CUORE: a cryogenic underground observatory for rare events Arnaboldi, C; Avignone III, F.T; Beeman, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
3
Journal Article
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CUORE is a proposed tightly packed array of 1000 TeO
2 bolometers, each being a cube
5
cm
on a side with a mass of
760
g
. The array consists of 25 vertical towers, arranged in a square of 5 towers×5 ...towers, each containing 10 layers of four crystals. The design of the detector is optimized for ultralow-background searches: for neutrinoless double-beta decay of
130
Te
(33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals
3×3×6
cm
3
of
340
g
has been completed, and a single CUORE tower is being constructed as a smaller-scale experiment called CUORICINO. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of present results, are reported.
•The first successful growth and processing at large scale of Zn82Se crystals is described.•Zn82Se crystals are compliant with harsh radio-purity requests of 0νDBD experiments.•Zn82Se crystals have ...good scintillating bolometer performance for 0νDBD application.•Guidelines for crystal production of upcoming one-ton 0νDBD experiment(s) are given.
High purity Zinc Selenide (ZnSe) crystals are produced starting from elemental Zn and Se to be used for the search of the neutrinoless double beta decay (0νDBD) of 82Se. In order to increase the number of emitting nuclides, enriched 82Se is used. Dedicated production lines for the synthesis and conditioning of the Zn82Se powder in order to make it suitable for crystal growth were assembled compliant with radio-purity constraints specific to rare event physics experiments. Besides routine check of impurities concentration, high sensitivity measurements are made for radio-isotope concentrations in raw materials, reactants, consumables, ancillaries and intermediary products used for ZnSe crystals production. Indications are given on the crystals perfection and how it is achieved. Since very expensive isotopically enriched material (82Se) is used, a special attention is given for acquiring the maximum yield in the mass balance of all production stages. Production and certification protocols are presented and resulting ready-to-use Zn82Se crystals are described.
► TeO2 crystals are good bolometer for neutrinoless double beta decay search. ► Up to now alpha background cannot be distinguished in TeO2 bolometers. ► We detected light from TeO2 crystals which ...allows alpha background rejection. ► The light can be explained as due to Cerenkov emission.
TeO2 crystals have proven to be superb bolometers for the search of neutrinoless double beta decay in many respects. However, if used alone, they do not exhibit any feature that allows to discriminate an α energy deposit from a β/γ one. This fact limits their ability to reject the background due to natural radioactivity and eventually affects the sensitivity of the search. In this paper we show the results of a TeO2 crystal where, in coincidence with its bolometric heat signal, also the luminescence light escaping the crystal is recorded. The results show that we are able to measure the light produced by β/γ particles, which can be explained as due to Cerenkov emission. No light is detected from α particles, allowing the rejection of this background source.
NaI(Tl) based scintillation detectors have become a staple in the field of direct dark matter searches, with the DAMA-LIBRA experiment being the standout for its reported observation of an annually ...modulating WIMP-like signal which is in direct contrast with other results. In order to accurately calibrate the energies of WIMP-induced nuclear recoil signals, precise measurements of the quenching factor of the NaI crystals are essential for each of these experiments, as it is well established that electron recoils and nuclear recoils have dissimilar scintillation light yields. In this contribution, we present first preliminary results of an ongoing systematic study that has been carried out by the COSINUS collaboration and Duke University to measure the quenching factor of Na recoils. Five ultra-pure NaI crystals, manufactured by the Shanghai Institute for Ceramics, each of which have varying Tl dopant concentrations, were irradiated with a mono-energetic neutron beam at the Triangle Universities National Laboratory, North Carolina, USA to extract the quenching factor values in the low recoil energies of 1-30keV
_{nr}
n
r
.
The increasing statistical significance of the DAMA/LIBRA annual modulation signal is a cause for tension in the field of dark matter direct detection. The COSINUS experiment aims at a ...model-independent cross-check of the DAMA/LIBRA signal claim, using NaI crystals operated as cryogenic scintillating calorimeters at millikelvin temperatures. Such a setup enables measurement of phonon and scintillation light signals via Transition Edge Sensors (TESs) and allows particle discrimination on an event-by-event basis. The non-standard properties of NaI cause an obstacle when attaching a TES directly onto the surface of the crystal. This can be overcome with the "remoTES" design, where the TES is attached to an external wafer crystal. We present the results from a first successful operation of NaI and other crystals as cryogenic calorimeters with the remoTES design.
For over twenty-five years the DAMA/LIBRA experiment has reported an annual modulation signal that is consistent with a dark matter explanation. This signal is, currently, in tension with the null ...results observed by other searches that utilize different target detectors. The COSINUS experiment will perform a model-independent cross-check of the DAMA/LIBRA result by using the same target material, NaI crystals, operated as scintillating calorimeters. By measuring both temperature and light the NaI crystals in COSINUS will be able to distinguish between electron and nuclear recoils on an event-by-event basis. However, background events induced by cosmic-rays, environmental radioactivity or the intrinsic contamination of the materials used in the crystal, shielding and infrastructure can pose an issue to any analysis and must be fully understood. We report on the status of the development of the simulation for an active water Cherenkov muon veto, as well as the results of the beginning radiogenic material screening.
The COSINUS (Cryogenic Observatory for SIgnals seen in Next-generation Underground Searches) project aims to provide a model independent cross-check of the long-standing DAMA/LIBRA claim on the ...observation of dark matter, by using the same target material (NaI) with a different experimental approach. The use of sodium iodide (NaI) crystals, operated at cryogenic temperature as scintillating calorimeters, provides both a low energy threshold for nuclear recoil events as expected from dark matter particle interactions, and the possibility to perform particle discrimination. Indeed, the dual read-out of phonon and light allows to perform signal-to-background discrimination on an event-by-event basis, a unique feature in comparison to other NaI-based dark matter searches. In this paper we will discuss in detail the COSINUS detector concept and we will present the performances of our first prototypes together with the results of the first measurements.
Large-mass bolometers are today extensively used for dark matter and double beta decay searches, in both cases the ultimate experimental sensitivity is defined by the background level reached in such ...devices. The most common background sources and the techniques used for their identification and reduction are here reviewed, with a particular focus on double beta decay searches. The relevant role played by Monte Carlo simulations in this field is discussed. As a real case, the background optimization in the MiDBD experiment is described.
A convincing observation of neutrino-less double beta decay (0vDBD) relies on the possibility of operating high-energy resolution detectors in background-free conditions. Scintillating cryogenic ...calorimeters are one of the most promising tools to fulfill the requirements for a next-generation experiment. Several steps have been taken to demonstrate the maturity of this technique, starting form the successful experience of CUPID-0. The CUPID-0 experiment collected almost 10 kg y of exposure, running 26 Zn82Se crystals during two years of continuous detector operation. The complete rejection of the dominant α background was demonstrated, measuring the lowest counting rate in the region of interest for this technique. Furthermore, the most stringent limit on the 82Se 0vDBD was established. In this contribution we present the final results of CUPID-0 phase-I, including a detailed model of the background and the measurement of the 2vDBD half-life.
In the framework of the CUPID-0 experiment, a numbers of ZnSe single crystals were produced and subjected to different thermal treatments, and later tested as cryogenic scintillating bolometers. We ...have found that a specific thermal treatment (24 hours under argon atmosphere at 900 °C) has a strong impact on some properties of ZnSe crystals (amplitude of signal, light yield, specific resistivity) and most interestingly, changes the quenching factor for alpha particles from values > 1 to values < 1. Thus such thermal treatment opens the possibility to modify this experimental parameter for a various applications.
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