Abstract
The CROSS experiment is proposing to use a new technology of surface sensitive bolometers for low-background neutrinoless double beta decay searches. Efficient rejection of surface
α
and
β
...events will allow to reach background in the region of interest below than 10
−4
cnts/keV/kg/yr. The isotopes of interest, which are
130
Te and
100
Mo, are investigated with TeO
2
and Li
2
MoO
4
bolometers. The surface sensitivity is achieved thanks to the evaporation of thin metallic film on the crystal surface that modifies the pulse shape of near-surface events. An investigation of various pulse shape parameters was performed. The analysis shows that one of the best parameters for discrimination is the integrated area of the raw signal both for TeO
2
and Li
2
MoO
4
with Pd-Al (10 nm - 100 nm) bi-layer.
Abstract Random coincidences of events could be one of the main sources of background in the search for neutrino-less double-beta decay of $$^{100}$$ 100 Mo with macro-bolometers, due to their modest ...time resolution. Scintillating bolometers as those based on Li $$_2$$ 2 MoO $$_4$$ 4 crystals and employed in the CROSS and CUPID experiments can eventually exploit the coincident fast signal detected in a light detector to reduce this background. However, the scintillation provides a modest signal-to-noise ratio, making difficult a pile-up pulse-shape recognition and rejection at timescales shorter than a few ms. Neganov–Trofimov–Luke assisted light detectors (NTL-LDs) offer the possibility to effectively increase the signal-to-noise ratio, preserving a fast time-response, and enhance the capability of pile-up rejection via pulse shape analysis. In this article we present: (a) an experimental work performed with a Li $$_2$$ 2 MoO $$_4$$ 4 scintillating bolometer, studied in the framework of the CROSS experiment, and utilizing a NTL-LD; (b) a simulation method to reproduce, synthetically, randomly coincident two-neutrino double-beta decay events; (c) a new analysis method based on a pulse-shape discrimination algorithm capable of providing high pile-up rejection efficiencies. We finally show how the NTL-LDs offer a balanced solution between performance and complexity to reach background index $$\sim $$ ∼ $$10^{-4}$$ 10 - 4 counts/keV/kg/year with 280 g Li $$_2$$ 2 MoO $$_4$$ 4 ( $$^{100}$$ 100 Mo enriched) bolometers at 3034 keV, the Q $$_{\beta \beta }$$ β β of the double-beta decay, and target the goal of a next generation experiment like CUPID.
Abstract
We report the measurement of the two-neutrino double-beta (
$$2\nu \beta \beta $$
2
ν
β
β
) decay of
$$^{100}$$
100
Mo to the ground state of
$$^{100}$$
100
Ru using lithium molybdate (
...$$\hbox {Li}_2^{\;\;100}\hbox {MoO}_4$$
Li
2
100
MoO
4
) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory (France). From a total exposure of 42.235 kg
$$\times $$
×
day, the half-life of
$$^{100}$$
100
Mo is determined to be
$$T_{1/2}^{2\nu }=7.12^{+0.18}_{-0.14}\,\mathrm {(stat.)}\pm 0.10\,\mathrm {(syst.)}\times 10^{18}$$
T
1
/
2
2
ν
=
7
.
12
-
0.14
+
0.18
(
stat
.
)
±
0.10
(
syst
.
)
×
10
18
years. This is the most accurate determination of the
$$2\nu \beta \beta $$
2
ν
β
β
half-life of
$$^{100}$$
100
Mo to date.
Abstract We report the measurement of the two-neutrino double-beta ($$2\nu \beta \beta $$ 2νββ ) decay of $$^{100}$$ 100 Mo to the ground state of $$^{100}$$ 100 Ru using lithium molybdate ($$\hbox ...{Li}_2^{\;\;100}\hbox {MoO}_4$$ Li2100MoO4 ) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory (France). From a total exposure of 42.235 kg$$\times $$ × day, the half-life of $$^{100}$$ 100 Mo is determined to be $$T_{1/2}^{2\nu }=7.12^{+0.18}_{-0.14}\,\mathrm {(stat.)}\pm 0.10\,\mathrm {(syst.)}\times 10^{18}$$ T1/22ν=7.12-0.14+0.18(stat.)±0.10(syst.)×1018 years. This is the most accurate determination of the $$2\nu \beta \beta $$ 2νββ half-life of $$^{100}$$ 100 Mo to date.
