LEGEND-1000 Preconceptual Design Report

TL;DR

LEGEND-1000 is a large-scale, low-background germanium detector experiment designed to detect neutrinoless double-beta decay, aiming to explore fundamental physics questions with high sensitivity and potential for unambiguous discovery.

Contribution

This report presents the design and expected performance of the first ton-scale germanium experiment targeting neutrinoless double-beta decay.

Findings

Projected half-life sensitivity of 1.3×10^28 years

Effective Majorana mass limit of 9-21 meV

Potential for unambiguous discovery with minimal background

Abstract

We propose the construction of LEGEND-1000, the ton-scale Large Enriched Germanium Experiment for Neutrinoless $\beta \beta$ Decay. This international experiment is designed to answer one of the highest priority questions in fundamental physics. It consists of 1000 kg of Ge detectors enriched to more than 90% in the $^{76}$Ge isotope operated in a liquid argon active shield at a deep underground laboratory. By combining the lowest background levels with the best energy resolution in the field, LEGEND-1000 will perform a quasi-background-free search and can make an unambiguous discovery of neutrinoless double-beta decay with just a handful of counts at the decay $Q$ value. The experiment is designed to probe this decay with a 99.7%-CL discovery sensitivity in the $^{76}$Ge half-life of $1.3\times10^{28}$ years, corresponding to an effective Majorana mass upper limit in the range of 9-21 meV, to cover the inverted-ordering neutrino mass scale with 10 yr of live time.