Energy Response Function of Stilbene and BC501 Neutron Detection System

Abstract

This paper discusses energy response of a single stilbene crystal and a liquid scintillator detector to a range of neutrons energies which could be generated using the 1.7 MV Tandetron accelerator at IIT Kanpur. Stilbene is a solid-state composite organic detector and an alternate choice for combined neutron-gamma detection. Previous works have shown that stilbene’s light output response is similar to the liquid scintillation detectors, such as BC501. In this work, we investigate and quantify stilbene’s response to neutrons lower than 3 MeV. We generate neutrons using (p, n) reactions by scattering protons with energy 3.4 MeV on 9Be target. The target thickness is determined by Monte Carlo simulations. Next, we measure pulse height distributions of the various energies incident on stilbene and BC501. The response of the stilbene crystal and BC501 to neutrons using the Tandetron is performed on an energy range spanning the fission neutron energy range. A general-purpose Monte Carlo (MC) simulation kit Geant4 is then used to simulate the detector response behavior. Stilbene shows 33% lower energy response for higher energies as compared to BC501 which is consistent as number density of hydrogen of same mass of stilbene contains 33% less than that of BC501 scintillation detector. For lower energies close to 0.7 MeV, the response of stilbene is 7% lower than BC501. The Geant4 simulations allow a more detailed analysis of the detector response physics to advance the detector development process for applications in nuclear security.