Double beta decay of 150Nd to the first 0+ excited level of 150Sm

Abstract

Abstract An experiment to measure the 2β – decay of 150Nd to excited levels of 150Sm using a highly purified 2.381 kg sample of Nd2O3 is in progress in the low-background set-up with 4 HPGe detectors (∼225 cm3 volume each). The detector is located deep underground (3600 m w.e.) at the STELLA facility of the Gran Sasso National Laboratory (LNGS) of the INFN (Italy). Two γ quanta with energies 334.0 keV and 406.5 keV emitted after deexcitation of the 01 + excited level of 150Sm have been observed in the experimental data accumulated over 39898 h. The preliminary half-life value for 2β – decay of 150Nd to the first 0+ excited level in 150Sm (after the exposure of 10.8 kg × yr) was estimated as T 1 / 2 = 9.7 − 1.9 + 2.9 stat . ± 1.5 syst . × 10 19 yr. The experiment is under data taking with the aim to improve the statistical uncertainties.