inexpensive boron carbide liner to shield the uranium sample from thermal and epithermal neutrons while allowing fast neutrons to reach the sample. Due to the relatively low and constant fission and absorption energy dependent cross-sections at high neutron energies for uranium isotopes, fast neutrons can penetrate the sample without significant attenuation. Fast neutron interrogation therefore creates a homogeneous fission rate in the sample, allowing for first principle methods to be used to determine the {sup 235}U mass in the sample. This paper discusses the measurement method concept and development, including measurements and simulations performed to date, as well as the potential

  16. Neutron intensity monitor with activation foil for p-Li neutron source for BNCT--Feasibility test of the concept.

    PubMed

    Murata, Isao; Otani, Yuki; Sato, Fuminobu

    2015-12-01

    Proton-lithium (p-Li) reaction is being examined worldwide as a candidate nuclear production reaction for accelerator based neutron source (ABNS) for BNCT. In this reaction, the emitted neutron energy is not so high, below 1 MeV, and especially in backward angles the energy is as low as about 100 keV. The intensity measurement was thus known to be difficult so far. In the present study, a simple method was investigated to monitor the absolute neutron intensity of the p-Li neutron source by employing the foil activation method based on isomer production reactions in order to cover around several hundreds keV. As a result of numerical examination, it was found that (107)Ag, (115)In and (189)Os would be feasible. Their features found out are summarized as follows: (107)Ag: The most convenient foil, since the half life is short. (115)In: The accuracy is the best at 0°, though it cannot be used for backward angles. And (189)Os: Suitable nuclide which can be used in backward angles, though the gamma-ray energy is a little too low. These would be used for p-Li source monitoring depending on measuring purposes in real BNCT scenes. PMID:26242557

  17. Present and Future Activities on Neutron Imaging in Argentina

    NASA Astrophysics Data System (ADS)

    Tartaglione, Aureliano; Blostein, Jerónimo; Cantargi, Florencia; Marín, Julio; Baruj, Alberto; Meyer, Gabriel; Santisteban, Javier; Sánchez, Fernando

    We present here a short review of the main work which has been done in the latest years in neutron imaging in Argentina, and the future plans for the development of this technique in the country, mainly focused in the design of a new neutron imaging instrument to be installed in the future research reactor RA10. We present here the results of the implementation of the technique in samples belonging to the Argentinean cultural heritage and experiments related with hydrogen storage. At the same time, the Argentinean RA10 project for the design and construction of a 30 MW multipurpose research reactor is rapidly progressing. It started to be designed by the National Atomic Energy Commission (CNEA) and the technology company INVAP SE, both from Argentina, in June 2010. The construction will start in the beginning of 2015 in the Ezeiza Atomic Center, at 36 km from Buenos Aires City, and is expected to be finished by 2020. One of the main aims of the project is to offer to the Argentinean scientific and technology system new capabilities based on neutron techniques. We present here the conceptual design of a neutron imaging facility which will use one of the cold neutron beams, and will be installed in the reactor hall. Preliminary simulation results show that at the farthest detection position, at about 17 m from the cold source, a uniform neutron beam on a detection screen with an intensity of about 108 n/cm2/s is expected.

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

    SciTech Connect

    Relson, E.; Wilson, P. P. H.; Biondo, E. D.

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Antonova, Valentina; Kryukov, Sergey; Lutsenko, Vadim

    2015-04-01

    We present results of the study of data of the monitoring of high-energy and thermal neutrons at Tien Shan at different stages of thunderstorm activity. The data of the neutron monitoring were used taking into account the barometric effect. The intensity of the neutron component of cosmic rays is recorded in seven energy ranges. The electric field has values of ~ 100 V/m under fair weather conditions. Standard deviation of minute values of the neutron monitor data at the high altitude station does not exceed 0.5-0.6 %. Found that the standard deviation of the data during thunderstorms always exceeds these values. We selected events during the passage of thunderstorm clouds over the high altitude station without lightning discharges or with a small number of them. It was found that the particle rate of the neutron monitor changes in antiphase with the electric field changes. Atmospheric electric field of positive polarity decreases the count rate of the neutron monitor, and negative polarity - increases. Change of the count rate occurs at values of electric field ≥ 10-15 kV/m and reaches 2 %. The neutron monitor at the high-altitude station has the ability to measure the energy of recorded particles through determination of their multiplicity. We experimentally established that the sensitivity of the detected particles to change in Ez increases with decreasing their energy. The upper energy threshold of sensitivity of neutrons to change electric field is ~10 GeV. The physical mechanism of effect is based on lead nucleus capture of soft negative muons with the subsequent generation of neutrons. It is known that 7% of the neutron monitor count rate caused by negative muons. Absence of this effect in thermal neutrons data confirms the conclusion since the main difference of the thermal neutrons detector from the neutron monitor is the absence of the lead. In the active phase of a thunderstorm in the formed thundercloud the picture of distribution of charges is

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

    SciTech Connect

    Robin P. Gardner

    2006-04-11

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

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  2. Initiation of Electron Transport Chain Activity in the Embryonic Heart Coincides with the Activation of Mitochondrial Complex 1 and the Formation of Supercomplexes

    PubMed Central

    Beutner, Gisela; Eliseev, Roman A.; Porter, George A.

    2014-01-01

    Mitochondria provide energy in form of ATP in eukaryotic cells. However, it is not known when, during embryonic cardiac development, mitochondria become able to fulfill this function. To assess this, we measured mitochondrial oxygen consumption and the activity of the complexes (Cx) 1 and 2 of the electron transport chain (ETC) and used immunoprecipitation to follow the generation of mitochondrial supercomplexes. We show that in the heart of mouse embryos at embryonic day (E) 9.5, mitochondrial ETC activity and oxidative phosphorylation (OXPHOS) are not coupled, even though the complexes are present. We show that Cx-1 of the ETC is able to accept electrons from the Krebs cycle, but enzyme assays that specifically measure electron flow to ubiquinone or Cx-3 show no activity at this early embryonic stage. At E11.5, mitochondria appear functionally more mature; ETC activity and OXPHOS are coupled and respond to ETC inhibitors. In addition, the assembly of highly efficient respiratory supercomplexes containing Cx-1, -3, and -4, ubiquinone, and cytochrome c begins at E11.5, the exact time when Cx-1 becomes functional activated. At E13.5, ETC activity and OXPHOS of embryonic heart mitochondria are indistinguishable from adult mitochondria. In summary, our data suggest that between E9.5 and E11.5 dramatic changes occur in the mitochondria of the embryonic heart, which result in an increase in OXPHOS due to the activation of complex 1 and the formation of supercomplexes. PMID:25427064

  3. Characteristics and application of spherical-type activation detectors in neutron spectrum measurements at a boron neutron capture therapy (BNCT) facility

    NASA Astrophysics Data System (ADS)

    Lin, Heng-Xiao; Chen, Wei-Lin; Liu, Yuan-Hao; Sheu, Rong-Jiun

    2016-03-01

    A set of spherical-type activation detectors was developed aiming to provide better determination of the neutron spectrum at the Tsing Hua Open-pool Reactor (THOR) BNCT facility. An activation foil embedded in a specially designed spherical holder exhibits three advantages: (1) minimizing the effect of neutron angular dependence, (2) creating response functions with broadened coverage of neutron energies by introducing additional moderators or absorbers to the central activation foil, and (3) reducing irradiation time because of improved detection efficiencies to epithermal neutron beam. This paper presents the design concept and the calculated response functions of new detectors. Theoretical and experimental demonstrations of the performance of the detectors are provided through comparisons of the unfolded neutron spectra determined using this method and conventional multiple-foil activation techniques.

  4. Trace element analysis of K, U and Th in high purity materials by neutron activation analysis

    SciTech Connect

    Pillalamarri, Ila

    2005-09-08

    The concept and usage of 'high purity' are explained. Trace element analysis of K, U and Th by neutron activation analysis is described, the radio-isotopes and their corresponding gamma-rays used to identify the elements are listed. The interfering elements are described. The advantages and disadvantages of using neutron activation analysis are discussed. Some examples of trace impurity determinations in high purity materials are provided.

  5. NOTE: Total body-calcium measurements: comparison of two delayed-gamma neutron activation facilities

    NASA Astrophysics Data System (ADS)

    Ma, R.; Ellis, K. J.; Yasumura, S.; Shypailo, R. J.; Pierson, R. N., Jr.

    1999-06-01

    This study compares two independently calibrated delayed-gamma neutron activation (DGNA) facilities, one at the Brookhaven National Laboratory (BNL), Upton, New York, and the other at the Children's Nutrition Research Center (CNRC), Houston, Texas that measure total body calcium (TBCa). A set of BNL phantoms was sent to CNRC for neutron activation analysis, and a set of CNRC phantoms was measured at BNL. Both facilities showed high precision (<2%), and the results were in good agreement, within 5%.

  6. Hydrogen analysis for granite using proton-proton elastic recoil coincidence spectrometry.

    PubMed

    Komatsubara, T; Sasa, K; Ohshima, H; Kimura, H; Tajima, Y; Takahashi, T; Ishii, S; Yamato, Y; Kurosawa, M

    2008-07-01

    In an effort to develop DS02, a new radiation dosimetry system for the atomic bomb survivors of Hiroshima and Nagasaki, measurements of neutron-induced activities have provided valuable information to reconstruct the radiation situation at the time of the bombings. In Hiroshima, the depth profile of (152)Eu activity measured in a granite pillar of the Motoyasu Bridge (128 m from the hypocenter) was compared with that calculated using the DS02 methodology. For calculation of the (152)Eu production due to the thermal-neutron activation reaction, (151)Eu(n,gamma)(152)Eu, information on the hydrogen content in granite is important because the transport and slowing-down process of neutrons penetrating into the pillar is strongly affected by collisions with the protons of hydrogen. In this study, proton-proton elastic recoil coincidence spectrometry has been used to deduce the proton density in the Motoyasu pillar granite. Slices of granite samples were irradiated by a 20 MeV proton beam, and the energies of scattered and recoil protons were measured with a coincidence method. The water concentration in the pillar granite was evaluated to be 0.30 +/- 0.07%wt. This result is consistent with earlier data on adsorptive water (II) and bound water obtained by the Karl Fisher method. PMID:18509666

  7. Hydrogen analysis for granite using proton-proton elastic recoil coincidence spectrometry.

    PubMed

    Komatsubara, T; Sasa, K; Ohshima, H; Kimura, H; Tajima, Y; Takahashi, T; Ishii, S; Yamato, Y; Kurosawa, M

    2008-07-01

    In an effort to develop DS02, a new radiation dosimetry system for the atomic bomb survivors of Hiroshima and Nagasaki, measurements of neutron-induced activities have provided valuable information to reconstruct the radiation situation at the time of the bombings. In Hiroshima, the depth profile of (152)Eu activity measured in a granite pillar of the Motoyasu Bridge (128 m from the hypocenter) was compared with that calculated using the DS02 methodology. For calculation of the (152)Eu production due to the thermal-neutron activation reaction, (151)Eu(n,gamma)(152)Eu, information on the hydrogen content in granite is important because the transport and slowing-down process of neutrons penetrating into the pillar is strongly affected by collisions with the protons of hydrogen. In this study, proton-proton elastic recoil coincidence spectrometry has been used to deduce the proton density in the Motoyasu pillar granite. Slices of granite samples were irradiated by a 20 MeV proton beam, and the energies of scattered and recoil protons were measured with a coincidence method. The water concentration in the pillar granite was evaluated to be 0.30 +/- 0.07%wt. This result is consistent with earlier data on adsorptive water (II) and bound water obtained by the Karl Fisher method.

  8. CD40-TNF activation in mice induces extended sickness behavior syndrome co-incident with but not dependent on activation of the kynurenine pathway.

    PubMed

    Cathomas, Flurin; Fuertig, Rene; Sigrist, Hannes; Newman, Gregory N; Hoop, Vanessa; Bizzozzero, Manuela; Mueller, Andreas; Luippold, Andreas; Ceci, Angelo; Hengerer, Bastian; Seifritz, Erich; Fontana, Adriano; Pryce, Christopher R

    2015-11-01

    The similarity between sickness behavior syndrome (SBS) in infection and autoimmune disorders and certain symptoms in major depressive disorder (MDD), and the high co-morbidity of autoimmune disorders and MDD, constitutes some of the major evidence for the immune-inflammation hypothesis of MDD. CD40 ligand-CD40 immune-activation is important in host response to infection and in development of autoimmunity. Mice given a single intra-peritoneal injection of CD40 agonist antibody (CD40AB) develop SBS for 2-3days characterized by weight loss and increased sleep, effects that are dependent on the cytokine, tumor necrosis factor (TNF). Here we report that CD40AB also induces behavioral effects that extend beyond acute SBS and co-occur with but are not mediated by kynurenine pathway activation and recovery. CD40AB led to decreased saccharin drinking (days 1-7) and decreased Pavlovian fear conditioning (days 5-6), and was without effect on physical fatigue (day 5). These behavioral effects co-occurred with increased plasma and brain levels of kynurenine and its metabolites (days 1-7/8). Co-injection of TNF blocker etanercept with CD40AB prevented each of SBS, reduced saccharin drinking, and kynurenine pathway activation in plasma and brain. Repeated oral administration of a selective indoleamine 2,3-dioxygenase (IDO) inhibitor blocked activation of the kynurenine pathway but was without effect on SBS and saccharin drinking. This study provides novel evidence that CD40-TNF activation induces deficits in saccharin drinking and Pavlovian fear learning and activates the kynurenine pathway, and that CD40-TNF activation of the kynurenine pathway is not necessary for induction of the acute or extended SBS effects.

  9. Validation of the MCNP computational model for neutron flux distribution with the neutron activation analysis measurement

    NASA Astrophysics Data System (ADS)

    Tiyapun, K.; Chimtin, M.; Munsorn, S.; Somchit, S.

    2015-05-01

    The objective of this work is to demonstrate the method for validating the predication of the calculation methods for neutron flux distribution in the irradiation tubes of TRIGA research reactor (TRR-1/M1) using the MCNP computer code model. The reaction rate using in the experiment includes 27Al(n, α)24Na and 197Au(n, γ)198Au reactions. Aluminium (99.9 wt%) and gold (0.1 wt%) foils and the gold foils covered with cadmium were irradiated in 9 locations in the core referred to as CT, C8, C12, F3, F12, F22, F29, G5, and G33. The experimental results were compared to the calculations performed using MCNP which consisted of the detailed geometrical model of the reactor core. The results from the experimental and calculated normalized reaction rates in the reactor core are in good agreement for both reactions showing that the material and geometrical properties of the reactor core are modelled very well. The results indicated that the difference between the experimental measurements and the calculation of the reactor core using the MCNP geometrical model was below 10%. In conclusion the MCNP computational model which was used to calculate the neutron flux and reaction rate distribution in the reactor core can be used for others reactor core parameters including neutron spectra calculation, dose rate calculation, power peaking factors calculation and optimization of research reactor utilization in the future with the confidence in the accuracy and reliability of the calculation.

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

    NASA Astrophysics Data System (ADS)

    Delgado-Correal, Camilo; Munera, Hector

    2008-03-01

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

  11. Using Electronic Neutron Generators in Active Interrogation to Detect Shielded Fissionable Material

    SciTech Connect

    D. L. Chichester; E. H. Seabury

    2008-10-01

    Experiments have been performed at Idaho National Laboratory to study methodology and instrumentation for performing neutron active interrogation die-away analyses for the purpose of detecting shielded fissionable material. Here we report initial work using a portable DT electronic neutron generator with a He-3 fast neutron detector to detect shielded fissionable material including >2 kg quantities of enriched uranium and plutonium. Measurements have been taken of bare material as well as of material hidden within a large plywood cube. Results from this work have demonstrated the efficacy of the die-away neutron measurement technique for quickly detecting the presence of special nuclear material hidden within plywood shields by analyzing the time dependent neutron signals in-between neutron generator pulses. Using a DT electronic neutron generator operating at 300 Hz with a yield of approximately 0.36 x 10**8 neutrons per second, 2.2 kg of enriched uranium hidden within a 0.60 m x 0.60 m x 0.70 m volume of plywood was positively detected with a measurement signal 2-sigma above the passive background within 1 second. Similarly, for a 500 second measurement period a lower detection limit of approaching the gram level could be expected with the same simple set-up.

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

    SciTech Connect

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

    2009-06-01

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

  13. Determination of (n,γ) Cross Sections of 241Am by Cold Neutron Activation

    NASA Astrophysics Data System (ADS)

    Genreith, C.; Rossbach, M.; Révay, Zs.; Kudejova, P.

    2014-05-01

    Accurate cross section data of actinides are crucial for criticality calculations of GEN IV reactors and transmutation but also for analytical purposes such as nuclear waste characterization, decommissioning of nuclear installations and safeguard applications. Tabulated data are inconsistent and sometimes associated with large uncertainties. Neutron activation with external cold neutron beams from high flux reactors offers a chance for determination of accurate capture cross sections scalable to the whole 1/√{E}-region even for isotopes with low-lying resonances like 241Am. Preparation of 241Am samples for irradiation at the PGAA station of the FRM II in Garching has been optimized together with PTB in Braunschweig. Two samples were irradiated together with gold flux monitors to extract the thermal neutron capture cross section after appropriate corrections for attenuation of neutrons and photons in the sample. For one sample, the thermal ground state neutron capture cross section was measured as 663.0 ± 28.8 b. The thermal neutron capture cross section was calculated to 725.4 ± 34.4 b. For the other sample, a ground state neutron capture cross section of 649.9 ± 28.2 b was measured and a thermal neutron capture cross section of 711.1 ± 33.9 b was derived.

  14. SWAN - Detection of explosives by means of fast neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Gierlik, M.; Borsuk, S.; Guzik, Z.; Iwanowska, J.; Kaźmierczak, Ł.; Korolczuk, S.; Kozłowski, T.; Krakowski, T.; Marcinkowski, R.; Swiderski, L.; Szeptycka, M.; Szewiński, J.; Urban, A.

    2016-10-01

    In this work we report on SWAN, the experimental, portable device for explosives detection. The device was created as part of the EU Structural Funds Project "Accelerators & Detectors" (POIG.01.01.02-14-012/08-00), with the goal to increase beneficiary's expertise and competencies in the field of neutron activation analysis. Previous experiences and budged limitations lead toward a less advanced design based on fast neutron interactions and unsophisticated data analysis with the emphasis on the latest gamma detection and spectrometry solutions. The final device has been designed as a portable, fast neutron activation analyzer, with the software optimized for detection of carbon, nitrogen and oxygen. SWAN's performance in the role of explosives detector is elaborated in this paper. We demonstrate that the unique features offered by neutron activation analysis might not be impressive enough when confronted with practical demands and expectations of a generic homeland security customer.

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

    SciTech Connect

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

    2013-01-01

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

  16. Passive and Active Fast-Neutron Imaging in Support of Advanced Fuel Cycle Initiative Safeguards Campaign

    SciTech Connect

    Blackston, Matthew A; Hausladen, Paul

    2010-04-01

    Results from safeguards-related passive and active coded-aperture fast-neutron imaging measurements of plutonium and highly enriched uranium (HEU) material configurations performed at Idaho National Laboratory s Zero Power Physics Reactor facility are presented. The imaging measurements indicate that it is feasible to use fast neutron imaging in a variety of safeguards-related tasks, such as monitoring storage, evaluating holdup deposits in situ, or identifying individual leached hulls still containing fuel. The present work also presents the first demonstration of imaging of differential die away fast neutrons.

  17. Active-Interrogation Measurements of Induced-Fission Neutrons from Low-Enriched Uranium

    SciTech Connect

    J. L. Dolan; M. J. Marcath; M. Flaska; S. A. Pozzi; D. L. Chichester; A. Tomanin; P. Peerani; G. Nebbia

    2012-07-01

    Protection and control of nuclear fuels is paramount for nuclear security and safeguards; therefore, it is important to develop fast and robust controlling mechanisms to ensure the safety of nuclear fuels. Through both passive- and active-interrogation methods we can use fast-neutron detection to perform real-time measurements of fission neutrons for process monitoring. Active interrogation allows us to use different ranges of incident neutron energy to probe for different isotopes of uranium. With fast-neutron detectors, such as organic liquid scintillation detectors, we can detect the induced-fission neutrons and photons and work towards quantifying a sample’s mass and enrichment. Using MCNPX-PoliMi, a system was designed to measure induced-fission neutrons from U-235 and U-238. Measurements were then performed in the summer of 2010 at the Joint Research Centre in Ispra, Italy. Fissions were induced with an associated particle D-T generator and an isotopic Am-Li source. The fission neutrons, as well as neutrons from (n, 2n) and (n, 3n) reactions, were measured with five 5” by 5” EJ-309 organic liquid scintillators. The D-T neutron generator was available as part of a measurement campaign in place by Padova University. The measurement and data-acquisition systems were developed at the University of Michigan utilizing a CAEN V1720 digitizer and pulse-shape discrimination algorithms to differentiate neutron and photon detections. Low-enriched uranium samples of varying mass and enrichment were interrogated. Acquired time-of-flight curves and cross-correlation curves are currently analyzed to draw relationships between detected neutrons and sample mass and enrichment. In the full paper, the promise of active-interrogation measurements and fast-neutron detection will be assessed through the example of this proof-of-concept measurement campaign. Additionally, MCNPX-PoliMi simulation results will be compared to the measured data to validate the MCNPX-PoliMi code

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

    NASA Astrophysics Data System (ADS)

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

    2005-09-01

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

  19. Development of the prototype pneumatic transfer system for ITER neutron activation system.

    PubMed

    Cheon, M S; Seon, C R; Pak, S; Lee, H G; Bertalot, L

    2012-10-01

    The neutron activation system (NAS) measures neutron fluence at the first wall and the total neutron flux from the ITER plasma, providing evaluation of the fusion power for all operational phases. The pneumatic transfer system (PTS) is one of the key components of the NAS for the proper operation of the system, playing a role of transferring encapsulated samples between the capsule loading machine, irradiation stations, counting stations, and disposal bin. For the validation and the optimization of the design, a prototype of the PTS was developed and capsule transfer tests were performed with the developed system.

  20. Benchmark test of neutron transport calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing.

    PubMed

    Iwatani, K; Hoshi, M; Shizuma, K; Hiraoka, M; Hayakawa, N; Oka, T; Hasai, H

    1994-10-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen. PMID:8083048

  1. Benchmark test of neutron transport calculations: Indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing

    SciTech Connect

    Iwatani, Kazuo; Shizuma, Kiyoshi; Hasai, Hiromi; Hoshi, Masaharu; Hiraoka, Masayuki; Hayakawa, Norihiko; Oka, Takamitsu

    1994-10-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated {sup 252}Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate {sup 152}Eu and {sup 60}Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated {sup 252}Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen. 18 refs., 10 figs., 4 tabs.

  2. Benchmark test of neutron transport calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing.

    PubMed

    Iwatani, K; Hoshi, M; Shizuma, K; Hiraoka, M; Hayakawa, N; Oka, T; Hasai, H

    1994-10-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen.

  3. Calibration of the Brookhaven National Laboratory delayed gamma neutron activation facility to measure total body calcium.

    PubMed

    Ma, R; Stamatelatos, I E; Yasumura, S

    2000-05-01

    Differences in body size and shape can cause large variances in the in vivo results of neutron activation analysis. To introduce corrections for body size for the delayed gamma neutron activation facility at Brookhaven National Laboratory, "reference man"-sized and "reference woman"-sized phantoms were constructed. Simulation results using the Monte Carlo Neutron and Photon Transport code also provided correction factors for people of different sizes. For individuals with a body mass index (BMI = weight (kg)/height (m)2) between 20 and 30, no correction was required. At BMIs greater than 30, the effects of neutron attenuation were significant and a correction factor of CF = -0.0192 x BMI + 1.5635 can be applied. PMID:10865727

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

    NASA Astrophysics Data System (ADS)

    Kehayias, J. J.

    2001-07-01

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

  5. Cold neutron prompt gamma-ray activation analysis at NIST - an overview

    SciTech Connect

    Paul, R.L.; Lindstrom, R.M.

    1994-12-31

    An instrument for cold neutron capture prompt gamma-ray activation analysis (CNPGAA), located in the cold neutron research facility (CNRF) at the National Institute of Standards and Technology (NIST) has proven useful for the analysis of hydrogen and other elements in a wide variety of materials. The intent of this paper is to provide an overview of the instrument, focusing on recent improvements and the impact of these improvement on measurements.

  6. Determination of hydrogen in titanium alloys by cold neutron prompt gamma activation analysis

    SciTech Connect

    Paul, R.L.; Lindstrom, R.M.; Greenberg, R.R.; Privett, H.M. III; Richards, W.J.

    1996-11-01

    Cold neutron prompt gamma-ray activation analysis (CNPGAA) has proven useful for the analysis of hydrogen in titanium alloys. The analysis is nondestructive, measures the entire sample, and the results are independent of the chemical form of hydrogen present. The authors have used the technique to measure H mass fractions as low as 50 mg/kg in titanium-alloy jet-engine compressor blades and to measure hydrogen in standards for neutron tomography.

  7. Simulation of a Novel Active Target for Neutron-Unbound State Measurements

    NASA Astrophysics Data System (ADS)

    Frank, Nathan; MoNA Collaboration

    2013-10-01

    Measurement of nuclei at extreme ratios of protons to neutrons is challenging due to the low production rate. New facilities will increase the production of neutron-rich isotopes, but still not reach the neutron dripline for heavier nuclei. We simulated a carbon-based active target system that could be constructed to both increase statistics while preserving the experimental resolution. This simulation is an adaptation of the in-house MoNA Collaboration C + + based simulation tool to extract the decay energy of neutron-unbound states. A number of experiments of this type have been carried out at the National Superconducting Cyclotron Laboratory (NSCL). In most experiments, we produce neutron-unbound nuclei by bombarding a Beryllium target with a radioactive beam. The nucleus of interest immediately decays into a charged particle and one or more neutrons. In this simulation, we have constructed a carbon-based active target that provides a measurement of energy loss, which is used to calculate the nuclear interaction point within the target. This additional information is used to improve the resolution or preserve the resolution of a thinner target while increasing statistics. This presentation will cover some aspects of the simulation process as well as show a resolution improvement of up to about 4 with a ~700 mg/cm2 active target compared to a Be-target. The simulation utilized experimental settings from published work. Work supported by National Science Foundation Grant #0969173.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  9. Implementation of an enhanced, permanently installed neutron activation diagnostic hardware for NIF

    NASA Astrophysics Data System (ADS)

    Jedlovec, Donald R.; Edwards, Ellen R.; Carrera, Jorge A.; Yeamans, Charles B.

    2015-08-01

    Neutron activation diagnostics are commonly employed as baseline neutron yield and relative spatial flux measurement instruments. Much insight into implosion performance has been gained by deployment of up to 19 identical activation diagnostic samples distributed around the target chamber at unique angular locations. Their relative simplicity and traceability provide neutron facilities with a diagnostic platform that is easy to implement and verify. However, the current National Ignition Facility (NIF) implementation relies on removable activation samples, creating a 1-2 week data turn-around time and considerable labor costs. The system described here utilizes a commercially-available lanthanum bromide (cerium-doped) scintillator with an integrated MCA emulator as the counting system and a machined zirconium-702 cap as the activation medium. The device is installed within the target bay and monitored remotely. Additionally, this system allows the placement of any activation medium tailored to the specific measurement needs. We discuss the design and function of a stand-alone and permanently installed neutron activation detector unit to measure the yield and average energy of a nominal 14 MeV neutron source with a pulse length less than one nanosecond.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  11. Physical and chemical limitations to preparation of beta radioactive stents by direct neutron activation.

    PubMed

    Petelenz, Barbara; Rajchel, Bogusław; Bilski, Paweł; Misiak, Ryszard; Bartyzel, Mirosław; Wilczek, Krzysztof; Alber, Dorothea

    2003-02-01

    Pure beta emitters are the sources of choice for intracoronary irradiations in restenosis prevention. In this work we reconsidered preparation of low activity 32P sources by ion-implantation of stable 31P into highly biocompatible pure titanium stents, followed by neutron activation. Gamma-spectrometrical analysis has shown that during activations with high thermal neutrons flux production of gamma-active long-lived contaminants is much beyond the dosimetrically acceptable limit, mainly due to the competing (n,p) reactions induced by the fast neutrons on isotopes of the bulk stent material, and to a lesser extent due to (n,gamma) reactions on chemical impurities. A potential applicability of this method for obtaining alternative beta radioactive stents is discussed.

  12. Neutron Activation Analysis of Soil Samples from Different Parts of Edirne in Turkey*

    NASA Astrophysics Data System (ADS)

    Zaim, N.; Dogan, C.; Camtakan, Z.

    2016-05-01

    The concentrations of constituent elements were determined in soil samples collected from different parts of the Maritza Basin, Edirne, Turkey. Neutron activation analysis, an extremely accurate technique, and the comparator method (using a standard) were applied for the first time in this region. After preparing the soil samples for neutron activation analysis, they were activated with thermal neutrons in a nuclear reactor, TRIGA-MARK II, at Istanbul Technical University. The activated samples were analyzed using a high-efficiency high-purity germanium detector, and gamma spectrometry was employed to determine the elemental concentration in the samples. Eight elements (chromium, manganese, cobalt, zinc, arsenic, molybdenum, cadmium, and barium) were qualitatively and quantitatively identified in 36 samples. The concentrations of some elements in the soil samples were high compared with values reported in the literature.

  13. Development of Enhanced, Permanently-Installed, Neutron Activation Diagnostic Hardware for NIF

    NASA Astrophysics Data System (ADS)

    Edwards, E. R.; Jedlovec, D. R.; Carrera, J. A.; Yeamans, C. B.

    2016-05-01

    Neutron activation diagnostics are baseline neutron yield and flux measurement instruments at the National Ignition Facility. Up to 19 activation samples are distributed around the target chamber. Currently the samples must be removed to be counted, creating a 1-2 week data turn-around time and considerable labor costs. An improved system consisting of a commercially available LaBr3(Ce) scintillator and Power over Ethernet electronics is under development. A machined zirconium-702 cap over the detector is the activation medium to measure the 90Zr(n,2n)89Zr reaction. The detectors are located at the current neutron activation diagnostic sites and monitored remotely. Because they collect data in real time yield values are returned within a few hours after a NIF shot.

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

    PubMed

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Landoas, Olivier; Yu Glebov, Vladimir; 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.

  16. Benchmarking of activation reaction distribution in an intermediate energy neutron field.

    PubMed

    Ogawa, Tatsuhiko; Morev, Mikhail N; Hirota, Masahiro; Abe, Takuya; Koike, Yuya; Iwai, Satoshi; Iimoto, Takeshi; Kosako, Toshiso

    2011-07-01

    Neutron-induced reaction rate depth profiles inside concrete shield irradiated by intermediate energy neutron were calculated using a Monte-Carlo code and compared with an experiment. An irradiation field of intermediate neutron produced in the forward direction from a thick (stopping length) target bombarded by 400 MeV nucleon(-1) carbon ions was arranged at the heavy ion medical accelerator in Chiba. Ordinary concrete shield of 90 cm thickness was installed 50 cm downstream the iron target. Activation detectors of aluminum, gold and gold covered with cadmium were inserted at various depths. Irradiated samples were extracted after exposure and gamma-ray spectrometry was performed for each sample. Comparison of experimental and calculated shows good agreement for both low- and high-energy neutron-induced reaction except for (27)Al(n,X)(24)Na reaction at the surface. PMID:21515619

  17. Validation of MCNP NPP Activation Simulations for Decommissioning Studies by Analysis of NPP Neutron Activation Foil Measurement Campaigns

    NASA Astrophysics Data System (ADS)

    Volmert, Ben; Pantelias, Manuel; Mutnuru, R. K.; Neukaeter, Erwin; Bitterli, Beat

    2016-02-01

    In this paper, an overview of the Swiss Nuclear Power Plant (NPP) activation methodology is presented and the work towards its validation by in-situ NPP foil irradiation campaigns is outlined. Nuclear Research and consultancy Group (NRG) in The Netherlands has been given the task of performing the corresponding neutron metrology. For this purpose, small Aluminium boxes containing a set of circular-shaped neutron activation foils have been prepared. After being irradiated for one complete reactor cycle, the sets have been successfully retrieved, followed by gamma-spectrometric measurements of the individual foils at NRG. Along with the individual activities of the foils, the reaction rates and thermal, intermediate and fast neutron fluence rates at the foil locations have been determined. These determinations include appropriate corrections for gamma self-absorption and neutron self-shielding as well as corresponding measurement uncertainties. The comparison of the NPP Monte Carlo calculations with the results of the foil measurements is done by using an individual generic MCNP model functioning as an interface and allowing the simulation of individual foil activation by predetermined neutron spectra. To summarize, the comparison between calculation and measurement serve as a sound validation of the Swiss NPP activation methodology by demonstrating a satisfying agreement between measurement and calculation. Finally, the validation offers a chance for further improvements of the existing NPP models by ensuing calibration and/or modelling optimizations for key components and structures.

  18. Investigation of the neutron activation of endohedral rare earth metallofullerenes

    SciTech Connect

    Shilin, V. A. Lebedev, V. T.; Kolesnik, S. G.; Kozlov, V. S.; Grushko, Yu. S.; Sedov, V. P.; Kukorenko, V. V.

