Search for double beta decay of Zinc and Tungsten with the help of low-background ZnWO4 crystal scintillators

TL;DR

This study used low-background ZnWO4 crystal scintillators at Gran Sasso to search for double beta decay in zinc and tungsten isotopes, setting new half-life limits and improving detection sensitivity over extensive measurement periods.

Contribution

It provides the first improved half-life limits for double beta decay modes in multiple isotopes using large volume low-background scintillators.

Findings

New half-life limits for 64-Zn decay modes at 10^20 years

Restrictions on decay modes in 70-Zn, 180-W, and 186-W at 10^17-10^20 years

Measurement time exceeded 10,000 hours

Abstract

Double beta processes in 64-Zn, 70-Zn, 180-W, and 186-W have been searched for with the help of large volume (0.1-0.7 kg) low background ZnWO4 crystal scintillators at the Gran Sasso National Laboratories of the INFN. Total time of measurements exceeds 10 thousands hours. New improved half-life limits on double electron capture and electron capture with positron emission in 64-Zn have been set, in particular (all the limits are at 90% C.L.): T1/2(0nu2EC)> 1.1e20 yr, T1/2(2nuECbeta+)>7.0e20 yr, and T1/2(0nuECbeta+)>4.3e20 yr. The different modes of double beta processes in 70-Zn, 180-W, and 186-W have been restricted at the level of 1e17-1e20 yr.