The MAJORANA DEMONSTRATOR experiment's construction, commissioning, and performance

TL;DR

The MAJORANA DEMONSTRATOR is a low-background germanium detector array designed to search for neutrinoless double-beta decay, achieving top energy resolution and low background levels, thus setting stringent limits on decay half-life.

Contribution

This paper details the construction, commissioning, and performance of the MAJORANA DEMONSTRATOR, demonstrating its low-background capabilities and setting a new half-life limit for neutrinoless double-beta decay in germanium.

Findings

Achieved the best energy resolution among similar experiments.

Attained the second-lowest background level in $etaeta(0 u)$ searches.

Set an upper half-life limit of $8.3\times 10^{25}$ years for neutrinoless double-beta decay.

Abstract

Background: The MAJORANA DEMONSTRATOR , a modular array of isotopically enriched high-purity germanium (HPGe) detectors, was constructed to demonstrate backgrounds low enough to justify building a tonne-scale experiment to search for the neutrinoless double-beta decay ($\beta\beta(0\nu)$) of $^{76}\mathrm{Ge}$. Purpose: This paper presents a description of the instrument, its commissioning, and operations. It covers the electroforming, underground infrastructure, enrichment, detector fabrication, low-background and construction techniques, electronics, data acquisition, databases, and data processing of the MAJORANA DEMONSTRATOR. Method: The MAJORANA DEMONSTRATOR operated inside an ultra-low radioactivity passive shield at the 4850-foot~level of the Sanford Underground Research Facility (SURF) from 2015-2021. Results and Conclusions: The MAJORANA DEMONSTRATOR achieved the best energy resolution and second-best background level of any $\beta\beta(0\nu)$ search. This enabled it to achieve an ultimate half-life limit on $\beta\beta(0\nu)$ in $^{76}\mathrm{Ge}$ of $8.3\times 10^{25}$~yr (90\% C.L.) and perform a rich set of searches for other physics beyond the Standard Model.