    2011-12-15

    Endohedral lanthanide metallofullerenes and their water-soluble biocompatible derivatives have been synthesized. The effect that fast-neutron irradiation has on the stability and nuclear physical properties of endohedral metallofullerenes that are used as magnetocontrast materials ({sup 46}Sc, {sup 140}La, {sup 141}Nd, {sup 153}Sm, {sup 152}Eu, {sup 154}Eu, {sup 153}Sm, {sup 160}Tb, {sup 169}Yb, {sup 170}Tm (isomers I and III), and {sup 177}Lu) is studied. Our hypothesis, according to which carbon-shell relaxation is based on the fast nonradiative processes of an electron shake-off type, is confirmed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  20. Device and software used to carry out Cyclic Neutron Activation Analysis

    NASA Astrophysics Data System (ADS)

    Castro-García, M. P.; Rey-Ronco, M. A.; Alonso-Sánchez, T.

    2014-11-01

    This paper discusses the device and software used to carry out Cyclic Neutron Activation Analysis (CNAA). The aim of this investigation is defining through this device the fluorite content present on different samples from fluorspar concentration plant through the DGNAA (Delayed Gamma Neutron Activation Analysis) method. This device is made of americium-beryllium neutron source, NaI (2"×2") and BGO (2"×2") gamma rays detectors, multichannel and an automatic mechanism which moves the samples from activation and reading position. This mechanism is controlled by a software which allows moving the samples precisely and in a safe way (~ms), which it is very useful when the radioactive isotopes have to be detected with a half time less than 8s.

  1. Probing Planetary Bodies for Subsurface Volatiles: GEANT4 Models of Gamma Ray, Fast, Epithermal, and Thermal Neutron Response to Active Neutron Illumination

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.

    2014-12-01

    Using an active source of neutrons as an in situ probe of a planetary body has proven to be a powerful tool to extract information about the presence, abundance, and location of subsurface volatiles without the need for drilling. The Dynamic Albedo of Neutrons (DAN) instrument on Curiosity is an example of such an instrument and is designed to detect the location and abundance of hydrogen within the top 50 cm of the Martian surface. DAN works by sending a pulse of neutrons towards the ground beneath the rover and detecting the reflected neutrons. The intensity and time of arrival of the reflection depends on the proportion of water, while the time the pulse takes to reach the detector is a function of the depth at which the water is located. Similar instruments can also be effective probes at the polar-regions of the Moon or on asteroids as a way of detecting sequestered volatiles. We present the results of GEANT4 particle simulation models of gamma ray, fast, epithermal, and thermal neutron responses to active neutron illumination. The results are parameterized by hydrogen abundance, stratification and depth of volatile layers, versus the distribution of neutron and gamma ray energy reflections. Models will be presented to approximate Martian, lunar, and asteroid environments and would be useful tools to assess utility for future NASA exploration missions to these types of planetary bodies.

  2. Active-Interrogation Measurements of Fast Neutrons from Induced Fission in Low-Enriched Uranium

    SciTech Connect

    J. L. Dolan; M. J. Marcath; M. Flaska; S. A. Pozzi; D. L. Chichester; A. Tomanin; P. Peerani

    2014-02-01

    A detection system was designed with MCNPX-PoliMi to measure induced-fission neutrons from U-235 and U-238 using active interrogation. Measurements were then performed with this system at the Joint Research Centre (JRC) in Ispra, Italy on low-enriched uranium samples. Liquid scintillators measured induced fission neutron to characterize the samples in terms of their uranium mass and enrichment. Results are presented to investigate and support the use of organic liquid scintillators with active interrogation techniques to characterize uranium containing materials.

  3. 3D mapping of lithium in battery electrodes using neutron activation

    NASA Astrophysics Data System (ADS)

    He, Yuping; Downing, R. Gregory; Wang, Howard

    2015-08-01

    The neutron depth profiling technique based on the neutron activation reaction, 6Li (n, α) 3H, was applied with two dimensional (2D) pinhole aperture scans to spatially map lithium in 3D. The technique was used to study model LiFePO4 electrodes of rechargeable batteries for spatial heterogeneities of lithium in two cathode films that had undergone different electrochemical cycling histories. The method is useful for better understanding the functioning and failure of batteries using lithium as the active element.

  4. Determination of sodium in biological materials by instrumental neutron activation analysis.

    PubMed

    Cunningham, W C; Capar, S G; Anderson, D L

    1997-01-01

    A formalized method for determining sodium in biological materials by instrumental neutron activation analysis is presented. The method includes common procedures from the numerous options available to this historically nonformalized analytical technique. The number of procedural options is restricted to minimize the method's complexity, yet the method is still applicable to a variety of neutron activation facilities. High accuracy and precision are achieved by placing bounds on allowed uncertainty at critical stages of the analysis. Analytical results from the U.S. Food and Drug Administration laboratory and 4 other laboratories demonstrate the method's performance.

  5. Determination of elements in National Bureau of Standards' geological Standard Reference Materials by neutron activation analysis

    SciTech Connect

    Graham, C.C.; Glascock, M.D.; Carni, J.J.; Vogt, J.R.; Spalding, T.G.

    1982-08-01

    Instrumental neutron activation analysis (INAA) and prompt gamma neutron activation analysis (PGNAA) have been used to determine elemental concentrations in two recently issued National Bureau of Standards (NBS) Standard Reference Materials (SRM's). The results obtained are in good agreement with the certified and information values reported by NBS for those elements in each material for which comparisons are available. Average concentrations of 35 elements in SRM 278 obsidian rock and 32 elements in SRM 688 basalt rock are reported for comparison with results that may be obtained by other laboratories.

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

    SciTech Connect

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

    1980-01-01

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

  7. Estimated neutron-activation data for TFTR. Part II. Biological dose rate from sample-materials activation

    SciTech Connect

    Ku, L.; Kolibal, J.G.

    1982-06-01

    The neutron induced material activation dose rate data are summarized for the TFTR operation. This report marks the completion of the second phase of the systematic study of the activation problem on the TFTR. The estimations of the neutron induced activation dose rates were made for spherical and slab objects, based on a point kernel method, for a wide range of materials. The dose rates as a function of cooling time for standard samples are presented for a number of typical neutron spectrum expected during TFTR DD and DT operations. The factors which account for the variations of the pulsing history, the characteristic size of the object and the distance of observation relative to the standard samples are also presented.

  8. Breakthrough in precision (0.3 percent) of neutron activation analyses applied to provenience studies of obsidian

    SciTech Connect

    Asaro, Frank; Stross, Fred H.; Burger, Richard L.

    2002-10-01

    A gamma ray spectrometer at LBNL (the Luis W. Alvarez Iridium Coincidence Spectrometer), that was specifically designed for high sensitivity measurements of iridium abundances, has been significantly modified in order to provide precisions of measurement in neutron activation analysis of obsidian significantly better than previously obtained (about 1%). Repeated measurements on a single sample of obsidian from a deposit near Chivay, Arequipa, Peru, showed a precision (average coefficient of variation) of 0.19% for the 6 best-measured elements, the value anticipated from the known random errors of measurement. In measurement of samples made from 7 different obsidian nodules from two locations near Chivay, a group of 5 had a spread of 0.30% for the 6 elements measured with counting statistics of better than 0.3% (and 1.8% for the remaining 6 elements). The data suggest there are source inhomogeneity and/or sample preparation contamination errors totaling 0.24 {+-} .05% for the 6 best measured elements. A sixth obsidian sample could be distinguished from the main group because it differed by +0.8% for most elements, and the last sample could be easily distinguished because several elements differed by more than 1%. The precision of measurements now being developed may provide a significantly more precise determination of the provenience of obsidian artifacts than has been heretofore possible. Also the techniques of measurement developed for obsidian will provide even better precisions with pottery, as many elements are more abundant in pottery than in obsidian.

  9. Residual 152Eu and 60Co activities induced by neutrons from the Hiroshima atomic bomb.

    PubMed

    Shizuma, K; Iwatani, K; Hasai, H; Hoshi, M; Oka, T; Morishima, H

    1993-09-01

    Specific activities of 152Eu:Eu in stone samples exposed to the Hiroshima atomic bomb were determined for 70 samples up to a 1,500-m slant range from the epicenter. The specific activities of 60Co:Co were also determined for six samples near the Hiroshima hypocenter. First, the 152Eu data were investigated to find out the directional dependence of neutron activation. Directional anisotropy was not definite; however, there was an indication that the activation in the west-southwest was lower than in other directions. Second, measured 152Eu and 60Co radioactivity data were compared with activation calculations based on DS86 neutrons. It is clearly shown that the measured data are lower than the calculation near the hypocenter and vice versa at long distances beyond 1,000 m. The calculated-to-measured ratios of 152Eu are 1.6 at the hypocenter, 1.0 at approximately 900 m, and 0.05 at a 1,500-m slant range. Present results indicate that systematic errors exist in the DS86 neutrons concerning the source-term spectrum, neutron transport calculations in air, and/or activation measurements.

  10. Accurate and precise measurement of selenium by instrumental neutron activation analysis.

    PubMed

    Kim, In Jung; Watson, Russell P; Lindstrom, Richard M

    2011-05-01

    An accurate and precise measurement of selenium in Standard Reference Material (SRM) 3149, a primary calibration standard for the quantitative determination of selenium, has been accomplished by instrumental neutron activation analysis (INAA) in order to resolve a question arising during the certification process of the standard. Each limiting factor of the uncertainty in the activation analysis, including the sample preparation, irradiation, and γ-ray spectrometry steps, has been carefully monitored to minimize the uncertainty in the determined mass fraction. Neutron and γ-ray self-shielding within the elemental selenium INAA standards contributed most significantly to the uncertainty of the measurement. An empirical model compensating for neutron self-shielding and reducing the self-shielding uncertainty was successfully applied to these selenium standards. The mass fraction of selenium in the new lot of SRM 3149 was determined with a relative standard uncertainty of 0.6%.

  11. Analysis of the neutron component at high altitude mountains using active and passive measurement devices.

    PubMed

    Hajek, M; Berger, T; Schoner, W; Vana, N

    2002-01-01

    The European Council directive 96/29/Euratom requires dosimetric precautions if the effective dose exceeds 1 mSv/a. On an average, this value is exceeded by aircrew members. Roughly half of the radiation exposure at flight altitudes is caused by cosmic ray-induced neutrons. Active (6LiI(Eu)-scintillator) and passive (TLDs) Bonner sphere spectrometers were used to determine the neutron energy spectra atop Mt. Sonnblick (3105 m) and Mt. Kitzsteinhorn (3029 m). Further measurements in a mixed radiation field at CERN as well as in a proton beam of 62 MeV at Paul Scherrer Institute, Switzerland, confirmed that not only neutrons but also charged particles contribute to the readings of active detectors, whereas TLD-600 and TLD-700 in pair allow the determination of the thermal neutron flux. Unfolding of the detector data obtained atop both mountains shows two relative maxima around 1 MeV and 85 MeV, which have to be considered for the assessment of the biologically relevant dose equivalent. By convoluting the spectra with appropriate conversion functions the neutron dose equivalent rate was determined to be 150 +/- 15 nSv/h. The total dose equivalent rate determined by the HTR-method was 210 +/- 15 nSv/h. The results are in good agreement with LET-spectrometer and Sievert counter measurements carried out simultaneously.

  12. Analysis of the neutron component at high altitude mountains using active and passive measurement devices

    NASA Astrophysics Data System (ADS)

    Hajek, M.; Berger, T.; Schöner, W.; Vana, N.

    2002-01-01

    The European Council directive 96/29/Euratom requires dosimetric precautions if the effective dose exceeds 1 mSv/a. On an average, this value is exceeded by aircrew members. Roughly half of the radiation exposure at flight altitudes is caused by cosmic ray-induced neutrons. Active ( 6LiI(Eu)-scintillator) and passive (TLDs) Bonner sphere spectrometers were used to determine the neutron energy spectra atop Mt. Sonnblick (3105 m) and Mt. Kitzsteinhorn (3029 m). Further measurements in a mixed radiation field at CERN as well as in a proton beam of 62 MeV at Paul Scherrer Institute, Switzerland, confirmed that not only neutrons but also charged particles contribute to the readings of active detectors, whereas TLD-600 and TLD-700 in pair allow the determination of the thermal neutron flux. Unfolding of the detector data obtained atop both mountains shows two relative maxima around 1 MeV and 85 MeV, which have to be considered for the assessment of the biologically relevant dose equivalent. By convoluting the spectra with appropriate conversion functions the neutron dose equivalent rate was determined to be 150±15 nSv/h. The total dose equivalent rate determined by the HTR-method was 210±15 nSv/h. The results are in good agreement with LET-spectrometer and Sievert counter measurements carried out simultaneously.

  13. Measuring neutron yield and ρR anisotropies with activation foils at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Bleuel, D. L.; Bernstein, L. A.; Bionta, R. M.; Cooper, G. W.; Drury, O. B.; Hagmann, C. A.; Knittel, K. M.; Leeper, R. J.; Ruiz, C. L.; Schneider, D. H. G.; Yeamans, C. B.

    2013-11-01

    Neutron yields at the National Ignition Facility (NIF) are measured with a suite of diagnostics, including activation of ˜20-200 g samples of materials undergoing a variety of energy-dependent neutron reactions. Indium samples were mounted on the end of a Diagnostic Instrument Manipulator (DIM), 25-50 cm from the implosion, to measure 2.45 MeV D-D fusion neutron yield. The 336.2 keV gamma rays from the 4.5 hour isomer of 115mIn produced by (n,n') reactions are counted in high-purity germanium detectors. For capsules producing D-T fusion reactions, zirconium and copper are activated via (n,2n) reactions at various locations around the target chamber and bay, measuring the 14 MeV neutron yield to accuracies on order of 7%. By mounting zirconium samples on ports at nine locations around the NIF chamber, anisotropies in the primary neutron emission due to fuel areal density asymmetries can be measured to a relative precision of 3%.

  14. Studies of neutron and proton nuclear activation in low-Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1982-01-01

    The expected induced radioactivity of experimental material in low Earth orbit was studied for characteristics of activating particles such as cosmic rays, high energy Earth albedo neutrons, trapped protons, and secondary protons and neutrons. The activation cross sections for the production of long lived radioisotopes and other existing nuclear data appropriate to the study of these reactions were compiled. Computer codes which are required to calculate the expected activation of orbited materials were developed. The decreased computer code used to predict the activation of trapped protons of materials placed in the expected orbits of LDEF and Spacelab II. Techniques for unfolding the fluxes of activating particles from the measured activation of orbited materials are examined.

  15. The fast neutron fluence and the activation detector activity calculations using the effective source method and the adjoint function

    SciTech Connect

    Hep, J.; Konecna, A.; Krysl, V.; Smutny, V.

    2011-07-01

    This paper describes the application of effective source in forward calculations and the adjoint method to the solution of fast neutron fluence and activation detector activities in the reactor pressure vessel (RPV) and RPV cavity of a VVER-440 reactor. Its objective is the demonstration of both methods on a practical task. The effective source method applies the Boltzmann transport operator to time integrated source data in order to obtain neutron fluence and detector activities. By weighting the source data by time dependent decay of the detector activity, the result of the calculation is the detector activity. Alternatively, if the weighting is uniform with respect to time, the result is the fluence. The approach works because of the inherent linearity of radiation transport in non-multiplying time-invariant media. Integrated in this way, the source data are referred to as the effective source. The effective source in the forward calculations method thereby enables the analyst to replace numerous intensive transport calculations with a single transport calculation in which the time dependence and magnitude of the source are correctly represented. In this work, the effective source method has been expanded slightly in the following way: neutron source data were performed with few group method calculation using the active core calculation code MOBY-DICK. The follow-up neutron transport calculation was performed using the neutron transport code TORT to perform multigroup calculations. For comparison, an alternative method of calculation has been used based upon adjoint functions of the Boltzmann transport equation. Calculation of the three-dimensional (3-D) adjoint function for each required computational outcome has been obtained using the deterministic code TORT and the cross section library BGL440. Adjoint functions appropriate to the required fast neutron flux density and neutron reaction rates have been calculated for several significant points within the RPV

  16. A passive-active neutron device for assaying remote-handled transuranic waste

    SciTech Connect

    Estep, R.J.; Coop, K.L.; Deane, T.M.; Lujan, J.E.

    1989-01-01

    A combined passive-active neutron assay device was constructed for assaying remote-handled transuranic waste. A study of matrix and source position effects in active assays showed that a knowledge of the source position alone is not sufficient to correct for position-related errors in highly moderating or absorbing matrices. An alternate function for the active assay of solid fuel pellets was derived, although the efficacy of this approach remains to be established. 4 refs., 7 figs., 1 tab.

  17. TFT-Based Active Pixel Sensors for Large Area Thermal Neutron Detection

    NASA Astrophysics Data System (ADS)

    Kunnen, George

    Due to diminishing availability of 3He, which is the critical component of neutron detecting proportional counters, large area flexible arrays are being considered as a potential replacement for neutron detection. A large area flexible array, utilizing semiconductors for both charged particle detection and pixel readout, ensures a large detection surface area in a light weight rugged form. Such a neutron detector could be suitable for deployment at ports of entry. The specific approach used in this research, uses a neutron converter layer which captures incident thermal neutrons, and then emits ionizing charged particles. These ionizing particles cause electron-hole pair generation within a single pixel's integrated sensing diode. The resulting charge is then amplified via a low-noise amplifier. This document begins by discussing the current state of the art in neutron detection and the associated challenges. Then, for the purpose of resolving some of these issues, recent design and modeling efforts towards developing an improved neutron detection system are described. Also presented is a low-noise active pixel sensor (APS) design capable of being implemented in low temperature indium gallium zinc oxide (InGaZnO) or amorphous silicon (a-Si:H) thin film transistor process compatible with plastic substrates. The low gain and limited scalability of this design are improved upon by implementing a new multi-stage self-resetting APS. For each APS design, successful radiation measurements are also presented using PiN diodes for charged particle detection. Next, detection array readout methodologies are modeled and analyzed, and use of a matched filter readout circuit is described as well. Finally, this document discusses detection diode integration with the designed TFT-based APSs.

  18. neutron activation analysis using thermochromatography. III. analysis of samples of biological origin

    SciTech Connect

    Sattarov, G.; Davydov, A.V.; Khamatov, S.; Kist, A.A.

    1986-07-01

    The use of gas thermochromatography (GTC) in the radioactivation analysis of biological materials is discussed. A group separation of a number of highly volatile elements from sodium and bromine radionuclides has been achieved. The limit of detection of the elements by INAA and neutron activation analysis was estimated using GTC. The advantages of the procedure and the analytical parameters are discussed.

  19. Upgrade of the NIST Thermal Neutron Prompt-Gamma-Ray Activation Analysis Facility

    SciTech Connect

    E. A. Mackey; D. L. Anderson; G. Lamaze; R. M. Lindstrom; P. J. Liposky

    2000-11-12

    The thermal neutron prompt-gamma-ray activation analysis facility at the National Institute of Standards and Technology (NIST) was designed and built in the late 1970s. An upgrade of the facility to reduce background and enhance analytical sensitivities is in progress, and is described in this report.

  20. Neutron activation analysis of fluid inclusions for copper, manganese, and zinc

    USGS Publications Warehouse

    Czamanske, G.K.; Roedder, E.; Burns, F.C.

    1963-01-01

    Microgram quantities of copper, manganese, and zinc, corresponding to concentrations greater than 100 parts per million, were found in milligram quantities of primary inclusion fluid extracted from samples of quartz and fluorite from two types of ore deposits. The results indicate that neutron activation is a useful analytical method for studying the content of heavy metal in fluid inclusions.

  1. A neutron activation analysis of iridium concentration in Yamato carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Yabushita, S.; Wada, K.; Moriyama, H.; Takeuchi, K.

    1988-09-01

    Iridium concentration in extra-terrestrial bodies is an important quantity in relation to Ir-rich geological layers. Ir concentration of a Yamato carbonaceous chondrite (Y-793321) has been measured by a neutron activation method. The measurement yields a value (0.57±0.06) μg per gramme for the chondrite.

  2. Minimum activation martensitic alloys for surface disposal after exposure to neutron flux

    DOEpatents

    Lechtenberg, Thomas

    1985-01-01

    Steel alloys for long-term exposure to neutron flux have a martensitic microstructure and contain chromium, carbon, tungsten, vanadium and preferably titanium. Activation of the steel is held to within acceptable limits for eventual surface disposal by stringently controlling the impurity levels of Ni, Mo, Cu, N, Co, Nb, Al and Mn.

  3. Radiochemical neutron activation analysis for certification of ion-implanted phosphorus in silicon.

    PubMed

    Paul, Rick L; Simons, David S; Guthrie, William F; Lu, John

    2003-08-15

    A radiochemical neutron activation analysis procedure has been developed, critically evaluated, and shown to have the necessary sensitivity, chemical specificity, matrix independence, and precision to certify phosphorus at ion implantation levels in silicon. 32P, produced by neutron capture of 31P, is chemically separated from the sample matrix and measured using a beta proportional counter. The method is used here to certify the amount of phosphorus in SRM 2133 (Phosphorus Implant in Silicon Depth Profile Standard) as (9.58 +/- 0.16) x 10(14) atoms x cm(-2). A detailed evaluation of uncertainties is given.

  4. Capability and limitation study of the DDT passive-active neutron waste assay instrument

    SciTech Connect

    Nicholas, N.J.; Coop, K.L.; Estep, R.J.

    1992-05-01

    The differential-dieaway-technique passive-active neutron assay system is widely used by transuranic waste generators to certify their drummed waste for eventual shipment to the Waste Isolation Pilot Plant (WIPP). Stricter criteria being established for waste emplacement at the WIPP site has led to a renewed interest in improvements to and a better understanding of current nondestructive assay (NDA) techniques. Our study includes the effects of source position, extreme matrices, high neutron backgrounds, and source self-shielding to explore the system`s capabilities and limitations and to establish a basis for comparison with other NDA systems. 11 refs.

  5. Capability and limitation study of the DDT passive-active neutron waste assay instrument

    SciTech Connect

    Nicholas, N.J.; Coop, K.L.; Estep, R.J.

    1992-05-01

    The differential-dieaway-technique passive-active neutron assay system is widely used by transuranic waste generators to certify their drummed waste for eventual shipment to the Waste Isolation Pilot Plant (WIPP). Stricter criteria being established for waste emplacement at the WIPP site has led to a renewed interest in improvements to and a better understanding of current nondestructive assay (NDA) techniques. Our study includes the effects of source position, extreme matrices, high neutron backgrounds, and source self-shielding to explore the system's capabilities and limitations and to establish a basis for comparison with other NDA systems. 11 refs.

  6. Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.

    SciTech Connect

    Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

    2007-12-01

    An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

  7. A New Automated Sample Transfer System for Instrumental Neutron Activation Analysis

    PubMed Central

    Ismail, S. S.

    2010-01-01

    A fully automated and fast pneumatic transport system for short-time activation analysis was recently developed. It is suitable for small nuclear research reactors or laboratories that are using neutron generators and other neutron sources. It is equipped with a programmable logic controller, software package, and 12 devices to facilitate optimal analytical procedures. 550 ms were only necessary to transfer the irradiated capsule (diameter: 15 mm, length: 50 mm, weight: 4 gram) to the counting chamber at a distance of 20 meters using pressurized air (4 bars) as a transport gas. PMID:20369063

  8. Luminescent and scintillating properties of lanthanum fluoride nanocrystals in response to gamma/neutron irradiation: codoping with Ce activator, Yb wavelength shifter, and Gd neutron captor

    NASA Astrophysics Data System (ADS)

    Vargas, J. M.; Blostein, J. J.; Sidelnik, I.; Rondón Brito, D.; Rodríguez Palomino, L. A.; Mayer, R. E.

    2016-09-01

    A novel concept for gamma radiation detection and spectroscopy, and detection of thermal neutrons based on co-doped lanthanum fluoride nanocrystals containing gadolinium is presented. The trends of colloidal synthesis of the mentioned material, LaF3 co-doped with Ce3+ as the activator, Yb3+ as the wavelength-shifter and Gd3+ as the neutron captor, is reported. Nanocrystals of the mentioned material were characterized by transmission electron microscopy, X ray diffraction, energy dispersive X ray spectroscopy, optical absorption, and photoluminescence spectroscopy. Gamma detection and its potential spectroscopy feature have been confirmed. The neutron detection capability has been confirmed by experiments performed using a 252Cf neutron source.

  9. Importance of neutron energy distribution in borehole activation analysis in relatively dry, low-porosity rocks

    USGS Publications Warehouse

    Senftle, F.E.; Moxham, R.M.; Tanner, A.B.; Philbin, P.W.; Boynton, G.R.; Wager, R.E.

    1977-01-01

    To evaluate the importance of variations in the neutron energy distribution in borehole activation analysis, capture gamma-ray measurements were made in relatively dry, low-porosity gabbro of the Duluth Complex. Although sections of over a meter of solid rock were encountered in the borehole, there was significant fracturing with interstitial water leading to a substantial variation of water with depth in the borehole. The linear-correlation coefficients calculated for the peak intensities of several elements compared to the chemical core analyses were generally poor throughout the depth investigated. The data suggest and arguments are given which indicate that the variation of the thermal-to-intermediate-to-fast neutron flux density as a function of borehole depth is a serious source of error and is a major cause of the changes observed in the capture gamma-ray peak intensities. These variations in neutron energy may also cause a shift in the observed capture gamma-ray energy.

  10. Apparatus for the measurement of total body nitrogen using prompt neutron activation analysis with californium-252.

    PubMed

    Mackie, A; Hannan, W J; Smith, M A; Tothill, P

    1988-01-01

    Details of clinical apparatus designed for the measurement of total body nitrogen (as an indicator of body protein), suitable for the critically ill, intensive-care patient are presented. Californium-252 radio-isotopic neutron sources are used, enabling a nitrogen measurement by prompt neutron activation analysis to be made in 40 min with a precision of +/- 3.2% for a whole body dose equivalent of 0.145 mSv. The advantages of Californium-252 over alternative neutron sources are discussed. A comparison between two irradiation/detection geometries is made, leading to an explanation of the geometry adopted for the apparatus. The choice of construction and shielding materials to reduce the count rate at the detectors and consequently to reduce the pile-up contribution to the nitrogen background is discussed. Salient features of the gamma ray spectroscopy system to reduce spectral distortion from pulse pile-up are presented.

  11. Recent upgrade of the in vivo neutron activation facility at Brookhaven National Laboratory

    SciTech Connect

    Ma, R.; Dilmanian, F.A..; Rarback, H.; Meron, M.; Kamen, Y.; Yasumura, S.; Weber, D.A.; Stamatelatos, I.E.; Lidofsky, L.J.; Pierson, R.N. Jr.

    1993-10-01

    The in vivo neutron activation facility at Brookhaven National Laboratory consists of a delayed- and a prompt-gamma neutron activation (DGNA and PGNA) system and an inelastic neutron scattering (INS) system. The total body contents of several basic elements, including potassium, calcium, chlorine, sodium, and phosphorus are measured at the DGNA system; total body carbon is measured at the INS system; and the nitrogen-tohydrogen ratio is measured at the PGNA system. Based on the elemental composition, body compartments, such as total body fat and total body protein can be computed with additional independently measured parameters, such as total body water, body size, and body weight. Information on elemental and compartmental body composition obtained through neutron activation analysis is useful, if not essential, for research on growth, malnutrition, aging diseases, such as osteoporosis and acquired immunodeficiency syndrome in which the progression of the illness is closely related to changes in major body compartments, such as bone, adipose tissue, and muscle. The DGNA system has been modified and upgraded several times since it was first built. Recently, all three systems underwent major upgrades. This upgrading and some preliminary studies carried out with the modified facilities are reported here.

  12. Study of proton and neutron activation of metal samples in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1984-01-01

    The analysis of the gamma-ray spectra taken from samples flown in Spacelab 1; the search for and review of neutron and proton activation cross-sections needed to analyze the results of the Long Duration Exposure Facility (LDEF) activation measurements; additional calculations of neutron induced activation for the LDEF samples; the data analysis plan for the LDEF and Spacelab 2 samples; the measurement of relevant cross-sections with activation of samples of V, Co, In, and Ta at the Indiana University Cyclotron Facility; and the preparation of an extended gamma-ray calibration source through the development of a proper technique to accurately deposit equal quantities of radioactive material onto a large number of point on the source are discussed.

  13. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC.

    PubMed

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-11-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed (28)Al, (24)Na, (54)Mn and (60)Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is (28)Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several (28)Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received.

  14. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC.

    PubMed

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-11-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed (28)Al, (24)Na, (54)Mn and (60)Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is (28)Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several (28)Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. PMID:26265661

  15. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC

    PubMed Central

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-01-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed 28Al, 24Na, 54Mn and 60Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is 28Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several 28Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. PMID:26265661

  16. neutron activation analysis using thermochromatography. II. thermochromatographic separation of elements in the analysis of geological samples

    SciTech Connect

    Sattarov, G.; Davydov, A.V.; Khamatov, S.; Kist, A.A.

    1986-07-01

    The use of gas thermochromatography (GTC) in the radioactivation analysis of difficulty soluble samples with a strongly activating substrate is discussed. The effect of sample coarseness and ore type on the rate of extraction of gold and accompanying elements was studied. The limits of detection of 22 elements were compared using neutron activation analysis with GTC and INAA. The analytical parameters of the procedure were estimated.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    The Pulsed Neutron Generator-Gamma Ray And Neutron Detectors (PNG-GRAND) experiment is an innovative application of the active neutron-gamma ray technology so successfully used in oil field well logging and mineral exploration on Earth. The objective of our active neutron-gamma ray technology program at NASA Goddard Space Flight Center (NASA-GSFC) is to bring the PNG-GRAND instrument to the point where it can be flown on a variety of surface lander or rover missions to the Moon, Mars, Menus, asteroids, comets and the satellites of the outer planets. Gamma-Ray Spectrometers (GRS) have been incorporated into numerous orbital planetary science missions and, especially its the case of the Mars Odyssey GRS, have contributed detailed maps of the elemental composition over the entire surface of Mars. However, orbital gamma ray measurements have low spatial sensitivity (100's of km) due to their low surface emission rates from cosmic rays and subsequent need to be averaged over large surface areas. PNG-GRAND overcomes this impediment by incorporating a powerful neutron excitation source that permits high sensitivity surface and subsurface measurements of bulk elemental compositions. PNG-GRAND combines a pulsed neutron generator (PNG) with gamma ray and neutron detectors to produce a landed instrument to determine subsurface elemental composition without needing to drill into a planet's surface a great advantage in mission design. We are currently testing PNG-GRAND prototypes at a unique outdoor neutron instrumentation test facility recently constructed at NASA/GSFC that consists of a 2 m x 2 in x 1 m granite structure placed outdoors in an empty field. Because an independent trace elemental analysis has been performed on the material, this granite sample is a known standard with which to compare both Monte Carlo simulations and our experimentally measured elemental composition data. We will present data from operating PNG-GRAND in various experimental configurations on a

  18. Boron-10 ABUNCL Active Testing

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2013-07-09

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from testing of the active mode of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) at Los Alamos National Laboratory using sources and fuel pins.

  19. Neutron-induced nucleation inside bubble chambers using Freon 115 as the active medium

    NASA Astrophysics Data System (ADS)

    Ghilea, M. C.; Meyerhofer, D. D.; Sangster, T. C.

    2011-08-01

    Neutron imaging is used in inertial confinement fusion (ICF) experiments to measure the core symmetry of imploded targets. Liquid bubble chambers have the potential to obtain higher resolution images of the targets for a shorter source-target distance than typical scintillator arrays. Due to the fact that nucleation models used in gel detectors research cannot always give correct estimates for the neutron-induced bubble density inside a liquid bubble chamber, an improved theoretical model to describe the mechanism of bubble formation for Freon 115 as the active medium has been developed. It shows that the size of the critical radius for the nucleation process determines the mechanism of bubble formation and the sensitivity of the active medium to the 14.1-MeV incident neutrons resulting from ICF implosions. The bubble-growth mechanism is driven by the excitation of the medium electronic levels and not by electrons ejected from the medium's atoms as happens for the bubble chambers used to detect charged particles. The model accurately predicts the neutron-induced bubble density measured on OMEGA with both liquid bubble chambers and gel detectors.

  20. Benchmark test of transport calculations of gold and nickel activation with implications for neutron kerma at Hiroshima.

    PubMed

    Hoshi, M; Hiraoka, M; Hayakawa, N; Sawada, S; Munaka, M; Kuramoto, A; Oka, T; Iwatani, K; Shizuma, K; Hasai, H

    1992-11-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a 252Cf fission neutron source to validate the use of the code for the energy spectrum analyses of Hiroshima atomic bomb neutrons. Nuclear data libraries used in the Monte Carlo neutron and photon transport code calculation were ENDF/B-III, ENDF/B-IV, LASL-SUB, and ENDL-73. The neutron moderators used were granite (the main component of which is SiO2, with a small fraction of hydrogen), Newlight [polyethylene with 3.7% boron (natural)], ammonium chloride (NH4Cl), and water (H2O). Each moderator was 65 cm thick. The neutron detectors were gold and nickel foils, which were used to detect thermal and epithermal neutrons (4.9 eV) and fast neutrons (> 0.5 MeV), respectively. Measured activity data from neutron-irradiated gold and nickel foils in these moderators decreased to about 1/1,000th or 1/10,000th, which correspond to about 1,500 m ground distance from the hypocenter in Hiroshima. For both gold and nickel detectors, the measured activities and the calculated values agreed within 10%. The slopes of the depth-yield relations in each moderator, except granite, were similar for neutrons detected by the gold and nickel foils. From the results of these studies, the Monte Carlo neutron and photon transport code was verified to be accurate enough for use with the elements hydrogen, carbon, nitrogen, oxygen, silicon, chlorine, and cadmium, and for the incident 252Cf fission spectrum neutrons. PMID:1399639

  1. Benchmark test of transport calculations of gold and nickel activation with implications for neutron kerma at Hiroshima.

