Geant4 simulation to study High-purity Germanium detector response

Understanding the origin of elements in the Universe and everything seen around us is the main goal of nuclear astrophysics. More than half of the elements on the periodic table are created in explosive stellar environments, such as supernovae and neutron star mergers. In the field of experimental nuclear astrophysics, specific measurements are made that allow us to shed light on how specific elements are synthesized in stars. This work focuses on commissioning a GC6019 Canberra High-purity Germanium (HPGe) detector for use in neutron activation analysis experiments at the Edwards Accelerator Laboratory. This new experimental set up will then be used to perform a neutron activation on a sample to investigate reactions of astrophysical interest.

A detailed simulation of the HPGe detector has been developed to investigate the detector's sensitivity to background radiation. Preliminary tests of the detector show that it is very sensitive to background radiation. During the tests the detector was shielded from background radiation using a lead “house” that was built, but even with the lead, the detector was still too sensitive. To better understand and suppress the contributions of the background seen by the detector a Geant4 simulation of the detector has been created, the simulation models both the detector geometry and the environmental background sources. Through this, the simulation provides insight into the detector response and demonstrates how background radiation contributes to experimental data.