OMC studies for the matrix elements in ββ decay

Energy and time spectra of gamma-rays following μ-capture in natural Kr, Se, Cd and Sm, as well as isotopic enriched 82Kr, 76Se, 106Cd and 150Sm, have been measured. Total life-times of muons in different isotopes, as well as partial μ-capture rates to the excited states of 48Sc, 76As and 106Ag, were extracted. These results are discussed in the context of the double-beta decay matrix elements. The data are also compared with data from theoretical calculations and with data from charge-exchange reactions on 48Ti. It is the first time that μ-capture and charge-exchange reaction data are being compared in the context of ββ decay.