Search for Double Beta Decay inCa48andZr96

Abstract

A new search for double beta decay in ${\mathrm{Ca}}^{48}$ and ${\mathrm{Zr}}^{96}$, using two scintillation detectors in a $4\pi$ solid angle geometry, was performed far underground, in order to reduce the background counting rates to small values in the spectral regions of interest. The results of this experiment showed no evidence for double beta decay in either ${\mathrm{Ca}}^{48}$ or ${\mathrm{Zr}}^{96}$. Lower limits for the half-lives of these isotopes were estimated as follows: ${\mathrm{Ca}}^{48}$, $T_{\frac{1}{2}}>2\mathrm{}\times {10}^{18}$ yr; ${\mathrm{Zr}}^{96}$, $T_{\frac{1}{2}}>0.5\mathrm{}\times {10}^{18}$ yr.