An improved half-life limit of the double beta decay of 94Zr into the excited state of 94Mo

Abstract

A search for the double beta decay transition of 94Zr into the first excited state of 94Mo has been performed at the Felsenkeller underground laboratory in Dresden, Germany. A 341.1 g zirconium sample with natural isotopic composition has been measured for 43.9 d in an ultra low background gamma spectroscopy setup. No signal has been observed and a new best lower half-life limit is set as 5.2 × 1019 yr (90% CI). This limit is valid for the 0νββ and 2νββ decay into excited states of 94Mo but cannot distinguish between the two modes. Existing limits are improved by 50%.