CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay (
0
ν
β
β
) of
100
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
Mo
-enriched 0.2 kg
Li
2
MoO
4
crystals operated as scintillating bolometers at
∼
20
mK
. The
Li
2
MoO
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
100
Mo
0
ν
β
β
. We present limits on the crystals’ radiopurity:
≤
3
μ
Bq/kg
of
226
Ra
and
≤
2
μ
Bq/kg
of
232
Th
. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the
100
Mo
0
ν
β
β
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
ν
β
β
experiment.
The advanced molybdenum-based rare process experiment (AMoRE) aims to search for neutrinoless double beta decay (
0
ν
β
β
) of
100
Mo with
∼
100
kg
of
100
Mo-enriched molybdenum embedded in cryogenic ...detectors with a dual heat and light readout. At the current, pilot stage of the AMoRE project we employ six calcium molybdate crystals with a total mass of 1.9 kg, produced from
48
Ca-depleted calcium and
100
Mo-enriched molybdenum (
48
depl
Ca
100
MoO
4
). The simultaneous detection of heat (phonon) and scintillation (photon) signals is realized with high resolution metallic magnetic calorimeter sensors that operate at milli-Kelvin temperatures. This stage of the project is carried out in the Yangyang underground laboratory at a depth of 700 m. We report first results from the AMoRE-Pilot
0
ν
β
β
search with a 111 kg day live exposure of
48
depl
Ca
100
MoO
4
crystals. No evidence for
0
ν
β
β
decay of
100
Mo is found, and a upper limit is set for the half-life of
0
ν
β
β
of
100
Mo of
T
1
/
2
0
ν
>
9.5
×
10
22
years
at 90% C.L. This limit corresponds to an effective Majorana neutrino mass limit in the range
⟨
m
β
β
⟩
≤
(
1.2
-
2.1
)
eV
.
High perfect single crystal of Li2W0·95Mo0·05O4, which is one of the perspective materials to search rare events, has been grown by a low-temperature-gradient Czochralski technique with weight ...control. Thermodynamics of obtained single crystal with emphasis on such basic characteristics as stabilization energy, lattice enthalpy, and standard formation enthalpy was studied using reaction calorimetry. It has been shown that dependences of lattice enthalpies and standard formation enthalpies on the molybdenum content (x) for Li2W1-xMoxO4 are linear. It has been established that stabilization energy of single crystal Li2W0·95Mo0·05O4 is several times more than stabilization energies of single crystals ZnMoO4 and CdWO4. The correlation was found between lattice energy of Li2W1-xMoxO4 compounds and luminescence wavelength. It was shown that for system Li2MoO4–Li2WO4, the luminescence wavelength is increased with increasing the lattice energy. The hypothesis to explain the correlation was formulated. The heat capacities for Li2MoO4 single crystal have been determined by DSC calorimetry in the temperature range of 303–819 K. No anomalies in heat capacities associated with phase transitions were found.
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•High perfect single crystal of Li2W0·95Mo0·05O4 has been grown.•Linear dependences of lattice enthalpies and formation enthalpies on x for Li2W1-xMoxO4 have been found.•Li2W0·95Mo0·05O4 stabilization energy has been found several times more than ZnMoO4 and CdWO4 ones.•Luminescence wavelength in Li2MoO4–Li2WO4 has been found increased with increasing the lattice energy.•Heat capacities for Li2MoO4 single crystal have been determined in the temperature range of 303–819 K.
The study results of disodium dimolybdate single crystal are presented on the basis of experimentally obtained data on heat capacity. The heat capacity of Na2Mo2O7 was measured by the adiabatic ...method in the range of 5.7–310 K. No anomalies in the heat capacity associated with the phase transition were found. Extrapolation of the heat capacity to 0 K by a physically reasonable equation was performed. The Debye temperature at absolute zero was obtained. Based on the experimental heat capacity, the phonon density of states and isobaric thermodynamic functions (entropy, enthalpy increment, and Gibbs free energy) from 0 to 310 K were calculated. Using information on Na2Mo2O7 density of states, zero-point energy and isochoric thermodynamic functions (entropy, internal energy increment, and reduced Helmholtz energy) from 0 to 848 K were calculated. The approach used to obtain the characteristics of solids is general and can be used to study a wide range of objects.
•Low temperature heat capacity of Na2Mo2O7 single crystal was measured.•Isobaric entropy, enthalpy, and Gibbs free energy were calculated.•Debye characteristic temperature at absolute zero was calculated.•Phonon density of states and zero-point energy were obtained.•Isochoric entropy, internal energy, and reduced Helmholtz energy were calculated.
