The R&D project COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) aims to develop a cryogenic scintillating calorimeter using an undoped NaI-crystal as ...target for direct dark matter search. Dark matter particles interacting with the detector material generate both a phonon signal and scintillation light. While the phonon signal provides a precise determination of the deposited energy, the simultaneously measured scintillation light allows for particle identification on an event-by-event basis, a powerful tool to study material-dependent interactions, and to suppress backgrounds. Using the same target material as the DAMA/LIBRA collaboration, the COSINUS technique may offer a unique possibility to investigate and contribute information to the presently controversial situation in the dark matter sector. We report on the dedicated design planned for the NaI proof-of-principle detector and the objectives of using this detection technique in the light of direct dark matter detection.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Radioactivity was recently discovered as a source of decoherence and correlated errors for the real-world implementation of superconducting quantum processors. In this work, we measure levels of ...radioactivity present in a typical laboratory environment (from muons, neutrons, and
γ
-rays emitted by naturally occurring radioactive isotopes) and in the most commonly used materials for the assembly and operation of state-of-the-art superconducting qubits. We present a GEANT-4 based simulation to predict the rate of impacts and the amount of energy released in a qubit chip from each of the mentioned sources. We finally propose mitigation strategies for the operation of next-generation qubits in a radio-pure environment.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the quest for direct dark matter detection, innovative approaches to lower the detection threshold and explore the sub-GeV mass range, have gained high relevance in the last decade. This study ...presents the pioneering use of Gallium Arsenide (GaAs) as a low-temperature calorimeter for probing dark matter-electron interactions within the DAREDEVIL (DARk-mattEr DEVIces for Low energy detection) project. Our experimental setup features a GaAs crystal at an ultralow temperature of 15 mK, coupled with a Neutron Transmutation Doped Germanium (NTD-Ge) thermal sensor for precise energy estimation. This configuration is the first step towards detecting single electrons scattered by dark matter particles within the GaAs crystal, to improve the sensitivity to low-mass dark matter candidates significantly. Taking advantage of the production of optical phonons in polar materials such as GaAs gives the possibility to study the scattering of sub-MeV dark matter. This paper presents a detailed analysis of the detector’s response, using a calibration spectrum using
α
particles and X-ray events. While the results do not meet the ambitious eV scale threshold yet, they establish a solid benchmark for assessing the detector’s current performance and sensitivity. This work not only highlights the detector’s potential but also sets the stage for future enhancements aimed at achieving the eV threshold, underscoring the promising direction of this detector technology. These findings demonstrate the feasibility of using GaAs as a cryogenic calorimeter and hence open new avenues for investigating the elusive nature of dark matter through innovative direct detection techniques.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
COSINUS is a dark matter (DM) direct search experiment that uses sodium iodide (NaI) crystals as cryogenic calorimeters. Thanks to the low nuclear recoil energy threshold and event-by-event ...discrimination capability, COSINUS will address the long-standing DM claim made by the DAMA/LIBRA collaboration. The experiment is currently under construction at the Laboratori Nazionali del Gran Sasso, Italy, and employs a large cylindrical water tank as a passive shield to meet the required background rate. However, muon-induced neutrons can mimic a DM signal therefore requiring an active veto system, which is achieved by instrumenting the water tank with an array of photomultiplier tubes (PMTs). This study optimizes the number, arrangement, and trigger conditions of the PMTs as well as the size of an optically invisible region. The objective was to maximize the muon veto efficiency while minimizing the accidental trigger rate due to the ambient and instrumental background. The final configuration predicts a veto efficiency of 99.63 ± 0.16% and 44.4 ± 5.6% in the tagging of muon events and showers of secondary particles, respectively. The active veto will reduce the cosmogenic neutron background rate to 0.11 ± 0.02 cts
·
kg
-
1
·
year
-
1
,
corresponding to less than one background event in the region of interest for the whole COSINUS-1
π
exposure of 1000 kg
·
days.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
.
Archaeological Roman lead (Pb) is known to be a suitable material for shielding experimental apparata in rare event searches. In the past years the intrinsic radiopurity of this material was ...investigated using different technologies. In this work we applied the latest advancements in cryogenic techniques to study the bulk radiopurity of a 1cm^3 sample of archaeological Roman Pb. We report the lowest ever measured limit on
210
Pb content in Roman Pb, with a concentration lower than 715μBq/kg. Furthermore, we also studied
238
U and
232
Th impurity concentrations. Our values concur with independent measurements reported in literature.
