Germanium Detector Test-Stands At The Max Planck Institute For Physics And Alpha Interactions On Passivated Surfaces

The GeDet group at the Max Planck Institute for Physics in Munich, Germany, operates a number of test stands in order to conduct research on novel germanium detectors. The test stands are of a unique design and construction that provide the ability to probe the properties of new detector types. The GALATEA test stand was especially designed for surface scans, specifically alpha-induced surface events, a problem faced in low background experiments due to unavoidable surface contamination of detectors. A special 19-fold segmented coaxial prototype detector has already been investigated inside GALATEA with an alpha-source. A top surface scan provided insight into the physics underneath the passivation layer. Detector segmentation provides a direct path towards background identification and characterisation. With this in mind, a 4-fold segmentation scheme was implemented on a broad-energy point-contact detector and is being investigated inside the groups K1 test stand. A cryogenic test-stand where detectors can be submerged directly in liquid nitrogen or argon is also available. The goal is to establish segmentation as a viable option to reduce background in future large scale experiments.