Abstract:
A study of signals originating near the lithium-diffused n+ contact of p-type
point contact (PPC) high purity germanium detectors (HPGe) is presented. The
transition region between the active germanium and the fully dead layer of the
n+ contact is examined. Energy depositions in this transition region are shown
to result in partial charge collection. This provides a mechanism for events
with a well defined energy to contribute to the continuum of the energy
spectrum at lower energies. A novel technique to quantify the contribution from
this source of background is introduced. Experiments that operate germanium
detectors with a very low energy threshold may benefit from the methods
presented herein.