Monte Carlo model of a BEGe detector to support gamma-spectrometry in an emergency response

摘要

One of the problems of measuring high radioactivity in an emergency scenario is the fact that the detector can become saturated or reach a measuring dead time too high to give reliable results, which means repeating the measurement in different conditions with the associated delay in obtaining the results and the laboratory workers' risk of exposure. The counting rate can be controlled by varying the sample-to-detector distance as well as by using different source volumes. A Monte Carlo model of a BEGe detector was developed to analyse the system efficiency response for several measuring configurations (distances and volumes) using the MCNP6 code. The total efficiency curves were obtained for an energy range between 59.5 keV and 1836 keV. The simulations provided an estimation of the admissible gamma-rate for different source volumes (in water matrix) and sample-to-detector distances to avoid detector saturation in given measurement conditions. The results were a compromise between geometry, distance and measuring time for certain emergency situations. Three case studies are provided to show the approach's effectiveness.