skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey

Abstract

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.

Authors:
; ; ; ; ; ; ;  [1]
  1. Colombian Geological Survey, Nuclear Affairs Technical Division, Neutron Activation Analysis Laboratory, Bogota D. C. (Colombia)
Publication Date:
OSTI Identifier:
22608527
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1753; Journal Issue: 1; Conference: Latin American symposium on nuclear physics and applications, Medellin (Colombia), 30 Nov - 4 Dec 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CRYSTALS; EFFICIENCY; GAMMA RADIATION; GERMANIUM; HIGH-PURITY GE DETECTORS; INTERACTIONS; MONTE CARLO METHOD; NEUTRON ACTIVATION ANALYSIS; NEUTRONS

Citation Formats

Sierra, O., E-mail: osierra@sgc.gov.co, Parrado, G., E-mail: gparrado@sgc.gov.co, Cañón, Y., Porras, A., Alonso, D., Herrera, D. C., Peña, M., E-mail: mlpena@sgc.gov.co, and Orozco, J. Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey. United States: N. p., 2016. Web. doi:10.1063/1.4955381.
Sierra, O., E-mail: osierra@sgc.gov.co, Parrado, G., E-mail: gparrado@sgc.gov.co, Cañón, Y., Porras, A., Alonso, D., Herrera, D. C., Peña, M., E-mail: mlpena@sgc.gov.co, & Orozco, J. Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey. United States. doi:10.1063/1.4955381.
Sierra, O., E-mail: osierra@sgc.gov.co, Parrado, G., E-mail: gparrado@sgc.gov.co, Cañón, Y., Porras, A., Alonso, D., Herrera, D. C., Peña, M., E-mail: mlpena@sgc.gov.co, and Orozco, J. 2016. "Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey". United States. doi:10.1063/1.4955381.
@article{osti_22608527,
title = {Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey},
author = {Sierra, O., E-mail: osierra@sgc.gov.co and Parrado, G., E-mail: gparrado@sgc.gov.co and Cañón, Y. and Porras, A. and Alonso, D. and Herrera, D. C. and Peña, M., E-mail: mlpena@sgc.gov.co and Orozco, J.},
abstractNote = {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.},
doi = {10.1063/1.4955381},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1753,
place = {United States},
year = 2016,
month = 7
}
  • 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 withmore » 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.« less
  • Scanning in the spectral region containing photopeaks, calculation of the energy and intensity of the photopeaks, identification of standard isotopes in the spectra, and calculation of the quantitative concentration of elements in the sample are carried out by the program. The processing time for a gamma spectrum with a capacity of 3200 channels on the M-220 computer takes 5 to 10 min. (tr-auth)
  • A new approach to {alpha} spectrometric determination of the radioisotopes of uranium and thorium was developed for environmental samples based on {sup 238}U and {sup 232}Th as internal standards. {sup 238}U and {sup 232}Th were accurately determined in the sample by simultaneous instrumental neutron activation analysis. Other aliquots of the sample were totally dissolved, uranium and thorium separated by anion exchange, and thin sources electroplated for {alpha} spectrometry. From the known mass concentrations of {sup 238}U and {sup 232}Th, their activity concentrations were obtained, and thus from the relative ratios of uranium ({sup 234}U, {sup 235}U, {sup 238}U) and thoriummore » ({sup 228}Th, {sup 230}Th, {sup 232}Th) radioisotopes in the {alpha} spectra, the absolute isotopic activity concentrations were derived. The advantages of the procedure are that neither the chemical recovery of the radiochemical separation nor the counting efficiency of the {alpha} spectrometer is required; the use of internal standards eliminates the need for addition of expensive, calibrated, external radioisotopic tracers such as {sup 232}U and {sup 229}Th. The new approach was tested on some certified environmental reference materials and compared with the classical method using external radioisotopic tracers. It may advantageously be combined with the standard approach to obtain an independent set of data for quality control. 25 refs.« less