Design and model of shielding for High-Purity Germanium Detector for the Edwards Accelerator Laboratory

Understanding the origin of elements in the Universe is one of the biggest questions in the field of Nuclear Astrophysics. More than half of the known elements of the universe are created in extreme environments through neutron-capture-reactions. The main mechanism of experimentally observing neutron-capture reactions is through the measurement of gamma-ray radiation from the reaction. High purity germanium detector (HPGe) are highly sensitive devices used to detect gamma rays. This project has focused on commissioning a new low background HPGe in the EAL. Preliminary tests of the detector show that it is very sensitive to background radiation. During the test experiment 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. In order to suppress the signals a model house has been designed using CAD, a 3-D modeling software to provide better shielding so that the background radiation is less prominent. The design of the lead house has been modeled using GEANT4, the results of which will be presented.