Recent Results from the Majorana Demonstrator

TL;DR

The paper reports on the MAJORANA DEMONSTRATOR's low-background operation for neutrinoless double-beta decay search, recent physics results from various beyond Standard Model searches, and discusses future tonne-scale experiments.

Contribution

It provides initial background measurements, recent experimental results, and outlines plans for a larger, more sensitive next-generation experiment.

Findings

Achieved low background levels in the $0 uetaeta$ region

Set new limits on bosonic dark matter and axions

Demonstrated feasibility of scaling to a tonne-scale experiment

Abstract

The MAJORANA Collaboration has completed construction and is now operating an array of high purity Ge detectors searching for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{76}$Ge. The array, known as the MAJORANA DEMONSTRATOR, is comprised of 44 kg of Ge detectors (30 kg enriched to 88% in $^{76}$Ge) installed in an ultra-low background compact shield at the Sanford Underground Research Facility in Lead, South Dakota. The primary goal of the DEMONSTRATOR is to establish a low-background design that can be scaled to a next-generation tonne-scale experiment. This work reports initial background levels in the $0\nu\beta\beta$ region of interest. Also presented are recent physics results leveraging P-type point-contact detectors with sub-keV energy thresholds to search for physics beyond the Standard Model; first results from searches for bosonic dark matter, solar axions, Pauli exclusion principle violation, and electron decay have been published. Finally, this work discusses the proposed tonne-scale $^{76}$Ge $0\nu\beta\beta$ LEGEND experiment.