    PubMed

    Hoshi, M; Hiraoka, M; Hayakawa, N; Sawada, S; Munaka, M; Kuramoto, A; Oka, T; Iwatani, K; Shizuma, K; Hasai, H

    1992-11-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a 252Cf fission neutron source to validate the use of the code for the energy spectrum analyses of Hiroshima atomic bomb neutrons. Nuclear data libraries used in the Monte Carlo neutron and photon transport code calculation were ENDF/B-III, ENDF/B-IV, LASL-SUB, and ENDL-73. The neutron moderators used were granite (the main component of which is SiO2, with a small fraction of hydrogen), Newlight [polyethylene with 3.7% boron (natural)], ammonium chloride (NH4Cl), and water (H2O). Each moderator was 65 cm thick. The neutron detectors were gold and nickel foils, which were used to detect thermal and epithermal neutrons (4.9 eV) and fast neutrons (> 0.5 MeV), respectively. Measured activity data from neutron-irradiated gold and nickel foils in these moderators decreased to about 1/1,000th or 1/10,000th, which correspond to about 1,500 m ground distance from the hypocenter in Hiroshima. For both gold and nickel detectors, the measured activities and the calculated values agreed within 10%. The slopes of the depth-yield relations in each moderator, except granite, were similar for neutrons detected by the gold and nickel foils. From the results of these studies, the Monte Carlo neutron and photon transport code was verified to be accurate enough for use with the elements hydrogen, carbon, nitrogen, oxygen, silicon, chlorine, and cadmium, and for the incident 252Cf fission spectrum neutrons.

  2. Analysis of the size, shape, and spatial distribution of microinclusions by neutron-activation autoradiography

    SciTech Connect

    Flitsiyan, E.S.; Romanovskii, A.V.; Gurvich, L.G.; Kist, A.A.

    1987-02-01

    The local concentration and spatial distribution of some elements in minerals, rocks, and ores can be determined by means of neutron-activation autoradiography. The local element concentration is measured in this method by placing an activated section of the rock to be analyzed, together with an irradiated standard, against a photographic emulsion which acts as a radiation detector. The photographic density of the exposed emulsion varies as a function of the tested element content in the part of the sample next to the detector. In order to assess the value of neutron-activation autoradiography in the analysis of element distribution, we considered the main factors affecting the production of selective autoradiographs, viz., resolution, detection limit, and optimal irradiation conditions, holding time, and exposure.

  3. New models for carrying out cyclic neutron activation. Discussion of the theoretical response

    NASA Astrophysics Data System (ADS)

    Castro-García, M. P.; Rey-Ronco, M. A.; Alonso-Sánchez, T.

    2014-11-01

    This paper studies two specific procedures for analyzing mining samples through a neutron activation technique called DGNAA (Delayed Gamma Neutron Activation Analysis). This particular study is part of a broader line of research, whose overall objective is to find the optimal procedure for analyzing the fluorite content of samples taken from different parts of a fluorite concentration plant, using the DGNAA method [1-2]. The mining sample is fluorspar, which contains other minerals in addition to fluorite, such as silica, barite, iron oxides and silicates. The main contribution of the article is the development of a new method for determining the fluorite content in minerals and the increase of sensitivity in respect to the symmetrical method and single-cycle activation.

  4. The affect of industrial activities on zinc in alluvial Egyptian soil determined using neutron activation analysis.

    PubMed

    Abdel-Sabour, M F; Abdel-Basset, N

    2002-07-01

    Thirty-two surface (0-20 cm) soil samples were collected from different locations in Egypt representing non-polluted, moderately and highly polluted soils. The aim of this study was to evaluate total Zn content in alluvial soils of Nile Delta in Egypt by using the delayed neutron activation analysis technique (DNAA), in the irradiation facilities of the first Egyptian research reactor (ET-RR-1). The gamma-ray spectra were recorded with a hyper pure germanium detection system. The well resolved gamma-ray peak at 1116.0 keV was efficiently used for 65Zn content determination. Zn content in non-polluted soil samples ranged between 74.1 and 103.8 ppm with an average of 98.5 +/- 5.1 ppm. Zn content in moderately polluted soils ranged between 136.0 and 232.5 ppm with an average of 180.1 +/- 32.6 ppm. The highest Zn levels ranging from 240.0 and 733.0 ppm with an average of 410.3 +/- 54.4 ppm, were observed in soil samples collected from, either highly polluted agricultural soils exposed to prolonged irrigation with industrial wastewater or surface soil samples from industrial sites. PMID:12211982

  5. New approach to calculate the true-coincidence effect of HpGe detector

    NASA Astrophysics Data System (ADS)

    Alnour, I. A.; Wagiran, H.; Ibrahim, N.; Hamzah, S.; Siong, W. B.; Elias, M. S.

    2016-01-01

    The corrections for true-coincidence effects in HpGe detector are important, especially at low source-to-detector distances. This work established an approach to calculate the true-coincidence effects experimentally for HpGe detectors of type Canberra GC3018 and Ortec GEM25-76-XLB-C, which are in operation at neutron activation analysis lab in Malaysian Nuclear Agency (NM). The correction for true-coincidence effects was performed close to detector at distances 2 and 5 cm using 57Co, 60Co, 133Ba and 137Cs as standard point sources. The correction factors were ranged between 0.93-1.10 at 2 cm and 0.97-1.00 at 5 cm for Canberra HpGe detector; whereas for Ortec HpGe detector ranged between 0.92-1.13 and 0.95-100 at 2 and 5 cm respectively. The change in efficiency calibration curve of the detector at 2 and 5 cm after correction was found to be less than 1%. Moreover, the polynomial parameters functions were simulated through a computer program, MATLAB in order to find an accurate fit to the experimental data points.

  6. Pax3 regulates morphogenetic cell behavior in vitro coincident with activation of a PCP/non-canonical Wnt-signaling cascade.

    PubMed

    Wiggan, O'Neil; Hamel, Paul A

    2002-02-01

    Mutations to Pax3 and other Pax family genes in both mice and humans result in numerous tissue-specific morphological defects. Little is known, however, about the cellular and molecular mechanisms by which Pax genes regulate morphogenesis. We previously showed that Pax3 induces cell aggregation and a mesenchymal-to-epithelial transition in Saos-2 cells. We show here that Pax3-induced aggregates arise through the formation of distinct structures involving cell rearrangements and cell behaviors resembling those that occur during gastrulation and neurulation known as convergent extension. During these Pax3-induced processes, Dishevelled and Frizzled are localized to the actin cytoskeleton and both proteins coimmunoprecipitate focal adhesion components from detergent-insoluble cell fractions. We show further that these Pax3-induced cell movements are associated with activation of a Wnt-signaling cascade, resulting in induction and activation of c-Jun-N-terminal kinase/stress activated protein kinase (JNK/SAPK). All of these Wnt-signaling factors exhibit altered subcellular distribution in Pax3-expressing cells. In particular, we show the localization of JNK/SAPK to both the nucleus and to cytoplasmic multi-vesicular structures. These data show that Pax3 regulates morphogenetic cell behavior and that regulation of a conserved, planar cell polarity/noncanonical Wnt-signaling cascade entailing JNK activation is a function of Pax3 activity.

  7. A History of In Vivo Neutron Activation Analysis in Measurement of Aluminum in Human Subjects.

    PubMed

    Mohseni, Hedieh K; Chettle, David R

    2016-01-01

    Aluminum, as an abundant metal, has gained widespread use in human life, entering the body predominantly as an additive to various foods and drinking water. Other major sources of exposure to aluminum include medical, cosmetic, and occupational routes. As a common environmental toxin, with well-known roles in several medical conditions such as dialysis encephalopathy, aluminum is considered a potential candidate in the causality of Alzheimer's disease. Aluminum mostly accumulates in the bone, which makes bone an indicator of the body burden of aluminum and an ideal organ as a proxy for the brain. Most of the techniques developed for measuring aluminum include bone biopsy, which requires invasive measures, causing inconvenience for the patients. There has been a considerable effort in developing non-invasive approaches, which allow for monitoring aluminum levels for medical and occupational purposes in larger populations. In vivo neutron activation analysis, a method based on nuclear activation of isotopes of elements in the body and their subsequent detection, has proven to be an invaluable tool for this purpose. There are definite challenges in developing in vivo non-invasive techniques capable of detecting low levels of aluminum in healthy individuals and aluminum-exposed populations. The following review examines the method of in vivo neutron activation analysis in the context of aluminum measurement in humans focusing on different neutron sources, interference from other activation products, and the improvements made in minimum detectable limits and patient dose over the past few decades.

  8. Consequences of Relativistic Neutron Outflow beyond the Accretion Disks of Active Galaxies

    NASA Astrophysics Data System (ADS)

    Ekejiuba, I. E.; Okeke, P. N.

    1993-05-01

    Three channels of relativistic electron injection in the jets of extragalactic radio sources (EGRSs) are discussed. With the assumption that an active galactic nucleus (AGN) is powered by a spinning supermassive black hole of mass ~ 10(8) M_⊙ which sits at the center of the nucleus and ingests matter and energy through an accretion disk, a model for extracting relativistic neutrons from the AGN is forged. In this model, the inelastic proton--proton and proton--photon interactions within the accretion disk, of relativistic protons with background thermal protons and photons, respectively, produce copious amounts of relativistic neutrons. These neutrons travel ballistically for ~ 10(3gamma_n ) seconds and escape from the disk before they decay. The secondary particles produced from the neutron decays then interact with the ambient magnetic field and/or other particles to produce the radio emissions observed in the jets of EGRSs. IEE acknowledges the support of the World Bank and the Federal University of Technology, Yola, Nigeria as well as the hospitality of Georgia State University.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  10. Soft coincidence in late acceleration

    SciTech Connect

    Campo, Sergio del; Herrera, Ramon; Pavon, Diego

    2005-06-15

    We study the coincidence problem of late cosmic acceleration by assuming that the present ratio between dark matter and dark energy is a slowly varying function of the scale factor. As the dark energy component we consider two different candidates, first a quintessence scalar field, and then a tachyon field. In either case analytical solutions for the scale factor, the field, and the potential are derived. Both models show a good fit to the recent magnitude-redshift supernovae data. However, the likelihood contours disfavor the tachyon field model as it seems to prefer a excessively high value for the matter component.

  11. Coincidence detection in phosphoinositide signaling

    PubMed Central

    Carlton, Jez G.; Cullen, Peter J.

    2006-01-01

    Phosphoinositide lipids function as both signaling molecules and as compartment-specific localization signals for phosphoinositide-binding proteins. In recent years, both phosphoinositides and phosphoinositide-binding proteins have been reported to display a restricted, rather than a uniform, distribution across intracellular membranes. Here, we examine recent data documenting the restricted distribution of both phosphoinositides and phosphoinositide-binding proteins and examine how phosphoinositide-binding proteins might engage multiple binding partners to achieve these restricted localizations, effectively acting as detectors of coincident localization signals. PMID:16139503

  12. A neutron activation analysis procedure for the determination of uranium, thorium and potassium in geologic samples

    USGS Publications Warehouse

    Aruscavage, P. J.; Millard, H.T.

    1972-01-01

    A neutron activation analysis procedure was developed for the determination of uranium, thorium and potassium in basic and ultrabasic rocks. The three elements are determined in the same 0.5-g sample following a 30-min irradiation in a thermal neutron flux of 2??1012 n??cm-2??sec-1. Following radiochemical separation, the nuclides239U (T=23.5 m),233Th (T=22.2 m) and42K (T=12.36 h) are measured by ??-counting. A computer program is used to resolve the decay curves which are complex owing to contamination and the growth of daughter activities. The method was used to determine uranium, throium and potassium in the U. S. Geological Survey standard rocks DTS-1, PCC-1 and BCR-1. For 0.5-g samples the limits of detection for uranium, throium and potassium are 0.7, 1.0 and 10 ppb, respectively. ?? 1972 Akade??miai Kiado??.

  13. Determination of thorium in seawater by neutron activation analysis and mass spectrometry

    SciTech Connect

    Huh, Chih-An

    1987-01-01

    The recent development of neutron activation analysis and mass spectrometric methods for the determination of /sup 232/Th in seawater has made possible rapid sampling and analysis of this long-lived, non-radiogenic thorium isotope on small-volume samples. The marine geochemical utility of /sup 232/Th, whose concentration in seawater is extremely low, warrants the development of these sensitive techniques. The analytical methods and some results are presented and discussed in this article. 24 refs., 3 figs.

  14. Survey of trace elements in coals and coal-related materials by neutron activation analysis

    USGS Publications Warehouse

    Ruch, R.R.; Cahill, R.A.; Frost, J.K.; Camp, L.R.; Gluskoter, H.J.

    1977-01-01

    Utilizing primarily instrumental neutron activation analysis (INAA) and other analytical methods as many as 61 elements were quantitatively surveyed in 170 U.S. whole coals, 70 washed coals, and 40 bench samples. Data on areal and vertical distributions in various regions were obtained along with extensive information on the mode of occurrence of various elements in the coal matrix itself. ?? 1977 Akade??miai Kiado??.

  15. Instrumental neutron activation analysis of soil and sediment samples from Siwa Oasis, Egypt

    NASA Astrophysics Data System (ADS)

    Badawy, Wael M.; Ali, Khaled; El-Samman, Hussein M.; Frontasyeva, Marina V.; Gundorina, Svetlana F.; Duliu, Octavian G.

    2015-07-01

    Instrumental neutron activation analysis was used to study geochemical peculiarities of the Siwa Oasis in the Western Egyptian Desert. A total of 34 elements were determined in soil and sediment samples (Na, Mg, Al, Cl, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Br, Rb, Sr, Zr, Sb, I, Cs, Ba, La, Ce, Nd, Eu, Tb, Dy, Tm, Yb, Hf, Ta, Th, and U). For data interpretation Cluster analysis was applied. Comparison with the available literature data was carried out.

  16. Neutron activation analysis of modern pottery: Insights for archaeological provenance research

    SciTech Connect

    Neff, H.; Arnold, D.E.; Benco, N.L.; Thieme, M.S.

    1996-12-31

    Neutron activation analysis has been employed to characterize ceramics and raw material samples from modern pottery-making communities. The original study focused on several villages in the central highlands of Guatemala. More recently, NAA data have been collected from communities in the Valley of Oaxaca, Mexico, the northern Yucatan Peninsula, and northern Morocco. The results from all four studies can now be combined to yield a comparative perspective on paste preparation effects in archaeological provenance research.

  17. Epithermal Neutron Activation Analysis of Some Geological Samples of Different Origin

    SciTech Connect

    Duliu, O. G.; Cristache, C. I.; Oaie, G.; Ricman, C.; Culicov, O. A.; Frontasyeva, M. V.

    2010-01-21

    Instrumental Epithermal Neutron Activation Analysis was used to investigate the distribution of six major elements and 34 trace elements in a set of eight igneous and metamorphic rocks collected from Carpathian and Macin Mountainsas well as unconsolidated sediments collected from anoxic zone of the Black Sea. All experimental data were interpreted within the Upper Continental Core and Mid Ocean Ridge Basalt model system that allowed getting more information concerning samples origin as well as the environmental peculiarities.

  18. Determination of selected trace elements in foodstuffs and biological materials by destructive neutron activation analysis.

    PubMed

    Bayat, I; Etehadiyan, M; Ansar, M

    1995-01-01

    Concentration of trace elements in Nescafé, Fariman sugar, and Sadaf turmeric and mercury content in cancerous blood were determined by radiochemical, neutron activation analysis. By this separation method levels of 110mAg, 198Au, 203Hg, 76Se, 51Cr, 24Na, 42K, 99Mo, 122Sb, 82Br, 59Fe, 60Co were measured without interference in the gamma spectroscopy. A nondestructive method has also been used for the analysis of sodium, potassium, and bromine. PMID:8748216

  19. Neutron activation analysis for reference determination of the implantation dose of cobalt ions

    SciTech Connect

    Garten, R.P.H.; Bubert, H.; Palmetshofer, L.

    1992-05-15

    The authors prepared depth profilling reference materials by cobalt ion implantation at an ion energy of 300 keV into n-type silicon. The implanted Co dose was then determined by instrumental neutron activation analysis (INAA) giving an analytical dynamic range of almost 5 decades and uncertainty of 1.5%. This form of analysis allows sources of error (beam spreading, misalignment) to be corrected. 70 refs., 3 tabs.

  20. HPGe well-type detectors for neutron activation measurements on the Frascati Tokamak Upgrade tokamak

    SciTech Connect

    Bertalot, L.; Damiani, M.; Esposito, B.; Lagamba, L.; Podda, S.; Batistoni, P.; De Felice, P.; Biagini, R.

    1997-01-01

    We describe an improvement of the neutron activation system in operation on the Frascati Tokamak Upgrade (FTU) tokamak for the measurement of the total neutron yield. A HPGe well-type detector (200 cm{sup 3} active volume) is used to detect the photoemission from neutron activated samples ({sup 115m}In336.2 keV {gamma} rays from DD neutrons on indium for FTU). Due to their high geometrical efficiency, HPGe well-type detectors are particularly suited to the FTU low-level activity measurements. A particular effort has been devoted to the calibration of the measuring system. In particular, a multi-{gamma} calibration source (59{endash}1332 keV energy range) with a density of 7.31 g/cm{sup 3} consisting of a stack of indium foils has been prepared. This assures that the shape and volume of the calibration source are the same as those of the samples used in the actual measurements. The full-energy-peak efficiency at the {sup 115m}In336.2 keV line is 0.197 with an overall uncertainty of 2{percent} (1{sigma}). For a better characterization of the detector response as a function of the sample density, a further calibration source with the same geometry has been prepared in a gel aqueous solution (density {approximately}1 g/cm{sup 3}). The calibration curves for the well-type detector at the two different density values are compared. {copyright} {ital 1997 American Institute of Physics.}

  1. A study of neutron radiation quality with a tissue-equivalent proportional counter for a low-energy accelerator-based in vivo neutron activation facility.

    PubMed

    Aslam; Waker, A J

    2011-02-01

    The accelerator-based in vivo neutron activation facility at McMaster University has been used successfully for the measurement of several minor and trace elements in human hand bones due to their importance to health. Most of these in vivo measurements have been conducted at a proton beam energy (E(p)) of 2.00 MeV to optimise the activation of the selected element of interest with an effective dose of the same order as that received in chest X rays. However, measurement of other elements at the same facility requires beam energies other than 2.00 MeV. The range of energy of neutrons produced at these proton beam energies comes under the region where tissue-equivalent proportional counters (TEPCs) are known to experience difficulty in assessing the quality factor and dose equivalent. In this study, the response of TEPCs was investigated to determine the quality factor of neutron fields generated via the (7)Li(p, n)(7)Be reaction as a function of E(p) in the range 1.884-2.56 MeV at the position of hand irradiation in the facility. An interesting trend has been observed in the quality factor based on ICRP 60, Q(ICRP60), such that the maximum value was observed at E(p)=1.884 MeV (E(n)=33±16 keV) and then continued to decline with increasing E(p) until achieving a minimum value at E(p)=2.0 MeV despite a continuous increase in the mean neutron energy with E(p). This observation is contrary to what has been observed with direct fast neutrons where the quality factor was found to increase continuously with an increase in E(p) (i.e. increasing E(n)). The series of measurements conducted with thermal and fast neutron fields demonstrate that the (14)N(n, p)(14)C produced 580 keV protons in the detector play an important role in the response of the counter under 2.0 MeV proton energy (E(n) ≤ 250 keV). In contrast to the lower response of TEPCs to low-energy neutrons, the quality factor is overestimated in the range 1-2 depending on beam energy <2.0 MeV. This study provides

  2. FY15 Status Report on NEAMS Neutronics Activities

    SciTech Connect

    Lee, C. H.; Shemon, E. R.; Smith, M. A.; Connaway, H. M.; Aliberti, G.

    2015-09-30

    This report summarizes the current status of NEAMS activities in FY2015. The tasks this year are (1) to improve solution methods for steady-state and transient conditions, (2) to develop features and user friendliness to increase the usability and applicability of the code, (3) to improve and verify the multigroup cross section generation scheme, (4) to perform verification and validation tests of the code using SFRs and thermal reactor cores, and (5) to support early users of PROTEUS and update the user manuals.

  3. Study of proton and neutron activation of metal samples in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1984-01-01

    Progress in the following activities has been made: the analysis of the gamma ray spectra taken from samples flown in Spacelab 2; the search for and review of neutron and proton activation cross sections needed to analyze the results of the Long Duration Exposure Facility (LDEF) activation measurements; the consideration given to data analysis of the LDEF and Spacelab 2 samples; the plan to measure relevant cross sections with nuclear accelerator measurements; and the preparation of an extended gamma ray calibration sources continues through planning and direct measurement of gamma ray efficiency for a Ge(Li) as a function of position along the surface of the detector housing.

  4. Facility for Ground Tests with Active Neutron Instrumentation for the Planetary Science Missions

    NASA Astrophysics Data System (ADS)

    Litvak, Maxim; Jun, Insoo; Kozyrev, Alexander; Mitrofanov, Igor; Sanin, Anton; Shvetsov, Valery; Starr, Richard; Timoshenko, Gennady

    2015-04-01

    To conduct a feasibility study of active neutron and gamma spectrometers a special radiation test facility has been developed and built at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. It has total area of about 62 m2 and with height from floor to roof up to 3.5 m. To provide measurements with prototypes of space instruments developed for the nuclear planetology applications and to test capabilities of such instruments we have designed and constructed special soil targets similar to planetary material with known elemental composition, appropriate geometry and layered structure. Here we also present results of first experimental work performed with a spare flight model of the DAN/MSL instrument selected as a flight prototype of an active neutron spectrometer applicable for the future landed missions to various solid solar system bodies. In our experiment we have tested the capability of neutron activation methods to detect thin layers of water/water ice lying on top of planetary dry regolith or buried within a dry regolith at different depths.

  5. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    DOEpatents

    Smith, D.L.; Ikeda, Yujiro; Uno, Yoshitomo

    1996-11-05

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the {sup 16}O(n,p){sup 16}N reaction using {sup 14}N-MeV neutrons produced at the neutron source via the {sup 3}H(d,n){sup 4}He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second {sup 16}N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1--2 minutes. 15 figs.

  6. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    DOEpatents

    Smith, Donald L.; Ikeda, Yujiro; Uno, Yoshitomo

    1996-01-01

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the .sup.16 O(n,p).sup.16 N reaction using .sup.14 -MeV neutrons produced at the neutron source via the .sup.3 H(d,n).sup.4 He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second .sup.16 N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1-2 minutes.

  7. Impurities analysis of polycrystalline silicon substrates: Neutronic Activation Analysis (NAA) and Secondary Ion Mass Spectrometry (SIMS)

    NASA Astrophysics Data System (ADS)

    Lounis, A.; Lenouar, K.; Gritly, Y.; Abbad, B.; Azzaz, M.; Taïbi, K.

    2010-01-01

    In this study we have determined the concentration of some impurities such as carbon, iron, copper, titanium, nickel of the flat product (polycrystalline silicon). These impurities generate a yield decrease in the photovoltaic components. The material (polycrystalline silicon) used in this work is manufactured by the Unit of Silicon Technology Development (UDTS Algiers, Algeria). The 80 kg ingot has been cutted into 16 briquettes in order to have plates (flat product) of 100 mm×100 mm dimensions. Each briquette is divided into three parts top (T), middle (M) and bottom (B). For this purpose, the following instrumental analysis techniques have been employed: neutronic analysis (neutronic activation analysis) and secondary ion mass spectrometry (SIMS). Masses of 80 mg are sampled and form of discs 18 mm in diameter, then exposed to a flux of neutron of 2.1012neutron cm-2 s-1 during 15 min. The energetic profile of incidental flux is constituted of fast neutrons (ΦR = 3.1012n.cm-2 s-1; E = 2 Mev), thermal neutrons (ΦTH = 1013n.cm-2 s-1; E = 0.025 ev) and epithermal neutrons (Φepi = 7.1011 n cm-2 s-1; E>4.9 ev), irradiation time 15 mn, after 20 mn of decrement, acquisitions of 300 s are carried out. The results are expressed by disintegration per second which does not exceed the 9000 Bq, 500 Bq and 2600 Bq, respectively for copper, titanium and nickel. It is observed that the impurities concentrations in the medium are higher. The impurities in the bottom of the ingots originate from the crucible. The impurities in the top originate from impurities dissolved in the liquid silicon, which have segregated to the top layer of the ingot and after solidification diffuse. Silicon corresponds to a mixture of three isotopes 28Si, 29Si and 30Si. These elements clearly appear on the mass spectrum (SIMS). The presence of iron and the one of nickel has been noticed.

  8. Alternative poly(A) site utilization during adenovirus infection coincides with a decrease in the activity of a poly(A) site processing factor.

    PubMed Central

    Mann, K P; Weiss, E A; Nevins, J R

    1993-01-01

    The recognition and processing of a pre-mRNA to create a poly(A) addition site, a necessary step in mRNA biogenesis, can also be a regulatory event in instances in which the frequency of use of a poly(A) site varies. One such case is found during the course of an adenovirus infection. Five poly(A) sites are utilized within the major late transcription unit to produce more than 20 distinct mRNAs during the late phase of infection. The proximal half of the major late transcription unit is also expressed during the early phase of a viral infection. During this early phase of expression, the L1 poly(A) site is used three times more frequently than the L3 poly(A) site. In contrast, the L3 site is used three times more frequently than the L1 site during the late phase of infection. Recent experiments have suggested that the recognition of the poly(A) site GU-rich downstream element by the CF1 processing factor may be a rate-determining step in poly(A) site selection. We demonstrate that the interaction of CF1 with the L1 poly(A) site is less stable than the interaction of CF1 with the L3 poly(A) site. We also find that there is a substantial decrease in the level of CF1 activity when an adenovirus infection proceeds to the late phase. We suggest that this reduction in CF1 activity, coupled with the relative instability of the interaction with the L1 poly(A) site, contributes to the reduced use of the L1 poly(A) site during the late stage of an adenovirus infection. Images PMID:8384308

  9. Neutron activation analysis of airborne thorium liberated during welding operations

    SciTech Connect

    Glasgow, D.C.; Robinson, L.; Janjovic, J.T.

    1996-02-01

    Typically, reactive metals such as aluminum are welded using a thoriated tungsten welding electrode which is attached to a source of argon gas such that the local atmosphere around the weld is inert. The metal is heated by the arc formed between the electrode and the grounded component to be welded. During this process, some of the electrode is vaporized in the arc and is potentially liberated to the surrounding air. This situation may result in a hazardous airborne thorium level. Because the electrode is consumed during welding, the electrode tip must be repeatedly dressed by grinding the tip to a fine point so that the optimal welding conditions are maintained. These grinding activities may also release thorium to the air. Data generated in the 1950s suggested that these electrodes posed no significant health hazard and seemed to justify their exemption from licensing requirements for source material. Since that time, other studies have been performed and present conflicting results as to the level of risk. Values both above and below the health protection limit in use in the United States, have been reported in the literature recently. This study is being undertaken to provide additional data which may be useful in evaluating both the chemical toxicity risk and radiological dose assessment criteria associated with thoriated tungsten welding operations.

  10. Neutron activation analysis of airborne thorium liberated during welding operations

    SciTech Connect

    Glasgow, D.C.; Robinson, L.; Jankovic, J.T.

    1996-12-31

    Typically, reactive metals such as aluminum are welded using a thoriated tungsten welding electrode that is attached to a source of argon gas such that the local atmosphere around the weld is inert. The metal is heated by the arc formed between the electrode and the grounded component to be welded. During this process, some of the electrode is vaporized in the arc and may be liberated to the surrounding air. This situation may result in a hazardous airborne thorium level. Because the electrode is consumed during welding, the electrode tip must be repeatedly dressed by grinding the tip to a fine point so that the optimal welding conditions are maintained. These grinding activities may also release thorium to the air. Data generated in the 1950s suggested that these electrodes posed no significant health hazard and seemed to justify their exemption from licensing requirements for source material. Since that time, other studies have been performed and present conflicting results as to the level of risk. Values both above and below the health protection limit in use in the United States have been reported in the literature recently. This study is being undertaken to provide additional data that may be useful in evaluating both the chemical toxicity risk and radiological dose assessment criteria associated with thoriated tungsten welding operations.

  11. Concepts for Alpha Coincidence Detection

    SciTech Connect

    Warren, Glen A.; Dion, Michael P.; Miller, Brian W.; Tatishvili, Gocha

    2015-03-01

    The effectiveness of conventional measurement techniques for environmental monitoring is limited by background and other interferences. We are exploring a new measurement approach involving the detection of α particles in coincidence with conversion electrons as a means to simultaneously assay environmental samples for actinides without chemical separation. The initial target isotopes studied in this work are 238Pu, 239Pu, 240Pu and 241Am. We explore various aspects of the design, such as impact of the mounting of the source material, resolution requirements and impact of a background on isotopic uncertainties. We conclude that a dual gas proportional counter and a dual-sided, large-area silicon detector could provide similar performance for the measurement scenario examined.

  12. Influence of neutron activation factors on matrix tablets for site specific delivery to the colon.

    PubMed

    Ahrabi, S F; Heinämäki, J; Sande, S A; Graffner, C

    2000-05-01

    The impact of the neutron activation procedure, i.e. incorporation of samarium oxide (Sm(2)O(3)) and neutron irradiation, on the compression properties (including the crushing strength) and in vitro dissolution of potential colonic delivery systems based on matrix tablets of amidated pectin (Am.P) or two types of hydroxypropyl methylcellulose (HPMC) was investigated. The neutron activation factors did not influence the compression properties of the tablets. Replacement of magnesium stearate with samarium stearate in directly compressed Am.P tablets to achieve both radiolabelling and lubrication resulted in a greater extent of concentration-dependent reduction of the crushing strength. Dissolution tests demonstrated that irradiation increased the release of the model drug ropivacaine from the tablets. The extent of this increase was unexpectedly low considering the previously observed degradation of the polymer expressed as an irradiation-induced viscosity reduction in solutions prepared from the polymers. Delayed-release coating with Eudragit L 100 protected the HPMC tablets against the release-increasing effect of irradiation until the late phases of release. Sm(2)O(3) retarded the release to a varying extent depending on particle characteristics. Incorporation of Sm(2)O(3) in the coating layer did not influence the release. However, one-third of the radioactivity leached from the coating within 60 min in 0.1 M HCl. PMID:10767600

  13. Neutron activation determination of iridium, gold, platinum, and silver in geologic samples

    USGS Publications Warehouse

    Millard, H.T.

    1987-01-01

    Low-level methods for the determination of iridium and other noble metals have become increasingly important in recent years due to interest in locating abundance anomalies associated with the Cretaceous and Tertiary (K-T) boundary. Typical iridium anomalies are in the range of 1 to 100 ??g/kg (ppb). Thus methods with detection limits near 0.1 ??g/kg should be adequate to detect K-T boundary anomalies. Radiochemical neutron activation analysis methods continue to be required although instrumental neutron activation analysis techniques employing elaborate gamma-counters are under development. In the procedure developed in this study samples irradiated in the epithermal neutron facility of the U. S. Geological Survey TRIGA Reactor (Denver, Colorado) are treated with a mini-fire assay technique. The iridium, gold, and silver are collected in a 1-gram metallic lead button. Primary contaminants at this stage are arsenic and antimony. These can be removed by heating the button with a mixture of sodium perioxide and sodium hydroxide. The resulting 0.2-gram lead bead is counted in a Compton suppression spectrometer. Carrier yields are determined by reirradiation of the lead beads. This procedure has been applied to the U.S.G.S. Standard Rock PCC-1 and samples from K-T boundary sites in the Western Interior of North America. ?? 1987 Akade??miai Kiado??.

  14. Pro-Inflammatory Endothelial Activation Detected by Molecular Imaging in Obese Non-Human Primates Coincides with the Onset of Insulin Resistance and Progressively Increases with Duration of Insulin Resistance

    PubMed Central

    Chadderdon, Scott M.; Belcik, J. Todd; Bader, Lindsay; Kirigiti, Melissa A.; Peters, Dawn M.; Kievit, Paul; Grove, Kevin L.; Lindner, Jonathan R.

