First search for double $\beta$ decay of dysprosium

TL;DR

This study conducted the first search for double beta decay in dysprosium isotopes using an ultra low-background germanium detector, setting new limits on decay half-lives and contamination levels.

Contribution

It is the first experimental attempt to detect double beta decay in dysprosium isotopes and establishes new half-life limits using low-background gamma spectroscopy.

Findings

Limits on double beta decay half-lives of $^{156}$Dy and $^{158}$Dy were set at $10^{14}-10^{16}$ years.

Constraints on resonant double electron captures in these isotopes were established.

Radioactive contamination levels and alpha decay limits of dysprosium isotopes were measured.

Abstract

A search for double $\beta$ decay of dysprosium was realized for the first time with the help of an ultra low-background HP Ge $\gamma$ detector. After 2512 h of data taking with a 322 g sample of dysprosium oxide limits on double beta processes in $^{156}$Dy and $^{158}$Dy have been established on the level of $T_{1/2}\geq 10^{14}-10^{16}$ yr. Possible resonant double electron captures in $^{156}$Dy and $^{158}$Dy were restricted on a similar level. As a by-product of the experiment we have measured the radioactive contamination of the Dy$_2$O$_3$ sample and set limits on the $\alpha$ decay of dysprosium isotopes to the excited levels of daughter nuclei as $T_{1/2}\geq 10^{15} - 10^{17}$ yr.