R. Cerulli

Low background detector with enriched 116CdWO4 crystal scintillators to search for double beta decay of 116Cd

A cadmium tungstate crystal boule enriched in 116Cd to 82% with mass of 1868 g was grown by the low-thermal-gradient Czochralski technique. The isotopic composition of cadmium and the trace contamination of the crystal were estimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The crystal scintillators produced from the boule were subjected to characterization that included measurements of transmittance and energy resolution. A low background scintillation detector with two 116CdWO4 crystal scintillators (586 g and 589 g) was developed. The detector was running over 1727 h deep underground at the Gran Sasso National Laboratories of the INFN (Italy), which allowed to estimate the radioactive contamination of the enriched crystal scintillators. The radiopurity of a third 116CdWO4 sample (326 g) was tested with the help of ultra-low background high purity germanium γ detector. Monte Carlo simulations of double β processes in 116Cd were used to estimate the sensitivity of an experiment to search for double β decay of 116Cd.

Search for double beta decay processes in 106Cd with the help of 106CdWO4 crystal scintillator

A search for the double processes in 106Cd was carried out at the Gran Sasso National Laboratories of the INFN (Italy) with the help of a 106CdWO4 crystal scintillator (215 g) enriched in 106Cd up to 66%. After 6590 h of data taking, new improved half-life limits on the double beta decay processes in 106Cd were established at the level of 10^{19} - 10^{21} yr. A possible resonant enhancement of the neutrinoless2EC processes is estimated in the framework of the QRPA approach. The radioactive contamination of the 106CdWO4 crystal scintillator is reported.

New search for correlated e+e- pairs in the \( \alpha\) decay of 241Am

Abstract.A new search for production of correlated

Search for

e^{+}e^{-}

2\beta

pairs in the

decay of

\alpha

^{106}

decay of 241Am has been carried out deep underground at the Gran Sasso National Laboratory of the INFN by using pairs of NaI(Tl) detectors of the DAMA/LIBRA set-up. The experimental data show an excess of double coincidences of events with energy around 511keV in faced pairs of detectors, which are not explained by known side reactions. This measured excess gives a relative activity

Cd with an enriched

\lambda=(4.70\pm 0.63)\times 10^{-9}

^{106}

for the Internal Pair Production (IPP) with respect to the alpha decay of 241Am; this value is of the same order of magnitude as previous determinations. In a conservative approach the upper limit

CdWO

\lambda < 5.5\times 10^{-9}