    2014-01-01

    Background Inflammation and insulin resistance (IR) are associated processes that potentiate risk for cardiovascular disease in obesity. The temporal relation between IR and inflammation is not completely characterized. We hypothesized that endothelial cell adhesion molecule (ECAM) expression in large arteries is an early event that coincides with diet-induced obesity and IR in primates. Methods and Results Ten adult male rhesus macaques were studied at baseline and every 4-6 months on high-fat diet (HFD) for 2 years. Truncal fat, carotid intima-media thickness (IMT), plasma inflammatory biomarkers, and carotid P-selectin and VCAM-1 expression by contrast-enhanced ultrasound molecular imaging were assessed. Intravenous glucose tolerance test (IVGTT) was performed at baseline, 4 and 18 months. HFD produced a rapid increase (p<0.01) in weight, truncal fat, and degree of IR indicated by the insulin area-under-the-curve and glucose disappearance rate on IVGTT; all of which worsened minimally thereafter. Molecular imaging detected a progressive increase in ECAM expression over time (5-7-fold greater than control agent signal at 2 yrs, p<0.01). Changes in IMT were not detected until 2 years and, while there was a trend toward an increase in plasma markers of inflammation (MCP-1, CRP), the pattern of increase varied considerably over time. Conclusions In primates with diet-induced obesity, endothelial inflammatory activation is an early event that occurs coincident with the development of IR and long before any measurable change carotid IMT. Endothelial activation is more related to the duration rather than severity of IR and is not mirrored by changes in plasma biomarkers. PMID:24163066

  15. Activation cross sections for reactions induced by 14 MeV neutrons on natural tantalum

    SciTech Connect

    Luo Junhua; Tuo Fei; Kong Xiangzhong

    2009-05-15

    Cross sections for (n,2n), (n,p), (n,n{sup '}{alpha}), (n,t), (n,d{sup '}), and (n,{alpha}) reactions have been measured on tantalum isotopes at the neutron energies of 13.5 to 14.7 MeV using the activation technique. Data are reported for the following reactions: {sup 181}Ta(n,2n){sup 180}Ta{sup g}, {sup 181}Ta(n,p){sup 181}Hf, {sup 181}Ta(n,n{sup '}{alpha}){sup 177}Lu{sup m}, {sup 181}Ta(n,t){sup 179}Hf{sup m2}, {sup 181}Ta(n,d{sup '}){sup 180}Hf{sup m}, and {sup 181}Ta(n,{alpha}){sup 178}Lu{sup m}. The neutron fluences were determined using the monitor reaction {sup 27}Al(n,{alpha}){sup 24}Na. Results were discussed and compared with the previous works.

  16. The feasibility of well-logging measurements of arsenic levels using neutron-activation analysis

    USGS Publications Warehouse

    Oden, C.P.; Schweitzer, J.S.; McDowell, G.M.

    2006-01-01

    Arsenic is an extremely toxic metal, which poses a significant problem in many mining environments. Arsenic contamination is also a major problem in ground and surface waters. A feasibility study was conducted to determine if neutron-activation analysis is a practical method of measuring in situ arsenic levels. The response of hypothetical well-logging tools to arsenic was simulated using a readily available Monte Carlo simulation code (MCNP). Simulations were made for probes with both hyperpure germanium (HPGe) and bismuth germanate (BGO) detectors using accelerator and isotopic neutron sources. Both sources produce similar results; however, the BGO detector is much more susceptible to spectral interference than the HPGe detector. Spectral interference from copper can preclude low-level arsenic measurements when using the BGO detector. Results show that a borehole probe could be built that would measure arsenic concentrations of 100 ppm by weight to an uncertainty of 50 ppm in about 15 min. ?? 2006 Elsevier Ltd. All rights reserved.

  17. Determination of inorganic components in Brazilian medicinal plants by neutron activation analysis.

    PubMed

    Saiki, M; Vasconcellos, M B; Sertié, J A

    1990-01-01

    Instrumental neutron activation analysis (INAA) has been applied to multielemental determinations of medicinal extracts obtained from the plants. Cordia Verbenacea DC, Folidago Microglossa DC, and Petiveria Alliacea. Concentrations of the elements Al, Br, Ca, Cl, Co, Cs, Fe, K, La, Mg, Mn, Na, Rb, Sb, and Zn have been determined in dried extracts of these herbs by short and long irradiations under a thermal neutron flux of 10(11)-10(13) n/cm2s in the IEA-R1 nuclear reactor. The NBS Tea Leaves (1572) and NIES Pepperbush (1) reference materials were analyzed simultaneously with the plant extracts. The results obtained in these analyses have shown a good accuracy and reproducibility of the method. The relative errors and the relative standard deviations were less than 10% for most of the elements analyzed.

  18. Estimation of the Performance of Multiple Active Neutron Interrogation Signatures for Detecting Shielded HEU

    SciTech Connect

    David L. Chichester; Scott J. Thompson; Scott M. Watson; James T. Johnson; Edward H. Seabury

    2012-10-01

    A comprehensive modeling study has been carried out to evaluate the utility of multiple active neutron interrogation signatures for detecting shielded highly enriched uranium (HEU). The modeling effort focused on varying HEU masses from 1 kg to 20 kg; varying types of shields including wood, steel, cement, polyethylene, and borated polyethylene; varying depths of the HEU in the shields, and varying engineered shields immediately surrounding the HEU including steel, tungsten, and cadmium. Neutron and gamma-ray signatures were the focus of the study and false negative detection probabilities versus measurement time were used as a performance metric. To facilitate comparisons among different approaches an automated method was developed to generate receiver operating characteristic (ROC) curves for different sets of model variables for multiple background count rate conditions. This paper summarizes results or the analysis, including laboratory benchmark comparisons between simulations and experiments. The important impact engineered shields can play towards degrading detectability and methods for mitigating this will be discussed.

  19. Performance of an improved thermal neutron activation detector for buried bulk explosives

    NASA Astrophysics Data System (ADS)

    McFee, J. E.; Faust, A. A.; Andrews, H. R.; Clifford, E. T. H.; Mosquera, C. M.

    2013-06-01

    First generation thermal neutron activation (TNA) sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on multi-sensor landmine detection systems. The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. The sensor is described, with emphasis on the improvements. Experiments to characterize the performance of the second generation TNA in detecting buried landmines and improvised explosive devices (IEDs) hidden in culverts are described. Performance results, including comparisons between the performance of the first and second generation systems are presented.

  20. Workplace testing of the new single sphere neutron spectrometer based on Dysprosium activation foils (Dy-SSS)

    NASA Astrophysics Data System (ADS)

    Bedogni, R.; Gómez-Ros, J. M.; Esposito, A.; Gentile, A.; Chiti, M.; Palacios-Pérez, L.; Angelone, M.; Tana, L.

    2012-08-01

    A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).

  1. SU-E-T-543: Measurement of Neutron Activation From Different High Energy Varian Linear Accelerators

    SciTech Connect

    Thatcher, T; Madsen, S; Sudowe, R; Meigooni, A Soleimani

    2015-06-15

    Purpose: Linear accelerators producing photons above 10 MeV may induce photonuclear reactions in high Z components of the accelerator. These liberated neutrons can then activate the structural components of the accelerator and other materials in the beam path through neutron capture reactions. The induced activity within the accelerator may contribute to additional dose to both patients and personnel. This project seeks to determine the total activity and activity per activated isotope following irradiation in different Varian accelerators at energies above 10 MeV. Methods: A Varian 21IX accelerator was used to irradiate a 30 cm × 30 cm × 20 cm solid water phantom with 15 MV x-rays. The phantom was placed at an SSD of 100 cm and at the center of a 20 cm × 20 cm field. Activation induced gamma spectra were acquired over a 5 minute interval after 1 and 15 minutes from completion of the irradiation. All measurements were made using a CANBERRA Falcon 5000 Portable HPGe detector. The majority of measurements were made in scattering geometry with the detector situated at 90° to the incident beam, 30 cm from the side of the phantom and approximately 10 cm from the top. A 5 minute background count was acquired and automatically subtracted from all subsequent measurements. Photon spectra were acquired for both open and MLC fields. Results: Based on spectral signatures, nuclides have been identified and their activities calculated for both open and MLC fields. Preliminary analyses suggest that activities from the activation products in the microcurie range. Conclusion: Activation isotopes have been identified and their relative activities determined. These activities are only gross estimates since efficiencies have not been determined for this source-detector geometry. Current efforts are focused on accurate determination of detector efficiencies using Monte Carlo calculations.

  2. Tracing footprints of environmental events in tree ring chemistry using neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Sahin, Dagistan

    The aim of this study is to identify environmental effects on tree-ring chemistry. It is known that industrial pollution, volcanic eruptions, dust storms, acid rain and similar events can cause substantial changes in soil chemistry. Establishing whether a particular group of trees is sensitive to these changes in soil environment and registers them in the elemental chemistry of contemporary growth rings is the over-riding goal of any Dendrochemistry research. In this study, elemental concentrations were measured in tree-ring samples of absolutely dated eleven modern forest trees, grown in the Mediterranean region, Turkey, collected and dated by the Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology laboratory at Cornell University. Correlations between measured elemental concentrations in the tree-ring samples were analyzed using statistical tests to answer two questions. Does the current concentration of a particular element depend on any other element within the tree? And, are there any elements showing correlated abnormal concentration changes across the majority of the trees? Based on the detailed analysis results, the low mobility of sodium and bromine, positive correlations between calcium, zinc and manganese, positive correlations between trace elements lanthanum, samarium, antimony, and gold within tree-rings were recognized. Moreover, zinc, lanthanum, samarium and bromine showed strong, positive correlations among the trees and were identified as possible environmental signature elements. New Dendrochemistry information found in this study would be also useful in explaining tree physiology and elemental chemistry in Pinus nigra species grown in Turkey. Elemental concentrations in tree-ring samples were measured using Neutron Activation Analysis (NAA) at the Pennsylvania State University Radiation Science and Engineering Center (RSEC). Through this study, advanced methodologies for methodological, computational and

  3. Near Threshold Coincident Electrofission of Uranium -238.

    NASA Astrophysics Data System (ADS)

    Dowell, David Harry

    Using the 100% duty cycle electron beam from the University of Illinois MUSL-2 accelerator, inelastic electron scattering form factors have been measured in coincidence with the fission decay of ('238)U. Data was taken at effective elastic momentum transfers of .36, .41 .45 and .59 fm(' -1) and electron-fission fragment angular correlations were measured perpendicular to and along the momentum transfer axis. The beam energies used were 67.11, 56.91 and 46.49 MeV, with the outgoing electron detected at 60(DEGREES) and 80(DEGREES), relative to the beam direction. The electron energy resolution was .1% and the form factors were measured for excitation energies from 2 to 12 MeV. Thin films of scintillator plastic (.5 mg/cm('2)) were used to detect the fission fragments from a 1 mg/cm('2) UF(,4) target evaporated onto a .240 mg/cm('2) aluminum backing. A prominent, anisotropic threshold peak is seen in the coincident form factors. An analysis of the q-dependence of the data and of the angular correlation indicates the observed strength is E2. Fission threshold for this E2 strength is about 5.7 MeV as compared with 6 MeV for E1 decays. The peak itself is due to the onset of neutron competition at 6.15 MeV. The threshold region, when analyzed using a Gaussian K-distribution to describe the statistical density of K -states near the fission barrier, exhibits a step-like change in the value of K(,0)('2) at .7 MeV above threshold. This indicates a possible energy gap in the E2 transition states. The decay is isotropic above 7.5 MeV excitation energy. From 7 to 11.7 MeV, the distribution of E2/EO strength is relatively flat with the total strength in this region exhausting approximately 10% of an energy weighted sum rule. A comparison with hadron scattering experiments suggests that some of the strength near 11.5 MeV is due to the fission decay of the giant monopole resonance with a fission probability similar to that of E2 transitions.

  4. A new active method for the measurement of slow-neutron fluence in modern radiotherapy treatment rooms

    NASA Astrophysics Data System (ADS)

    Gómez, F.; Iglesias, A.; Sánchez Doblado, F.

    2010-02-01

    This work focuses on neutron monitoring at clinical linac facilities during high-energy modality radiotherapy treatments. Active in-room measurement of neutron fluence is a complex problem due to the pulsed nature of the fluence and the presence of high photon background, and only passive methods have been considered reliable until now. In this paper we present a new active method to perform real-time measurement of neutron production around a medical linac. The device readout is being investigated as an estimate of patient neutron dose exposure on each radiotherapy session. The new instrument was developed based on neutron interaction effects in microelectronic memory devices, in particular using neutron-sensitive SRAM devices. This paper is devoted to the description of the instrument and measurement techniques, presenting the results obtained together with their comparison and discussion. Measurements were performed in several standard clinical linac facilities, showing high reliability, being insensitive to the photon fluence and EM pulse present inside the radiotherapy room, and having detector readout statistical relative uncertainties of about 2% on measurement of neutron fluence produced by 1000 monitor units irradiation runs.

  5. Using CHIMERA detector at LNS for gamma-particle coincidences

    NASA Astrophysics Data System (ADS)

    Cardella, G.; Acosta, L.; Auditore, L.; Chatterjiee, M. B.; Castoldi, A.; De Filippo, E.; Dell'Aquila, D.; De Luca, S.; Gnoffo, B.; Guazzoni, C.; Francalanza, L.; Lanzalone, G.; Lombardo, I.; Martorana, N.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2016-05-01

    We have recently evaluated the quality of γ-ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ-rays have been detected using the CsI(Tl) detectors of the spherical part of the CHIMERA array. Very clean γ-rays angular distributions were extracted in reactions induced by different stable beams impinging on 12C thin targets. The results evidenced an effect of projectile spin flip on the γ-rays angular distributions. γ-particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.

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

    SciTech Connect

    Livingston, R. A.; Al-Sheikhly, M.; Grissom, C.; Aloiz, E.; Paul, R.

    2014-02-18

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

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

    SciTech Connect

    Staples, P.; Prettyman, T.; Lestone, J.

    1998-12-01

    The authors have used a tomographic gamma scanner (TGS) to produce tomographic prompt gamma-ray neutron activation analysis imaging (PGNAA) of heterogeneous matrices. The TGS was modified by the addition of graphite reflectors that contain isotopic neutron sources for sample interrogation. The authors are in the process of developing the analysis methodology necessary for a quantitative assay of large containers of heterogeneous material. This nondestructive analysis (NDA) technique can be used for material characterization and the determination of neutron assay correction factors. The most difficult question to be answered is the determination of the source-to-sample coupling term. To assist in the determination of the coupling term, the authors have obtained images for a range of sample that are very well characterized, such as, homogenous pseudo one-dimensional samples to three-dimensional heterogeneous samples. They then compare the measurements to MCNP calculations. For an accurate quantitative measurement, it is also necessary to determine the sample gamma-ray self attenuation at higher gamma-ray energies, namely pair production should be incorporated into the analysis codes.

  8. The Prompt Gamma Neutron Activation Analysis Facility at ICN-Pitesti

    SciTech Connect

    Barbos, D.; Paunoiu, C.; Mladin, M.; Cosma, C.

    2008-08-14

    PGNAA is a very widely applicable technique for determining the presence and amount of many elements simultaneously in samples ranging in size from micrograms to many grams. PGNAA is characterized by its capability for nondestructive multi-elemental analysis and its ability to analyse elements that cannot be determined by INAA. By means of this PGNAA method we are able to increase the performance of INAA method. A facility has been developed at Institute for Nuclear Research-Pitesti so that the unique features of prompt gamma-ray neutron activation analysis can be used to measure trace and major elements in samples. The facility is linked at the radial neutron beam tube at ACPR-TRIGA reactor. During the PGNAA-facility is in use the ACPR reactor will be operated in steady-state mode at 250 KW maximum power. The facility consists of a radial beam-port, external sample position with shielding, and induced prompt gamma-ray counting system.Thermal neutron flux with energy lower than cadmium cut-off at the sample position was measured using thin gold foil is: {phi}{sub scd} = 1.10{sup 6} n/cm{sup 2}/s with a cadmium ratio of:80.The gamma-ray detection system consist of an HpGe detector of 16% efficiency (detector model GC1518) with 1.85 keV resolution capability. The HpGe is mounted with its axis at 90 deg. with respect to the incident neutron beam at distance about 200mm from the sample position. To establish the performance capabilities of the facility, irradiation of pure element or sample compound standards were performed to identify the gama-ray energies from each element and their count rates.

  9. Artifacts in digital coincidence timing

    SciTech Connect

    Moses, W. W.; Peng, Q.

    2014-10-16

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.

  10. Multiverse understanding of cosmological coincidences

    SciTech Connect

    Bousso, Raphael; Hall, Lawrence J.; Nomura, Yasunori

    2009-09-15

    There is a deep cosmological mystery: although dependent on very different underlying physics, the time scales of structure formation, of galaxy cooling (both radiatively and against the CMB), and of vacuum domination do not differ by many orders of magnitude, but are all comparable to the present age of the universe. By scanning four landscape parameters simultaneously, we show that this quadruple coincidence is resolved. We assume only that the statistical distribution of parameter values in the multiverse grows towards certain catastrophic boundaries we identify, across which there are drastic regime changes. We find order-of-magnitude predictions for the cosmological constant, the primordial density contrast, the temperature at matter-radiation equality, the typical galaxy mass, and the age of the universe, in terms of the fine structure constant and the electron, proton and Planck masses. Our approach permits a systematic evaluation of measure proposals; with the causal patch measure, we find no runaway of the primordial density contrast and the cosmological constant to large values.

  11. An investigation of the neutron flux in bone-fluorine phantoms comparing accelerator based in vivo neutron activation analysis and FLUKA simulation data

    NASA Astrophysics Data System (ADS)

    Mostafaei, F.; McNeill, F. E.; Chettle, D. R.; Matysiak, W.; Bhatia, C.; Prestwich, W. V.

    2015-01-01

    We have tested the Monte Carlo code FLUKA for its ability to assist in the development of a better system for the in vivo measurement of fluorine. We used it to create a neutron flux map of the inside of the in vivo neutron activation analysis irradiation cavity at the McMaster Accelerator Laboratory. The cavity is used in a system that has been developed for assessment of fluorine levels in the human hand. This study was undertaken to (i) assess the FLUKA code, (ii) find the optimal hand position inside the cavity and assess the effects on precision of a hand being in a non-optimal position and (iii) to determine the best location for our γ-ray detection system within the accelerator beam hall. Simulation estimates were performed using FLUKA. Experimental measurements of the neutron flux were performed using Mn wires. The activation of the wires was measured inside (1) an empty bottle, (2) a bottle containing water, (3) a bottle covered with cadmium and (4) a dry powder-based fluorine phantom. FLUKA was used to simulate the irradiation cavity, and used to estimate the neutron flux in different positions both inside, and external to, the cavity. The experimental results were found to be consistent with the Monte Carlo simulated neutron flux. Both experiment and simulation showed that there is an optimal position in the cavity, but that the effect on the thermal flux of a hand being in a non-optimal position is less than 20%, which will result in a less than 10% effect on the measurement precision. FLUKA appears to be a code that can be useful for modeling of this type of experimental system.

  12. Monte-Carlo simulations of neutron-induced activation in a Fast-Neutron and Gamma-Based Cargo Inspection System

    NASA Astrophysics Data System (ADS)

    Bromberger, B.; Bar, D.; Brandis, M.; Dangendorf, V.; Goldberg, M. B.; Kaufmann, F.; Mor, I.; Nolte, R.; Schmiedel, M.; Tittelmeier, K.; Vartsky, D.; Wershofen, H.

    2012-03-01

    An air cargo inspection system combining two nuclear reaction based techniques, namely Fast-Neutron Resonance Radiography and Dual-Discrete-Energy Gamma Radiography is currently being developed. This system is expected to allow detection of standard and improvised explosives as well as special nuclear materials. An important aspect for the applicability of nuclear techniques in an airport inspection facility is the inventory and lifetimes of radioactive isotopes produced by the neutron radiation inside the cargo, as well as the dose delivered by these isotopes to people in contact with the cargo during and following the interrogation procedure. Using MCNPX and CINDER90 we have calculated the activation levels for several typical inspection scenarios. One example is the activation of various metal samples embedded in a cotton-filled container. To validate the simulation results, a benchmark experiment was performed, in which metal samples were activated by fast-neutrons in a water-filled glass jar. The induced activity was determined by analyzing the gamma spectra. Based on the calculated radioactive inventory in the container, the dose levels due to the induced gamma radiation were calculated at several distances from the container and in relevant time windows after the irradiation, in order to evaluate the radiation exposure of the cargo handling staff, air crew and passengers during flight. The possibility of remanent long-lived radioactive inventory after cargo is delivered to the client is also of concern and was evaluated.

  13. Determination of hydrogen in metals, semiconductors, and other materials by cold neutron prompt gamma-ray activation analysis

    SciTech Connect

    Paul, R.L.; Lindstrom, R.M.

    1998-12-31

    Cold neutron prompt gamma-ray activation analysis has proven useful for nondestructive measurement of trace hydrogen. The sample is irradiated in a beam of neutrons; the presence of hydrogen is confirmed by the emission of a 2223 keV gamma-ray. Detection limits for hydrogen are 3 mg/kg in quartz and 8 mg/kg in titanium. The authors have used the technique to measure hydrogen in titanium alloys, germanium, quartz, fullerenes and their derivatives, and other materials.

  14. Gamma neutron assay method and apparatus

    DOEpatents

    Cole, J.D.; Aryaeinejad, R.; Greenwood, R.C.

    1995-01-03

    The gamma neutron assay technique is an alternative method to standard safeguards techniques for the identification and assaying of special nuclear materials in a field or laboratory environment, as a tool for dismantlement and destruction of nuclear weapons, and to determine the isotopic ratios for a blend-down program on uranium. It is capable of determining the isotopic ratios of fissionable material from the spontaneous or induced fission of a sample to within approximately 0.5%. This is based upon the prompt coincidence relationships that occur in the fission process and the proton conservation and quasi-conservation of nuclear mass (A) that exists between the two fission fragments. The system is used in both passive (without an external neutron source) and active (with an external neutron source) mode. The apparatus consists of an array of neutron and gamma-ray detectors electronically connected to determine coincident events. The method can also be used to assay radioactive waste which contains fissile material, even in the presence of a high background radiation field. 7 figures.

  15. Gamma neutron assay method and apparatus

    DOEpatents

    Cole, Jerald D.; Aryaeinejad, Rahmat; Greenwood, Reginald C.

    1995-01-01

    The gamma neutron assay technique is an alternative method to standard safeguards techniques for the identification and assaying of special nuclear materials in a field or laboratory environment, as a tool for dismantlement and destruction of nuclear weapons, and to determine the isotopic ratios for a blend-down program on uranium. It is capable of determining the isotopic ratios of fissionable material from the spontaneous or induced fission of a sample to within approximately 0.5%. This is based upon the prompt coincidence relationships that occur in the fission process and the proton conservation and quasi-conservation of nuclear mass (A) that exists between the two fission fragments. The system is used in both passive (without an external neutron source and active (with an external neutron source) mode. The apparatus consists of an array of neutron and gamma-ray detectors electronically connected to determine coincident events. The method can also be used to assay radioactive waste which contains fissile material, even in the presence of a high background radiation field.

  16. Analysis of 125Xe electron–photon coincidence decay

    SciTech Connect

    Klingberg, Franziska J.; Biegalski, Steven R.; Prinke, Amanda; Haas, Derek A.; Lowrey, Justin D.

    2015-10-26

    In this study, as part of the verification component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), environmental gas samples originating from nuclear fission are analyzed for the presence of 131mXe, 133mXe, 133Xe, and 135Xe. In this work, the non-traditional radioxenon isotope 125Xe was investigated. The isotope was produced as an isotopically pure sample via neutron activation of 124Xe at the University of Texas at Austin Nuclear Engineering Teaching Lab’s TRIGA MARK II Reactor. The sample was then measured using a HPGe detector as well as an ARSA-style β–γ coincidence detector. Potential sources and sensitivities for production of 125Xe are also considered for relevance to the CTBT verification mission.

  17. L'analyse par activation de neutrons de réacteur

    NASA Astrophysics Data System (ADS)

    Meyer, G.

    2003-02-01

    Quand les neutrons traversent la matière, certains sont transmis sans interaction, les autres interagissent avec le milieu traversé par diffusion et par absorption. Ce phénomène d'absorption est utilisé pour se protéger des neutrons, mais aussi pour les détecter; il peut également être utilisé pour identifier les noyaux “absorbants" et ainsi analyser le milieu traversé. En effet par différentes réactions nucléaires (n,γ), (n,p), (n,α), (n,fission), on obtient des noyaux résiduels qui sont souvent radioactifs; on dit que l'échantillon est “activé". Si l'on connaît le rendement d'activation et donc le pourcentage de noyaux ainsi “transmutés", les mesures de radioactivité induite vont permettre de déterminer la composition de l'échantillon irradié. Cette méthode dite d'analyse par activation neutronique est pratiquée depuis la découverte du neutron. Elle a permis grâce à sa sélectivité et à sa sensibilité d'avoir accès au domaine des traces et des ultra-traces dans des champs d'application très divers comme la métallurgie, l'archéologie, la biologie, la géochimie etc...

  18. Preconcentration with dithiocarbamate extraction for determination of molybdenum in seawater by neutron activation analysis

    SciTech Connect

    Mok, W.M.; Wai, C.M.

    1984-01-01

    Molybdenum in seawater can be quantitatively extracted with pyrrolidinedithiocarbamate and diethyldithiocarbamate at pH 1.4 into chloroform, for neutron activation analysis. Uranium in seawater cannot be extracted at this pH, and hence eliminates the interference from the /sup 235/U(n,f)/sup 99/Mo reaction. Interferences from matrix species in seawater, such as sodium and bromine, are also removed during the extraction. The proposed method, with good accuracy and sensitivity, is suitable for the determination of molybdenum in natural waters. 10 references, 2 figures.

  19. Determination of alumina in sintered aluminium powder by activation with 14-MeV neutrons.

    PubMed

    Español, C E; Marafuschi, A M

    1970-07-01

    Fast neutrons of 14 MeV produced in the IMICAM CISE 150-kV generator by the (d, t) reaction in a tritium-titanium target, were used in the indirect determination of Al(2)O(3). The samples were irradiated for 30 sec and the total (16)N activity was determined, by counting for ten 2-sec periods and graphically integrating. The standards were a known sintered aluminium powder and nylon pieces of identical shape. The method is competitive with the chemical one, because of its quickness, sensitivity and precision. PMID:18960787

  20. Multi-element analysis of emeralds and associated rocks by k(o) neutron activation analysis

    PubMed

    Acharya; Mondal; Burte; Nair; Reddy; Reddy; Reddy; Manohar

    2000-12-01

    Multi-element analysis was carried out in natural emeralds, their associated rocks and one sample of beryl obtained from Rajasthan, India. The concentrations of 21 elements were assayed by Instrumental Neutron Activation Analysis using the k0 method (k0 INAA method) and high-resolution gamma ray spectrometry. The data reveal the segregation of some elements from associated (trapped and host) rocks to the mineral beryl forming the gemstones. A reference rock standard of the US Geological Survey (USGS BCR-1) was also analysed as a control of the method.

  1. Determination of carrier yields for neutron activation analysis using energy dispersive X-ray spectrometry

    USGS Publications Warehouse

    Johnson, R.G.; Wandless, G.A.

    1984-01-01

    A new method is described for determining carrier yield in the radiochemical neutron activation analysis of rare-earth elements in silicate rocks by group separation. The method involves the determination of the rare-earth elements present in the carrier by means of energy-dispersive X-ray fluorescence analysis, eliminating the need to re-irradiate samples in a nuclear reactor after the gamma ray analysis is complete. Results from the analysis of USGS standards AGV-1 and BCR-1 compare favorably with those obtained using the conventional method. ?? 1984 Akade??miai Kiado??.

  2. Selenium contents in tobacco and main stream cigarette smoke determined using neutron activation analysis

    SciTech Connect

    Sorak-Pokrajac, M.; Dermelj, M.; Slejkovec, Z.

    1994-01-01

    In the domain of the essential trace elements, the role of selenium is extremely important. As one of the volatile elements it can be partly absorbed through the pulmonary system during smoking and transported to different organs of the body. Thus a knowledge of its concentration levels in various sorts of tobacco and in the smoke of commercial cigarettes, as well as in the same type of cigarettes from plants treated with selenium, is of interest for various research fields. The purpose of this contribution is to present reliable quantitative data on selenium contents in tobacco, soil, and main stream cigarette smoke, obtained by destructive neutron activation analysis.

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

    USGS Publications Warehouse

    Devine, T.; Peterle, T.J.

    1968-01-01

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

  4. Evaluation of homogeneity of a certified reference material by instrumental neutron activation analysis

    SciTech Connect

    Kratochvil, B.; Duke, M.J.M.; Ng, D.

    1986-01-01

    The homogeneity of the marine reference material TORT-1, a spray-dried and acetone-extracted hepatopancreatic material from the lobster, was tested for 26 elements by instrumental neutron activation analysis (INAA). Through a one-way analysis of variance based on six analyses on each of six bottles of TORT-1, it was concluded that the between-bottle heterogeneity is no greater than the within-bottle heterogeneity. The analytical results for those elements for which values were provided by NRC agree with the NRC values within 95% confidence limits. 8 references, 6 tables.

  5. The determination of uranium in food samples by Compton suppression epithermal neutron activation analysis.

    PubMed

    Kapsimalis, R; Landsberger, S; Ahmed, Y A

    2009-12-01

    Eight foods common to the Nigerian diet were analyzed for trace amounts of uranium using epithermal neutron activation analysis. Food sample sizes of roughly one-half gram, irradiated for 10 min, with a 15 min decay time and counting time for 10 min yielded detection limits between 0.02 and 0.04 Bq/kg. Dried milk, chicken pasta, spaghetti and biscuits had less than detectable amounts of uranium, while sorghum, wheat and brown beans contained 0.73, 0.23 and 0.16 Bq/kg, respectively.

  6. Multi-element analysis of emeralds and associated rocks by k(o) neutron activation analysis

    PubMed

    Acharya; Mondal; Burte; Nair; Reddy; Reddy; Reddy; Manohar

    2000-12-01

    Multi-element analysis was carried out in natural emeralds, their associated rocks and one sample of beryl obtained from Rajasthan, India. The concentrations of 21 elements were assayed by Instrumental Neutron Activation Analysis using the k0 method (k0 INAA method) and high-resolution gamma ray spectrometry. The data reveal the segregation of some elements from associated (trapped and host) rocks to the mineral beryl forming the gemstones. A reference rock standard of the US Geological Survey (USGS BCR-1) was also analysed as a control of the method. PMID:11077961

  7. In vivo Prompt Gamma Neutron Activation Analysis Facility for Total Body Nitrogen and Cd

    SciTech Connect

    Munive, Marco; Revilla, Angel; Solis, Jose L.

    2007-10-26

    A Prompt Gamma Neutron Activation Analysis (PGNAA) system has been designed and constructed to measure the total body nitrogen and Cd for in vivo studies. An aqueous solution of KNO{sub 3} was used as phantom for system calibration. The facility has been used to monitor total body nitrogen (TBN) of mice and found that is related to their diet. Some mice swallowed diluted water with Cl{sub 2}Cd, and the presence of Cd was detected in the animals. The minimum Cd concentration that the system can detect was 20 ppm.

  8. Simultaneous determination of tantalum and hafnium in silicates by neutron activation analysis

    USGS Publications Warehouse

    Greenland, L.P.

    1968-01-01

    A neutron activation procedure suitable for the routine determination of tantalum and hafnium in silicates is described. The irradiated sample is fused with sodium peroxide and leached, and the insoluble hydroxides are dissolved in dilute hydrofluoric acid-hydrochloric acid. After LaF3 and AgCl scavenges, tantalum and hafnium are separated by anion exchange. Tantalum is obtained radiochemically pure; 233Pa and 95Zr contaminants in the hafnium fraction are resolved by ??-ray spectrometry. The chemical yield of the procedure is detemined after counting by re-irradiation. Values for the 8 U.S. Geological Survey standard rocks are reported. ?? 1968.

  9. Advanced liquid and solid extraction procedures for ultratrace determination of rhenium by radiochemical neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Mizera, J.; Kučera, J.; Řanda, Z.; Lučaníková, M.

    2006-01-01

    Radiochemical neutron activation analysis (RNAA) procedures for determination of Re at the ultratrace level based on use of liquid-liquid extraction (LLE) and extraction chromatography (EXC) have been developed. Two different LLE procedures were used depending on the way of sample decomposition using either 2-butanone or tetraphenylarsonium chloride in CHCl3. EXC employed new solid extractant materials prepared by incorporation of the liquid trioctyl-methyl-ammonium chloride into an inert polyacrylonitrile matrix. The RNAA procedures presented have been compared and applied for Re determination in several biological and environmental reference materials.

  10. Artifacts in digital coincidence timing

    DOE PAGES

    Moses, W. W.; Peng, Q.

    2014-10-16

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into amore » time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.« less

  11. Methods for preparing comparative standards and field samples for neutron activation analysis of soil

    SciTech Connect

    Glasgow, D.C.; Dyer, F.F.; Robinson, L.

    1994-06-01

    One of the more difficult problems associated with comparative neutron activation analysis (CNAA) is the preparation of standards which are tailor-made to the desired irradiation and counting conditions. Frequently, there simply is not a suitable standard available commercially, or the resulting gamma spectrum is convoluted with interferences. In a recent soil analysis project, the need arose for standards which contained about 35 elements. In response, a computer spreadsheet was developed to calculate the appropriate amount of each element so that the resulting gamma spectrum is relatively free of interferences. Incorporated in the program are options for calculating all of the irradiation and counting parameters including activity produced, necessary flux/bombardment time, counting time, and appropriate source-to-detector distance. The result is multi-element standards for CNAA which have optimal concentrations. The program retains ease of use without sacrificing capability. In addition to optimized standard production, a novel soil homogenization technique was developed which is a low cost, highly efficient alternative to commercially available homogenization systems. Comparative neutron activation analysis for large scale projects has been made easier through these advancements. This paper contains details of the design and function of the NAA spreadsheet and innovative sample handling techniques.

