LArGe:: Background suppression using liquid argon (LAr) scintillation for 0νββ decay search with enriched germanium (Ge) detectors

Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK-Heidelberg are reported. The liquid argon-germanium system (LArGe) is operated as a 4 pi anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the GERDA experiment which searches for 0 nu beta beta decays with HPGe detectors enriched in Ge-76. The goal of this work is to develop a novel method to discriminate backgrounds in 0 nu beta beta search which would ultimately allow to investigate the effective neutrino mass free of background events down to the inverse mass hierarchy scale. Other applications in low-background counting are expected.