Search for double beta decay of $^{136}$Ce and $^{138}$Ce with HPGe gamma detector

TL;DR

This study searched for double beta decay in cerium isotopes using a highly sensitive HPGe detector, setting new half-life limits that significantly surpass previous measurements, thereby advancing the understanding of rare nuclear decay processes.

Contribution

It provides the first ultra-low background measurement of cerium isotopes with improved half-life limits, enhancing constraints on double beta decay models.

Findings

New half-life limits at 10^{17}-10^{18} years

Many limits are two orders of magnitude better than previous results

No positive detection of double beta decay was observed

Abstract

Search for double $\beta$ decay of $^{136}$Ce and $^{138}$Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe $\gamma$ detector with a volume of 465 cm$^3$ at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of $\lim T_{1/2}\sim 10^{17}-10^{18}$~yr; many of them are even two orders of magnitude larger than the best previous results.