The NUCLEUS experiment aims for the detection of coherent elastic neutrino-nucleus scattering at a nuclear power reactor with gram-scale, ultra-low-threshold cryogenic detectors. This technology ...leads to a miniaturization of neutrino detectors and allows to probe physics beyond the Standard Model of particle physics. A 0.5 g NUCLEUS prototype detector, operated above ground in 2017, reached an energy threshold for nuclear recoils of below 20 eV. This sensitivity is achieved with tungsten transition edge sensors which are operating at temperatures of 15 mK and are mainly sensitive to non-thermal phonons. These small recoil energies become accessible for the first time with this technology, which allows collecting large-statistics neutrino event samples with a moderate detector mass. A first-phase cryogenic detector array with a total mass of 10 g enables a 5-sigma observation of coherent scattering within several weeks. We identified a suitable experimental site at the Chooz Nuclear Power Plant and performed muon and neutron background measurements there. The operation of a NUCLEUS cryogenic detector array at such a site requires highly efficient background suppression. NUCLEUS plans to use an innovative technique consisting of separate cryogenic anticoincidence detectors against surface backgrounds and penetrating (gamma, neutron) radiation. We present first results from prototypes of these veto detectors and their operation in coincidence with a NUCLEUS target detector.
The projected background for the CUORE experiment Alduino, C.; Avignone, F. T.; Azzolini, O. ...
European physical journal. C, Particles and fields,
08/2017, Letnik:
77, Številka:
8
Journal Article
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Odprti dostop
The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of
130
Te with an array of 988 TeO
2
bolometers operating at temperatures ...around 10 mK. The experiment is currently being commissioned in Hall A of Laboratori Nazionali del Gran Sasso, Italy. The goal of CUORE is to reach a 90% C.L. exclusion sensitivity on the
130
Te decay half-life of 9
×
10
25
years after 5 years of data taking. The main issue to be addressed to accomplish this aim is the rate of background events in the region of interest, which must not be higher than 10
-
2
counts/keV/kg/year. We developed a detailed Monte Carlo simulation, based on results from a campaign of material screening, radioassays, and bolometric measurements, to evaluate the expected background. This was used over the years to guide the construction strategies of the experiment and we use it here to project a background model for CUORE. In this paper we report the results of our study and our expectations for the background rate in the energy region where the peak signature of neutrinoless double beta decay of
130
Te is expected.
Coherent elastic neutrino–nucleus scattering (
CE
ν
NS
) offers a unique way to study neutrino properties and to search for new physics beyond the Standard Model. Nuclear reactors are promising ...sources to explore this process at low energies since they deliver large fluxes of anti-neutrinos with typical energies of a few MeV. In this paper, a new-generation experiment to study
CE
ν
NS
is described. The NUCLEUS experiment will use cryogenic detectors which feature an unprecedentedly low-energy threshold and a time response fast enough to be operated under above-ground conditions. Both sensitivity to low-energy nuclear recoils and a high event rate tolerance are stringent requirements to measuring
CE
ν
NS
of reactor anti-neutrinos. A new experimental site, the Very-Near-Site (VNS), at the Chooz nuclear power plant in France is described. The VNS is located between the two 4.25
GW
th
reactor cores and matches the requirements of NUCLEUS. First results of on-site measurements of neutron and muon backgrounds, the expected dominant background contributions, are given. In this paper a preliminary experimental set-up with dedicated active and passive background reduction techniques and first background estimations are presented. Furthermore, the feasibility to operate the detectors in coincidence with an active muon veto at shallow overburden is studied. The paper concludes with a sensitivity study pointing out the physics potential of NUCLEUS at the Chooz nuclear power plant.
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.
Rare event physics demands very detailed background control, high-performance detectors, and custom analysis strategies. Cryogenic calorimeters combine all these ingredients very effectively, ...representing a promising tool for next-generation experiments. CUPID-0 is one of the most advanced examples of such a technique, having demonstrated its potential with several results obtained with limited exposure. In this paper, we present a further application. Exploiting the analysis of delayed coincidence, we can identify the signals caused by the 220Rn-216Po decay sequence on an event-by-event basis. The analysis of these events allows us to extract the time differences between the two decays, leading to a new evaluation of 216Po half-life, estimated as (143.3±2.8) ms.
The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of Se-82. The matrix which embeds the source is an ...array of ZnSe crystals, where enriched Se-82 is used as decay isotope. The radiopurity of the initial components employed for manufacturing crystals, that can be operated as bolometers, is crucial for achieving a null background level in the region of interest for double-beta decay investigations. In this work, we evaluated the radioactive content in 2.5 kg of 96.3 % enriched Se-82 metal, measured with a high-purity germanium detector at the Gran Sasso deep underground laboratory. The limits on internal contaminations of primordial decay chain elements of Th-232, U-238 and U-235 are respectively: <61,<110 and <74 mu Bq/kg at 90 % C.L. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the Se-82 allowed us to establish the most stringent lower limits on the half-lives of the double-beta decay of Se-82 to 0(+)(1), 2(2)(+) and 2(1)(+) excited states of Kr-82 of 3.4.10(22), 1.3.10(22) and 1.0.10(22) y, respectively, with a 90 % C.L.
RES-NOVA is a newly proposed experiment for detecting neutrinos from astrophysical sources, mainly Supernovae, using an array of cryogenic detectors made of PbWO
4
crystals produced from ...archaeological Pb. This unconventional material, characterized by intrinsic high radiopurity, enables low-background levels in the region of interest for the neutrino detection via Coherent Elastic neutrino-Nucleus Scattering (CE
ν
NS). This signal lies at the detector energy threshold,
O
(1 keV), and it is expected to be hidden by naturally occurring radioactive contaminants of the crystal absorber. Here, we present the results of a radiopurity assay on a 0.84 kg PbWO
4
crystal produced from archaeological Pb operated as a cryogenic detector. The crystal internal radioactive contaminations are:
232
Th <40
μ
Bq/kg,
238
U <30
μ
Bq/kg,
226
Ra 1.3 mBq/kg and
210
Pb 22.5 mBq/kg. We also present a background projection for the final experiment and possible mitigation strategies for further background suppression. The achieved results demonstrate the feasibility of realizing this new class of detectors.
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