Detector Response Simulations of Hydrocarbon Neutron Scintillators

DESCANT is a novel neutron detector array for use in nuclear structure and astrophysics studies with radioactive-ion beams. Comprised of 70 hexagonical deuterated scintillation detectors, DESCANT is located at the ISAC facility of TRIUMF, where it can be used in combination with the GRIFFIN or TIGRESS gamma-ray spectrometers in a multitude of nuclear decay and reaction experiments. The deuterated scintillator used in the DESCANT detectors produces a peaked structure in the detector response spectra that can provide neutron energy measurements without using traditional time-of-flight methods. This thesis will present the framework for a comprehensive GEANT4 simulation of the DESCANT array. The capabilities of the G4NeutronHP physics library in accurately reproducing interaction cross-sections below 10 MeV is verified. The G4Scintillation model is then used to investigate the geometric dependence of the light collection process in a single DESCANT detector. This is followed by an extensive study of simulated response functions of two neutron scintillators. The first is a well studied proton-recoil scintillator (NE-213) and the second is a deuteron-recoil scintillator (EJ-315), similar to that which is used by DESCANT. The detector response to mono-energetic neutrons is then measured for the two scintillators using cylindrical detectors with 11.43 cm diameter and 2.54 cm thickness geometries. A parameterization of the light yield is then calculated for both scintillators by conducting a chi-squared minimization between experimental and simulated pulse-height spectra. Finally, the current status of the DESCANT array geometry in GEANT4 is presented.