The future
Ricochet
experiment aims to search for new physics in the electroweak sector by measuring the Coherent Elastic Neutrino-Nucleus Scattering process from reactor antineutrinos with high ...precision down to the sub-100 eV nuclear recoil energy range. While the
Ricochet
collaboration is currently building the experimental setup at the reactor site, it is also finalizing the cryogenic detector arrays that will be integrated into the cryostat at the Institut Laue Langevin in early 2024. In this paper, we report on recent progress from the Ge cryogenic detector technology, called the CryoCube. More specifically, we present the first demonstration of a 30 eVee (electron equivalent) baseline ionization resolution (RMS) achieved with an early design of the detector assembly and its dedicated High Electron Mobility Transistor (HEMT) based front-end electronics with a total input capacitance of about 40 pF. This represents an order of magnitude improvement over the best ionization resolutions obtained on similar phonon-and-ionization germanium cryogenic detectors from the EDELWEISS and SuperCDMS dark matter experiments, and a factor of three improvement compared to the first fully-cryogenic HEMT-based preamplifier coupled to a CDMS-II germanium detector with a total input capacitance of 250 pF. Additionally, we discuss the implications of these results in the context of the future
Ricochet
experiment and its expected background mitigation performance.
CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation
0
ν
β
β
decay experiment, CUPID. It consisted of an array of 20 enriched Li
2
100
MoO
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
ν
β
β
decay and other processes with high precision. We also measure the radio-purity of the Li
2
100
MoO
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
-
0.8
+
0.9
(stat)
-
0.7
+
1.5
(syst)
×
10
-
3
counts/
Δ
E
FWHM
/
mol
iso
/
year
,
the lowest in a bolometric
0
ν
β
β
decay experiment.
The only naturally occurring isotope of bismuth, 209Bi, is commonly regarded as the heaviest stable isotope. But like most other heavy nuclei abundant in nature and characterized by an exceptionally ...long lifetime, it is metastable with respect to α-decay. However, the decay usually evades observation because the nuclear structure of 209Bi gives rise to an extremely low decay probability and, moreover, generates low-energy α-particles difficult to detect. Indeed, dedicated experiments attempting to record the α-decay of 209Bi in nuclear emulsions failed. However, scintillating bolometers operated at temperatures below 100 mK offer improved detection efficiency and sensitivity, whereas a broad palette of targets could be available. Here we report the successful use of this method for the unambiguous detection of 209Bi α-decay in bismuth germanate detectors cooled to 20 mK. We measure an energy release of 3,137 ± 1 (statistical) ± 2 (systematic) keV and a half-life of (1.9 ± 0.2) × 1019 yr, which are in agreement with expected values.
Scintillating bolometers of sapphire, BGO and LiF have been recently tested both at the Institut d’Astrophysique Spatiale (IAS) and the Laboratorio Subterráneo de Canfranc (LSC) in the frame of the ...ROSEBUD collaboration. We report on their response to different particles (
α
,
β
,
γ
and nuclear recoils) both in the heat and light channel. Signal output parameters for the different particles have been compared. We have focused on the study of the nuclear recoils discrimination against
β
/
γ
background events at low energy. The
β
/
γ
and nuclear recoil spectra obtained in the different runs are shown and analyzed. We also discuss the sensitivity of the LiF bolometer for measuring thermal neutron flux at LSC.
The introduction of a small quantity of tungsten oxide (in the range 0.2–0.5wt%) into the melt improves the growth of ZnMoO4 crystals. No significant difference in the kinetics of scintillation ...decay, scintillation efficiency, emission spectra, optical transmittance was observed for three ZnMoO4 crystal samples grown from the melt of stoichiometric composition, with excess of molybdenum and doped with tungsten. Using CaWO4 as reference, the absolute light yield of ZnMoO4 is found to be equal to 3550±550ph/MeV at 77K. For two ZnMoO4 samples 20mm in diameter and 40mm in length (grown from the melt of stoichiometric composition and doped with tungsten) it is confirmed that scintillation and bolometric response are similar at milli-Kelvin temperature.
The CUPID-Mo experiment, located at Laboratoire Souterrain de Modane (France), was a demonstrator experiment for CUPID. It consisted of an array of 20 Li2 100MoO4 (LMO) calorimeters each equipped ...with a Ge light detector (LD) for particle identification. In this work, we present the result of a search for two-neutrino and neutrinoless double beta decays of 100Mo to the first 0+ and 2+ excited states of 100Ru using the full CUPID-Mo exposure (2.71 kg yr of LMO). We measure the half-life of 2νββ decay to the $0^+_1$ state as $T^{2ν→0^+_1}_{1/2}$ = (7.5 ± 0.8 (stat.) $^{+0.4}_{-0.3}$ (syst.)) × 1020 yr. The bolometric technique enables measurement of the electron energies as well as the gamma rays from nuclear de-excitation and this allows us to set new limits on the two-neutrino decay to the $2^+_1$ state of $T^{2ν→2^+_1}_{1/2}$ > 4.4×1021 yr (90% c.i.) and on the neutrinoless modes of $T^{0ν→2^+_1}_{1/2}$ > 2.1×1023 yr (90% c.i.), $T^{0ν→0^+_1}_{1/2}$ > 1.2 × 1023 yr (90% c.i.). Information on the electrons spectral shape is obtained which allows us to make the first comparison of the single state (SSD) and higher state (HSD) 2νββ decay models for the $0^+_1$ excited state of 100Ru.
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.
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