A search for various double beta decay modes of tin isotopes Original Research Article

For the first time an extensive search for various double beta decay modes of 124Sn and 112Sn has been performed. A total exposure of 43.29 kg days has been accumulated. New half-life limits of 124Sn into excited states of 124Te have been obtained; the lower half-life limit for the first excited 2+ state at 602.7 keV is T1/2>3.1×1018 yr (90% CL) and for the first excited 0+ state T1/2>7.7×1018 yr (90% CL). For the very first time, ground state and excited state transitions of 112Sn have been experimentally explored. The obtained half-life limits for EC/EC and β+/EC into the first excited 2+ state of 112Cd are both T1/2>1.4×1018 yr (90% CL). A resonance enhancement in the decay rate for 0νEC/EC might be expected for the 0+-state at 1870.9 keV due to degeneracy with the 112Sn ground state. No signal was found resulting in a lower half-life limit of T1/2>1.6×1018 yr (90% CL) for this decay. As all the excited state searches are based on gamma-lines, all half-life limits apply for both neutrino and neutrino-less modes. Neutrinoless ground state transitions were searched for in the EC/EC and β+/EC mode and a limit of T1/2>1.5×1018 yr (90% CL) was obtained for EC/EC decays of 112Sn, whilst the β+/EC mode results are inconclusive.