  12. New thermal neutron prompt γ-ray activation analysis instrument at the National Institute of Standards and Technology Center for Neutron Research

    NASA Astrophysics Data System (ADS)

    Mackey, E. A.; Anderson, D. L.; Liposky, P. J.; Lindstrom, R. M.; Chen-Mayer, H.; Lamaze, G. P.

    2004-11-01

    A new thermal neutron prompt γ-ray activation analysis (PGAA) instrument was designed and built to replace the original PGAA system at the NIST Center for Neutron Research. By placing a sapphire filter in the neutron beam shutter assembly, the fast neutron fluence rate was reduced by a factor of 5 and low-energy (50-200 keV) γ-ray intensities were reduced by factors of 5-10. The thermal neutron fluence rate was reduced by only a factor of 1.13. A new external beam tube, sample chamber, beam stop, and support structure were built and a new detection system installed. The new beam tube is made of two cylindrical aluminum sections lined with a lithiated polymer. Both sections are kept under vacuum to reduce the number of neutrons scattered by air into the beam tube walls. The sample chamber is also fabricated from aluminum and lined with lithiated polymer, and may be evacuated to minimize the number of neutrons scattered and absorbed by air. The beam tube and sample chamber assembly is suspended from the aluminum support structure. The detection system consists of a 40% efficient (relative) germanium detector (resolution 2.0 at 1332.5 keV) and a bismuth germanate Compton suppressor. The detection system is shielded by lead, surrounded by borated and lithiated polyethylene, and placed on a table attached to the support structure. The new, more compact beam stop is welded to the support structure. Capture γ-ray photopeaks from H, B, C, N, Na, Al, Fe, Ge, I and Pb in the background spectrum were either of lower intensity or eliminated with the new PGAA instrument. The more efficient detection system, positioned closer to the sample, yielded element sensitivity increases of 5-50%. Limits of detection have been greatly reduced compared with those of the original instrument due to reduced Compton and scattered γ-ray backgrounds (especially in the low-energy region), increased sensitivities, and reduction of background γ-ray photopeak intensities.

  13. Combining attosecond XUV pulses with coincidence spectroscopy

    NASA Astrophysics Data System (ADS)

    Sabbar, M.; Heuser, S.; Boge, R.; Lucchini, M.; Gallmann, L.; Cirelli, C.; Keller, U.

    2014-10-01

    Here we present a successful combination of an attosecond beamline with a COLTRIMS apparatus, which we refer to as AttoCOLTRIMS. The setup provides either single attosecond pulses or attosecond pulse trains for extreme ultraviolet-infrared pump-probe experiments. We achieve full attosecond stability by using an active interferometer stabilization. The capability of the setup is demonstrated by means of two measurements, which lie at the heart of the COLTRIMS detector: firstly, we resolve the rotating electric field vector of an elliptically polarized few-cycle infrared laser field by attosecond streaking exploiting the access to the 3D momentum space of the charged particles. Secondly, we show streaking measurements on different atomic species obtained simultaneously in a single measurement making use of the advantage of measuring ions and electrons in coincidence. Both of these studies demonstrate the potential of the AttoCOLTRIMS for attosecond science.

  14. Active Well Counting Using New PSD Plastic Detectors

    SciTech Connect

    Hausladen, Paul; Newby, Jason; McElroy, Robert Dennis

    2015-11-01

    This report presents results and analysis from a series of proof-of-concept measurements to assess the suitability of segmented detectors constructed from Eljen EJ-299-34 PSD-plastic scintillator with pulse-shape discrimination capability for the purposes of quantifying uranium via active neutron coincidence counting. Present quantification of bulk uranium materials for international safeguards and domestic materials control and accounting relies on active neutron coincidence counting systems, such as the Active Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL), that use moderated He-3 proportional counters along with necessarily low-intensity 241Am(Li) neutron sources. Scintillation-based fast-neutron detectors are a potentially superior technology to the existing AWCC and UNCL designs due to their spectroscopic capability and their inherently short neutron coincidence times that largely eliminate random coincidences and enable interrogation by stronger sources. One of the past impediments to the investigation and adoption of scintillation counters for the purpose of quantifying bulk uranium was the commercial availability of scintillators having the necessary neutron-gamma pulse-shape discrimination properties only as flammable liquids. Recently, Eljen EJ-299-34 PSD-plastic scintillator became commercially available. The present work is the first assessment of an array of PSD-plastic detectors for the purposes of quantifying bulk uranium. The detector panel used in the present work was originally built as the focal plane for a fast-neutron imager, but it was repurposed for the present investigation by construction of a stand to support the inner well of an AWCC immediately in front of the detector panel. The detector panel and data acquisition of this system are particularly well suited for performing active-well fast-neutron counting of LEU and HEU samples because the active detector volume is solid, the 241Am(Li) interrogating

  15. Neutron Emission Characteristics of Two Mixed-Oxide Fuels: Simulations and Initial Experiments

    SciTech Connect

    D. L. Chichester; S. A. Pozzi; J. L. Dolan; M. Flaska; J. T. Johnson; E. H. Seabury; E. M. Gantz

    2009-07-01

    Simulations and experiments have been carried out to investigate the neutron emission characteristics of two mixed-oxide (MOX) fuels at Idaho National Laboratory (INL). These activities are part of a project studying advanced instrumentation techniques in support of the U.S. Department of Energy's Fuel Cycle Research and Development program and it's Materials Protection, Accounting, and Control for Transmutation (MPACT) campaign. This analysis used the MCNP-PoliMi Monte Carlo simulation tool to determine the relative strength and energy spectra of the different neutron source terms within these fuels, and then used this data to simulate the detection and measurement of these emissions using an array of liquid scintillator neutron spectrometers. These calculations accounted for neutrons generated from the spontaneous fission of the actinides in the MOX fuel as well as neutrons created via (alpha,n) reactions with oxygen in the MOX fuel. The analysis was carried out to allow for characterization of both neutron energy as well as neutron coincidences between multiple detectors. Coincidences between prompt gamma rays and neutrons were also analyzed. Experiments were performed at INL with the same materials used in the simulations to benchmark and begin validation tests of the simulations. Data was collected in these experiments using an array of four liquid scintillators and a high-speed waveform digitizer. Advanced digital pulse-shape discrimination algorithms were developed and used to collect this data. Results of the simulation and modeling studies are presented together with preliminary results from the experimental campaign.

  16. Ultra Sensitive Neutron Activation Measurements of {sup 232}Th in Copper

    SciTech Connect

    Clemenza, M.; Previtali, E.; Borio di Tigliole, A.; Salvini, A.

    2011-04-27

    Copper, thanks to its low content in radioactive contaminations, is a material widely used for shielding, holders and other objects close to the sensitive parts of the detectors in many experiments in rare event physics. This implies that tools able to reach sensitivity of the order of <10{sup -12} gram of contaminants per gram of copper are of crucial importance. A methodology based in Neutron Activation Analysis (NAA) has been developed to obtain an extremely high sensitivity in the analysis of {sup 232}Th in copper samples. A detection limit of 5x10{sup -13} g {sup 232}Th/g Cu has been achieved through the irradiation of 200 g of copper sample which subsequently was radio-chemically concentrated using nitric acid and then actinide resin from Eichrom Inc. Several elutions were performed with various inorganic acids to concentrate the {sup 232}Th activation product ({sup 233}Pa) from the copper matrix and to also eliminate the radioactive background induced by the neutron bombardment to reach higher sensitivity.

  17. Self-Shielding Correlation of Foil Activation Neutron Spectra Analysis by SAND-II.

    2008-11-21

    Version 00 SELFS-3 corrects for the influence of the self-shielding effect in neutron spectrum determinations by means of the multifoil activation method. It is used in combination with the SAND-II program for unfolding the responses of an irradiated set of activation detectors in 620 groups. The program SELFS can calculate a corrected 620 group cross section data set for specified reactions used in the SAND-II library, and for specified foil thicknesses. This procedure requires nomore » additional assumption on the shape of the neutron spectrum and on other experimental conditions, but only some foil characteristics (reaction type, material composition, foil thickness). Application of this procedure is possible when multigroup unfolding programs are used with suitably small energy intervals. This code system was developed in the 1970’s at Reactor Centrum Nederland, Petten, The Netherlands, and was contributed to RSICC through the NEA Data Bank. No changes were made to the package when it was released by RSICC in 2008. Modifications will be required to run SELFS-3 on current computer systems.« less

  18. MIT-EAPS Neutron Activation Analysis and Radiometric Laboratory Contribution to Geosciences: Past, Present, and Future

    SciTech Connect

    Pillalamarri, Ila

    2005-09-08

    The Instrumental Neutron Activation Analysis (INAA) and Radiometric Laboratory's current system is described. This laboratory has been in continuous operation for the past thirty years. A review is provided about the laboratory's analytical participation in trace element geochemical studies of the earth's upper mantle, trace impurity studies of high purity materials, the provenance study of archaeological glass beads, trace multi-element analyses of standard reference materials, the preparation of synthetic analytical standards for Neutron Activation Analysis, and providing a training course in nuclear analytical techniques for environmental samples. The multi-element analysis by INAA consists of determining elements like the rare earths La, Ce, Nd, Sm Eu, Tb, Dy, Ho, Yb, Lu, and also As, Ba, Cl, Co, Cr, Cs, Dy, Fe, Hf, Hg, K, Mn, Na, Ta, Th, U. The projected future of the laboratory is explained in terms of its resources, expertise in high precision analysis of trace impurities for the material selection that is to be used in rare event physics experiments. For example, this 'surface' laboratory can be efficiently interfaced/integrated with a deep underground low background counting facility, especially in the initial stages.

  19. Neutron activation analysis of nuclides from stellar and man-induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Oliver, L. L.

    Neutron activation and gamma counting were used to determine the relative abundances of six stable tellurium isotopes in the acid-etched residues of the Allende meteorite. The results were correlated with the isotopic compositions of xenon and the elemental abundances of helium and neon in similarly prepared residues. Nucleosynthesis appears to be the only viable explanation or the anomalous isotopic and elemental compositions observed in these residues. Results suggest that the solar system condensed from an isotopically and chemically zoned nebula that was produced by the explosion of a supernova, concentric with the present Sun. A combination of neutron activation and mass spectrometry was used to determine the concentrations of fissiogenic iodine 129 and stable iodine 127 in rain, milk and the thyroids of man, cow and deer from Missouri. Rain and deer thyroids show the highest average values of the iodine 129/iodine 127 ratio. Milk and the thyroids of cattle and humans show successively lower values of the iodine 129/iodine 127 ratio due to dietary additives of mineral iodine and to biological averaging.

  20. Neutron-activation analysis of several US Geological Survey and National Bureau of Standards reference materials

    SciTech Connect

    Daly, A.T.

    1981-01-01

    In this work, several US Geological Survey (U.S.G.S.) and National Bureau of Standards (N.B.S.) reference samples have been analyzed in an effort to improve the quality of elemental concentration data available on these materials, so they can be used in a program of verification of factor analysis source resolution procedures. The analyses of these samples were performed by instrumental neutron activation analysis (INAA). The samples analyzed were: U.S.G.S. Green River Shale, N.B.S. 45b Homogeneous River Sediment, U.S.G.S. Analyzed Peridotite N.B.S. 1579 Powdered Lead-based Paint, U.S.G.S. Hawaian Basalt U.S.G.S. Marine Mud, U.S.G.S. Analyzed Cody Shale U.S.G.S. Glass Mountain Rhyolite, N.B.S. Argillaceous Limestone No. 1, and a sample of Spex ultrapure graphite. Neutron activation analysis was employed because of the high sensitivity that can be attained in determining elemental concentrations. Although INAA is a relatively simple method and the reproducibility of the data is good, the method shows some inaccuracies. The basic theory and technique are reviewed in an attempt to show where problems can arise and how they can be dealt with.

  1. Improvement of analytical capabilities of neutron activation analysis laboratory at the Colombian Geological Survey

    NASA Astrophysics Data System (ADS)

    Parrado, G.; Cañón, Y.; Peña, M.; Sierra, O.; Porras, A.; Alonso, D.; Herrera, D. C.; Orozco, J.

    2016-07-01

    The Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey has developed a technique for multi-elemental analysis of soil and plant matrices, based on Instrumental Neutron Activation Analysis (INAA) using the comparator method. In order to evaluate the analytical capabilities of the technique, the laboratory has been participating in inter-comparison tests organized by Wepal (Wageningen Evaluating Programs for Analytical Laboratories). In this work, the experimental procedure and results for the multi-elemental analysis of four soil and four plant samples during participation in the first round on 2015 of Wepal proficiency test are presented. Only elements with radioactive isotopes with medium and long half-lives have been evaluated, 15 elements for soils (As, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sb, Sc, Th, U and Zn) and 7 elements for plants (Br, Co, Cr, Fe, K, Na and Zn). The performance assessment by Wepal based on Z-score distributions showed that most results obtained |Z-scores| ≤ 3.

  2. In vivo neutron activation analysis: body composition studies in health and disease

    SciTech Connect

    Ellis, K.J.; Cohn, S.H.

    1984-01-01

    In vivo analysis of body elements by neutron activation is an important tool in medical research. It has provided a direct quantitative measure of body composition of human beings in vivo. Basic physiological differences related to age, sex, race, and body size have been assessed by this noninvasive technique. The diagnosis and management of patients with various metabolic disorders and diseases has also been demonstrated. Two major facilities at Brookhaven are being utilized exclusively for in vivo neutron activation analysis (IVNAA) of calcium, phosphorus, sodium, chlorine, nitrogen, hydrogen, and potassium. These elements serve as the basis for a four compartment model of body composition: protein, water, mineral ash, and fat. Variations in these compartments are demonstrated in clinical research programs investigating obesity, anorexia, cancer, renal failure, osteoporosis, and normal aging. IVNAA continues to provide a unique approach to the evaluation of clinical diagnosis, efficacy of therapeutic regimens, and monitoring of the aging process. Classical balance studies usually require the patient to be admitted to a hospital for extended periods of confinement. IVNAA, however, allows for clinical management of the patient on an out-patient basis, an important aspect for treatment of chronic diseases. 25 references, 3 figures, 5 tables.

  3. Thermal neutron radiative capture cross-section of 186W(n, γ)187W reaction

    NASA Astrophysics Data System (ADS)

    Tan, V. H.; Son, P. N.

    2016-06-01

    The thermal neutron radiative capture cross section for 186W(n, γ)187W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of Rcd = 420 and peak energy En = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction 197Au(n, γ)198Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations.

  4. Applicability of self-activation of an NaI scintillator for measurement of photo-neutrons around a high-energy X-ray radiotherapy machine.

    PubMed

    Wakabayashi, Genichiro; Nohtomi, Akihiro; Yahiro, Eriko; Fujibuchi, Toshioh; Fukunaga, Junichi; Umezu, Yoshiyuki; Nakamura, Yasuhiko; Nakamura, Katsumasa; Hosono, Makoto; Itoh, Tetsuo

    2015-01-01

    The applicability of the activation of an NaI scintillator for neutron monitoring at a clinical linac was investigated experimentally. Thermal neutron fluence rates are derived by measurement of the I-128 activity generated in an NaI scintillator irradiated by neutrons; β-rays from I-128 are detected efficiently by the NaI scintillator. In order to verify the validity of this method for neutron measurement, we irradiated an NaI scintillator at a research reactor, and the neutron fluence rate was estimated. The method was then applied to neutron measurement at a 10-MV linac (Varian Clinac 21EX), and the neutron fluence rate was estimated at the isocenter and at 30 cm from the isocenter. When the scintillator was irradiated directly by high-energy X-rays, the production of I-126 was observed due to photo-nuclear reactions, in addition to the generation of I-128 and Na-24. From the results obtained by these measurements, it was found that the neutron measurement by activation of an NaI scintillator has a great advantage in estimates of a low neutron fluence rate by use of a quick measurement following a short-time irradiation. Also, the future application of this method to quasi real-time monitoring of neutrons during patient treatments at a radiotherapy facility is discussed, as well as the method of evaluation of the neutron dose.

  5. MICROSCOPIC DETERMINATION OF BONE PHOSPHORUS BY QUANTITATIVE AUTORADIOGRAPHY OF NEUTRON-ACTIVATED SECTIONS

    PubMed Central

    Vincent, Jacques; Haumont, Stanislas; Roels, Joseph

    1965-01-01

    Longitudinal sections of human cortical bone were submitted to thermal neutrons. γ-ray spectra were recorded repeatedly during 15 days following irradiation. They showed that Na24 is predominant as early as 3 hours after activation and that all the γ-emitters have decayed on the 15th day. When the γ-rays have disappeared, β-rays are still produced by the sections. It was proved by the absorption curve in aluminium that all these β-rays are issued from the P32 induced in the sections by activation of P31. Therefore autoradiograms registered 15 days after activation reveal the distribution of P32 in the sections. γ-ray spectra and β-ray absorption curves of neutron activated sections of ivory demonstrated a mineral composition similar to that of bone. Autoradiograms of ivory sections activated for various times were used to establish the relation between the optical density of the autoradiograms and the radioactivity in P32. When the bone autoradiograms are compared with the ivory standards of known radioactivity, the optical densities of single osteons (Haversian systems), can be related to their phosphorus contents. Autoradiograms and microradiograms of the same sections were examined side by side. The least calcified osteons, that contain 80 per cent of the calcium of the fully calcified osteons, also contain about 80 per cent of the phosphorus of the fully mineralized osteons. It is concluded that the Ca:P ratio remains constant while mineralization of bone tissue is being completed. PMID:14286295

  6. Radionuclide characterization of reactor decommissioning waste and neutron-activated metals

    SciTech Connect

    Robertson, D.E.; Thomas, C.W.; Wynhoff, N.L.; Haggard, D.L.

    1993-06-01

    This study is providing the NRC and licensees with a more comprehensive data base for regulatory assessment of the radiological factors associated with reactor decommissioning and disposal of wastes generated during these activities. The objectives of this study are being accomplished during the actual decommissioning of Shippingport Station and the detailed analysis of neutron-activated materials from commercial reactors. The radiological characterization studies of Shippingport decommissioning materials have now been completed, and analyses of dismantled piping and scabbled concrete have shown that neutron activation products, dominated by {sup 60}Co, comprised the residual radionuclide inventory. Waste classification assessment have shown that all decommissioning materials (except reactor pressure vessel internals) could be disposed of as Class A waste. Spent fuel disassembly hardware from the Shippingport Core-3 was analyzed for long-lived activation products. {sup 94}Nb and {sup 63}Ni concentrations in Inconel-X750 and stainless steel components exceeded their Class C limits. Measurements and assessments of {sup 14}C in spent fuel disassembly hardware from three commercial nuclear power stations showed that this radionuclide never exceeded the Class C limit for all components. However, the {sup 63}Ni and {sup 94}Nb concentrations in some of these materials did exceed the Class C limits. These measurements are providing the basis for an assessment of the disposal options for these types of highly radioactive materials. Work is continuing on radiological characterization of spent PWR and BWR control rod assemblies. Three control rods, including a BWR cruciform control rod blade, a PWR control rod cluster assembly, and a PWR burnable poison rod assembly, have been characterized for their long-lived activation product concentrations and distribution by direct assay methods. These spent control rods could all be classified as Class C low-level waste.

  7. Radionuclide characterization of reactor decommissioning waste and neutron-activated metals

    SciTech Connect

    Robertson, D.E.; Thomas, C.W.; Wynhoff, N.L.; Haggard, D.L.

    1993-06-01

    This study is providing the NRC and licensees with a more comprehensive data base for regulatory assessment of the radiological factors associated with reactor decommissioning and disposal of wastes generated during these activities. The objectives of this study are being accomplished during the actual decommissioning of Shippingport Station and the detailed analysis of neutron-activated materials from commercial reactors. The radiological characterization studies of Shippingport decommissioning materials have now been completed, and analyses of dismantled piping and scabbled concrete have shown that neutron activation products, dominated by Co-60, comprised the residual radionuclide inventory. Waste classification assessment have shown that all decommissioning materials (except reactor pressure vessel internals) could be disposed of as Class A waste. Spent fuel disassembly hardware from the Shippingport Core-3 was analyzed for long-lived activation products. Nb-94 and Ni-63 concentrations in Inconel-X750 and stainless steel components exceeded their Class C limits. Measurements and assessments of C-14 in spent fuel disassembly hardware from three commercial nuclear power stations showed that this radionuclide never exceeded the Class C limit for al components. However, the Ni-63 and Nb-94 concentrations in some of these materials did exceed the Class C limits. These measurements are providing the basis for an assessment of the disposal options for these types of highly radioactive materials. Work is continuing on radiological characterization of spent PWR and BWR control rod assemblies. Three control rods, including a BWR cruciform control rod blade, a PWR control rod cluster assembly, and a PWR burnable poison rod assembly, have been characterized for their long-lived activation product concentrations and distribution by direct assay methods. These spent control rods could all be classified as Class C low-level waste. These rods are presently being sampled.

  8. Boron-10 ABUNCL Prototype Models And Initial Active Testing

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2013-04-23

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from MCNPX model simulations and initial testing of the active mode variation of the Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) design built by General Electric Reuter-Stokes. Initial experimental testing of the as-delivered passive ABUNCL was previously reported.

  9. Thermally activated post-glitch response of the neutron star inner crust and core. I. Theory

    SciTech Connect

    Link, Bennett

    2014-07-10

    Pinning of superfluid vortices is predicted to prevail throughout much of a neutron star. Based on the idea of Alpar et al., I develop a description of the coupling between the solid and liquid components of a neutron star through thermally activated vortex slippage, and calculate the response to a spin glitch. The treatment begins with a derivation of the vortex velocity from the vorticity equations of motion. The activation energy for vortex slippage is obtained from a detailed study of the mechanics and energetics of vortex motion. I show that the 'linear creep' regime introduced by Alpar et al. and invoked in fits to post-glitch response is not realized for physically reasonable parameters, a conclusion that strongly constrains the physics of a post-glitch response through thermal activation. Moreover, a regime of 'superweak pinning', crucial to the theory of Alpar et al. and its extensions, is probably precluded by thermal fluctuations. The theory given here has a robust conclusion that can be tested by observations: for a glitch in the spin rate of magnitude Δν, pinning introduces a delay in the post-glitch response time. The delay time is t{sub d} = 7(t{sub sd}/10{sup 4} yr)((Δν/ν)/10{sup –6}) d, where t{sub sd} is the spin-down age; t{sub d} is typically weeks for the Vela pulsar and months in older pulsars, and is independent of the details of vortex pinning. Post-glitch response through thermal activation cannot occur more quickly than this timescale. Quicker components of post-glitch response, as have been observed in some pulsars, notably, the Vela pulsar, cannot be due to thermally activated vortex motion but must represent a different process, such as drag on vortices in regions where there is no pinning. I also derive the mutual friction force for a pinned superfluid at finite temperature for use in other studies of neutron star hydrodynamics.

  10. Elemental characterization of Hazm El-Jalamid phosphorite by instrumental neutron activation analysis.

    PubMed

    El-Taher, A; Khater, Ashraf E M

    2016-08-01

    Instrumental neutron activation analyses (INAA) have been used to achieve accurate knowledge about the elemental analysis of phosphate ore deposits collected from Hazm El-Jalamid Northeast of Saudi Arabia. The samples were prepared for irradiation by thermal neutrons using a thermal neutron flux of 7×10(12)ncm(-2)s(-1) at ACT Lab Canada. The concentrations of 19 elements were determined. These included 12 major, minor and trace elements (Au, As, Ba, Br, Cr, Mo, Sb, Sc, Sr, Th, U and Zn) and 7 rare earth elements (REEs) (La, Ce, Nd, Sm, Eu, Yb and Lu). Major elements (Si, Al, Fe, Ca, Mg, Na, K, Cr, Ti, Mn, P, Sr and Ba) were determined using an inductively coupled plasma-mass spectrometer (ICP-MS). The comparison of the concentration of U and the REEs in the Hazm El-Jalamid phosphate samples with those of the Umm Wu'al phosphate from Saudi Arabia and El-Sibayia and El Hamrawein phosphate from Egypt shows that the contents of U and REEs are clearly higher in the Umm Wu'al, El-Sibayia and El Hamrawein phosphates than in the Hazm El-Jalamid phosphate samples. The results of major, trace elements, uranium and rare earth elements (REE) from El Jalamid phosphate have been compared with the global values of these elements. The concentrations for most of the elements studied are lower than the concentrations reported in the literature. The acquired data will serve as a reference for the follow-up studies to assess the agronomic effectiveness of the Hazm El-Jalamid phosphate rocks. PMID:27235886

  11. Implementation of gamma-ray instrumentation for solid solar system bodies using neutron activation method

    NASA Astrophysics Data System (ADS)

    Litvak, M. L.; Golovin, D. V.; Jun, I.; Kozyrev, A. S.; Mitrofanov, I. G.; Sanin, A. B.; Shvetsov, V. N.; Timoshenko, G. N.; Zontikov, A.

    2016-06-01

    In this paper we present the results of ground tests performed with a flight model and with industry prototypes of passive and active gamma ray spectrometers with the objective of understanding their capability to distinguish the elemental composition of planetary bodies in the solar system. The gamma instrumentation, which was developed for future space missions was used in the measurements at a special ground test facility where a simulant of planetary material was fabricated with a martian-like composition. In this study, a special attention was paid to the gamma lines from activation reaction products generated by a pulsed neutron generator. The instrumentation was able to detect and identify gamma lines attributed to O, Na, Mg, Al, Si, K, Ca and Fe.

  12. Radiological and instrumental neutron activation analysis determined characteristics of size-fractionated fly ash.

    PubMed

    Peppas, T K; Karfopoulos, K L; Karangelos, D J; Rouni, P K; Anagnostakis, M J; Simopoulos, S E

    2010-09-15

    The concentration of trace elements and radionuclides in fly ash particles of different size can exhibit significant variation, due to the various processes taking place during combustion inside a coal-fired power plant. An investigation of this effect has been performed by analyzing samples of fly ash originating in two different coal-fired power plants, after separation into size fractions by sieving. The samples were analyzed by gamma-ray spectrometry, including low-energy techniques, radon exhalation measurement and instrumental neutron activation analysis for the determination of Al, As, Ga, K, La, Na, Mn, Mg, Sr, Sc, and V. Variations are observed in the results of various samples analyzed, while the activity balances calculated from the results of individual size fractions are consistent with those of the raw ash samples. Correlations among the radionuclides examined are also observed, while individual nuclide behavior varies between the two types of fly ash examined. PMID:20605322

  13. Ion Uptake Determination of Dendrochronologically-Dated Trees Using Neutron Activation Analysis

    SciTech Connect

    Kenan Unlu; P.I. Kuniholm; D.K.H. Schwarz; N.O. Cetiner; J.J. Chiment

    2009-03-30

    Uptake of metal ions by plan roots is a function of the type and concentration of metal in the soil, the nutrient biochemistry of the plant, and the immediate environment of the root. Uptake of gold (Au) is known to be sensitive to soil pH for many species. Soil acidification due to acid precipitation following volcanic eruptions can dramatically increase Au uptake by trees. Identification of high Au content in tree rings in dendrochronologically-dated, overlapping sequences of trees allows the identification of temporally-conscribed, volcanically-influenced periods of environmental change. Ion uptake, specifically determination of trace amounts of gold, was performed for dendrochronologically-dated tree samples utilizing Neutron Activation Analysis (NAA) technique. The concentration of gold was correlated with known enviironmental changes, e.g. volcanic activities, during historic periods.

  14. Low-background instrumental neutron activation analysis of silicon semiconductor materials

    SciTech Connect

    Smith, A.R.; McDonald, R.J.; Manini, H.; Hurley, D.L.; Norman, E.B.; Vella, M.C.; Odom, R.W.

    1996-01-01

    Samples of silicon wafers, some implanted with zinc, some with memory circuits fabricated on them, and some with oxide coatings were activated with neutrons and analyzed for trace element impurities with low-background germanium gamma-ray spectrometers. Results are presented for these samples as well as for a reference material. Because the silicon matrix activation is so small, reduced spectrometer system background permits the detection of significantly lower impurity concentrations than would otherwise be possible. For the highest efficiency and lowest background system, limits on the lowest levels of trace element concentrations have been measured for wafer sized (1 to 10 g) samples and inferred for bulk sized (365 g) samples. For wafer-sized samples, part-per-trillion detection capabilities are demonstrated for a variety of elemental contaminants important in semiconductor fabrication.

  15. Determination of trace elements in metallic materials by neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Grassi, B.; La Vecchia, G. M.; Manera, S.; Salvini, A.; Zenoni, A.

    2006-05-01

    The aim of the present paper is to verify the applicability of neutron activation analysis to a metallurgic problem as a possible alternative technique to the standard investigation methodologies. A first series of measurements was performed in order to check the feasibility of irradiation and counting over metallic samples. Some of the feared problems concerned an excessive activation of the matrix and the consequent difficulties in the spectrum interpretation, as well as the removal of the radioactive waste created by the irradiation. Afterwards, a second series of measurements was performed to collect results aimed at the solution of a specific metallurgic case. The tests were performed at the TRIGA MARK II reactor facility of the LENA (Laboratorio Energia Nucleare Applicata) Institute of the Pavia University.

  16. Neutron chopper development at LANSCE

    SciTech Connect

    Nutter, M.; Lewis, L.; Tepper, S.; Silver, R.N.; Heffner, R.H.

    1985-01-01

    Progress is reported on neutron chopper systems for the Los Alamos Neutron Scattering Center pulsed spallation neutron source. This includes the development of 600+ Hz active magnetic bearing neutron chopper and a high speed control system designed to operate with the Proton Storage Ring to phase the chopper to the neutron source. 5 refs., 3 figs.

  17. Pulsed and monoenergetic beams for neutron cross-section measurements using activation and scattering techniques at Triangle Universities Nuclear Laboratory

    NASA Astrophysics Data System (ADS)

    Hutcheson, A.; Angell, C. T.; Becker, J. A.; Boswell, M.; Crowell, A. S.; Dashdorj, D.; Fallin, B.; Fotiades, N.; Howell, C. R.; Karwowski, H. J.; Kelley, J. H.; Kiser, M.; Macri, R. A.; Nelson, R. O.; Pedroni, R. S.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Weisel, G. J.; Wilhelmy, J. B.

    2007-08-01

    In support of the Stewardship Science Academic Alliances initiative, an experimental program has been developed at Triangle Universities Nuclear Laboratory (TUNL) to measure (n,xn) cross-sections with both in-beam and activation techniques with the goal of improving the partial cross-section database for the NNSA Stockpile Stewardship Program. First experimental efforts include excitation function measurements on 235,238U and 241Am using pulsed and monoenergetic neutron beams with En = 5-15 MeV. Neutron-induced partial cross-sections were measured by detecting prompt γ rays from the residual nuclei using various combinations of clover and planar HPGe detectors in the TUNL shielded neutron source area. Complimentary activation measurements using DC neutron beams have also been performed in open geometry in our second target area. The neutron-induced activities were measured in the TUNL low-background counting area. In this presentation, we include detailed information about the irradiation procedures and facilities and preliminary data on first measurements using this capability.

  18. Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey

    NASA Astrophysics Data System (ADS)

    Sierra, O.; Parrado, G.; Cañón, Y.; Porras, A.; Alonso, D.; Herrera, D. C.; Peña, M.; Orozco, J.

    2016-07-01

    This paper presents the progress made by the Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey (SGC in its Spanish acronym), towards the characterization of its gamma spectrometric systems for Instrumental Neutron Activation Analysis (INAA), with the aim of introducing corrections to the measurements by variations in sample geometry. Characterization includes the empirical determination of the interaction point of gamma radiation inside the Germanium crystal, through the application of a linear model and the use of a fast Monte Carlo N-Particle (MCNP) software to estimate correction factors for differences in counting efficiency that arise from variations in sample density between samples and standards.

  19. In vivo monitoring of toxic metals: assessment of neutron activation and x-ray fluorescence techniques

    SciTech Connect

    Ellis, K.J.

    1986-01-01

    To date, cadmium, lead, aluminum, and mercury have been measured in vivo in humans. The possibilities of monitoring other toxic metals have also been demonstrated, but no human studies have been performed. Neutron activation analysis appears to be most suitable for Cd and Al measurements, while x-ray fluorescence is ideally suited for measurement of lead in superficial bone. Filtered neutron beams and polarized x-ray sources are being developed which will improve in vivo detection limits. Even so, several of the current facilities are already suitable for use in epidemiological studies of selected populations with suspected long-term low-level ''environmental'' exposures. Evaluation and diagnosis of patients presenting with general clinical symptoms attributable to possible toxic metal exposure may be assisted by in vivo examination. Continued in vivo monitoring of industrial workers, especially follow-up measurements, will provide the first direct assessment of changes in body burden and a direct measure of the biological life-times of these metals in humans. 50 refs., 4 figs., 2 tabs.

