A study for improving detection efficiency of an HPGe detector based gamma spectrometer using Monte Carlo simulation and genetic algorithms

This work aims at improving the detection efficiency of an HPGe detector based gamma spectrometer for measurements of environmental radioactivity sample. Application of a simple genetic algorithm and the Monte Carlo simulation computer code MCNP5 allows to search for optimal dimensions of the Marinelli beaker typed source geometry that maximizes the detector efficiency for a fixed configuration of the gamma spectrometer. The interested gamma energies are in the range of 255-1926 key. Optimization calculation was repeated several times to deduce average dimensions of an optimal Marinelli beaker typed sample with a volume of 450 cm(3). Effects of gamma energy, sample chemical composition and sample density on the optimal dimensions were also investigated. Calculated results showed that the effects were negligible. A validated experiment with arrangements using an optimal beaker and three other ones was carried out to verify calculated results. It is shown that experimental and calculated results of the detector efficiency are in a good agreement. (C) 2012 Elsevier Ltd. All rights reserved.