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

TL;DR

This study reports preliminary results on the double beta decay of $^{150}$Nd to an excited state of $^{150}$Sm, measuring a half-life consistent with prior experiments using an underground germanium detector setup.

Contribution

First detection of gamma quanta from $^{150}$Nd double beta decay to the excited $0^+$ state with a measured half-life, confirming previous findings with a new experimental approach.

Findings

Half-life measured as approximately 4.7 x 10^{19} years.

Gamma quanta detected at 334.0 keV and 406.5 keV.

Results agree with previous experimental data.

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 ${\gamma}$ 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 $\rightarrow$ $^{150}$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.