Determination of the Muon Lifetime in $^{76}$Se with the MONUMENT experiment

TL;DR

The paper reports an improved measurement of the muon lifetime in $^{76}$Se, relevant for nuclear physics models of neutrinoless double beta decay, using advanced detection techniques at PSI.

Contribution

It provides a more accurate muon lifetime measurement in $^{76}$Se, supporting theoretical models with experimental data.

Findings

Muon lifetime in $^{76}$Se is (135.1 ± 0.5) ns.

Results agree with quasiparticle random phase approximation calculations.

Enhanced experimental setup improved measurement accuracy.

Abstract

Ordinary muon capture provides a benchmark for the nuclear physics models of neutrinoless double beta decay under comparable momentum transfer conditions. The total capture strength defines the lifetime of the muonic atom. The muon lifetime in $^{76}$Se, the daughter nucleus of $^{76}$Ge, was determined with improved accuracy by the MONUMENT collaboration, using an array of high-purity germanium detectors and a set of scintillator counters at the $\pi$E1 muon beam line of the Paul Scherrer Institute. The new value of (135.1 $\pm$ 0.5) ns agrees with phenomenological calculations based on the quasiparticle random phase approximation with unquenched axial-vector coupling.