Low background detector with enriched¹¹⁶CdWO₄crystal scintillators to search for double β decay of¹¹⁶Cd

Abstract

A cadmium tungstate crystal boule enriched in $^{116}$Cd to 82% with mass of\n1868 g was grown by the low-thermal-gradient Czochralski technique. The\nisotopic composition of cadmium and the trace contamination of the crystal were\nestimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The\ncrystal scintillators produced from the boule were subjected to\ncharacterization that included measurements of transmittance and energy\nresolution. A low background scintillation detector with two $^{116}$CdWO$_4$\ncrystal scintillators (586 g and 589 g) was developed. The detector was running\nover 1727 h deep underground at the Gran Sasso National Laboratories of the\nINFN (Italy), which allowed to estimate the radioactive contamination of the\nenriched crystal scintillators. The radiopurity of a third $^{116}$CdWO$_4$\nsample (326 g) was tested with the help of ultra-low background high purity\ngermanium $\\gamma$ detector. Monte Carlo simulations of double $\\beta$\nprocesses in $^{116}$Cd were used to estimate the sensitivity of an experiment\nto search for double $\\beta$ decay of $^{116}$Cd.\n