In this work, we want to highlight the potential of lithium as a target for spin-dependent dark matter search in cryogenic experiments, with a special focus on the low-mass region of the parameter ...space. We operated a prototype detector module based on a Formula omitted target crystal in an above-ground laboratory. Despite the high background environment, the detector sets a competitive limit on spin-dependent interactions of dark matter particles with protons and neutrons for masses between Formula omitted and Formula omitted.
The electronic structure of lanarkite-type Pb2MoO5 was explored by experimental and theoretical methods. The XPS and XES measurements were carried out at the cleaved atomic-smooth (201̅) surface ...prepared from the Pb2MoO5 crystal grown by the LTG Cz technique. The ab initio calculations of total and partial densities of states of the atoms constituting Pb2MoO5 were obtained employing the full potential linearized augmented plane wave (FP-LAPW) method. The principal contributors to the valence band of Pb2MoO5 are the O 2p states which contribute predominantly at the top and in the central portions of the valence band. The Pb 6s and Mo 4d states are among other principal contributors: their main contributions occur at the bottom and in the central portion of the valence band, respectively. Our FP-LAPW data reveal that the Pb2MoO5 compound is an indirect-gap material: the valence band maximum and conduction band minimum occur at the X and M points, respectively. The XPS core-level and valence-band spectra were measured for pristine and Ar+ ion-irradiated Pb2MoO5(201̅) surfaces and the measurements reveal high chemical stability of the Pb2MoO5(201̅) cleaved surface in reference to the 3.0keV Ar+ ion-irradiation.
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•The Pb2MoO5 single crystal was obtained by the LTG Cz technique.•The electronic structure of Pb2MoO5 was explored by XPS and XES.•The Pb2MoO5(201̅) cleaved surface is stable in reference to the 3.0keV Ar+ ion-irradiation.•The band structure of Pb2MoO5 was obtained employing the FP-LAPW method.•The O 2p states contribute predominantly at the top and in the central portions of the valence band.
The heat capacity of barium tungstate single crystal was measured by the adiabatic method in the range of 5.7–304 K. No anomalies in the heat capacity associated with the phase transition were found. ...The analysis of the functional behavior of heat capacity near zero revealed a low-frequency peak in the phonon density of states of BaWO4. An approach was proposed to allow quantitative description of the acoustic wing of the phonon density of states. The approximation of experimental data by an analytical expression was done, including the temperature region near 0 K. The Debye temperature at absolute zero has been obtained. The thermodynamic functions were calculated: entropy, enthalpy increment and Gibbs free energy.
•Low temperature heat capacity of BaWO4 single crystal was measured.•Thermodynamic functions (entropy, enthalpy increment, and Gibbs free energy) were calculated.•Debye characteristic temperature at absolute zero was calculated.•Phonon density of states description near zero was obtained.•Low-frequency peak in the phonon density of states was discovered.
Single crystals of lithium molybdate tungstates containing 10 and 15 mol % molybdenum were grown by the low-temperature-gradient Czochralski technique. It was shown that the single crystals have the ...phenakite structure (space group
). The heat capacity of the Li
2
W
0.85
Mo
0.15
O
4
single crystal was measured by differential scanning calorimetry in two temperature ranges: 190–370 and 320–970 K. The heat capacity in the temperature range 190–970 K is well described by the equation
C
p
= 37.95541 + 0.42875
T
− 4.87201 × 10
–4
T
2
+ 2.15184 × 10
–7
T
3
J/(K mol). It was determined that there are no phase transitions in the Li
2
W
0.85
Mo
0.15
O
4
single crystal in the studied temperature range. This makes this single crystal promising for the search for rare events, such as neutrinoless double β-decay and elastic coherent neutrino scattering off nuclei.
A single crystal of Formula omitted (NWO) was grown by a low-thermal-gradient Czochralski technique (LTG-CZ). The scintillation properties of the crystal were evaluated for the first time as a ...potential material for dark matter search experiments. The luminescence and scintillation characteristics of the crystal were studied at room temperature and low temperatures by using a light-emitting diode (LED) and a Formula omitted beta source. The luminescence and scintillation light yield at 10 K were significantly higher than those at room temperature. The crystal showed higher light yield at 10 K than a CaMoO Formula omitted (CMO) crystal. The decay time of the crystal was investigated at temperatures between 10 and 300 K. The sensitivity to spin-independent weakly interacting massive particle-nucleon interactions based on 10 kg (2 months) and 50 kg (12 months) data for the NWO crystal detectors was estimated by a simulated experiment using the standard halo model. The luminescence, scintillation, and sensitivity results revealed that the NWO crystal is a promising candidate for a dark matter search experiment in the near future.
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