We report the measurement of the two-neutrino double-beta ($2\nu \beta \beta $) decay of $^{100}$Mo to the ground state of $^{100}$Ru using lithium molybdate ($\hbox {Li}_2^{\;\;100}\hbox {MoO}_4$) ...scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory (France). From a total exposure of 42.235 kg$\times $day, the half-life of $^{100}$Mo is determined to be $T_{1/2}^{2\nu }=7.12^{+0.18}_{-0.14}\,\mathrm {(stat.)}\pm 0.10\,\mathrm {(syst.)}\times 10^{18}$ years. This is the most accurate determination of the $2\nu \beta \beta $ half-life of $^{100}$Mo to date.
Neutrinoless double beta decay (0νββ) is a yet unobserved nuclear process that would demonstrate Lepton number violation, a clear evidence of beyond standard model physics. The process two neutrino ...double beta decay (2νββ) is allowed by the standard model and has been measured in numerous experiments. In this Letter, we report a measurement of 2νββ decay half-life of ^{100}Mo to the ground state of ^{100}Ru of 7.07±0.02(stat)±0.11(syst)×10^{18} yr by the CUPID-Mo experiment. With a relative precision of ±1.6% this is the most precise measurement to date of a 2νββ decay rate in ^{100}Mo. In addition, we constrain higher-order corrections to the spectral shape, which provides complementary nuclear structure information. We report a novel measurement of the shape factor ξ_{3,1}=0.45±0.03(stat)±0.05(syst) based on a constraint on the ratio of higher-order terms from theory, which can be reliably calculated. This is compared to theoretical predictions for different nuclear models. We also extract the first value for the effective axial vector coupling constant obtained from a spectral shape study of 2νββ decay.
Abstract CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation $$0\nu \beta \beta $$ 0 ν β β decay experiment, CUPID. It consisted of an array ...of 20 enriched Li $$_{2}$$ 2 $$^{100}$$ 100 MoO $$_4$$ 4 bolometers and 20 Ge light detectors and has demonstrated that the technology of scintillating bolometers with particle identification capabilities is mature. Furthermore, CUPID-Mo can inform and validate the background prediction for CUPID. In this paper, we present a detailed model of the CUPID-Mo backgrounds. This model is able to describe well the features of the experimental data and enables studies of the $$2\nu \beta \beta $$ 2 ν β β decay and other processes with high precision. We also measure the radio-purity of the Li $$_{2}$$ 2 $$^{100}$$ 100 MoO $$_4$$ 4 crystals which are found to be sufficient for the CUPID goals. Finally, we also obtain a background index in the region of interest of 3.7 $$^{+0.9}_{-0.8}$$ - 0.8 + 0.9 (stat) $$^{+1.5}_{-0.7}$$ - 0.7 + 1.5 (syst) $$\times ~10 ^{-3}$$ × 10 - 3 counts/ $$\Delta E_{\text {FWHM}}/\text {mol}_{\text {iso}}/\text {year},$$ Δ E FWHM / mol iso / year , the lowest in a bolometric $$0\nu \beta \beta $$ 0 ν β β decay experiment.
Abstract The CUPID-Mo experiment to search for 0 $$\nu \beta \beta $$ ν β β decay in $$^{100}$$ 100 Mo has been recently completed after about 1.5 years of operation at Laboratoire Souterrain de ...Modane (France). It served as a demonstrator for CUPID, a next generation 0 $$\nu \beta \beta $$ ν β β decay experiment. CUPID-Mo was comprised of 20 enriched $$\hbox {Li}_{{2}}$$ Li 2 $$^{100}$$ 100 $$\hbox {MoO}_4$$ MoO 4 scintillating calorimeters, each with a mass of $$\sim 0.2$$ ∼ 0.2 kg, operated at $$\sim 20$$ ∼ 20 mK. We present here the final analysis with the full exposure of CUPID-Mo ( $$^{100}$$ 100 Mo exposure of 1.47 $$\hbox {kg} \times \hbox {year}$$ kg × year ) used to search for lepton number violation via 0 $$\nu \beta \beta $$ ν β β decay. We report on various analysis improvements since the previous result on a subset of data, reprocessing all data with these new techniques. We observe zero events in the region of interest and set a new limit on the $$^{100}$$ 100 Mo 0 $$\nu \beta \beta $$ ν β β decay half-life of $$T_{1/2}^{0\nu }$$ T 1 / 2 0 ν $$> {1.8}\times 10^{24}$$ > 1.8 × 10 24 year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of $$\left<m_{\beta \beta }\right>$$ m β β $$<~{(0.28{-}0.49)} $$ < ( 0.28 - 0.49 ) eV, dependent upon the nuclear matrix element utilized.