Ordinary muon capture studies for the matrix elements in $\beta\beta$ decay

TL;DR

This study measures gamma-ray emissions following muon capture in various isotopes to inform calculations of nuclear matrix elements relevant for neutrinoless double beta decay.

Contribution

It provides detailed experimental data on muon capture rates and gamma emissions in isotopes linked to double beta decay, aiding theoretical models.

Findings

Measured muon capture rates and gamma-ray spectra.

Determined partial capture rates to excited nuclear states.

Provided data crucial for nuclear matrix element calculations.

Abstract

Precise measurement of $\gamma$-rays following ordinary (non-radiative) capture of negative muons by natural Se, Kr, Cd and Sm, as well as isotopically enriched $^{48}$Ti, $^{76}$Se, $^{82}$Kr, $^{106}$Cd and $^{150}$Sm targets was performed by means of HPGe detectors. Energy and time distributions were investigated and total life time of negative muon in different isotopes was deduced. Detailed analysis of $\gamma$-lines intensity allows to extract relative yield of several daughter nuclei and partial rates of ($\mu$,$\nu$) capture to numerous excited levels of the $^{48}$Sc, $^{76}$As, $^{82}$Br, $^{106}$Ag and $^{150}$Tc isotopes which are considered to be virtual states of an intermediate odd-odd nucleus in 2$\beta$-decay of $^{48}$Ca, $^{76}$Ge, $^{82}$Se, $^{106}$Cd and $^{150}$Nd, respectively. These rates are important as an experimental input for the theoretical calculation of the nuclear matrix elements of 2$\beta$-decay.