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R P Gardner - One of the best experts on this subject based on the ideXlab platform.

  • the monte carlo code cearcpg for coincidence prompt gamma ray Neutron Activation analysis
    Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007
    Co-Authors: Xiaogang Han, R P Gardner
    Abstract:

    Prompt gamma-ray Neutron Activation analysis (PGNAA) is widely used to determine the elemental composition of bulk samples. The detection sensitivities of PGNAA are often restricted by the inherent poor signal-to-noise ratio (SNR). There are many sources of noise (background) including the natural background, Neutron Activation of the detector, gamma-rays associated with the Neutron source and prompt gamma-rays from the structural materials of the analyzer. Results of the prompt gamma-ray coincidence technique show that it could greatly improve the SNR by removing almost all of the background interferences. The first specific Monte Carlo code (CEARCPG) for coincidence PGNAA has been developed at the Center for Engineering Application of Radioisotopes (CEAR) to explore the capabilities of this technique. Benchmark bulk sample experiments have been performed with coal, sulfur, and mercury samples and indicate that the code is accurate and will be very useful in the design of coincidence PGNAA devices.

  • cearpga ii a monte carlo simulation code for prompt gamma ray Neutron Activation analysis
    Nuclear Science and Engineering, 2005
    Co-Authors: Wenchao Zhang, R P Gardner
    Abstract:

    A Monte Carlo simulation code, CEARPGA II, has been developed to generate the complete set of library spectra that are required for the application of the Monte Carlo-Library Least-Squares approach in prompt-gamma-ray Neutron Activation analysis. Compared to the previous version, the CEARPGA I code, several important improvements have been made including eliminating the 'big weight' problem by implementing the Analog Linear Interpolation technique, generating the appropriate detector response functions using improved simulation models that account for NaI detector nonlinearity and flat continua, generating the Neutron Activation backgrounds by directly sampling detector-activated gamma-ray energies, generating the natural background libraries by interpolating the energy-score tables, and tracking the annihilation gamma rays from the pair production interaction that occurs outside the detector. The coal sample spectrum calculated with the CEARPGA II code is benchmarked against those calculated from the CEARPGA I code, the MCNP code, and experimentally measured data.

  • nai detector Neutron Activation spectra for pgnaa applications
    Applied Radiation and Isotopes, 2000
    Co-Authors: R P Gardner, El Sayyed, Yuanshui Zheng, Stephanie Hayden, Charles W Mayo
    Abstract:

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

Sheldon Landsberger - One of the best experts on this subject based on the ideXlab platform.

  • An online Neutron Activation analysis database (NAADB)
    Journal of Radioanalytical and Nuclear Chemistry, 2020
    Co-Authors: Mete Bayrak, Sheldon Landsberger, Michael D Glascock
    Abstract:

    An online computer program for an interactive database was specifically developed for Neutron Activation analysis (NAA). The software written in Java includes gamma-ray catalog, Neutron Activation calculator for activity calculations and decay schemes. For the novice, expert and educator this program can greatly reduce needed information in NAA.

  • characterization of bauxite residue red mud for 235u 238u 232th and 40k using Neutron Activation analysis and the radiation dose levels as modeled by mcnp
    Journal of Environmental Radioactivity, 2017
    Co-Authors: Sheldon Landsberger, A Sharp, S Wang, Yiannis Pontikes, Alan H Tkaczyk
    Abstract:

    This study employs thermal and epithermal Neutron Activation analysis (NAA) to quantitatively and specifically determine absorption dose rates to various body parts from uranium, thorium and potassium. Specifically, a case study of bauxite residue (red mud) from an industrial facility was used to demonstrate the feasibility of the NAA approach for radiological safety assessment, using small sample sizes to ascertain the activities of 235U, 238U, 232Th and 40K. This proof-of-concept was shown to produce reliable results and a similar approach could be used for quantitative assessment of other samples with possible radiological significance. 238U and 232Th were determined by epithermal and thermal Neutron Activation analysis, respectively. 235U was determined based on the known isotopic ratio of 238U/235U. 40K was also determined using epithermal Neutron Activation analysis to measure total potassium content and then subtracting its isotopic contribution. Furthermore, the work demonstrates the application of Monte Carlo Neutral-Particle (MCNP) simulations to estimate the radiation dose from large quantities of red mud, to assure the safety of humans and the surrounding environment. Phantoms were employed to observe the dose distribution throughout the human body demonstrating radiation effects on each individual organ.