A new study of double beta decay processes in natural Zr isotopes using Zr metal samples and an ultra-low-background high-purity germanium detectors was performed at Laboratori Nazionali del Gran ...Sasso of INFN (Italy). Two data sets were collected with a 736.35 g and a 129.94 g Zr metal over 59.7 days and 37.3 days, respectively, and were used for a detailed analysis. A new limit on the double beta decay of
94
Zr to the 1st excited level of
94
Mo was set as
T
1
/
2
β
β
>
2.1
×
10
20
year
, which is a factor of three better than the previous result. It is shown that the current radiopurity of Zr metal (tens of Bq/kg), produced via two methods, do not comply with the radiopurity requirements for low-background experiments. Hence, we propose to use a purified ZrCl
4
powder in an optimized geometry as a new approach for future experiments with extended sensitivity focused on studies of rare nuclear processes in Zr isotopes.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
A new study of double beta decay processes in natural Zr isotopes using Zr metal samples and an ultra-low-background high-purity germanium detectors was performed at Laboratori Nazionali del ...Gran Sasso of INFN (Italy). Two data sets were collected with a 736.35 g and a 129.94 g Zr metal over 59.7 days and 37.3 days, respectively, and were used for a detailed analysis. A new limit on the double beta decay of
$$^{94}$$
94
Zr to the 1st excited level of
$$^{94}$$
94
Mo was set as
$$T_{1/2}^{\beta \beta } > 2.1\times 10^{20}~\text {year}$$
T
1
/
2
β
β
>
2.1
×
10
20
year
, which is a factor of three better than the previous result. It is shown that the current radiopurity of Zr metal (tens of Bq/kg), produced via two methods, do not comply with the radiopurity requirements for low-background experiments. Hence, we propose to use a purified ZrCl
$$_{4}$$
4
powder in an optimized geometry as a new approach for future experiments with extended sensitivity focused on studies of rare nuclear processes in Zr isotopes.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the framework of rare event searches, the identification of radioactive contaminants in ultra-pure samples is a challenging task, because the signal is often at the same level of the instrumental ...background. This is a rather common situation for
α
-spectrometers and other detectors used for low-activity measurements. In order to obtain the target sensitivity without extending the data taking live-time, analysis strategies that highlight the presence of the signal sought should be developed. In this paper, we show how to improve the contaminant tagging capability relying on the time-correlation of radioactive decay sequences. We validate the proposed technique by measuring the impurity level of both contaminated and ultra-pure copper samples, demonstrating the potential of this analysis tool in disentangling different background sources and providing an effective way to mitigate their impact in rare event searches.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
RES-NOVA is a new proposed experiment for the investigation of astrophysical neutrino sources with archaeological Pb-based cryogenic detectors. RES-NOVA will exploit Coherent Elastic neutrino-Nucleus ...Scattering (CEνNS) as detection channel, thus it will be equally sensitive to all neutrino flavors produced by Supernovae (SNe). RES-NOVA with only a total active volume of (60 cm)3 and an energy threshold of 1 keV will probe the entire Milky Way Galaxy for (failed) core-collapse SNe with > 3 σ detection significance. The high detector modularity makes RES-NOVA ideal also for reconstructing the main parameters (e.g. average neutrino energy, star binding energy) of SNe occurring in our vicinity, without deterioration of the detector performance caused by the high neutrino interaction rate. For the first time, distances <3 kpc can be surveyed, similarly to the ones where all known past galactic SNe happened. We discuss the RES-NOVA potential, accounting for a realistic setup, considering the detector geometry, modularity and background level in the region of interest. We report on the RES-NOVA background model and on the sensitivity to SN neutrinos as a function of the distance travelled by neutrinos.
The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) experiment aims at the detection of dark matter-induced recoils in sodium iodide (NaI) crystals ...operated as scintillating cryogenic calorimeters. The detection of both scintillation light and phonons allows performing an event-by-event signal to background discrimination, thus enhancing the sensitivity of the experiment. The choice of using NaI crystals is motivated by the goal of probing the long-standing DAMA/LIBRA results using the same target material. The construction of the experimental facility is foreseen to start by 2021 at the INFN Gran Sasso National Laboratory (LNGS) in Italy. It consists of a cryostat housing the target crystals shielded from the external radioactivity by a water tank acting, at the same time, as an active veto against cosmic ray-induced events. Taking into account both environmental radioactivity and intrinsic contamination of materials used for cryostat, shielding and infrastructure, we performed a careful background budget estimation. The goal is to evaluate the number of events that could mimic or interfere with signal detection while optimising the geometry of the experimental setup. In this paper we present the results of the detailed Monte Carlo simulations we performed, together with the final design of the setup that minimises the residual amount of background particles reaching the detector volume.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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