The Majorana Demonstrator: A Search for Neutrinoless Double-beta Decay of 76Ge

TL;DR

The paper discusses the design, goals, and status of the Majorana Demonstrator, an experiment aiming to detect neutrinoless double-beta decay of 76Ge to explore neutrino properties and matter-antimatter asymmetry.

Contribution

It introduces the Majorana Demonstrator, a novel 40-kg germanium detector array designed to achieve ultra-low background rates for neutrinoless double-beta decay search.

Findings

Design of the detector array and background reduction techniques

Achieved background rate goals in prototype tests

Status report on the experimental setup and readiness

Abstract

Neutrinoless double-beta decay is a hypothesized process where in some even-even nuclei it might be possible for two neutrons to simultaneously decay into two protons and two electrons without emitting neutrinos. This is possible only if neutrinos are Majorana particles, i.e. fermions that are their own antiparticles. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and might play a role in the matter-antimatter asymmetry in the universe. The observation of neutrinoless double-beta decay would also provide complementary information related to neutrino masses. The Majorana Collaboration is constructing the Majorana Demonstrator, a 40-kg modular germanium detector array, to search for the Neutrinoless double-beta decay of 76Ge and to demonstrate a background rate at or below 3 counts/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039 keV Q-value for 76Ge Neutrinoless double-beta decay. In this paper, we discuss the physics of neutrinoless double beta decay and then focus on the Majorana Demonstrator, including its design and approach to achieve ultra-low backgrounds and the status of the experiment.