  20. Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

    PubMed

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Kamari, Halimah Mohamed; Kong, Yap Chee; Hamzah, Mohd Suhaimi; Elias, Md Suhaimi

    2016-01-01

    A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82. PMID:26405840

  1. Rare-earth elements in Egyptian granite by instrumental neutron activation analysis.

    PubMed

    El-Taher, A

    2007-04-01

    The mobilization of rare-earth elements (REEs) in the environment requires monitoring of these elements in environmental matrices, in which they are mainly present at trace levels. The similarity in REEs chemical behavior makes the separate determination of each element by chemical methods difficult; instrumental neutron activation analysis (INAA), based on nuclear properties of the elements to be determined, is a method of choice in trace analysis of REEs and related elements. Therefore, INAA was applied as a sensitive nondestructive analytical tool for the determination of REEs to find out what information could be obtained about the REEs of some Egyptian granite collected from four locations in Aswan area in south Egypt as follows wadi El-Allaqi, El-Shelal, Gabel Ibrahim Pasha and from Sehyel Island and to estimate the accuracy, reproducibility and detection limit of NAA method in case of the given samples. The samples were properly prepared together with standards and simultaneously irradiated in a neutron flux of 7 x 10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The following elements have been determined: La, Ce, Nd, Sm, Eu, Yb and Lu. The gamma spectra was collected by HPGe detector and the analysis was done by means of computerized multichannel analyzer. The X-ray fluorescence (XRF) was also used.

  2. Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

    PubMed

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Kamari, Halimah Mohamed; Kong, Yap Chee; Hamzah, Mohd Suhaimi; Elias, Md Suhaimi

    2016-01-01

    A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82.

  3. Neutron activation of natural zinc samples at kT=25 keV

    NASA Astrophysics Data System (ADS)

    Reifarth, R.; Dababneh, S.; Heil, M.; Käppeler, F.; Plag, R.; Sonnabend, K.; Uberseder, E.

    2012-03-01

    The neutron-capture cross sections of 64Zn, 68Zn, and 70Zn have been measured with the activation technique in a quasistellar neutron spectrum corresponding to a thermal energy of kT=25 keV. By a series of repeated irradiations with different experimental conditions, an uncertainty of 3% could be achieved for the 64Zn(n,γ)65Zn cross section and for the partial cross section 68Zn(n,γ)69Znm feeding the isomeric state in 69Zn. For the partial cross sections 70Zn(n,γ)71Znm and 70Zn(n,γ)71Zng, which had not been measured so far, uncertainties of only 16% and 6% could be reached because of limited counting statistics and decay intensities. Compared to previous measurements on 64,68Zn, the uncertainties could be significantly improved, while the 70Zn cross section was found to be two times smaller than existing model calculations. From these results Maxwellian average cross sections were determined between 5 and 100 keV. Additionally, the β-decay half-life of 71Znm could be determined with significantly improved accuracy. The consequences of these data have been studied by network calculations for convective core He burning and convective shell C burning in massive stars.

  4. Neutron activation analysis of ceramic tiles and its component and radon exhalation rate.

    PubMed

    El-Shershaby, A; Sroor, A; Ahmed, F; Abdel-Haleem, A S; Abdel, Z

    2004-01-01

    The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis(NAA) technique. The samples and standard were irradiated with reactor for 4 h (in the Second Research Egyptian Reactor(Et-RR-2)) with thermal neutron flux 5.9 x 10(13) n/(cm2 x s). The gamma-ray spectra obtained were measured for several times by means of the hyper pure germanium detection system(HPGe). Also a solid state nuclear track detector(SSNTD) CR-39, was used to measure the emanation rate of radon for these samples. The radium concentrations were found to vary from 0.39-3.59 ppm and the emanation rates were found to vary from (0.728-5.688) x 10(-4) kg/(m2 x s). The elemental analysis of the ceramic tiles and ceramic composites have a great importance in assigning the physical properties and in turn the quality of the material.

  5. Characterization of airborne particulates in Bangkok urban area by neutron activation analysis.

    PubMed

    Nouchpramool, S; Sumitra, T; Leenanuphunt, V

    1999-01-01

    Samples of airborne particulates were collected in a residential area and in an area near a busy highway in Bangkok during the period from January 1997 to May 1998. A stacked filter system was used for the former site and a Partisol 2000 was used for the latter site. Both 2.5 microns and 10-micron particulates were collected every week. The total suspended particulate matters were also collected at the latter site. The samples were analyzed by neutron activation analysis utilizing neutron flux from a 2-MW TRIGA MARK III research reactor. The elements most frequently detected in the airborne particulates were Al, As, Br, Ca, Ce, Cl, Co, Cr, Cs, Fe, I, K, La, Mg, Mn, Na, Rb, Sb, Sc, Sm, Th, Ti, V, and Zn. The enrichment factor and factor analysis were used to investigate trends, sources, and origin of the atmospheric aerosols. Anthropogenic elements in road dust, construction dust, motor vehicles emission, and other combustion components were identified. A comparative study of data between both sites was performed and it was found that the mass concentration in the area close to the highway was about three times higher than in the residential area. PMID:10676491

  6. Sensitivity to coincidences and paranormal belief.

    PubMed

    Hadlaczky, Gergö; Westerlund, Joakim

    2011-12-01

    Often it is difficult to find a natural explanation as to why a surprising coincidence occurs. In attempting to find one, people may be inclined to accept paranormal explanations. The objective of this study was to investigate whether people with a lower threshold for being surprised by coincidences have a greater propensity to become believers compared to those with a higher threshold. Participants were exposed to artificial coincidences, which were formally defined as less or more probable, and were asked to provide remarkability ratings. Paranormal belief was measured by the Australian Sheep-Goat Scale. An analysis of the remarkability ratings revealed a significant interaction effect between Sheep-Goat score and type of coincidence, suggesting that people with lower thresholds of surprise, when experiencing coincidences, harbor higher paranormal belief than those with a higher threshold. The theoretical aspects of these findings were discussed.

  7. Evaluation of neutron flux parameters in irradiation sites of research reactor using the Westcott-formalism for the k0 neutron activation analysis method

    NASA Astrophysics Data System (ADS)

    Kasban, H.; Hamid, Ashraf

    2015-12-01

    Instrumental Neutron Activation Analysis using k0 (k0-INAA) method has been used to determine a number of elements in sediment samples collected from El-Manzala Lake in Egypt. k0-INAA according to Westcott's formalism has been implemented using the complete irradiation kit of the fast pneumatic rabbit and some selected manually loaded irradiation sites for short and long irradiation at Egypt Second Research Reactor (ETRR-2). Zr-Au and Co sets as neutron flux monitors are used to determine the neutron flux parameters (f and α) in each irradiation sites. Two reference materials IAEA Soil-7 samples have been inserted and implemented for data validation and an internal monostandard multi monitor used (k0 based IM-NAA). It was given a good agreement between the experimental analyzed values and that obtained of the certified values. The major and trace elements in the sediment samples have been evaluated with the use of Co as an internal and Au as an external monostandard comparators. The concentrations of the elements (Cr, Mn and Zn) in the sediment samples of the present work are discussed regarding to those obtained from other sites.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    In the present study ⌀ 5''× 3'' and ⌀ 2''× 2'' EJ-313 liquid fluorocarbon as well as ⌀ 2'' × 3'' BaF2 scintillators were exposed to neutrons from a 252Cf neutron source and a Sodern Genie 16GT deuterium-tritium (D+T) neutron generator. The scintillators responses to β- particles with maximum endpoint energy of 10.4 MeV from the n+19F reactions were studied. Response of a ⌀ 5'' × 3'' BC-408 plastic scintillator was also studied as a reference. The β- particles are the products of interaction of fast neutrons with 19F which is a component of the EJ-313 and BaF2 scintillators. The method of fast neutron detection via fluorine activation is already known as Threshold Activation Detection (TAD) and was proposed for photofission prompt neutron detection from fissionable and Special Nuclear Materials (SNM) in the field of Homeland Security and Border Monitoring. Measurements of the number of counts between 6.0 and 10.5 MeV with a 252Cf source showed that the relative neutron detection efficiency ratio, defined as epsilonBaF2 / epsilonEJ-313-5'', is 32.0% ± 2.3% and 44.6% ± 3.4% for front-on and side-on orientation of the BaF2, respectively. Moreover, the ⌀ 5'' EJ-313 and side-on oriented BaF2 were also exposed to neutrons from the D+T neutron generator, and the relative efficiency epsilonBaF2 / epsilonEJ-313-5'' was estimated to be 39.3%. Measurements of prompt photofission neutrons with the BaF2 detector by means of data acquisition after irradiation (out-of-beam) of nuclear material and between the beam pulses (beam-off) techniques were also conducted on the 9 MeV LINAC of the SAPHIR facility.

  9. Neutronics and activation analysis of lithium-based ternary alloys in IFE blankets

    DOE PAGES

    Jolodosky, Alejandra; Kramer, Kevin; Meier, Wayne; DeMuth, James; Reyes, Susana; Fratoni, Massimiliano

    2016-04-09

    Here we report that an attractive feature of using liquid lithium as the breeder and coolant in fusion blankets is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. The Lawrence Livermore National Laboratory is carrying an effort to develop a lithium-based alloy that maintains the beneficial properties of lithium (e.g. high tritium breeding and solubility) and at the same time reduces overall flammability concerns. This study evaluates the neutronics performance of lithium-based alloys inmore » the blanket of an inertial fusion energy chamber in order to inform such development. 3-D Monte Carlo calculations were performed to evaluate two main neutronics performance parameters for the blanket: tritium breeding ratio (TBR), and the fusion energy multiplication factor (EMF). It was found that elements that exhibit low absorption cross sections and higher q-values such as lead, tin, and strontium, perform well with those that have high neutron multiplication such as lead and bismuth. These elements meet TBR constrains ranging from 1.02 to 1.1. However, most alloys do not reach EMFs greater than 1.15. Additionally, it was found that enriching lithium significantly increases the TBR and decreases the minimum lithium concentration by more than 60%. The amount of enrichment depends on how much total lithium is in the alloy to begin with. Alloys that performed well in the TBR and EMF calculations were considered for activation analysis. Activation simulations were executed with 50 years of irradiation and 300 years of cooling. It was discovered that bismuth is a poor choice due to achieving the highest decay heat, contact dose rates, and accident doses. In addition, it does not meet the waste disposal ratings (WDR). Some of the activation results for alloys with tin, zinc, and gallium were in

  10. Comparison of IUPAC k0 Values and Neutron Cross Sections to Determine a Self-consistent Set of Data for Neutron Activation Analysis

    SciTech Connect

    Firestone, Richard B; Revay, Zsolt

    2009-12-01

    Independent databases of nuclear constants for Neutron Activation Analysis (NAA) have been independently maintained by the physics and chemistry communities for many year. They contain thermal neturon cross sections s0, standardization values k0, and transition probabilities Pg. Chemistry databases tend to rely upon direct measurements of the nuclear constants k0 and Pg which are often published in chemistry journals while the physics databases typically include evaluated s0 and Pg data from a variety of experiments published mainly in physics journals. The IAEA/LBNL Evaluated Gamma-ray Activation File (EGAF) also contains prompt and delayed g-ray cross sections sg from Prompt Gamma-ray Activation Analysis (PGAA) measurements that can also be used to determine k0 and s0 values. As a result several independent databases of fundamental constants for NAA have evolved containing slightly different and sometimes discrepant results. An IAEA CRP for a Reference Database for Neutron Activation Analysis was established to compare these databases and investigate the possibilitiy of producing a self-consistent set of s0, k0, sg, and Pg values for NAA and other applications. Preliminary results of this IAEA CRP comparison are given in this paper.

  11. ANDI-03: a genetic algorithm tool for the analysis of activation detector data to unfold high-energy neutron spectra.

    PubMed

    Mukherjee, Bhaskar

    2004-01-01

    The thresholds of (n,xn) reactions in various activation detectors are commonly used to unfold the neutron spectra covering a broad energy span, i.e. from thermal to several hundreds of MeV. The saturation activities of the daughter nuclides (i.e. reaction products) serve as the input data of specific spectra unfolding codes, such as SAND-II and LOUHI-83. However, most spectra unfolding codes, including the above, require an a priori (guess) spectrum to starting up the unfolding procedure of an unknown spectrum. The accuracy and exactness of the resulting spectrum primarily depends on the subjectively chosen guess spectrum. On the other hand, the Genetic Algorithm (GA)-based spectra unfolding technique ANDI-03 (Activation-detector Neutron DIfferentiation) presented in this report does not require a specific starting parameter. The GA is a robust problem-solving tool, which emulates the Darwinian Theory of Evolution prevailing in the realm of biological world and is ideally suited to optimise complex objective functions globally in a large multidimensional solution space. The activation data of the 27Al(n,alpha)24Na, 116In(n,gamma)116mIn, 12C(n,2n)11C and 209Bi(n,xn)(210-x)Bi reactions recorded at the high-energy neutron field of the ISIS Spallation source (Rutherford Appleton Laboratory, UK) was obtained from literature and by applying the ANDI-03 GA tool, these data were used to unfold the neutron spectra. The total neutron fluence derived from the neutron spectrum unfolded using GA technique (ANDI-03) agreed within +/-6.9% (at shield top level) and +/-27.2% (behind a 60 cm thick concrete shield) with the same unfolded with the SAND-II code.

  12. ANDI-03: a genetic algorithm tool for the analysis of activation detector data to unfold high-energy neutron spectra.

    PubMed

    Mukherjee, Bhaskar

    2004-01-01

    The thresholds of (n,xn) reactions in various activation detectors are commonly used to unfold the neutron spectra covering a broad energy span, i.e. from thermal to several hundreds of MeV. The saturation activities of the daughter nuclides (i.e. reaction products) serve as the input data of specific spectra unfolding codes, such as SAND-II and LOUHI-83. However, most spectra unfolding codes, including the above, require an a priori (guess) spectrum to starting up the unfolding procedure of an unknown spectrum. The accuracy and exactness of the resulting spectrum primarily depends on the subjectively chosen guess spectrum. On the other hand, the Genetic Algorithm (GA)-based spectra unfolding technique ANDI-03 (Activation-detector Neutron DIfferentiation) presented in this report does not require a specific starting parameter. The GA is a robust problem-solving tool, which emulates the Darwinian Theory of Evolution prevailing in the realm of biological world and is ideally suited to optimise complex objective functions globally in a large multidimensional solution space. The activation data of the 27Al(n,alpha)24Na, 116In(n,gamma)116mIn, 12C(n,2n)11C and 209Bi(n,xn)(210-x)Bi reactions recorded at the high-energy neutron field of the ISIS Spallation source (Rutherford Appleton Laboratory, UK) was obtained from literature and by applying the ANDI-03 GA tool, these data were used to unfold the neutron spectra. The total neutron fluence derived from the neutron spectrum unfolded using GA technique (ANDI-03) agreed within +/-6.9% (at shield top level) and +/-27.2% (behind a 60 cm thick concrete shield) with the same unfolded with the SAND-II code. PMID:15353654

  13. Small-angle neutron and X-ray scattering reveal conformational changes in rhodopsin activation

    NASA Astrophysics Data System (ADS)

    Shrestha, Utsab R.; Bhowmik, Debsindhu; Perera, Suchitrhanga M. C. D.; Chawla, Udeep; Struts, Andrey V.; Graziono, Vito; Pingali, Sai Venkatesh; Heller, William T.; Qian, Shuo; Brown, Michael F.; Chu, Xiang-Qiang

    2015-03-01

    Understanding G-protein-coupled receptor (GPCR) activation plays a crucial role in the development of novel improved molecular drugs. During photo-activation, the retinal chromophore of the visual GPCR rhodopsin isomerizes from 11-cis to all-trans conformation, yielding an equilibrium between inactive Meta-I and active Meta-II states. The principal goals of this work are to address whether the activation of rhodopsin leads to a single state or a conformational ensemble, and how protein organizational structure changes with detergent environment in solution. We use both small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) techniques to answer the above questions. For the first time we observe the change in protein conformational ensemble upon photo-activation by SANS with contrast variation, which enables the separate study of the protein structure within the detergent assembly. In addition, SAXS study of protein structure within detergent assembly suggests that the detergent molecules form a belt of monolayer (micelle) around protein with different geometrical shapes to keep the protein in folded state.

  14. Redesign of the GATE PET coincidence sorter

    NASA Astrophysics Data System (ADS)

    Strydhorst, Jared; Buvat, Irène

    2016-09-01

    The GATE software platform, based on the Geant4 toolkit for simulating particle interactions with matter, enables simulation of, among other medical imaging and treatment systems, positron emission tomography. However, at least one publication (Moraes et al 2015 Phys. Med. 31 43-8) has reported discrepancies between the expected results and those obtained using GATE simulations, specifically with respect to the coincidence sorter which processes single events detected by the scanner to find coincidence pairs. In particular, the current software appears to overestimate the number of ‘true’ coincidence pairs when in multi-window mode, while the delayed coincidence window, used to estimate the randoms present in the prompt coincidence window, underestimates the randoms. Both effects are particularly evident at high count rates. We have investigated this discrepancy and reproduced the reported problems. We have also rewritten the relevant portion of the GATE code to correct the issue. In this note we describe the modifications to the coincidence sorter and repeat the simulations which previously showed unexpected results. Some discrepancies remain in the estimation of the randoms with the single-window mode which are a consequence of the algorithm itself. In multi-window mode however, the simulation agrees exactly with the expected results. The modifications to the coincidence sorter code will be incorporated into the next release of GATE (> version 7.2).

  15. Redesign of the GATE PET coincidence sorter

    NASA Astrophysics Data System (ADS)

    Strydhorst, Jared; Buvat, Irène

    2016-09-01

    The GATE software platform, based on the Geant4 toolkit for simulating particle interactions with matter, enables simulation of, among other medical imaging and treatment systems, positron emission tomography. However, at least one publication (Moraes et al 2015 Phys. Med. 31 43–8) has reported discrepancies between the expected results and those obtained using GATE simulations, specifically with respect to the coincidence sorter which processes single events detected by the scanner to find coincidence pairs. In particular, the current software appears to overestimate the number of ‘true’ coincidence pairs when in multi-window mode, while the delayed coincidence window, used to estimate the randoms present in the prompt coincidence window, underestimates the randoms. Both effects are particularly evident at high count rates. We have investigated this discrepancy and reproduced the reported problems. We have also rewritten the relevant portion of the GATE code to correct the issue. In this note we describe the modifications to the coincidence sorter and repeat the simulations which previously showed unexpected results. Some discrepancies remain in the estimation of the randoms with the single-window mode which are a consequence of the algorithm itself. In multi-window mode however, the simulation agrees exactly with the expected results. The modifications to the coincidence sorter code will be incorporated into the next release of GATE (> version 7.2).

  16. Determination of seven noble metals in standard rock samples by means of thermal neutron activation analysis.

    PubMed

    Ayabe, M; Hirao, Y; Kimura, K

    1980-10-01

    Ruthenium, silver, rhenium, osmium, iridium, platinum and gold in standard rock samples from Geological Survey of Japan (JB-1, JB-2, JG-1 and JA-1) were determined by thermal neutron activation method with a systematic chemical separation. U.S. Geological Survey standard rocks (BCR-1 and G-2) were also analyzed to obtain an information about the accuracy and precision on the method. Generally agreement of our results with previous values for BCR-1 and G-2 was excellent. The noble metal contents in the igneous rocks from Japanese region were approximately comparable to those in the corresponding rocks from the continental region, and showed a tendency to decrease with increasing silica contents, with weak interrelations to other major elements.

  17. Neutron activation analysis of thermal power plant ash and surrounding area soils.

    PubMed

    Al-Masri, M S; Haddad, Kh; Alsomel, N; Sarhil, A

    2015-08-01

    Elemental concentrations of As, Cd, Co, Cr, Fe, Hg, Mo, Ni, Se, and Zn have been determined in fly and bottom ash collected from Syrian power plants fired by heavy oil and natural gas using instrumental neutron activation analysis. The results showed that all elements were more concentrated in fly ash than in the fly ash; there was a clear increasing trend of the elemental concentrations in the fly ash along the flue gas pathway. The annual emission of elements was estimated. Elemental concentrations were higher inside the campus area than in surrounding areas, and the lowest values were found in natural-gas-fired power plant. In addition, the levels have decreased as the distance from power plant campus increases. However, the levels in the surrounding villages were within the Syrian standard for agriculture soil.

  18. Instrumental neutron activation analysis data for cloud-water particulate samples, Mount Bamboo, Taiwan

    USGS Publications Warehouse

    Lin, Neng-Huei; Sheu, Guey-Rong; Wetherbee, Gregory A.; Debey, Timothy M.

    2013-01-01

    Cloud water was sampled on Mount Bamboo in northern Taiwan during March 22-24, 2002. Cloud-water samples were filtered using 0.45-micron filters to remove particulate material from the water samples. Filtered particulates were analyzed by instrumental neutron activation analysis (INAA) at the U.S. Geological Survey National Reactor Facility in Denver, Colorado, in February 2012. INAA elemental composition data for the particulate materials are presented. These data complement analyses of the aqueous portion of the cloud-water samples, which were performed earlier by the Department of Atmospheric Sciences, National Central University, Taiwan. The data are intended for evaluation of atmospheric transport processes and air-pollution sources in Southeast Asia.

  19. Neutron activation analysis of thermal power plant ash and surrounding area soils.

    PubMed

    Al-Masri, M S; Haddad, Kh; Alsomel, N; Sarhil, A

    2015-08-01

    Elemental concentrations of As, Cd, Co, Cr, Fe, Hg, Mo, Ni, Se, and Zn have been determined in fly and bottom ash collected from Syrian power plants fired by heavy oil and natural gas using instrumental neutron activation analysis. The results showed that all elements were more concentrated in fly ash than in the fly ash; there was a clear increasing trend of the elemental concentrations in the fly ash along the flue gas pathway. The annual emission of elements was estimated. Elemental concentrations were higher inside the campus area than in surrounding areas, and the lowest values were found in natural-gas-fired power plant. In addition, the levels have decreased as the distance from power plant campus increases. However, the levels in the surrounding villages were within the Syrian standard for agriculture soil. PMID:26220782

  20. Activation cross sections for reactions induced by 14 MeV neutrons on natural ruthenium

    NASA Astrophysics Data System (ADS)

    Luo, Junhua; Liu, Gang; Tuo, Fei; Kong, Xiangzhong; Liu, Rong; Jiang, Li; Lou, Benchao

    2007-11-01

    Cross sections for (n,2n), (n,p), (n,α), and (n,d*)1 reactions have been measured on ruthenium isotopes at the neutron energies of 13.5 to 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Data are reported for the following reactions: Ru104(n,2n)Ru103, Ru98(n,2n)Ru97, Ru96(n,2n)Ru95, Ru96(n,p)Tc96g, Ru96(n,p)Tc96m, Ru104(n,p)Tc104, Ru102(n,p)Tc102m, Ru104(n,α)Mo101, Ru102(n,α)Mo99, Ru96(n,α)Mo93m, and Ru96(n,d*)Tc95m. Results were discussed and compared with the previous works.

  1. Elemental characterization of the Avogadro silicon crystal WASO 04 by neutron activation analysis

    NASA Astrophysics Data System (ADS)

    D'Agostino, G.; Bergamaschi, L.; Giordani, L.; Mana, G.; Massa, E.; Oddone, M.

    2012-12-01

    Impurity measurements of the 28Si crystal used for the determination of the Avogadro constant are essential to prevent biased results or underestimated uncertainties. A review of the existing data confirmed the high purity of silicon with respect to a large number of elements. In order to obtain direct evidence of purity, we developed a relative analytical method based on neutron activation. As a preliminary test, this method was applied to a sample of the Avogadro natural silicon crystal WASO 04. The investigation concerned 29 elements. The mass fraction of Au was quantified to be (1.03 ± 0.18) × 10-12. For the remaining 28 elements, the mass fractions were below the detection limits, which ranged between 1 × 10-12 and 1 × 10-5.

  2. Microwave acid digestion and preconcentration neutron activation analysis of biological and diet samples for iodine.

    PubMed

    Rao, R R; Chatt, A

    1991-07-01

    A simple preconcentration neutron activation analysis (PNAA) method has been developed for the determination of low levels of iodine in biological and nutritional materials. The method involves dissolution of the samples by microwave digestion in the presence of acids in closed Teflon bombs and preconcentration of total iodine, after reduction to iodide with hydrazine sulfate, by coprecipitation with bismuth sulfide. The effects of different factors such as acidity, time for complete precipitation, and concentrations of bismuth, sulfide, and diverse ions on the quantitative recovery of iodide have been studied. The absolute detection limit of the PNAA method is 5 ng of iodine. Precision of measurement, expressed in terms of relative standard deviation, is about 5% at 100 ppb and 10% at 20 ppb levels of iodine. The PNAA method has been applied to several biological reference materials and total diet samples. PMID:1897721

  3. Analysis of low levels of rare earths by radiochemical neutron activation analysis

    USGS Publications Warehouse

    Wandless, G.A.; Morgan, J.W.

    1985-01-01

    A procedure for the radiochemical neutron-activation analysis for the rare earth elements (REE) involves the separation of the REE as a group by rapid ion-exchange methods and determination of yields by reactivation or by energy dispersive X-ray fluorescence (EDXRF) spectrometry. The U. S. Geological Survey (USGS) standard rocks, BCR-1 and AGV-1, were analyzed to determine the precision and accuracy of the method. We found that the precision was ??5-10% on the basis of replicate analysis and that, in general the accuracy was within ??5% of accepted values for most REE. Data for USGS standard rocks BIR-1 (Icelandic basalt) and DNC-1 (North Carolina diabase) are also presented. ?? 1985 Akade??miai Kiado??.

  4. Instrumental neutron activation analysis of mass fractions of toxic metals in plastic.

    PubMed

    Park, Kwangwon; Kang, Namgoo

    2007-10-15

    It is very challenging to decompose a plastic product for the purpose of analysis of hazardous elements contained. To circumvent such technical problem, it is imperative that an analyst employ a nondestructive analytical method free of any pretreatments. The analytical results of the concentrations of toxic metals such as Cd and Cr in polypropylene for seven samples at two different levels were obtained using the instrumental neutron activation analysis. This work was intended ultimately to establish certified reference materials (CRMs) of these metals in the polypropylene, traceable to the SI. The uncertainties associated with the analytical procedures were estimated in accordance with the ISO guideline. The results were subsequently validated by a comparison with those for CRM-680 and -681 of the Bureau Communautaire de Reference (BCR), which demonstrated acceptable agreement within their uncertainty ranges.

  5. Neutron activation analysis of major, minor, and trace elements in marine sediments

    SciTech Connect

    Stone, S.F.; Zeisler, R.; Koster, B.J.

    1988-01-01

    Neutron activation analysis (NAA) techniques are well established in the multielement assay of geological materials. Similarly, applications of NAA to the analysis of marine sediments have been described. The different emphasis on elemental composition in studying and monitoring the health of the environment, however, presents a new challenge to the analyst. To investigate as many elements as possible, previous multielement procedures need to be reevaluated and modified. In this work, the authors have utilized the NAA steps of a recently developed sequential analysis procedure that obtained concentrations for 45 biological and pollutant elements in marine bivalves. This procedure, with modification, was applied to samples of marine sediments collected for the National Oceanic and Atmospheric Administration (NOAA) National Status and Trends (NS T) specimen banking program.

  6. Neutron activation analysis on the surface of the Moon and other terrestrial planets

    NASA Astrophysics Data System (ADS)

    Golovin, Dmitry; Litvak, Maxim; Kozyrev, S. Alexander; Tretiyakov, Vladislav; Sanin, Anton; Vostrukhin, Andrey; Mitrofanov, Igor; Malakhov, Alexey

    Determine of elements composition of the planet subsurface in situ is important scientific task for understanding of origin and formation processes of terrestrial planets, moons and asteroids. Also this study will be very perspective in terms of utilization of mineral resources for future lunar base. Creation of such outpost will open doors for robotic and human exploration in the distant parts of Solar System. ADRON instrument onboard landing platforms Russian near-pole lunar missions (Glob and Resource) will be first example of using Neutron Activation method in space. It will measure nuclear composition of the lunar regolith in the landing sites up to 1 m depth. This instrument is able to use for different planets and conditions. For Venus surface, taking into account short lifetime of spacecraft one or two hours of operation will be enough to perform such measurements. Another good opportunity is using similar instrument on Lunar or Martian rovers for searching of important minerals.

  7. Investigation of therapeutic potentials of some selected medicinal plants using neutron activation analysis

    SciTech Connect

    Abubakar, Sani; Isa, Nasiru Fage; Usman, Ahmed Rufa’i; Khandaker, Mayeen Uddin; Abubakar, Nuraddeen

    2015-04-24

    Series of attempts were made to investigate concentrations of trace elements and their therapeutic properties in various medicinal plants. In this study, samples of some commonly used plants were collected from Bauchi State, Nigeria. They includes leaves of azadirachta indica (neem), Moringa Oleifera (moringa), jatropha curcas (purgin Nut), guiera senegalensis (custard apple) and anogeissus leiocarpus (African birch). These samples were analyzed for their trace elements contents with both short and long irradiation protocols of Instrumental Neutron Activation Analysis (INAA) at Nigerian Research Reactor-1 (NIRR-1) of Ahmadu Bello University, Zaria, Nigeria. The level of trace elements found varies from one sample to another, with some reported at hundreds of mg/Kg dry weight. The results have been compared with the available literature data. The presence of these trace elements indicates promising potentials of these plants for relief of certain ailments.

  8. Neutron Activation Analysis of the Rare Earth Elements (REE) - With Emphasis on Geological Materials

    NASA Astrophysics Data System (ADS)

    Stosch, Heinz-Günter

    2016-08-01

    Neutron activation analysis (NAA) has been the analytical method of choice for rare earth element (REE) analysis from the early 1960s through the 1980s. At that time, irradiation facilitieswere widely available and fairly easily accessible. The development of high-resolution gamma-ray detectors in the mid-1960s eliminated, formany applications, the need for chemical separation of the REE from the matrix material, making NAA a reliable and effective analytical tool. While not as precise as isotopedilution mass spectrometry, NAA was competitive by being sensitive for the analysis of about half of the rare earths (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu). The development of inductively coupled plasma mass spectrometry since the 1980s, together with decommissioning of research reactors and the lack of installation of new ones in Europe and North America has led to the rapid decline of NAA.

  9. Microwave acid digestion and preconcentration neutron activation analysis of biological and diet samples for iodine.

    PubMed

    Rao, R R; Chatt, A

    1991-07-01

    A simple preconcentration neutron activation analysis (PNAA) method has been developed for the determination of low levels of iodine in biological and nutritional materials. The method involves dissolution of the samples by microwave digestion in the presence of acids in closed Teflon bombs and preconcentration of total iodine, after reduction to iodide with hydrazine sulfate, by coprecipitation with bismuth sulfide. The effects of different factors such as acidity, time for complete precipitation, and concentrations of bismuth, sulfide, and diverse ions on the quantitative recovery of iodide have been studied. The absolute detection limit of the PNAA method is 5 ng of iodine. Precision of measurement, expressed in terms of relative standard deviation, is about 5% at 100 ppb and 10% at 20 ppb levels of iodine. The PNAA method has been applied to several biological reference materials and total diet samples.

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

    SciTech Connect

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

    1987-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Kasviki, K.; Stamatelatos, I. E.; Yannakopoulou, E.; Papadopoulou, P.; Kalef-Ezra, J.

    2007-10-01

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

  12. Investigation of therapeutic potentials of some selected medicinal plants using neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Abubakar, Sani; Usman, Ahmed Rufa'i.; Isa, Nasiru Fage; Khandaker, Mayeen Uddin; Abubakar, Nuraddeen

    2015-04-01

    Series of attempts were made to investigate concentrations of trace elements and their therapeutic properties in various medicinal plants. In this study, samples of some commonly used plants were collected from Bauchi State, Nigeria. They includes leaves of azadirachta indica (neem), Moringa Oleifera (moringa), jatropha curcas (purgin Nut), guiera senegalensis (custard apple) and anogeissus leiocarpus (African birch). These samples were analyzed for their trace elements contents with both short and long irradiation protocols of Instrumental Neutron Activation Analysis (INAA) at Nigerian Research Reactor-1 (NIRR-1) of Ahmadu Bello University, Zaria, Nigeria. The level of trace elements found varies from one sample to another, with some reported at hundreds of mg/Kg dry weight. The results have been compared with the available literature data. The presence of these trace elements indicates promising potentials of these plants for relief of certain ailments.

  13. The accuracy of instrumental neutron activation analysis of kilogram-size inhomogeneous samples.

    PubMed

    Blaauw, M; Lakmaker, O; van Aller, P

    1997-07-01

    The feasibility of quantitative instrumental neutron activation analysis (INAA) of samples in the kilogram range without internal standardization has been demonstrated by Overwater et al. (Anal. Chem. 1996, 68, 341). In their studies, however, they demonstrated only the agreement between the "corrected" γ ray spectrum of homogeneous large samples and that of small samples of the same material. In this paper, the k(0) calibration of the IRI facilities for large samples is described, and, this time in terms of (trace) element concentrations, some of Overwater's results for homogeneous materials are presented again, as well as results obtained from inhomogeneous materials and subsamples thereof. It is concluded that large-sample INAA can be as accurate as ordinary INAA, even when applied to inhomogeneous materials.

