The Simulation of Slow Pulses in PPC Detectors

The Majorana Demonstrator project, an international collaboration among 20 universities, is attempting to determine the mass of the neutrino by using an array of P-type point contact (PPC) germanium detectors to identify neutrinoless double beta decay. This point contact configuration allows us to identify neutrinoless double-beta decay events based on pulse-shape analysis. However, the dead layer around the perimeter of the PPC germanium detector significantly slows the collection of charge deposited there and distorts the shape of the resultant pulse. We have been developing simulations to further understand the physical mechanism that produces the slow pulses, namely diffusion and recombination in the dead layer. The results from these simulations are compared to experimental data obtained from a PPC detector.