Double beta decay of ${}^{150}$Nd to the first excited $0^{+}$ level of ${}^{150}$Sm: preliminary results

Abstract

The double beta decay of ${}^{150}$Nd to the first excited 0${}^{+}$ level of ${}^{150}$Sm ($E_{exc}$ = 740.5 keV) has been investigated with the help of the ultra-low-background setup consisting of four HP Ge (high-purity germanium) detectors ($\approx$ 225 cm${}^3$ volume each one) at the Gran Sasso underground laboratory of INFN (Italy). A highly purified 2.381-kg sample of neodymium oxide (Nd${}_2$O${}_3$) was used as a source of ${\hat{I}}^3$ quanta expected in the decays. Gamma quanta with energies 334.0 keV and 406.5 keV emitted after deexcitation of the $0_1^{+}$ 740.5 keV level of ${}^{150}$Sm are observed in the coincidence spectra accumulated over 16375 h. The half-life relatively to the two neutrino double beta decay ${}^{150}$Nd $\to$ ${}^{150}$Sm(0${}_1^{+}$) is measured as $T_{1/2}=[4.7_{-1.9}^{+4.1}\text{(stat)}\pm 0.5\text{(syst)}]\times 10^{19}y$, in agreement with results of previous experiments.

13 pages, 7 figures and 2 tables