High voltage testing for the MAJORANA Demonstrator

Abstract The M ajorana Collaboration is constructing the M ajorana D emonstrator , an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in 76 Ge. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of the M ajorana D emonstrator . This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of the high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the M ajorana D emonstrator was characterized and the micro-discharge effects during the M ajorana D emonstrator commissioning phase were studied. A stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge.