The indication for the α decay of 180 W with a half-life T

Energy resolution, a=b ratio, and the pulse shape discrimination ability of the ZnWO 4 crystal scintillators were studied. The radioactive contamination of a ZnWO 4 crystal was investigated in the Solotvina Underground Laboratory. Possibilities to apply ZnWO 4 crystals for the dark matter and double beta decay searches are discussed. New improved half-life limits on double beta decay in zinc isotopes were established, in particular, for eb þ decay of 64 Zn as: T 2n 1=2 X8:9 Â 10 18 years and T 0n 1=2 X3:6 Â 10 18 years, both at 68% CL. r

The R&D project COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) aims to develop a cryogenic scintillating calorimeter using an undoped NaI-crystal as target for direct dark matter search. Dark matter particles interacting with the detector material generate both a phonon signal and scintillation light. While the phonon signal provides a precise determination of the deposited energy, the simultaneously measured scintillation light allows for particle identification on an event-by-event basis, a powerful tool to study materialdependent interactions, and to suppress backgrounds. Using the same target material as the DAMA/LIBRA collaboration, the COSINUS technique may offer a unique possibility to investigate and contribute information to the presently controversial situation in the dark matter sector. We report on the dedicated design planned for the NaI proof-of-principle detector and the objectives of using this detection technique in the light of direct dark matter detection.

β decay of 113 Cd was studied with the help of a low background CdWO 4 crystal scintillator (mass of 434 g) in an experiment at the Gran Sasso National Laboratories of the INFN for a period of 2758 h. The shape of the spectrum of the non-unique fourth-forbidden decay of 113 Cd was measured, and the half-life of 113 Cd was determined as T 1/2 = (8.04 ± 0.05) × 10 15 yr.

CUPID-0 is the first pilot experiment of CUPID, a next-generation project for the measurement of neutrinoless double beta decay (0νDBD) with scintillating bolometers. The detector, consisting of 24 enriched and 2 natural ZnSe crystals, has been taking data at Laboratori Nazionali del Gran Sasso from June 2017 to December 2018, collecting a 82 Se exposure of 5.29 kg×yr. In this paper we present the phase-I results in the search for 0νDBD. We demonstrate that the technology implemented by CUPID-0 allows us to reach the lowest background for calorimetric experiments: (3.5 +1.0 −0.9 ) × 10 −3 counts/(keV kg yr). Monitoring 3.88×10 25 82 Se nuclei×yr we reach a 90% credible interval median sensitivity of T 0ν 1/2 > 5.0 × 10 24 yr and set the most stringent limit on the half-life of 82 Se 0νDBD: T 0ν 1/2 > 3.5 × 10 24 yr (90% credible interval), corresponding to m ββ < (311-638) meV depending on the nuclear matrix element calculations.Nowadays, neutrinoless double beta decay (0νDBD) is considered one of the most sensitive probes for Physics Beyond the Standard Model. This hypothetical nuclear transition foresees the simultaneous decay of two neutrons into protons and electrons without the emission of neutrinos [1]. Its detection would prove the nonconservation of the total lepton number, setting an important milestone for leptogenesis and baryogenesis theories [2]. The observation of 0νDBD would give precious insights also in Particle Physics, as this transition can occur only if neutrinos coincide with their own antiparticles, according to the Majorana hypothesis. As a consequence, its detection would allow to establish the fundamental nature of these particles [3]. Furthermore, if the mechanism at the basis of 0νDBD is the exchange of light Majorana neutrinos, the half-life of the transition (T 0ν 1/2 ) would scale as T 0ν 1/2 ∝ m −2 ββ , where the parameter m ββ (effective Majorana neutrino mass) is a superimposition of the neutrino mass eigenvalues m i weighted by the elements of the neutrino mixing matrix (U ei ): m ββ =| i U 2 ei m i | [4]. Thus, a measurement of T 0ν 1/2 would also allow to constrain the absolute mass scale of neutrinos.The increasing interest in the search for 0νDBD motivated a huge international effort in the development of several technologies [5-9] to study some of the candidate isotopes: elements with even atomic number and even neutron number, for which the single beta decay is strongly forbidden by energy conservation law. These experiments are now envisioning next-generation detectors to probe half-lives exceeding 10 27 yr and, thus, the whole range of the inverted hierarchy region of neutrino masses, whose lower bound is at m ββ ∼10 meV. The main handles to improve the sensitivity are the detector exposure, the background in the region of interest and the energy resolution [10]. To ensure a competitive discovery potential, next-generation detectors will need more than 10 27 emitters (hundreds of kg of source), a background as close as possible to zero in 5-10 years of data-taking, and a...