  14. Neutron activation analysis of nickel purified by floating zone-refining and anion exchange.

    PubMed

    Isshiki, M; Yakushiji, K; Kikuchi, T; Sato, M; Yanagisawa, E; Igaki, K; Mizohata, A; Mamuro, T; Tsujimoto, T

    1981-04-01

    Nondestructive neutron activation analysis was performed on the nickel purified by floating zone-refining and anion exchange. It is found that floating zone-refining in vacuum is effective to remove Na, Sc, Cr, Zn, As, Ag, Sb and Hg through vaporization in addition to elimination of Se, Sb, Ta, Sm and Tb through segregation. Anion exchange method is also effective to separate Fe, Co, Zn, Mo, Hg, Th and U usually contained in the commercial nickel sources. It is concluded that combination of these two purification methods is required to obtain high purity nickel, since floating zone-refining is known ineffective to eliminate Fe and Co, main impurities in commercial nickel sources. PMID:7291628

  15. Chemical characterization of gas- and oil-bearing shales by instrumental neutron activation analysis

    USGS Publications Warehouse

    Frost, J.K.; Koszykowski, R.F.; Klemm, R.C.

    1982-01-01

    The concentration of As, Ba, Ca, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, K, La, Lu, Mn, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, and Zn were determined by instrumental neutron activation analysis in block shale samples of the New Albany Group (Devonian-Mississippian) in the in the Illinois Basin. Uranium content of the samples was as high as 75 ppm and interfered in the determination of samarium, molybdenum, barium and cerium. In the determination of selenium a correction was made for interference from tantalum. U, As, Co, Mo, Ni and Sb as well as Cu, V and pyritic sulphur which were determined by other methods, were found to correlate positively with the organic carbon content of the samples. ?? 1982 Akade??miai Kiado??.

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

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

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

  17. Neutron activation analyses and half-life measurements at the usgs triga reactor

    NASA Astrophysics Data System (ADS)

    Larson, Robert E.

    Neutron activation of materials followed by gamma spectroscopy using high-purity germanium detectors is an effective method for making measurements of nuclear beta decay half-lives and for detecting trace amounts of elements present in materials. This research explores applications of neutron activation analysis (NAA) in two parts. Part 1. High Precision Methods for Measuring Decay Half-Lives, Chapters 1 through 8 Part one develops research methods and data analysis techniques for making high precision measurements of nuclear beta decay half-lives. The change in the electron capture half-life of 51Cr in pure chromium versus chromium mixed in a gold lattice structure is explored, and the 97Ru electron capture decay half-life are compared for ruthenium in a pure crystal versus ruthenium in a rutile oxide state, RuO2. In addition, the beta-minus decay half-life of 71mZn is measured and compared with new high precision findings. Density Functional Theory is used to explain the measured magnitude of changes in electron capture half-life from changes in the surrounding lattice electron configuration. Part 2. Debris Collection Nuclear Diagnostic at the National Ignition Facility, Chapters 9 through 11 Part two explores the design and development of a solid debris collector for use as a diagnostic tool at the National Ignition Facility (NIF). NAA measurements are performed on NIF post-shot debris collected on witness plates in the NIF chamber. In this application NAA is used to detect and quantify the amount of trace amounts of gold from the hohlraum and germanium from the pellet present in the debris collected after a NIF shot. The design of a solid debris collector based on material x-ray ablation properties is given, and calculations are done to predict performance and results for the collection and measurements of trace amounts of gold and germanium from dissociated hohlraum debris.

  18. Ensemble Activation of G-Protein -Coupled Receptors Revealed by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Chu, Xiang-Qiang; Perera, Suchithranga; Shrestha, Utsab; Chawla, Udeep; Struts, Andrey; Qian, Shuo; Brown, Michael

    2014-03-01

    Rhodopsin is a G-protein -coupled receptor (GPCR) involved in visual light perception and occurs naturally in a membrane lipid environment. Rhodopsin photoactivation yields cis-trans isomerization of retinal giving equilibrium between inactive Meta-I and active Meta-II states. Does photoactivation lead to a single Meta-II conformation, or do substates exist as described by an ensemble-activation mechanism (EAM)? We use small-angle neutron scattering (SANS) to investigate conformational changes in rhodopsin-detergent and rhodopsin-lipid complexes upon photoactivation. Meta-I state is stabilized in CHAPS-solubilized rhodopsin, while Meta-II is trapped in DDM-solubilized rhodopsin. SANS data are acquired from 80% D2O solutions and at contrast-matching points for both DDM and CHAPS samples. Our experiments demonstrate that for detergent-solubilized rhodopsin, SANS with contrast variation can detect structural differences between the rhodopsin dark-state, Meta-I, Meta-II, and ligand-free opsin states. Dark-state rhodopsin has more conformational flexibility in DDM micelles compared to CHAPS, which is consistent with an ensemble of activated Meta-II states. Furthermore, time-resolved SANS enables study of the time-dependent structural transitions between Meta-I and Meta-II, which is crucial to understanding the ensemble-based activation.

  19. Neutron activation analysis and numerical taxonomy of thin orange ceramics from the manufacturing site of Rio Carnero, Puebla, Mexico

    SciTech Connect

    Rattray, E. . Inst. de Investigaciones Antropologicas); Harbottle, G. )

    1991-04-01

    Examples of different types of Thin Orange ceramics found at the recently-discovered manufacturing sites in the state of Puebla have been analyzed by neutron activation. A full multivariate numerical analysis indicates that this material is chemically identical with the well-known Thin Orange of Teotihuacan.'' 33 refs., 2 figs., 2 tabs.

  20. Studies on osteoporosis. V. Comparison of methods of evaluation of osteoporosis and study of chromosome changes induced by neutron activation

    SciTech Connect

    Robin, J.C.; Sirianni, S.R.; Pragay, D.A.; Ambrus, J.L.

    1981-01-01

    In vivo activation analysis was compared with ashing and atomic absorption spectrophotometry for the determination of total skeletal calcium content in mice. The results were close to identical. The possible mutagenic-carcinogenic effect of repeated exposure to whole body neutron irradiation was studied by chromosome analysis. Under the conditions of these experiments, no significant chromosome changes were seen.

  1. [A new correction method for radionuclide formation in neutron activation analysis using a reactor power meter coupled with a microcomputer].

    PubMed

    Hirai, S; Yoshino, Y; Suzuki, S; Horiuchi, N

    1982-05-01

    Neutron flux and irradiation time should be accurately known in neutron activation analysis using very short lived nuclides in which conventional monitoring methods i.e., a comparator method, flux monitor method and so on cannot be used satisfactorily. Especially, fluctuation of neutron flux has not been corrected. We noted a change of reactor power at a pneumatic operation, and found out a new correction method for its correction in activation analysis. In our small nuclear reactor, TRIGA-II, the reactor power increased rapidly a few % when a pneumatic-operated capsule arrived at a core of the reactor, and decreased when the capsule left from the core. If the duration between these two changes of the reactor power is equal to the irradiation time, and that the reactor power is proportional to the neutron flux, we can regard an activity formation as a time integration of the reactor power. Then, the correction system was made of a reactor power meter, a V-F converter (voltage to frequency converter), a clock time, a counter, a microcomputer, electric circuits and so on. The signal of the reactor power during the irradiation was counted through the V-F converter, and was accumulated in a memory of the microcomputer. The neutron fluence was calculated in this microcomputer. This method was examined by means of activation of copper and selenium standard samples by 9-11 sec irradiations. The observed activity involved +/- 10% error. However, the error in the corrected activity was decreased to a few % using this correction method. As a result, we found that this method can be used to obtain accurate value for radionuclide formation.

  2. A method for measuring tissue-equivalent dose using a pin diode and activation foil in epithermal neutron beams with EN < 100 keV.

    PubMed

    Carolan, Martin G; Rosenfeld, Anatoly B

    2006-01-01

    Silicon (Si) pin diodes can be used for neutron dosimetry by observing the change in forward bias voltage caused by neutron induced displacement damage in the diode junction. Pin diode energy response depends on Si displacement damage KERMA (K(Si)). It is hypothesised that tissue-equivalent (TE) neutron dose could be expressed as a linear combination of K(Si) and foil activation terms. Monte Carlo simulations (MCNP) of parallel monoenergetic neutron beams incident on a cylindrical TE phantom were used to calculate TE dose, K(Si) and Au, Cu and Mn foil activations along the central axis of the phantom. For spectra with neutron energies <100 keV, it is possible to estimate the TE kerma based on silicon damage kerma and Cu or Mn foil measurements. More accurate estimates are possible for spectra where the maximum neutron energy does not exceed 30 keV. PMID:16644975

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

    PubMed

    Ghassoun, J; Mostacci, D

    2011-08-01

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

  4. Coincident indices of exons and introns.

    PubMed

    Xu, J; Chen, R; Ling, L; Shen, R; Sun, J

    1993-07-01

    In this paper, the coincident index, proposed by W. F. Friedman in cryptology, is made use of in DNA sequence analysis and exon prediction. The coincident index of exons exceeds that of introns by many times, and is mainly affected by window length, which is correlated negatively with the coincident index. An optimal exon prediction scheme was obtained by experimental analysis with an orthogonal table. Besides exons, many other special sites such as tandem repeats can be identified by using the coincident index approach. The application of this approach to the ARV-2 (AIDS associated retrovirus 2) genome found three new possible coding regions and some unusual base composition regions which are probably related to definite biological functions.

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

    SciTech Connect

    Dahing, Lahasen Normanshah; Yahya, Redzuan; Yahya, Roslan; Hassan, Hearie

    2014-09-03

    In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm{sup 3} and 15×15×15 cm{sup 3} were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed.

  6. Parametric Evaluation of Active Neutron Interrogation for the Detection of Shielded Highly-Enriched Uranium in the Field

    SciTech Connect

    D. L. Chcihester; E. H. Seabury; S. J. Thompson; R. R. C. Clement

    2011-10-01

    Parametric studies using numerical simulations are being performed to assess the performance capabilities and limits of active neutron interrogation for detecting shielded highly enriched uranium (HEU). Varying the shield material, HEU mass, HEU depth inside the shield, and interrogating neutron source energy, the simulations account for both neutron and photon emission signatures from the HEU with resolution in both energy and time. The results are processed to represent different irradiation timing schemes and several different classes of radiation detectors, and evaluated using a statistical approach considering signal intensity over background. This paper describes the details of the modeling campaign and some preliminary results, weighing the strengths of alternative measurement approaches for the different irradiation scenarios.

  7. New class of neutron detectors

    SciTech Connect

    Czirr, J.B.

    1997-09-01

    An optimized neutron scattering instrument design must include all significant components, including the detector. For example, useful beam intensity is limited by detector dead time; detector pixel size determines the optimum beam diameter, sample size, and sample to detector distance; and detector efficiency vs. wavelength determines the available energy range. As an example of the next generation of detectors that could affect overall instrumentation design, we will describe a new scintillator material that is potentially superior to currently available scintillators. We have grown and tested several small, single crystal scintillators based upon the general class of cerium-activated lithium lanthanide borates. The outstanding characteristic of these materials is the high scintillation efficiency-as much as five times that of Li-glass scintillators. This increase in light output permits the practical use of the exothermic B (n, alpha) reaction for low energy neutron detection. This reaction provides a four-fold increase in capture cross section relative to the Li (n, alpha) reaction, and the intriguing possibility of demanding a charged-particle/gamma ray coincidence to reduce background detection rates. These new materials will be useful in the thermal and epithermal energy ran at reactors and pulsed neutron sources.

  8. SU-E-T-557: Measuring Neutron Activation of Cardiac Devices Irradiated During Proton Therapy Using Indium Foils

    SciTech Connect

    Avery, S; Christodouleas, J; Delaney, K; Diffenderfer, E; Brown, K

    2014-06-01

    Purpose: Measuring Neutron Activation of Cardiac devices Irradiated during Proton Therapy using Indium Foils Methods: The foils had dimensions of 25mm x 25mm x 1mm. After being activated, the foils were placed in a Canberra Industries well chamber utilizing a NaI(Tl) scintillation detector. The resulting gamma spectrum was acquired and analyzed using Genie 2000 spectroscopy software. One activation foil was placed over the upper, left chest of RANDO where a pacemaker would be. The rest of the foils were placed over the midline of the patient at different distances, providing a spatial distribution over the phantom. Using lasers and BBs to align the patient, 200 MU square fields were delivered to various treatment sites: the brain, the pancreas, and the prostate. Each field was shot at least a day apart, giving more than enough time for activity of the foil to decay (t1=2 = 54.12 min). Results: The net counts (minus background) of the three aforementioned peaks were used for our measurements. These counts were adjusted to account for detector efficiency, relative photon yields from decay, and the natural abundance of 115-In. The average neutron flux for the closed multi-leaf collimator irradiation was measured to be 1.62 x 106 - 0.18 x 106 cm2 s-1. An order of magnitude estimate of the flux for neutrons up to 1 keV from Diffenderfer et al. gives 3 x 106 cm2 s-1 which does agree on the order of magnitude. Conclusion: Lower energy neutrons have higher interaction cross-sections and are more likely to damage pacemakers. The thermal/slow neutron component may be enough to estimate the overall risk. The true test of the applicability of activation foils is whether or not measurements are capable of predicting cardiac device malfunction. For that, additional studies are needed to provide clinical evidence one way or the other.

  9. Organic metal neutron detector

    DOEpatents

    Butler, M.A.; Ginley, D.S.

    1984-11-21

    A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

  10. Determination of Interesting Toxicological Elements in PM2.5 by Neutron and Photon Activation Analysis

    PubMed Central

    Capannesi, Geraldo; Lopez, Francesco

    2013-01-01

    Human activities introduce compounds increasing levels of many dangerous species for environment and population. In this way, trace elements in airborne particulate have a preeminent position due to toxic element presence affecting the biological systems. The main problem is the analytical determination of such species at ultratrace levels: a very specific methodology is necessary with regard to the accuracy and precision and contamination problems. Instrumental Neutron Activation Analysis and Instrumental Photon Activation Analysis assure these requirements. A retrospective element analysis in airborne particulate collected in the last 4 decades has been carried out for studying their trend. The samples were collected in urban location in order to determine only effects due to global aerosol circulation; semiannual samples have been used to characterize the summer/winter behavior of natural and artificial origin. The levels of natural origin element are higher than those in other countries owing to geological and meteorological factors peculiar to Central Italy. The levels of artificial elements are sometimes less than those in other countries, suggesting a less polluted general situation for Central Italy. However, for a few elements (e.g., Pb) the levels measured are only slight lower than those proposed as air ambient standard. PMID:23878525

  11. Neutron activation of holmium poly(L-lactic acid) microspheres for hepatic arterial radio-embolization: a validation study.

    PubMed

    Vente, M A D; Nijsen, J F W; de Roos, R; van Steenbergen, M J; Kaaijk, C N J; Koster-Ammerlaan, M J J; de Leege, P F A; Hennink, W E; van Het Schip, A D; Krijger, G C

    2009-08-01

    Poly(L-lactic acid) microspheres loaded with holmium-166 acetylacetonate (166Ho-PLLA-MS) are a novel microdevice for intra-arterial radio-embolization in patients with unresectable liver malignancies. The neutron activation in a nuclear reactor, in particular the gamma heating, damages the 166Ho-PLLA-MS. The degree of damage is dependent on the irradiation characteristics and irradiation time in a particular reactor facility. The aim of this study was to standardize and objectively validate the activation procedure in a particular reactor. The methods included light- and scanning electron microscopy (SEM), particle size analysis, differential scanning calorimetry, viscometry, thermal neutron flux measurements and energy deposition calculations. Seven hours-neutron irradiation results in sufficient specific activity of the 166Ho-PLLA-MS while structural integrity is preserved. Neutron flux measurements and energy deposition calculations are required in the screening of other nuclear reactors. For the evaluation of microsphere quality, light microscopy, SEM and particle size analysis are appropriate techniques.

  12. Neutron-induced 63Ni activity and microscopic observation of copper samples exposed to the Hiroshima atomic bomb

    NASA Astrophysics Data System (ADS)

    Shizuma, Kiyoshi; Endo, Satoru; Shinozaki, Kenji; Fukushima, Hiroshi

    2013-05-01

    Fast neutron activation data for 63Ni in copper samples exposed to the Hiroshima atomic bomb are important in evaluating neutron doses to the survivors. Up to until now, accelerator mass spectrometry and liquid scintillation counting methods have been applied in 63Ni measurements and data were accumulated within 1500 m from the hypocenter. The slope of the activation curve versus distance shows reasonable agreement with the calculation result, however, data near the hypocenter are scarce. In the present work, two copper samples obtained from the Atomic bomb dome (155 m from the hypocenter) and the Bank of Japan building (392 m) were utilized in 63Ni beta-ray measurement with a Si surface barrier detector. Additionally, microscopic observation of the metal surfaces was performed for the first time. Only upper limit of 63Ni production was obtained for copper sample of the Atomic bomb dome. The result of the 63Ni measurement for Bank of Japan building show reasonable agreement with the AMS measurement and to fast neutron activation calculations based on the Dosimetry System 2002 (DS02) neutrons.

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

    SciTech Connect

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

    2013-10-01

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

  14. Analysis of Induced Gamma Activation by D-T Neutrons in Selected Fusion Reactor Relevant Materials with EAF-2010

    NASA Astrophysics Data System (ADS)

    Klix, Axel; Fischer, Ulrich; Gehre, Daniel

    2016-02-01

    Samples of lanthanum, erbium and titanium which are constituents of structural materials, insulating coatings and tritium breeder for blankets of fusion reactor designs have been irradiated in a fusion peak neutron field. The induced gamma activities were measured and the results were used to check calculations with the European activation system EASY-2010. Good agreement for the prediction of major contributors to the contact dose rate of the materials was found, but for minor contributors the calculation deviated up to 50%.

  15. Instrumental activation analysis of coal and fly ash with thermal and epithermal neutrons and short-lived nuclides

    USGS Publications Warehouse

    Steinnes, E.; Rowe, J.J.

    1976-01-01

    Instrumental neutron activation analysis is applied to the determination of about 25 elements in coals and fly ash by means of nuclides with half-lives of less than 48 h ; thermal and epithermal irradiations are used. The results indicate that epithermal activation is preferable for twelve of the elements (Ga, As, Br, Sr, In, Cs, Ba, La, Sm, Ho, W and U). Data for SRM 1632 (coal) and SRM 1633 (fly ash) compare favorably with the results obtained by other investigators. ?? 1976.

  16. Measurement of reaction-in-flight neutrons using thulium activation at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Grim, G. P.; Rundberg, R.; Fowler, M. M.; Hayes, A. C.; Jungman, G.; Boswell, M.; Klein, A.; Wilhelmy, J.; Tonchev, A.; Yeamans, C. B.

    2014-09-01

    We report on the first observation of tertiary reaction-in-flight (RIF) neutrons produced in compressed deuterium and tritium filled capsules using the National Ignition Facility at Lawrence Livermore National Laboratory, Livermore, CA. RIF neutrons are produced by third-order, out of equilibrium ("in-flight") fusion reactions, initiated by primary fusion products. The rate of RIF reactions is dependent upon the range of the elastically scattered fuel ions and therefore a diagnostic of Coulomb physics within the plasma. At plasma temperatures of ˜5 keV, the presence of neutrons with kinetic energies greater than 15 MeV is a unique signature for RIF neutron production. The reaction 169Tm(n,3n)167Tm has a threshold of 15.0 MeV, and a unique decay scheme making it a suitable diagnostic for observing RIF neutrons. RIF neutron production is quantified by the ratio of 167Tm/168Tm observed in a 169Tm foil, where the reaction 169Tm(n,2n)168Tm samples the primary neutron fluence. Averaged over 4 implosions1-4 at the NIF, the 167Tm/168Tm ratio is measured to be 1.5 +/- 0.3 x 10-5, leading to an average ratio of RIF to primary neutron ratio of 1.0 +/- 0.2 x 10-4. These ratios are consistent with the predictions for charged particle stopping in a quantum degenerate plasma.

  17. Development of a transportable neutron activation analysis system to quantify manganese in bone in vivo: feasibility and methodology

    PubMed Central

    Liu, Yingzi; Koltick, David; Byrne, Patrick; Wang, Haoyu; Zheng, Wei; Nie, Linda H

    2014-01-01

    This study was conducted to investigate the methodology and feasibility of developing a transportable neutron activation analysis (NAA) system to quantify manganese (Mn) in bone using a portable deuterium–deuterium (DD) neutron generator as the neutron source. Since a DD neutron generator was not available in our laboratory, a deuterium–tritium (DT) neutron generator was used to obtain experimental data and validate the results from Monte Carlo (MC) simulations. After validation, MC simulations using a DD generator as the neutron source were then conducted. Different types of moderators and reflectors were simulated, and the optimal thicknesses for the moderator and reflector were determined. To estimate the detection limit (DL) of the system, and to observe the interference of the magnesium (Mg) γ line at 844 keV to the Mn γ line at 847 keV, three hand phantoms with Mn concentrations of 30 parts per million (ppm), 150 ppm, and 500 ppm were made and irradiated by the DT generator system. The Mn signals in these phantoms were then measured using a 50% high-efficiency high-purity germanium (HPGe) detector. The DL was calculated to be about 4.4 ppm for the chosen irradiation, decay, and measurement time. This was calculated to be equivalent to a DL of about 3.3 ppm for the DD generator system. To achieve this DL with one 50% high-efficiency HPGe detector, the dose to the hand was simulated to be about 37 mSv, with the total body equivalent dose being about 23μSv. In conclusion, it is feasible to develop a transportable NAA system to quantify Mn in bone in vivo with an acceptable radiation exposure to the subject. PMID:24165395

  18. Development of a transportable neutron activation analysis system to quantify manganese in bone in vivo: feasibility and methodology.

    PubMed

    Liu, Yingzi; Koltick, David; Byrne, Patrick; Wang, Haoyu; Zheng, Wei; Nie, Linda H

    2013-12-01

    This study was conducted to investigate the methodology and feasibility of developing a transportable neutron activation analysis (NAA) system to quantify manganese (Mn) in bone using a portable deuterium-deuterium (DD) neutron generator as the neutron source. Since a DD neutron generator was not available in our laboratory, a deuterium-tritium (DT) neutron generator was used to obtain experimental data and validate the results from Monte Carlo (MC) simulations. After validation, MC simulations using a DD generator as the neutron source were then conducted. Different types of moderators and reflectors were simulated, and the optimal thicknesses for the moderator and reflector were determined. To estimate the detection limit (DL) of the system, and to observe the interference of the magnesium (Mg) γ line at 844 keV to the Mn γ line at 847 keV, three hand phantoms with Mn concentrations of 30 parts per million (ppm), 150 ppm, and 500 ppm were made and irradiated by the DT generator system. The Mn signals in these phantoms were then measured using a 50% high-efficiency high-purity germanium (HPGe) detector. The DL was calculated to be about 4.4 ppm for the chosen irradiation, decay, and measurement time. This was calculated to be equivalent to a DL of about 3.3 ppm for the DD generator system. To achieve this DL with one 50% high-efficiency HPGe detector, the dose to the hand was simulated to be about 37 mSv, with the total body equivalent dose being about 23µSv. In conclusion, it is feasible to develop a transportable NAA system to quantify Mn in bone in vivo with an acceptable radiation exposure to the subject.

  19. Data processing of the active neutron experiment DAN for a Martian regolith investigation

    NASA Astrophysics Data System (ADS)

    Sanin, A. B.; Mitrofanov, I. G.; Litvak, M. L.; Lisov, D. I.; Starr, R.; Boynton, W.; Behar, A.; DeFlores, L.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Jun, I.; Kozyrev, A. S.; Kuzmin, R. O.; Malakhov, A.; Milliken, R.; Mischna, M.; Moersch, J.; Mokrousov, M. I.; Nikiforov, S.; Shvetsov, V. N.; Tate, C.; Tret'yakov, V. I.; Vostrukhin, A.

    2015-07-01

    Searching for water in the soil of Gale Crater is one of the primary tasks for the NASA Mars Science Laboratory rover named Curiosity. The primary task of the Dynamic Albedo of Neutrons (DAN) experiment on board the rover is to investigate and qualitatively characterize the presence of water along the rover's traverse across Gale Crater. The water depth distribution may be found from measurements of neutrons generated by the Pulsing Neutron Generator (PNG) included in the DAN instrument, scattered by the regolith and returned back to the detectors. This paper provides a description of the data processing of such measurements and data products of DAN investigation.

  20. ACDOS1: a computer code to calculate dose rates from neutron activation of neutral beamlines and other fusion-reactor components

    SciTech Connect

    Keney, G.S.

    1981-08-01

    A computer code has been written to calculate neutron induced activation of neutral-beam injector components and the corresponding dose rates as a function of geometry, component composition, and time after shutdown. The code, ACDOS1, was written in FORTRAN IV to calculate both activity and dose rates for up to 30 target nuclides and 50 neutron groups. Sufficient versatility has also been incorporated into the code to make it applicable to a variety of general activation problems due to neutrons of energy less than 20 MeV.

  1. Characterization of Alpha Contamination in Lanthanum Trichloride Scintillators Using Coincidence Measurements

    SciTech Connect

    Milbrath, Brian D.; Runkle, Robert C.; Hossbach, Todd W.; Kaye, William R.; Lepel, Elwood A.; McDonald, Benjamin S.; Smith, Leon E.

    2005-08-01

    The commercial availability of LaCl3:Ce scintillators has been much anticipated due to their significantly lower resolution relative to NaI(Tl). Our investigation of these scintillators in regards to the effect of their improved resolution for coincidence gamma-ray measurement applications revealed that the scintillators had a large, internal alpha contamination affecting the gamma-ray energy range from 1700-3000 keV. One passive method of identifying contaminants relies on exploiting coincident signatures. Aided by a coincidence lookup library developed at PNNL, we determined that the parent contaminant is Ac-227 via an alpha-gamma coincidence measurement. In this paper, we characterize the level of contamination and describe our coincidence measurement technique. The Ac-227 concentration was approximately 0.13 ppt. We demonstrate that this coincidence technique measures minimum detectable activities much lower than singles gamma-ray spectroscopy. We also discuss gamma- and beta-contamination in these scintillators.

  2. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1957-09-24

    Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are um-formly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted sunface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.

  3. Provenance study of ancient Chinese Yaozhou porcelain by neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Li, G. X.; Y Gao, Z.; Li, R. W.; Zhao, W. J.; Xie, J. Z.; Feng, S. L.; Zhuo, Z. X.; Y Fan, D.; Zhang, Y.; Cai, Z. F.; Liu, H.

    2003-09-01

    This paper reports our study of the provenance of ancient Chinese Yaozhou porcelain. The content of 29 elements in the Yaozhou porcelain samples was measured by neutron activation analysis (NAA). The NAA data were further analysed using fuzzy cluster analysis to obtain the trend fuzzy cluster diagrams. These samples with different glaze colour, ranging over more than 700 years, were fired in different kilns. Our analysis indicates the relatively concentrated distribution of the sources of the raw material for the Yaozhou porcelain body samples. They can be classified into two independent periods, i.e. the Tang (AD 618-907) and the Five Dynasties (AD 907-960) period, and the Song (AD 960-1279) and Jin (AD 1115-1234) period. Our analysis also indicates that the sources of the raw material for the ancient Yaozhou porcelain glaze samples are quite scattered and those for the black glaze in the Tang Dynasty are very concentrated. The sources of the raw material for the celadon glaze and the white glaze in the Tang Dynasty are widely distributed and those for the celadon glaze in the Song Dynasty are close to those of the bluish white glaze in the Jin Dynasty, and they are very concentrated. The sources of the raw material for the porcelain glazes cover those of the porcelain bodies.

  4. Body composition of two human cadavers by neutron activation and chemical analysis

    SciTech Connect

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

    1986-02-01

    In vivo neutron activation analysis (NAA) is currently used to measure body composition in metabolic and nutritional studies in many clinical situations, but has not previously been validated by comparison with chemical analysis of human cadavers. Total body nitrogen (TBN) and chlorine (TBCl) were measured in two human cadavers by NAA before homogenization and chemical analysis (CHEM) after (cadaver 1: TBN, 1.47 NAA, 1.51 CHEM; TBCl, 0.144 NAA, 0.147 CHEM; cadaver 2: TBN, 0.576 NAA, 0.572 CHEM; TBCl, 0.0227 NAA, 0.0250 CHEM). The homogenates were also analyzed by NAA, and no significant differences were found, indicating that the effects of elemental inhomogeneity on the measurement of TBN and TBCl are insignificant. Total body water, fat, protein, minerals, and carbohydrates were measured chemically for each cadaver and compared with estimates for these compartments obtained from a body composition model, which when used in vivo involves NAA and tritium dilution. The agreement found justifies the use of the model for the measurement of changes in total body protein, water, and fat in sequential studies in groups of patients.

  5. Accurate measurement of bromine contents in plastic samples by instrumental neutron activation analysis.

    PubMed

    Kim, I J; Lee, K S; Hwang, E; Min, H S; Yim, Y H

    2013-03-26

    Accurate measurements of bromine contents in plastic samples were made by the direct comparator instrumental neutron activation analysis (INAA). Individual factors affecting the measurements were comprehensively evaluated and compensated, including the volatility loss of bromine from standard comparators, the background bromine level in the filter papers used for preparation of the standard comparators, nuclear interference, γ-ray spectral interference and the variance among replicates of the samples. Uncertainty contributions from those factors were thoroughly evaluated and included in the uncertainty budgeting of the INAA measurement. (81)Br was chosen as the target isotope, and the INAA measurements for bromine were experimentally confirmed to exhibit good linearity within a bromine content range of 10-170 μg. The established method has been applied to the analysis of eight plastic samples: four commercially available certified reference materials (CRMs) of polyethylene and polystyrene and four acrylonitrile butadiene styrene (ABS) samples prepared as the candidate reference materials (KRISS CRM 113-01-012, -013, -014 and -015). The bromine contents of the samples were calculated at three different γ-ray energies and compared, showing good agreement. The results of the four CRMs also showed good consistency with their certified values within the stated uncertainties. Finally, the bromine contents of the ABS samples were determined with expanded uncertainties (at a 95% level of confidence) between 2.5% and 5% in a bromine content range of 25-900 mg kg(-1).

  6. Quality assurance program for the determination of selenium in foods and diets by instrumental neutron activation

    SciTech Connect

    Zhang, W.H.; Chatt, A.

    1996-12-31

    The biological essentially of selenium for animals was first evidenced in 1957. However, it was not until 1973 that an enzyme called glutathione peroxidase was proven to be a selenoenzyme. At present, selenium is known to be a normal component of several enzymes, proteins, and some aminoacryl transfer nucleic acids. A few selenium compounds have been reported to possess anticarcinogenic properties. There is an increasing interest in understanding the role of selenium in human nutrition and metabolism. Analytical methods are being developed in several laboratories for the determination of total and species-specific selenium in whole blood, serum, urine, soft and hard tissues, food, water, proteins, etc. We have developed several instrumental neutron activation analysis (INAA) methods using the, Dalhousie University SLOWPOKE-2 reactor facility for the determination of parts-per-billion levels of selenium. These methods include cyclic INAA (CINAA) and pseudocyclic INAA (PCINAA) using both conventional and anticoincidence gamma-ray spectrometry. Considering the immense health significance, it is imperative that the selenium levels in foods and diets be measured under an extensive quality assurance program for routine monitoring purposes.

  7. Epithermal neutron activation analysis of Cr(VI)-reducer basalt-inhabiting bacteria.

    PubMed

    Tsibakhashvili, Nelly Yasonovna; Frontasyeva, Marina Vladimirovna; Kirkesali, Elena Ivanovna; Aksenova, Nadezhda Gennadievna; Kalabegishvili, Tamaz Levanovich; Murusidze, Ivana Georgievich; Mosulishvili, Ligury Mikhailovich; Holman, Hoi-Ying N

    2006-09-15

    Epithermal neutron activation analysis (ENAA) has been applied to study elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance, demonstrating that the bacteria differ in their rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 microg/g of dry weight) indicate bacterial adaptation to the environmental conditions typical of the basalts. The concentrations of at least 12-19 different elements were determined in each type of bacteria simultaneously starting with the major to ultratrace elements. The range of concentrations spans over 8 orders of magnitude.

  8. Breast Milk Concentration of Rubidium in Lactating Mothers by Instrumental Neutron Activation Analysis Method

    PubMed Central

    Khatami, Seyedeh-Fatemeh; Parvaresh, Pouya; Parvaresh, Parviz; Madani Kouchak, Sara Sadat; Khorsandi, Jamshid

    2014-01-01

    Objective: Relatively little is known about the trace elements content of human milk from different countries. This has not been fully investigated especially among Iranian women. This study aimed to assess the concentration of Rubidium (Rb) as a poisonous trace element in transitional breast milk of lactating mothers living in Mashhad. Methods: Forty nursing mothers in early lactation 3 days to 15 days postpartum, free from any medical disorder and/or medication were randomly selected. We have applied Instrumental Neutron Activation Analysis (INAA) to assess the long-lived isotope trace element Rb in transitional milk of these economically moderate 18–39 year old Iranian women. Findings: The average concentration level of Rb was 32.176 ppm dry weight (min 8.660, max 107.210 ppm). No significant correlation was observed between Rb concentration and maternal weight and age (P=0.06, P=0.05 respectively) and newborns’ weight, age and sex (P=0.07, P=0.2, P=0.2 respectively). Conclusion: Although the Rubidium concentration found in this study is among the highest reported in the literature, it could not be compared to other studies because of differences in analytical performance, state of lactation, and unavailable reference ranges, so this finding needs further investigations. PMID:26019773

  9. Environmental monitoring for uranium and neptunium at Yucca Mountain using epithermal neutron activation analysis

    SciTech Connect

    Riggle, K.J.

