Victoria Wagner Max-Planck Institut für Kernphysik

Pulse Shape Discrimination with BEGe Detectors in GERDA Phase I(pdf)

The GERDA experiment searches for the lepton number violating neutrinoless double beta decay of Ge-76. The experiment uses HPGe crystals enriched in Ge-76 as source and detector. In addition to 8 coaxial detectors, 5 broad energy Ge (BEGe) detectors were deployed in a liquid argon (LAr) cryostat for the GERDA Phase I. BEGe diodes are distinguished for their improved energy resolution and enhanced pulse shape discrimination (PSD) against background events. Recently, the GERDA collaboration published the results of Phase I. It was shown that BEGe detectors can be operated in LAr with an excellent energy resolution. Moreover, the PSD cut removes efficiently background events. After PSD the background index is 5 x 10^{-3} cts/(keV kg yr) whereas the signal acceptance is 0.92. However, time instabilities of the pulse shape parameter were observed. This talk will review the BEGe PSD method as applied on the GERDA Phase I data.