  • determination of selenium in coal fly ash via γ γ coincidence Neutron Activation analysis
    Journal of Radioanalytical and Nuclear Chemistry, 2016
    Co-Authors: M Yoho, Sheldon Landsberger
    Abstract:

    The determination of selenium (Se) in fly-ash poses difficulties to the Neutron Activation analyst due to high Compton backgrounds as well as interference peaks from the 180Hf(n, γ)181Hf and 181Ta(n, γ)182Ta Activation products. A methodology is presented to eliminate these interferences in geological samples via γ–γ coincidence. The methodology includes experimentally correcting for dead-time and random-summing. Random-coincidence gains which may lead to an over-estimation of concentration are corrected via post-acquisition analysis of the list-mode data. Calculated Se concentrations in fly-ash and other geological and biological reference materials agreed very well with the certified values.

  • the simultaneous determination of 235u and 239pu using delayed Neutron Activation analysis
    Journal of Radioanalytical and Nuclear Chemistry, 2013
    Co-Authors: R Kapsimalis, David C Glasgow, Brian B Anderson, Sheldon Landsberger
    Abstract:

    Delayed Neutron Activation analysis (DNAA) remains one of the most sensitive methods of nondestructively determining fissile materials in a variety of sample matrices, provided that the samples contain only a single fissile component. This has historically been the limiting factor in many applications of DNAA, and often chemically destructive methods of analysis have needed to be utilized for many real-world samples. This work seeks to develop a method that will allow for DNAA to be utilized on samples containing multiple fissile components. Initial efforts, presented here, show that using a multivariate linear regression model to describe the delayed Neutron emission profile of an irradiated sample allows for the concurrent determination of fissile nuclides in samples containing both 235U and 239Pu, without chemical separations and using only a single counting step.

Richard M Lindstrom - One of the best experts on this subject based on the ideXlab platform.

  • Prompt gamma Neutron Activation analysis (PGAA): recent developments and applications
    Journal of Radioanalytical and Nuclear Chemistry, 2017
    Co-Authors: Richard M Lindstrom, Zsolt Révay
    Abstract:

    Prompt gamma Neutron Activation analysis has become an important part of the analytical toolkit, practiced at several research reactors worldwide. An extensive review of the physics, engineering, and applications of the technique was published in 2004: the present work gives an overview and survey of the literature in the succeeding dozen years.

  • delayed Neutron Activation analysis at nist
    Journal of Radioanalytical and Nuclear Chemistry, 2013
    Co-Authors: Sofia M Eriksson, Richard M Lindstrom, Elizabeth A Mackey, George P Lamaze, Kelly P Grogan, Dennis E Brady
    Abstract:

    An automated delayed-Neutron Activation analysis system has been installed at the NIST research reactor. This work involved characterization of the transfer time of the system, evaluation of blanks, and tests of the system’s analytical capabilities through quantitative analysis for uranium in several natural matrix standard reference materials (SRMs). The calibration curve was shown to be linear up to at least 20 μg of uranium, and the well-thermalized reactor irradiation position makes the system insensitive to thorium and oxygen. For SRMs 1646a Estuarine Sediment and 2710a Montana Soil the values determined for this work agree with the reference and certified values, respectively. The mass fraction of uranium in SRM 695 Multi-Nutrient Fertilizer is the first reported for this material. For this system and the irradiation, transfer, and counting times used, the limit of detection for natural uranium is 20 ng, which corresponds to approximately 200 pg of 235U.

  • γγ coincidence spectrometer for instrumental Neutron Activation analysis
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2008
    Co-Authors: Bryan E Tomlin, Rolf Zeisler, Richard M Lindstrom
    Abstract:

    Abstract Neutron-Activation analysis (NAA) is an important technique for the accurate and precise determination of trace and ultra-trace elemental compositions. The application of γ γ coincidence counting to NAA in order to enhance specificity was first explored over 40 years ago but has not evolved into a regularly used technique. A γ γ coincidence spectrometer has been constructed at the National Institute of Standards and Technology, using two HPGe γ -ray detectors and an all-digital data-acquisition system, for the purpose of exploring coincidence NAA and its value in characterizing reference materials. This paper describes the initial evaluation of the quantitative precision of coincidence counting versus singles spectrometry, based upon a sample of Neutron-irradiated bovine liver material.

