Initial Results from the Majorana Demonstrator

TL;DR

The paper reports initial results from the MAJORANA Demonstrator, a Ge detector array designed to search for neutrinoless double-beta decay, assessing background levels and potential for future large-scale experiments.

Contribution

It presents the first physics results and background estimates from the MAJORANA Demonstrator, demonstrating its readiness for neutrinoless double-beta decay searches.

Findings

Background levels consistent with design goals

Initial data shows potential for low-energy physics searches

Projections indicate feasibility for ton-scale experiments

Abstract

The MAJORANA Collaboration has assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in $^{76}$Ge with the goal of establishing the required background and scalability of a Ge-based next-generation ton-scale experiment. The MAJORANA DEMONSTRATOR consists of 44 kg of high-purity Ge (HPGe) detectors (30 kg enriched in $^{76}$Ge) with a low-noise p-type point contact (PPC) geometry. The detectors are split between two modules which are contained in a single lead and high-purity copper shield at the Sanford Underground Research Facility in Lead, South Dakota. Following a commissioning run that started in June 2015, the full detector array has been acquiring data since August 2016. We will discuss the status of the MAJORANA DEMONSTRATOR and initial results from the first physics run; including current background estimates, exotic low-energy physics searches, projections on the physics reach of the DEMONSTRATOR, and implications for a ton-scale Ge-based neutrinoless double-beta decay search.