Development and validation of a Geant4 application to calculate the Response Matrix of a set of Superheated Drop Detectors under various external pressures

Abstract

Abstract In this paper, a Geant4 user application program was developed and validated to calculate the response of Superheated Drop Detectors (SDDs) by Monte Carlo simulation. As the most important quantity to be incorporated in the program, the thermodynamic efficiency “ η ” of the superheated droplets was determined through comparison of the simulation results with the experimental data including the results reported in the literature as well as the measured values obtained in this study. For validation of the simulation program, the determined values of “ η ” for each of the three types of detectors made from R-12 (CCl2F2), R-114 (C2Cl2F4) and isobutene (C4H10) were incorporated in the simulation program to predict the response of each type of these detectors for other neutron fields or under other external pressures. The simulation program predicted the response for different neutron energies and external pressures, with less than 15% relative difference from the measured values. Then by using the evaluated simulation program, the response matrix of a set of indigenously fabricated R-12 SDDs was calculated under external pressures of 0.86, 1.32, 1.87, 2.40 and 3.01 atm for 18 neutron energy bins from 1.415 MeV to 514 MeV. The calculated response matrix will be used for spectrum unfolding of the data obtained from these detectors. In conclusion, it was found that the developed Monte Carlo based simulation application program, validated through comparisons with experimental data, can be applied as a suitable tool for calculating the response of SDDs, made from various superheated materials at given temperature and pressure, as well as the response matrix of several detectors under various external pressures, to spectrum unfolding of a set of experimental measured values.