MCNPX Monte Carlo simulations of particle transport in SiC semiconductor detectors of fast neutrons

• Published in: Journal of instrumentation 2014-05, Vol.9 (5), p.C05016-C05016
• Main Authors: Sedlačková, K, Zat'ko, B, Šagátová, A, Pavlovič, M, Nečas, V, Stacho, M
• Format: Article
• Language: English
• Subjects: Carbon; Computer simulation; Detectors; Fast neutrons; Reactions (nuclear); Semiconductors; Silicon carbide; Transport
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/9/05/C05016

The aim of this paper was to investigate particle transport properties of a fast neutron detector based on silicon carbide. MCNPX (Monte Carlo N-Particle eXtended) code was used in our study because it allows seamless particle transport, thus not only interacting neutrons can be inspected but also secondary particles can be banked for subsequent transport. Modelling of the fast-neutron response of a SiC detector was carried out for fast neutrons produced by super(239)Pu-Be source with the mean energy of about 4.3 MeV. Using the MCNPX code, the following quantities have been calculated: secondary particle flux densities, reaction rates of elastic/inelastic scattering and other nuclear reactions, distribution of residual ions, deposited energy and energy distribution of pulses. The values of reaction rates calculated for different types of reactions and resulting energy deposition values showed that the incident neutrons transfer part of the carried energy predominantly via elastic scattering on silicon and carbon atoms. Other fast-neutron induced reactions include inelastic scattering and nuclear reactions followed by production of alpha -particles and protons. Silicon and carbon recoil atoms, alpha -particles and protons are charged particles which contribute to the detector response. It was demonstrated that although the bare SiC material can register fast neutrons directly, its detection efficiency can be enlarged if it is covered by an appropriate conversion layer. Comparison of the simulation results with experimental data was successfully accomplished.