Studies of prompt gamma and neutron yield due to 2.5 MeV neutrons using GEANT4

Abstract

In the present work the software GEANT4, a particle transport toolkit based on the Monte Carlo method, developed mostly by CERN, but also by other institutions and universities. GEANT4 is here used to simulate the dispersive effects that 2.5 MeV neutrons undergo after interacting with different elements. This study has the main interest of identifying spectral signatures, that is the type and number of particles yielded after neutron bombardment of special nuclear material under various shielding conditions. Shielding is composed of various attenuating materials with simple geometrical configurations, that can evolve into more intricate geometries through Boolean operations, enclosing a simulated mass of Uranium and a Uranium ore, Margaritasite. Margaritasite is of interest since it has a natural proportion of various Uranium isotopes that represent a dilute sample of special nuclear material. This work is inspired in the implementation of active detection methods that improve control over transport of fissile and fertile nuclear material. Passive methods that rely on the radiation that would typically be produced by radioactive material may not be adequate enough when shielding is in place. It is thus necessary to induce the production of radiation signatures that disclose the nature of nuclear material of interest. One such probe are neutrons, particularly those in the MeV regime, which are easily accomplished by well known nuclear reactions involving deuterium-deuterium collisions. The lack of charge of neutrons allows penetration through shielding of various types, and once the neutron interacts with the material of interest, a nuclear reaction can take place that should be characteristic of such material. With this idea in mind a small subset of basic aspects about the complex topic of hadronic interactions will be discussed.