Elsevier Editorial System(tm) for Applied Radiation and Isotopes Title: Calculation of the decision thresholds for radionuclides identified in gamma-ray spectra (original) (raw)
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Review Article : Applicable methods of evaluating peak area of gamma ray spectra
Maǧallaẗ ǧāmiʻaẗ al-anbār li-l-ʻulūm al-ṣirfaẗ, 2022
Gamma ray spectra have interesting information about energy and intensity of gamma photons. Normally, this information is available in the peak area and background region. A full energy peak sits on a background continuum and produced by full energy absorption of high energy photons, while background region is produced by Compton scattering of the photons. The most essential concern of errors is in the method of determining the events in both peak and background areas. The uncertainty is low when the background counts are small relative to the peak counts. However, it becomes high when the counts of the peak area are low with respect to that of background. The detection threshold for the peak is ultimately determined by the uncertainty in the background counts. This depends on the technique used and the form of the produced spectra. This paper reviews different methods of determining peak area and their associated uncertainties in terms of the principle and application of the techniques used. .
Applied Radiation and Isotopes, 2019
The probabilities of locatingdetecting peaks with a high relative peak-area uncertainty were determined empirically with nine types of peak-location software used in laboratories engaged in gamma-ray spectrometry measurements. It was found that it is not possible to locate the peaks with a probability of 0.95, for those peaks that have a relative peak-area uncertainty in excess of 50%. LocatingIdentifying peaks at these relative peak-area uncertainties with a probability greater than 0.95 is only possible in the librarydriven mode, where the peak positions are supposed a-priori. The deficiencies of the library-driven mode and the possibilities to improve the probabilities of locating peaks are briefly discussed.
A baseline estimation procedure to improve MDA evaluation in gamma-ray spectrometry
The European Physical Journal Plus
The evaluation of minimum detectable activity (MDA) for a radionuclide in a gamma-ray spectrum is generally carried out through the computation of a suitable background count. This task is sometimes difficult for complex spectra for the presence of many photopeaks which make the trend of continuum extremely variable due to multiple dispersion effects and interference factors. It follows that the MDA assessment must be take into account the contributions of all gamma emissions of radionuclides contained in a sample and its value can be significantly higher than that determined by considering only the background of the spectrometric system due to the overlapping of other peaks. A procedure or an algorithm to determine, each time, the count values to be used for the calculation of MDA is interesting and useful. In this work, some of the more recent algorithms proposed for background subtraction in a gamma-ray spectrum have been examined, applying them in an inverse way for the evaluati...
Gamma spectrometry in the determination of radionuclides comprised in radioactive series
Gamma spectrometry is an analytical technique extensively employed in radionuclide determination. The usual ease of sampling preparation, the wide range of natural and artificial radionuclides that can be determined, and the applicability of this technique in a variety of sample matrices are some of its advantages. However, some care is needed when the technique is intended to be used as a tool for identification and quantification of radionuclides comprised in radioactive decay series. In such situations, as the radioactivity contents in the sample can naturally vary along the time, the results are critically dependent of the radioactive equilibrium conditions of the sample. In this work, we outline some criteria to decide about the radionuclide equilibrium situation expected to occur in various kinds of samples and thus decide the procedure to be taken to assure the reliability of the results in such complex situations. Provided that such analysis is carried out, gamma spectrometr...
Journal of Radioanalytical and Nuclear Chemistry, 2008
High-resolution gamma-spectrometry provides fast, accurate, non-destructive isotopic analysis of natural radionuclides in environmental samples. Low energy HPGe detectors (30%) with resolution less than 2.0 keV at 1332 keV of 60 Co and with linked analytical software, provide good peakto-background performance and accurate unfolding of multiplet regions. A procedure regarding high-resolution gamma-spectrometry measurements of naturally occurring radioactive samples is presented here including calibration, background interference, self-absorption, practical considerations and validation with respect to IAEA reference materials. Recommended peaks for quantitative measurements, deriving from the analysis of observed spectral interferences as well as from radioactive equilibrium considerations, are reported.
Applied Radiation and Isotopes, 2017
The results of peak analysis programs were tested on a statistical basis. Peak areas with a large statistical uncertainty were tested for their trueness. The test was performed on five different programs for analyzing the spectra. It was found that peak areas with a large statistical uncertainty are too large. A way, how to calculate uncertainty-dependent correction factors is described.
Brazilian Journal of Radiation Sciences, 2020
This paper aims to propose an easy and fast method of optimization of the gamma-ray spectrometry counting time in determining natural radionuclides (210 Pb, 212 Pb, 214 Pb, 212 Bi, 214 Bi and 228 Ac) in order to minimize uncertainties in the concentration. The samples were measured by gamma-ray spectrometry with a hyper-pure germanium detector Canberra, 25% relative efficiency, effective resolution of 1.9 keV on the 1332.5 keV 60Co with associated electronics and coupled to a microcomputer. Multichannel Maestro A65-I model was used for spectrum acquisition and peak net area determination, and WinnerGamma/Interwinner 6.01 software was used for gamma-ray spectra analysis and to calculate the concentrations and associated uncertainties. The counting times used were 86,000 s and 150,000 s.
The Evaluated Gamma-ray Activation File (EGAF)
2006
The Evaluated Gamma-ray Activation File (EGAF), a new database of prompt and delayed neutron capture γ ray cross sections, has been prepared as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project to develop a "Database of Prompt Gamma-rays from Slow Neutron Capture for Elemental Analysis". Recent elemental γ-ray cross-section measurements performed with the guided neutron beam at the Budapest Reactor have been combined with data from the literature to produce the EGAF database. EGAF contains thermal cross sections for ≈35,000 prompt and delayed γ-rays from 262 isotopes. New precise total thermal radiative cross sections have been derived for many isotopes from the primary and secondary gamma-ray cross sections and additional level scheme data. An IAEA TECDOC describing the EGAF evaluation and tabulating the most prominent γ-rays will be published in 2004. The TECDOC will include a CD-ROM containing the EGAF database in both ENSDF and tabular formats with an interactive viewer for searching and displaying the data. The Isotopes Project, Lawrence Berkeley National Laboratory continues to maintain and update the EGAF file. These data are available on the Internet from both the IAEA and Isotopes Project websites.
The 1995 IAEA intercomparison of γ-ray spectrum analysis software
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1997
In an intercomparison organized by the IAEA, 12 PC-based programs for y-ray spectrum analysis were tested using seven reference spectra and a sum of squared differences method. It was found that all programs yield peak areas without bias, relative to each other. Most of the programs could analyze a spectrum containing only singlets in reasonable statistical control with respect to peak areas. Peak positions generally are reported with too small or absent uncertainties. Statistical control was found to be lacking in the analysis of doublet peak areas.