Abstract
The Majorana Collaboration is constructing a system containing 44 kg of high-purity Ge (HPGe) detectors to demonstrate the feasibility and potential of a future tonne-scale experiment capable of probing the neutrino mass scale to ∼15 meV. To realize this, a major goal of the Majorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 count/(ROI-t-y) in the 4 keV region of interest (ROI) around the Q-value at 2039 keV. This goal is pursued through a combination of a significant reduction of radioactive impurities in construction materials and analytical methods for background rejection, for example using powerful pulse shape analysis techniques profiting from the p-type point contact (PPC) HPGe detectors technology. The effectiveness of these methods is assessed using simulations of the different background components whose purity levels are constrained from radioassay measurements. Preliminary background results obtained during the engineering runs of the Demonstrator are presented.
Highlights
The Majorana Demonstrator [12] is an array of enriched and natural germanium detectors that will search for the 0νββ-decay of 76Ge
The Majorana Demonstrator will be composed of 40 kg of HPGe detectors which act as the source of 76Ge 0νββ-decay
The Majorana Demonstrator is under construction: the shielding is being installed, the HPGe detectors are being characterized, and the Prototype Module, an initial prototype cryostat fabricated from commercially produced copper, is taking data with two strings of detectors produced from natural germanium
Summary
The expected background in the Majorana Demonstrator, 4.1 cnts/(ROI-t-y) after analysis cuts, will project to a background level of 1 cnt/(ROI-t-y) in a large scale experiment after accounting for additional modest improvements from thicker shielding, better self-shielding, and if necessary, increased depth. Background signals from radioactive decay often include a β and/or one or more γ rays that can scatter into different detectors, and these decays sometimes occur in chains that result in time-correlated event signatures. It is always a multiple-site energy deposit and we reject much of this background through PSA. This suite is run every time there is a major update to MaGe or Geant to verify that the critical physics processes do not show degraded performance between versions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
