Evaluation of radioactive background rejection in 76Ge neutrino-less double-beta decay experiments using a highly segmented HPGe detector

A highly segmented coaxial HPGe detector was operated in a low background counting facility for over 1 year to experimentally evaluate possible segmentation strategies for the proposed Majorana neutrino-less double-beta decay experiment. Segmentation schemes were evaluated on their ability to reject multi-segment events while retaining single-segment events. To quantify a segmentation schemeʹs acceptance efficiency the percentage of peak area due to single segment events was calculated for peaks located in the energy region 911–2614 keV. Single interaction site events were represented by the double-escape peak from the 2614 keV decay in 208Tl located at 1592 keV. In spite of its prototypical nature, the detector performed well under realistic operating conditions and required only minimal human interaction. Though the energy resolution for events with interactions in multiple segments was impacted by inter-segment cross-talk, the implementation of a cross-talk correlation matrix restored acceptable resolution. Additionally, simulations utilizing the MaGe simulation package were performed and found to be in good agreement with experimental observations verifying the external nature of the background radiation.