    1992-12-31

    Epithermal Neutron Activation Analysis (ENAA) is investigated as an analysis method for uranium and neptunium in environmental samples from Yucca Mountain. The design and construction of a facility for this technique are described. Theoretical improvement in sensitivity for ENAA over thermal NAA (TNAA) is discussed and compared to experimental results for different sample types. Uranium is analyzed in eight different sample matrices, including samples from Yucca Mountain. Neptunium has been studied only in AGV-1 Granite. As predicted by theory, uranium shows a high experimental sensitivity improvement factor (average = 7.76), while neptunium has a factor of only 0.49. Detection limits for uranium using ENAA range from 6 to 52 ppb by weight (2.6 to 17 ng in sample) for the different matrices. Neptunium shows a detection limit of 57 ppb by weight (6.2 ng in sample) in AGV-1 Granite using ENAA. Using TNAA, neptunium can be analyzed to 35 ppb by weight (3.4 ng in sample).

  10. Neutron Activation Analysis of Single Grains Recovered by the Hayabusa Spacecraft

    NASA Technical Reports Server (NTRS)

    Ebihara, M.; Sekimoto, S.; Hamajima, Y.; Yamamoto, M.; Kumagai, K.; Oura, Y.; Shirai, N.; Ireland. T. R.; Kitajima, F.; Nagao, K.; Nakamura, T.; Naraoka, H.; Noguchi, T.; Okazaki, R.; Tsuchiyama, A.; Uesugi, M.; Yurimoto, H.; Zolensky, M. E.; Abe, M.; Fujimura, A.; Mukai, T.; Yada, T.

    2011-01-01

    The Hayabusa spacecraft was launched on May 9, 2003 and reached an asteroid Itokawa (25143 Itokawa) in September 2005. After accomplishing several scientific observations, the spacecraft tried to collect the surface material of Itokawa by touching down to the asteroid in November. The spacecraft was then navigated for the earth. In encountering several difficulties, Hayabusa finally returned to the earth on June 12, 2010 and the entry capsule was successfully recovered. Initially, a g-scale of solid material was aimed to be captured into the entry capsule. Although the sample collection was not perfectly performed, it was hoped that some extraterrestrial material was stored into the capsule. After careful and extensive examination, more than 1500 particles were recognized visibly by microscopes, most of which were eventually judged to be extraterrestrial, highly probably originated from Itokawa [1]. Several years before the launching of the Hayabusa spacecraft, the initial analysis team was officially formed under the selection panel at ISAS. As a member of this team, we have been preparing for the initial inspection of the returned material from many scientific viewpoints [2]. Once the recovered material had been confirmed to be much less than 1 g, a scheme for the initial analysis was updated accordingly [3]. In this study, we aim to analyze tiny single grains by instrumental neutron activation analysis (INAA). As the initial analysis is to be started in mid-January, 2011, some progress for the initial analysis using INAA is described here. Analytical procedure

  11. Determination of uranium at trace levels by radiochemical neutron-activation analysis employing radioisotopic yield evaluation.

    PubMed

    Byrne, A R; Benedik, L

    1988-03-01

    Nanogram and picogram quantities of uranium were determined in biological materials by radiochemical neutron-activation analysis. Two different approaches using either (239)U or (239)Np were employed for cross-checking, and the question of negative errors due to incomplete acid dissolution of any possible inorganic (siliceous) fraction was studied. In the first and main approach, radiochemical separation of the short-lived (239)U (23.5 min) nuclide was based on TBP extraction following rapid conventional wet-ashing. Addition of large amounts of uranium carrier (ca. 50 mg) allowed the chemical yield to be evaluated from the gamma spectrum of the isolated fraction by means of the 186 keV peak of (235)U. In the second approach, the longer-lived (239)Np (56.5 hr) daughter was separated by anion-exchange; this nuclide allowed use of lengthier dissolution procedures employing total decomposition with hydrofluoric acid. Nanogram quantities of (237)Np were irradiated simultaneously with the sample and an aliquot of the resulting solution containing (237)Np and (238)Np (51 hr) was added prior to sample destruction, these isotopes serving as carrier and yield tracer, respectively. Results are presented for a series of reference materials. The methodologies and results from the two approaches are discussed and evaluated. PMID:18964488

  12. Determination of laser-evaporated uranium dioxide by neutron activation analysis

    SciTech Connect

    Allred, R.

    1987-05-01

    Safety analyses of nuclear reactors require information about the loss of fuel which may occur at high temperatures. In this study, the surface of a uranium dioxide target was heated rapidly by a laser. The uranium surface was vaporized into a vacuum. The uranium bearing species condensed on a graphite disk placed in the pathway of the expanding uranium vapor. Scanning electron microscopy and X-ray analysis showed very little droplet ejection directly from the laser target surface. Neutron activation analysis was used to measure the amount of uranium deposited. The surface temperature was measured by a fast-response automatic optical pyrometer. The maximum surface temperature ranged from 2400 to 3700/sup 0/K. The Hertz-Langmuir formula, in conjunction with the measured surface temperature transient, was used to calculate the theoretical amount of uranium deposited. There was good agreement between theory and experiment above the melting point of 3120/sup 0/K. Below the melting point much more uranium was collected than was expected theoretically. This was attributed to oxidation of the surface. 29 refs., 16 figs., 7 tabs.

  13. Determination of trace elements by instrumental neutron activation analysis in Anatolian bentonitic clays

    NASA Astrophysics Data System (ADS)

    Güngör, N.; Tulun, T.; Alemdar, A.

    1998-08-01

    Instrumental Neutron Activation Analysis (INAA) was carried out for the determination of trace elements in non-swelling type bentonitic clays. Samples were irradiated in Triga Mark II type of reactor at the Nuclear Institute of Technical University of Istanbul. Irradiation was performed in two steps for "short and long lived" isotopes. The γ spectra of short lived isotopes were interpreted with respect to Al, Ca, Mg, Na, K, Ti, Mn, V qualitatively and that of long lived isotopes with respect to Sc, Cr, Br, Sb, Cs, La, Ce, Sm, Yb, Hf quantitatively. The relative richness of the trace elements (Al, Ti, Ca, Mg, Na, K) observed in the Sampo 90 program was obtained using Atomic Absorption technique by normalizing its value to that of sodium. The silicon content of samples was determined by gravimetry. The results indicated that Sample I contained relatively higher amount of REE, Sb, Ca and Na than Sample II. The amount of Sc, Cr and Br were about similar in both samples. Concentrations of La, Ce, Sm and Yb are higher than REE abundances found in all natural waters. These results suggest that Ca-bentonite samples are representative of primary deposition environment. In addition, the Sc content of both the samples indicates that Ca-bentonite deposits originated from continental crust. The relatively high amount of REE might bring about porosity problems in the use of Ca-bentonite in cement and concrete production.

  14. Accurate measurement of bromine contents in plastic samples by instrumental neutron activation analysis.

    PubMed

    Kim, I J; Lee, K S; Hwang, E; Min, H S; Yim, Y H

    2013-03-26

    Accurate measurements of bromine contents in plastic samples were made by the direct comparator instrumental neutron activation analysis (INAA). Individual factors affecting the measurements were comprehensively evaluated and compensated, including the volatility loss of bromine from standard comparators, the background bromine level in the filter papers used for preparation of the standard comparators, nuclear interference, γ-ray spectral interference and the variance among replicates of the samples. Uncertainty contributions from those factors were thoroughly evaluated and included in the uncertainty budgeting of the INAA measurement. (81)Br was chosen as the target isotope, and the INAA measurements for bromine were experimentally confirmed to exhibit good linearity within a bromine content range of 10-170 μg. The established method has been applied to the analysis of eight plastic samples: four commercially available certified reference materials (CRMs) of polyethylene and polystyrene and four acrylonitrile butadiene styrene (ABS) samples prepared as the candidate reference materials (KRISS CRM 113-01-012, -013, -014 and -015). The bromine contents of the samples were calculated at three different γ-ray energies and compared, showing good agreement. The results of the four CRMs also showed good consistency with their certified values within the stated uncertainties. Finally, the bromine contents of the ABS samples were determined with expanded uncertainties (at a 95% level of confidence) between 2.5% and 5% in a bromine content range of 25-900 mg kg(-1). PMID:23498117

  15. Activation Cross-Sections for 14.2 MeV Neutrons on Molybdenum

    NASA Astrophysics Data System (ADS)

    Srinivasa Rao, C. V.; Lakshmana Das, N.; Thirumala Rao, B. V.; Rama Rao, J.

    1981-12-01

    Using the activation method, the cross-section for the following reactions on molybdenum were measured employing the mixed powder technique and Ge(Li) gamma-ray spectroscopy: 94Mo(n, 2n)93mMo, 3.5 ± 0.5 mbarn; 92Mo(n, 2n)91mMo, 19 ± 3 mbarn; 92Mo(n, 2n)91m+gMo, 226 ± 11 mbarn; 100Mo(n, p)100m2Nb, 9 ± 1 mbarn; 98Mo(n, p)98Nb, 10 ± 1 mbarn; 97Mo(n, p)97mNb, 5 ± 1 mbarn; 96Mo(n, p)96Nb, 12 ± 2 mbarn; 92Mo(n, α)89mZr, 2.1 ± 0.5 mbarn; and 92Mo(n, α)89m+gZr 24 ± 6 mbarn; the neutron energy was 14.2 ± 0.2 MeV. The experimental cross-sections were compared with the predictions of evaporation model and of different versions of pre-equilibrium model. The master equation approach appears to give satisfactory results.

  16. Chemical characterization of ancient pottery from the greater Accra region of Ghana using neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Tandoh, J. B.; Bredwa-Mensah, Y.; Dampare, S. B.; Akaho, E. H. K.; Nyarko, B. J. B.

    2009-06-01

    Archaeology in Ghana has a long and respectable tradition. Despite this encouraging situation, significant gaps still exist in our understanding of the history of some early societies in Ghana. Accumulated evidence revealed that the Ga (Ayawaso), Dangme-Shai and the Wullf had trade and other cultural contacts with their Akan and Guan neighbours as well as the various European factors that traded and established footholds in the Accra coast. In an attempt to reconstruct the early history of the Ga, Dangme-Shai and Wullf, the archaeological material remains recovered from these communities during excavation have been studied. In all, 15 trace elements were determined in 40 pottery shards using instrumental neutron activation analysis. The elemental concentrations were processed using multivariate statistical methods, such as cluster, factor and discriminant analyses. The results revealed patterns of trade between these communities and also classified the 40 samples into two major groups based on variations in elemental compositions. The groupings suggested a clear separation between the shards from Shai and Ayawaso. The shards from Wullf scattered amongst the two groups, consistent with the archaeological findings that the Wullf community never produced their own pots.

  17. Evaluation of precision and accuracy of selenium measurements in biological materials using neutron activation analysis

    SciTech Connect

    Greenberg, R.R.

    1988-01-01

    In recent years, the accurate determination of selenium in biological materials has become increasingly important in view of the essential nature of this element for human nutrition and its possible role as a protective agent against cancer. Unfortunately, the accurate determination of selenium in biological materials is often difficult for most analytical techniques for a variety of reasons, including interferences, complicated selenium chemistry due to the presence of this element in multiple oxidation states and in a variety of different organic species, stability and resistance to destruction of some of these organo-selenium species during acid dissolution, volatility of some selenium compounds, and potential for contamination. Neutron activation analysis (NAA) can be one of the best analytical techniques for selenium determinations in biological materials for a number of reasons. Currently, precision at the 1% level (1s) and overall accuracy at the 1 to 2% level (95% confidence interval) can be attained at the U.S. National Bureau of Standards (NBS) for selenium determinations in biological materials when counting statistics are not limiting (using the {sup 75}Se isotope). An example of this level of precision and accuracy is summarized. Achieving this level of accuracy, however, requires strict attention to all sources of systematic error. Precise and accurate results can also be obtained after radiochemical separations.

  18. Studies of generalized elemental imbalances in neurological disease patients using INAA (instrumental neutron activation analysis)

    SciTech Connect

    Ehmann, W.D.; Vance, D.E.; Khare, S.S.; Kasarskis, E.J.; Markesbery, W.R.

    1988-01-01

    Evidence has been presented in the literature to implicate trace elements in the etiology of several age-related neurological diseases. Most of these studies are based on brain analyses. Using instrumental neutron activation analysis (INAA), we have observed trace element imbalances in brains of patients with Alzheimer's disease, amyotrophic lateral sclerosis (ALS), and Picks's disease. The most prevalent elemental imbalances found in the brain were for bromine, mercury, and the alkali metals. In this study the authors report INAA studies of trace elements in nonneural tissues from Alzheimer's disease and ALS patients. Samples from household relatives were collected for use as controls wherever possible. Hair samples were washed according to the International Atomic Energy Agency recommended procedure. Fingernail samples were scraped with a quartz knife prior to washing by the same procedure. For ALS patients, blood samples were also collected. These data indicate that elemental imbalances in Alzheimer's disease and ALS are not restricted to the brain. Many elements perturbed in the brain are also altered in the several nonneural tissues examined to date. The imbalances in different tissues, however, are not always in the same direction. The changes observed may represent causes, effects, or simply epiphenomena. Longitudinal studies of nonneural tissues and blood, as well as tissue microprobe analyses at the cellular and subcellular level, will be required in order to better assess the role of trace elements in the etiology of these diseases.

  19. Fast neutron activation analysis of oxide inclusions in magnesium alloy ingots

    NASA Astrophysics Data System (ADS)

    Fuerst, C. D.; James, W. D.

    1999-06-01

    Magnesium will have an increasingly important role to play in the automotive industry's materials strategy. In addition to its obvious use as a lightweight alternative, magnesium offers advantages in areas such as component integration and NVH (noise, vibration and harshness). Although the metallic composition of magnesium alloys has been carefully defined, there is no uniform industry standard for non-metallic inclusions, such as oxides, which are believed to adversely impact the material's strength. A definitive test has been needed, preferably one that provides a highly sensitive, calibrated, nondestructive evaluation of the metal's bulk oxide content. In response to this need, fast neutron activation analysis (FNAA) has emerged as an important tool for providing highly accurate quantitative information on the oxygen content in magnesium alloys. Oxygen levels from less than 50 to several thousand ppm have been observed in these alloys, with the highest levels concentrated at the top center of the ingot. Several operational procedures have been developed to optimize the analysis, including: a new automated, blank-free procedure which pneumatically transports machined magnesium cylinders between the irradiation and counting facilities; the use of an oxygen standard prepared from polyethylene and titanium dioxide, machined to match the sample dimensions; and implementation of new background subtraction software.

  20. Detection sensitivities in 3-8 MeV neutron activation

    NASA Technical Reports Server (NTRS)

    Wahlgren, M. A.; Wing, J.

    1968-01-01

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

  1. Current Activities of Neutron Imaging Facilities in KUR (Kyoto University Research Reactor)

    NASA Astrophysics Data System (ADS)

    Kawabata, Yuji; Saito, Yasushi

    Kyoto University research Reactor (KUR) restarted in Spring 2010 with low enriched fuel (20%) after 4 years tentative interruption for fuel conversion. There are two facilities for neutron imaging: 1) B4 port at supermirror neutron guide tube (5x107 n/cm2/s at 5 MW, 1 cmx7.5 cm), 2) E2 port (3x105 n/cm2/s at 5 MW, 15 cm dia.). As we have large experimental space at the end of the guide tube and need small shielding because the neutron flux of KUR is not high, we have very large flexibility in the experimental set up. Thus, experiments in B4 should be specialized in the measurements which require large and/or unconventional equipments to accommodate special sample conditions. The E2 port with the low neutron flux is used for experiments which need very long or frequent machine times.

  2. Use of fast-neutron activation analysis for the determination of the silicon content in coal, flyash, and soil

    SciTech Connect

    Chan, K. K.

    1982-01-01

    The values of the silicon content and the associated precisions obtained for the samples analyzed in this study are listed. It was the purpose of this study to employ fast neutron activation analysis for the determination of silicon content in coal, flyash, and soil. The silicon content of coal, flyash, and soil samples have been obtained with accuracies and precisions in good agreement with the accuracies and precisions reported by other researchers performing similar analyses. Terramethylsilane was found to be a suitable standard for this study. Finally, careful sample packaging and handling techniques were found to be crucial for obtaining accurate and precise results. It can be concluded that fast neutron activation analysis using the system at the University of Illinois can be used successfully to determine silicon content.

  3. Project of the borehole neutron generator for the direct determination of oxygen and carbon by activation method

    NASA Astrophysics Data System (ADS)

    Bogdanovich, B. Yu; Vovchenko, E. D.; Iliinskiy, A. V.; Isaev, A. A.; Kozlovskiy, K. I.; Nesterovich, A. V.; Senyukov, V. A.; Shikanov, A. E.

    2016-09-01

    The paper deals with application features of borehole neutron generator (BNG) based on the vacuum accelerating tube (AT) with laser-plasma ion source for determination of oxygen isotope 16O and carbon isotope 12C by direct activation. The project of pulsed BNG for realization of an activation method in the conditions of natural presence of productive hydrocarbons is offered. The diode system with radial acceleration, magnetic electron insulation and laser-plasma source of deuterons at the anode in a sealed-off vacuum accelerating tube is applied. The permanent NdFeB magnet with induction about 0.5 T for produce the insulating magnetic field in the diode gap is proposed. In the experiments on the model of BNG with the accelerating voltage source (≈350 kV), performed by the scheme of Arkadiev-Marx generator, the output of (d, d) neutrons was ∼107 pulse-1.

  4. Heavy metals and rare earth elements source-sink in some Egyptian cigarettes as determined by neutron activation analysis.

    PubMed

    Nada, A; Abdel-Wahab, M; Sroor, A; Abdel-Haleem, A S; Abdel-Sabour, M F

    1999-07-01

    Heavy metals and rare earth elements in two types of cigarettes were studied. The contents of trace elements were determined by using delayed neutron activation analysis. In the present study 11 elements have been detected in popular and fine brand cigarettes marketed in Egypt. Evaluation of these elements with their potential hazards for smokers is briefly discussed. The material balance (source and sink) for each element was determined. Also the ratio of element recovery to the total amount was assessed.

  5. Heavy metals and rare earth elements source-sink in some Egyptian cigarettes as determined by neutron activation analysis.

    PubMed

    Nada, A; Abdel-Wahab, M; Sroor, A; Abdel-Haleem, A S; Abdel-Sabour, M F

    1999-07-01

    Heavy metals and rare earth elements in two types of cigarettes were studied. The contents of trace elements were determined by using delayed neutron activation analysis. In the present study 11 elements have been detected in popular and fine brand cigarettes marketed in Egypt. Evaluation of these elements with their potential hazards for smokers is briefly discussed. The material balance (source and sink) for each element was determined. Also the ratio of element recovery to the total amount was assessed. PMID:10376325

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

    SciTech Connect

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

    2003-04-01

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

  7. Determination of platinum and palladium in geological materials by neutron-activation analysis after fire-assay preconcentration

    USGS Publications Warehouse

    Rowe, J.J.; Simon, F.O.

    1971-01-01

    Fire-asay preconcentration followed by neutron-activation analysis permits the determination of as little as 0.5 ppM of platinum and 0.5 ppM of palladium on a 20-g sample. Platinum and palladium are separated with carriers and beta-counted. Results for the platinum and palladium content of seven U.S.G.S. standard rocks are presented. ?? 1971.

  8. Study of the accumulation of air pollution by the biological indicators, using 14 MeV neutron activation

    NASA Astrophysics Data System (ADS)

    Senhou, A.; Khoukhi, T. El; Chouak, A.; Cherkaoui, R. El Moursili; Yahiaoui, A. El; Lferde, M.

    2001-06-01

    14 MeV neutron activation analysis was used to determine air polluting elements in samples of mosses, lichens and tree barks, collected from different regions in Morocco. The analysis of spectra shows clearly that the elements Mg, Al, Si, Cl, J, Ca, Ti and Fe can easily be determined by 14 NAA with good precision, while results for Zn, Rb, Sr, Ba and La are less precise. Curves showing correlation between Al and Mg concentrations are given for different sites.

  9. Detection of Neutrons with Scintillation Counters

    DOE R&D Accomplishments Database

    Hofstadter, R.

    1948-11-01

    Detection of slow neutrons by: detection of single gamma rays following capture by cadmium or mercury; detection of more than one gamma ray by observing coincidences after capture; detection of heavy charged particles after capture in lithium or baron nuclei; possible use of anthracene for counting fast neutrons investigated briefly.

  10. Nuclear Rocket Facility Decommissioning Project: Controlled Explosive Demolition of Neutron-Activated Shield Wall

    SciTech Connect

    Michael R. Kruzic

    2008-06-01

    centimeters squared (cm2) beta/gamma. Removable beta/gamma contamination levels seldom exceeded 1,000 dpm/100 cm2, but, in railroad trenches on the reactor pad containing soil on the concrete pad in front of the shield wall, the beta dose rates ranged up to 120 milli-roentgens per hour from radioactivity entrained in the soil. General area dose rates were less than 100 micro-roentgens per hour. Prior to demolition of the reactor shield wall, removable and fixed contaminated surfaces were decontaminated to the best extent possible, using traditional decontamination methods. Fifth, large sections of the remaining structures were demolished by mechanical and open-air controlled explosive demolition (CED). Mechanical demolition methods included the use of conventional demolition equipment for removal of three main buildings, an exhaust stack, and a mobile shed. The 5-foot (ft), 5-inch (in.) thick, neutron-activated reinforced concrete shield was demolished by CED, which had never been performed at the NTS.

  11. Neutron flux measurements at the TRIGA reactor in Vienna for the prediction of the activation of the biological shield.

    PubMed

    Merz, Stefan; Djuricic, Mile; Villa, Mario; Böck, Helmuth; Steinhauser, Georg

    2011-11-01

    The activation of the biological shield is an important process for waste management considerations of nuclear facilities. The final activity can be estimated by modeling using the neutron flux density rather than the radiometric approach of activity measurements. Measurement series at the TRIGA reactor Vienna reveal that the flux density next to the biological shield is in the order of 10(9)cm(-2)s(-1) at maximum power; but it is strongly influenced by reactor installations. The data allow the estimation of the final waste categorization of the concrete according to the Austrian legislation. PMID:21646026

  12. MONDE: MOmentum Neutron DEtector

    NASA Astrophysics Data System (ADS)

    Santa Rita, P.; Acosta, L.; Favela, F.; Huerta, A.; Ortiz, M. E.; Policroniades, R.; Chávez, E.

    2016-07-01

    MONDE is a large area neutron momentum detector, consisting of a 70x160x5 cm3 plastic scintillator slab surrounded by 16 photomultiplier tubes, standard NIM signal processing electronics and a CAMAC data acquisition system. In this work we present data from a characterization run using an external trigger. For that purpose, coincident gamma rays from a 60Co radioactive source were used together with a NaI external detector. First results with an "external" trigger are presented.

  13. DS86 neutron dose: Monte Carlo analysis for depth profile of 152Eu activity in a large stone sample.

    PubMed

    Endo, S; Iwatani, K; Oka, T; Hoshi, M; Shizuma, K; Imanaka, T; Takada, J; Fujita, S; Hasai, H

    1999-06-01

    The depth profile of 152Eu activity induced in a large granite stone pillar by Hiroshima atomic bomb neutrons was calculated by a Monte Carlo N-Particle Transport Code (MCNP). The pillar was on the Motoyasu Bridge, located at a distance of 132 m (WSW) from the hypocenter. It was a square column with a horizontal sectional size of 82.5 cm x 82.5 cm and height of 179 cm. Twenty-one cells from the north to south surface at the central height of the column were specified for the calculation and 152Eu activities for each cell were calculated. The incident neutron spectrum was assumed to be the angular fluence data of the Dosimetry System 1986 (DS86). The angular dependence of the spectrum was taken into account by dividing the whole solid angle into twenty-six directions. The calculated depth profile of specific activity did not agree with the measured profile. A discrepancy was found in the absolute values at each depth with a mean multiplication factor of 0.58 and also in the shape of the relative profile. The results indicated that a reassessment of the neutron energy spectrum in DS86 is required for correct dose estimation.

  14. 2010 American Conference on Neutron Scattering (ACNS 2010)

    SciTech Connect

    Billinge, Simon

    2011-06-17

    The ACNS provides a focal point for the national neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as “would-be” neutron users. The American Conference on Neutron Scattering thus serves a dual role as a national user meeting and a scientific meeting. As a venue for scientific exchange, the ACNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. As a “super-user” meeting, the ACNS fulfills the main objectives of users' meetings previously held periodically at individual national neutron facilities, with the advantage of a larger and more diverse audience. To this end, each of the major national neutron facilities (NIST, LANSCE, HFIR and SNS) have an opportunity to exchange information and update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities. For many of the national facilities, this super-user meeting should obviate the need for separate user meetings that tax the time, energy and budgets of facility staff and the users alike, at least in years when the ACNS is held. We rely upon strong participation from the national facilities. The NSSA intends that the American Conference on Neutron Scattering (ACNS) will occur approximately every two years, but not in years that coincide with the International or European Conferences on Neutron Scattering. The ACNS is to be held in association with one of the national neutron centers in a rotating sequence, with the host facility providing local organization

  15. Measuring the noble metal and iodine composition of extracted noble metal phase from spent nuclear fuel using instrumental neutron activation analysis.

    PubMed

    Palomares, R I; Dayman, K J; Landsberger, S; Biegalski, S R; Soderquist, C Z; Casella, A J; Brady Raap, M C; Schwantes, J M

    2015-04-01

    Masses of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis. Nuclide presence is predicted using fission yield analysis, and radionuclides are identified and the masses quantified using neutron activation analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO2 fuel dissolved in nitric acid and UO2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. PMID:25644079

  16. Grain-boundary structures in hexagonal materials: Coincident and near coincident grain boundaries

    NASA Astrophysics Data System (ADS)

    Farkas, Diana

    1994-07-01

    Embedded atom method (EAM) simulations of the structure of grain boundaries in hexagonal metals are presented. The simulations use recently developed interatomic potentials for Ti and Co. Structures were calculated for various symmetrical tilt boundaries with the [1¯100] tilt axis. The structures obtained for both metals are very similar. The energies for the Co boundaries are higher than those for Ti by a factor of 2. The structural unit model was applied to the computed grain-boundary structures in these hexagonal materials. As in cubic materials, the structural unit model can describe a series of symmetrical tilt coincident boundaries. In addition, when the coincidence ratio in the grain-boundary plane varies with the c/a ratio, a structural unit-type model can describe the variation of grain-boundary structure with c/a ratio. This model is adequate for describing series of symmetrical tilt boundaries with the grain-boundary plane oriented perpendicular to a fixed crystallographic direction and varying c/a ratios. For the structures of the so-called near coincident boundaries that appear in these materials, it was concluded that near coincident boundaries behave similarly to exact coincidence boundaries if there is a coincident periodic structure in the grain-boundary plane. This may occur even without a three-dimensional (3-D) coincident site lattice.

  17. Determination of tin in human blood serum by radiochemical neutron activation analysis.

    PubMed

    Versieck, J; Vanballenberghe, L

    1991-06-01

    A method was developed for the determination of tin in human serum by radiochemical neutron activation analysis, using the long-lived radioisotope Sn(T1/2 = 115.09 days). This radioisotope decays to a daughter isotope 113mIn, the most suitable nuclide for counting (T1/2 = 1.658 h, gamma-ray of 391.7 keV). Experience showed that, with the exception of the serum samples with the lowest tin levels, in the experimental conditions of the present study tin could mostly also be determined by using its radioisotope 117mSn(T1/2 = 13.61 days, gamma-ray of 158.5 keV). Samples were collected and prepared by using the procedure elaborated by the authors, which proved its effectiveness in preventing significant sample contamination on several occasions. Because samples had to be irradiated at 10(14) n.cm-2.s-1, dry ashing was necessary. After irradiation, tin was separated by solvent extraction of tin(IV) iodide from a sulfuric acid-ammonium iodide solution with toluene. The dry ashing and solvent extraction steps were exhaustively tested by means of radioactive tracer experiments whereas the accuracy and precision of the analytical method were thoroughly checked by analyzing biological reference materials (Bowen's kale powder, the NBS' bovine liver, the NBS' nonfat milk powder, and the "second-generation" biological reference material--freeze-dried human serum--for trace element determinations, developed by the authors).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1883071

  18. Three-compartment model: critical evaluation based on neutron activation analysis.

    PubMed

    Silva, Analiza M; Shen, Wei; Wang, ZiMian; Aloia, John F; Nelson, Miriam E; Heymsfield, Steven B; Sardinha, Luis B; Heshka, Stanley

    2004-11-01

    There is renewed interest in Siri's classic three-compartment (3C) body composition model, requiring body volume (BV) and total body water (TBW) estimates, because dual-energy X-ray absorptiometry (DEXA) and in vivo neutron activation (IVNA) systems cannot accommodate subjects with severe obesity. However, the 3C model assumption of a constant ratio (alpha) of mineral (M) to total body protein (TBPro) and related residual mass density (D(RES)) based on cadaver analyses might not be valid across groups differing in sex, race, age, and weight. The aim of this study was to derive new 3C model coefficients in vivo and to compare these estimates to those derived by Siri. Healthy adults (n = 323) were evaluated with IVNA and DEXA and the measured components used to derive alpha and D(RES). For all subjects combined, values of alpha and D(RES) (means +/- SD, 0.351 +/- 0.043; 1.565 +/- 0.023 kg/l) were similar to Siri's proposed values of 0.35 and 1.565 kg/l, respectively. However, alpha and D(RES) varied significantly as a function of sex, race, weight, and age. Expected errors in percent body fat arising by application of Siri's model were illustrated in a second group of 264 adults, including some whose size exceeded DEXA limits but whose BV and TBW had been measured by hydrodensitometry and (2)H(2)O dilution, respectively. Extrapolation of predictions by newly developed models to very high weights allows percent fat error estimation when Siri's model is applied in morbidly obese subjects. The present study results provide a critical evaluation of potential errors in the classic 3C model and present new formulas for use in selected populations.

  19. Fast determination of impurities in metallurgical grade silicon for photovoltaics by instrumental neutron activation analysis.

    PubMed

    Hampel, J; Boldt, F M; Gerstenberg, H; Hampel, G; Kratz, J V; Reber, S; Wiehl, N

    2011-10-01

    Standard wafer solar cells are made of near-semiconductor quality silicon. This high quality material makes up a significant part of the total costs of a solar module. Therefore, new concepts with less expensive so called solar grade silicon directly based on physiochemically upgraded metallurgical grade silicon are investigated. Metallurgical grade silicon contains large amounts of impurities, mainly transition metals like Fe, Cr, Mn, and Co, which degrade the minority carrier lifetime and thus the solar cell efficiency. A major reduction of the transition metal content occurs during the unidirectional crystallization due to the low segregation coefficient between the solid and liquid phase. A further reduction of the impurity level has to be done by gettering procedures applied to the silicon wafers. The efficiency of such cleaning procedures of metallurgical grade silicon is studied by instrumental neutron activation analysis (INAA). Small sized silicon wafers of approximately 200mg with and without gettering step were analyzed. To accelerate the detection of transition metals in a crystallized silicon ingot, experiments of scanning whole vertical silicon columns with a diameter of approximately 1cm by gamma spectroscopy were carried out. It was demonstrated that impurity profiles can be obtained in a comparably short time. Relatively constant transition metal ratios were found throughout an entire silicon ingot. This led to the conclusion that the determination of several metal profiles might be possible by the detection of only one "leading element". As the determination of Mn in silicon can be done quite fast compared to elements like Fe, Cr, and Co, it could be used as a rough marker for the overall metal concentration level. Thus, a fast way to determine impurities in photovoltaic silicon material is demonstrated.

  20. (30)Si mole fraction of a silicon material highly enriched in (28)Si determined by instrumental neutron activation analysis.

    PubMed

    D'Agostino, Giancarlo; Di Luzio, Marco; Mana, Giovanni; Oddone, Massimo; Pramann, Axel; Prata, Michele

    2015-06-01

    The latest determination of the Avogadro constant, carried out by counting the atoms in a pure silicon crystal highly enriched in (28)Si, reached the target 2 × 10(-8) relative uncertainty required for the redefinition of the kilogram based on the Planck constant. The knowledge of the isotopic composition of the enriched silicon material is central; it is measured by isotope dilution mass spectrometry. In this work, an independent estimate of the (30)Si mole fraction was obtained by applying a relative measurement protocol based on Instrumental Neutron Activation Analysis. The amount of (30)Si isotope was determined by counting the 1266.1 keV γ-photons emitted during the radioactive decay of the radioisotope (31)Si produced via the neutron capture reaction (30)Si(n,γ)(31)Si. The x((30)Si) = 1.043(19) × 10(-6) mol mol(-1) is consistent with the value currently adopted by the International Avogadro Coordination.