New limit on two neutrino electron capture with positron emission in 106Cd

An experiment to search for double beta processes in 106Cd is in progress with the help of 106CdWO4 crystal scintillator (enriched in 106Cd to 66%) in coincidence with two large volume CdWO4 crystal scintillators in close geometry at the Gran Sasso Underground Laboratory. The time resolution of the set-up was analyzed, and the methods of pulse-shape discrimination of α and γ(β) events was applied to estimate the radioactive contamination of the crystal and to reduce the background counting rate. The possible double beta decay processes and the background components have been simulated by a Monte Carlo method with GEANT4. The experimental sensitivity is approaching the theoretical predictions for the two-neutrino electron capture with positron emission in 106Cd: lim T1/2≥4×10^21 yr at 90% C.L. (the best previous limit was established in the previous stage of the experiment as T1/2≥1.1× 10^21 yr, while the theoretical predictions are in the region of T1/2∼10^21−10^22 yr)

Nouveau mode de regulation du chauffage a eau

SIGLECNRS RP 400 (1051) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

developmwnts of enriched cadmium tungstate crystal scintillators to search for double beta decay processes of 106Cd

R&D of cadmium tungstate (CdWO 4 ) crystal scintillators with cadmium enriched in 106 Cd is in progress with aim to realize an experiment to search for double beta processes in 106 Cd. Samples of cadmium (with natural isotopic composition and enriched in 106 Cd) were purified by vacuum distillation. Cadmium tungstate compounds (natural and enriched) to grow CdWO 4 crystals were synthesized from solutions. Contamination of the cadmium samples and synthesized compounds were measured by mass spectrometry. Concentration of iron was determined by atomic absorption spectroscopy. CdWO 4 crystal boule was grown by Czochralsky method from the natural cadmium tungstate compound. The total losses of cadmium on the stages of purification, raw material synthesis, crystal growth and scintillator production do not exceed 4 %. An excellent energy resolution FWHM = 8.1 % was measured by ∅22 × 29 mm CdWO 4 scintillator for 662 keV γ quanta of 137 Cs source

Recent Developments and Results on Double Beta Decays with Crystal Scintillators and HPGe Spectrometry

Recent developments, results, and perspectives arising from double beta decay experiments at the Gran Sasso National Laboratory (LNGS) of the INFN by using HPGe detectors and crystal scintillators and by exploiting various approaches and different isotopes are summarized. The measurements here presented have been performed in the experimental set-ups of the DAMA collaboration. These setups are optimized for low-background studies and operate deep underground at LNGS. The presented results are of significant value to the field, and the sensitivity achieved for some of the considered isotopes is one of the best available to date

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay (0 νββ) of 100Mo. In this article, we detail the CUPID-Mo detector concept, assembly and installation in the Modane underground laboratory, providing results from the first datasets. The CUPID-Mo detector consists of an array of 20 100Mo -enriched 0.2 kg Li 2MoO 4 crystals operated as scintillating bolometers at ∼20mK. The Li 2MoO 4 crystals are complemented by 20 thin Ge optical bolometers to reject α events by the simultaneous detection of heat and scintillation light. We observe a good detector uniformity and an excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Light collection ensures the rejection of α particles at a level much higher than 99.9% – with equally high acceptance for γ/β events – in the region of interest for 100Mo 0 νββ. We present limits on the crystals’ radiopurity: ≤3μBq/kg of 226Ra and ≤2μBq/kg of 232Th. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the 100Mo 0 νββ decay in half-a-year’s livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology developed by the LUMINEU project and subsequently selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale bolometric 0 νββ experiment

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

International audienceCUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ($0\nu \beta \beta$) of $^{100}\hbox {Mo}$. In this article, we detail the CUPID-Mo detector concept, assembly and installation in the Modane underground laboratory, providing results from the first datasets. The CUPID-Mo detector consists of an array of 20 $^{100}\hbox {Mo}$-enriched 0.2 kg $\hbox {Li}_2\hbox {MoO}_4$ crystals operated as scintillating bolometers at $\sim 20\hbox { mK}$. The $\hbox {Li}_2\hbox {MoO}_4$ crystals are complemented by 20 thin Ge optical bolometers to reject $\alpha$ events by the simultaneous detection of heat and scintillation light. We observe a good detector uniformity and an excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Light collection ensures the rejection of $\alpha$ particles at a level much higher than 99.9% – with equally high acceptance for $\gamma$/$\beta$ events – in the region of interest for $^{100}\hbox {Mo}0\nu \beta \beta$. We present limits on the crystals’ radiopurity: $\le 3~\mu \hbox {Bq/kg}$ of $^{226}\hbox {Ra}$ and $\le 2~\mu \hbox {Bq/kg}$ of $^{232}\hbox {Th}$. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the $^{100}\hbox {Mo}0\nu \beta \beta$ decay in half-a-year’s livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology developed by the LUMINEU project and subsequently selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale bolometric $0\nu \beta \beta$ experiment

New Limit for Neutrinoless Double-Beta Decay of ^{100}Mo from the CUPID-Mo Experiment.

The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale bolometric 0νββ experiment. It consists of a 4.2 kg array of 20 enriched Li_{2}^{100}MoO_{4} scintillating bolometers to search for the lepton-number-violating process of 0νββ decay in ^{100}Mo. With more than one year of operation (^{100}Mo exposure of 1.17  kg×yr for physics data), no event in the region of interest and, hence, no evidence for 0νββ is observed. We report a new limit on the half-life of 0νββ decay in ^{100}Mo of T_{1/2}>1.5×10^{24}  yr at 90% C.I. The limit corresponds to an effective Majorana neutrino mass ⟨m_{ββ}⟩<(0.31-0.54)  eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation

Pulse shape discrimination in CUPID-Mo using principal component analysis

CUPID-Mo is a cryogenic detector array designed to search for neutrinoless double-beta decay (0νββ) of 100Mo. It uses 20 scintillating 100Mo-enriched Li2MoO4 bolometers instrumented with Ge light detectors to perform active suppression of α backgrounds, drastically reducing the expected background in the 0νββ signal region. As a result, pileup events and small detector instabilities that mimic normal signals become non-negligible potential backgrounds. These types of events can in principle be eliminated based on their signal shapes, which are different from those of regular bolometric pulses. We show that a purely data-driven principal component analysis based approach is able to filter out these anomalous events, without the aid of detector response simulations

New Limit for Neutrinoless Double-Beta Decay of ^{100}Mo from the CUPID-Mo Experiment.

The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale bolometric 0νββ experiment. It consists of a 4.2 kg array of 20 enriched Li_{2}^{100}MoO_{4} scintillating bolometers to search for the lepton-number-violating process of 0νββ decay in ^{100}Mo. With more than one year of operation (^{100}Mo exposure of 1.17  kg×yr for physics data), no event in the region of interest and, hence, no evidence for 0νββ is observed. We report a new limit on the half-life of 0νββ decay in ^{100}Mo of T_{1/2}>1.5×10^{24}  yr at 90% C.I. The limit corresponds to an effective Majorana neutrino mass ⟨m_{ββ}⟩<(0.31-0.54)  eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation