Automatic modeling using PENELOPE of two HPGe detectors used for measurement of environmental samples byγ-spectrometry from a few sets of experimental efficiencies

Abstract

a b s t r a c tThe aim of this paper is to characterize two HPGe gamma-ray detectors used in two different laboratories for environmental radioactivity measurements, so as to perform efficiency calibrations by means of Monte Carlo Simulation. To achieve such an aim, methodologies developed in previous papers have been applied, based on the automatic optimization of the model of detector, so that the differences between computational and reference FEPEs are minimized. In this work, such reference FEPEs have been obtained experimentally from several measurements of the IAEA RGU-1 reference material for specific source-detector arrangements. The models of both detectors built through these methodologies have been validated by comparing with experimental results for several reference materials and different measurement geometries, showing deviations below 10% in most cases. (J.G. Guerra). work [16,17], in which automatic computational methodologies for the characterization of HPGe detectors have been developed.In the first paper [16], a simple methodology of characterization is proposed, consisting in an implementation of a mono-objective optimization evolutionary algorithm, called Differential Evolution or DE [18], together with the Monte Carlo Simulation code PENE-LOPE [19], so that a computational model of the detector would be built automatically, with the only requirements of an accurate set of reference FEPEs for a specific sample-detector arrangement and material of the sample, but restricted to those beakers with a diameter lower than the crystal diameter of the detector. In the second [17], the methodology proposed in the first work was upgraded, eliminating such restriction by both improving the detector model and implementing a multi-objective Differential Evolution algorithm or DEMO [20] instead of its monoobjective precursor DE. In both cases, the methodologies proved to obtain successfully a detector model which generated FEPEs equivalent to the ones taken as reference, which were calculated, for a given

Investigation of the Effect of Hydrothermal Waters on Radionuclide Activity Concentrations in Natural Marble with Multivariate Statistical Analysis

“…The minimum detectable activity (MDA) values of the 226 Ra, 232 Th, and 40 K radionuclides of the 1 kg samples measured for 10,000 s by the gamma spectroscopy system are given in Table 1. Similar studies have been conducted on radiometric measurements of rocks and soils [15,[23][24][25]. Radiological parameters and hazard indices were calculated using the results of the radiometric analysis.…”