  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 $^{76}$Ge. 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.