A Smith - One of the best experts on this subject based on the ideXlab platform.

  • gamma Neutron Activation experiments using laser wakefield accelerators
    Physics of Plasmas, 2001
    Co-Authors: W P Leemans, D Rodgers, P Catravas, C G R Geddes, G Fubiani, E Esarey, B A Shadwick, R Donahue, A Smith
    Abstract:

    Gamma-Neutron Activation experiments have been performed with relativistic electron beams produced by a laser wakefield accelerator. The electron beams were produced by tightly focusing (spot diameter ≈6 μm) a high power (up to 10 TW), ultra-short (⩾50 fs) laser beam from a high repetition rate (10 Hz) Ti:sapphire (0.8 μm) laser system, onto a high density (>1019 cm−3) pulsed gasjet of length ≈1.5 mm. Nuclear Activation measurements in lead and copper targets indicate the production of electrons with energy in excess of 25 MeV. This result was confirmed by electron distribution measurements using a bending magnet spectrometer. Measured γ-ray and Neutron yields are also found to be in reasonable agreement with simulations using a Monte Carlo transport code.

Michael D Glascock - One of the best experts on this subject based on the ideXlab platform.

  • An online Neutron Activation analysis database (NAADB)
    Journal of Radioanalytical and Nuclear Chemistry, 2020
    Co-Authors: Mete Bayrak, Sheldon Landsberger, Michael D Glascock
    Abstract:

    An online computer program for an interactive database was specifically developed for Neutron Activation analysis (NAA). The software written in Java includes gamma-ray catalog, Neutron Activation calculator for activity calculations and decay schemes. For the novice, expert and educator this program can greatly reduce needed information in NAA.

  • acknowledging fifty years of Neutron Activation analysis in archaeology
    Archaeometry, 2007
    Co-Authors: Robert J Speakman, Michael D Glascock
    Abstract:

    Neutron Activation analysis has been an important analytical technique for chemical characterization studies of archaeological materials since 1957, and remains one of the best analytical approaches for bulk chemical characterization of archaeological ceramics and other materials. This paper introduces a series of reports that document the history of NAA applied to archaeological materials.

  • instrumental Neutron Activation analysis and multivariate statistics for pottery provenance
    Hyperfine Interactions, 2004
    Co-Authors: Michael D Glascock, Hector Neff, Kevin J Vaughn
    Abstract:

    The application of instrumental Neutron Activation analysis and multivariate statistics to archaeological studies of ceramics and clays is described. A small pottery data set from the Nasca culture in southern Peru is presented for illustration.

  • Neutron Activation analysis and provenance research in archaeology
    Measurement Science and Technology, 2003
    Co-Authors: Michael D Glascock, Hector Neff
    Abstract:

    Neutron Activation analysis is a powerful quantitative analytical technique with application in a broad range of disciplines such as agriculture, archaeology, geochemistry, health and human nutrition, environmental monitoring and semiconductor technology. Due to its excellent sensitivity, great accuracy and precision, and versatility, the technique is a suitable method for analysing many different types of samples. Archaeologists, in particular, have made extensive use of Neutron Activation analysis for the purpose of characterizing archaeological materials and determining their provenance. This paper presents a brief history of the technique and its application to archaeology, describes the physics behind the analytical method, and explains how the method is generally employed to determine the sources of archaeological materials.

  • steatite source characterization in eastern north america new results using instrumental Neutron Activation analysis
    Archaeometry, 1998
    Co-Authors: James Joseph Trunce, Michael D Glascock, Hecto Neff
    Abstract:

    Doubts have recently been cast on the ability to characterize steatite sources using rare earth elements (REEs). By increasing the number of samples and elements examined using instrumental Neutron Activation analysis (INAA) and multivariate statistics, this study shows that, with unhomogenized samples, transition metals, not REEs, make the greatest contribution in characterizing steatite sources in the Middle Atlantic region of eastern North America. Preliminary results suggest that INAA has the potential to assign provenance to steatite artefacts, at least at a regional level.