A search for various double beta decay modes of tin isotopes

Abstract

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 602.7keV is T_1/2 > 3.1 *10^{18}yrs (90 % CL) and for the first excited 0+ state T_1/2 > 7.7 *10^{18}yrs (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 ECEC and beta+/EC into the first excited 2+ state of 112Cd are both T_1/2 >1.4 *10^{18}yrs (90 % CL). A resonance enhancement in the decay rate for 0nuECEC might be expected for the 0+-state at 1870.9keV due to degeneracy with the 112Sn ground state. No signal was found resulting in a lower half-life limit of T_1/2 > 1.6 *10^{18} yrs (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 ECEC and beta+/EC mode and a limit of T_1/2 > 1.5 *10^{18} yrs (90 % CL) was obtained for ECEC decays of 112Sn, whilst the beta+/EC mode results are inconclusive.Comment: 19 pages, 11 figure

Shell model predictions forSn124double-βdecay

“…First, because it was not included in the finetuning, and in addition, the experimental data available is not very clear about the first excited 0 + state, which is very important for our analysis. In particular, although the recent double-beta decay experimental studies [28][29][30] assume that this state is at 1.156 MeV excitation energy, the latest Nuclear Data Sheets [71,72] Fig. 1).…”

“…As we mentioned in the Introduction, double-beta decay modes of 124 Sn were recently investigated experimentally by several groups [28][29][30][31]. The emphasis was on decays to the excited states, but no signal has been seen so far.…”

“…As a consequence, the phase space factor (see below) for 2νββ decay of 124 Sn is about ten times larger than that of 76 Ge, while the 0νββ phase space factor of 124 Sn is about four times larger than that of 76 Ge. Double-beta decay modes of 124 Sn were also recently investigated experimentally by several groups [28][29][30][31], but no signal has been seen so far. The best upper limit obtained was about 1×10…”

Search for double-βdecay processes in106Cd with the help of a106CdWOBelli1, Bernabei2, Boiko3 et al. 2012Phys. Rev. C

“…The results of the searches for the capture of two electrons from atomic shells (2ε), electron capture with positron emission (εβ + ), and emission of two positrons (2β + ) are at the level of 10 16 -10 21 yr (see review [2] and original works [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]); although allowed, the two-neutrino mode of these processes has not yet been detected. 1 High-sensitivity experiments to search for neutrinoless 2ε and εβ + decays are also important because they could clarify a contribution of right-handed admixtures in weak interactions [31].…”

Uncertainties in nuclear transition matrix elements forβ+β+andɛβ+modes of neutrinoless positron double-Rath1, Chandra2, Chaturvedi3 et al. 2013Phys. Rev. C110100View full textAdd to dashboardCite

“…Subsequently, detailed theoretical studies on the resonant enhancement of (εε) 0ν mode have also been performed [8,9]. In the mean time, experimental studies on resonance enhancement of (εε) 0ν mode in 74 Ge [10,11], 96 Ru [12], 106 Cd [13,14], 112 Sn [15][16][17][18][19], 136 Ce [20], and 180 W [21] isotopes have already been carried out and the study of this (εε) 0ν mode is emerging as an interesting possibility for the investigation of (ββ) 0ν decay.…”