First search for double beta decay of platinum by ultra-low background HP Ge gamma spectrometry

TL;DR

This study conducted the first search for double beta decay in platinum isotopes using ultra-low background gamma spectrometry, setting new half-life limits that surpass previous measurements by several orders of magnitude.

Contribution

It provides the first experimental half-life limits for double beta decay in 190Pt and 198Pt using underground HP Ge spectrometry, improving sensitivity significantly.

Findings

Established new half-life limits for 190Pt double beta processes (10^{14}-10^{16} yr)

Set the first limit for 198Pt double beta decay (>3.5×10^{18} yr)

Restricted resonant double electron capture in 190Pt to 2.9×10^{16} yr

Abstract

A search for double beta processes in 190Pt and 198Pt was realized with the help of ultra-low background HP Ge 468 cm^3 gamma spectrometer in the underground Gran Sasso National Laboratories of the INFN (Italy). After 1815 h of data taking with 42.5 g platinum sample, T_{1/2} limits on 2beta processes in 190Pt (\epsilon\beta^+ and 2\epsilon) have been established on the level of 10^{14}-10^{16} yr, 3 to 4 orders of magnitude higher than those known previously. In particular, a possible resonant double electron capture in 190Pt was restricted on the level of 2.9 \times 10^{16} yr at 90% C.L. In addition, T_{1/2} limit on 2 beta^- decay of 198Pt (2\nu+0\nu) to the 2^+_1 excited level of 198Hg has been set at the first time: T_{1/2}>3.5 \times 10^{18} yr. The radiopurity level of the used platinum sample is reported.