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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.

In this paper we present the first measurement of a Gallium Arsenide (GaAs) crystal as a scintillating calorimeter with dual heat and light readout within the DAREDEVIL project. The experimental setup features a 4.3 g GaAs ( GaAs-1) crystal, operated at approximately 10 mK coupled with a Neutron Transmutation Doped (NTD) thermal sensor for phonon detection and an auxiliary calorimeter for the detection of scintillation light. For the GaAs-1 crystal, a baseline resolution of 121 ± 2 eV has been achieved. While, with a 3.5 g GaAs (GaAs-2) crystal an even better baseline resolution of 44.5 ± 0.8 eV was achieved. Alpha and X-ray calibration sources were used to study the scintillation light response to different types of interacting radiation. The GaAs crystal exhibits a strong particle discrimination capability based on the emitted scintillation light, featuring a light yield (LY) of 0.9 ± 0.2 keV/MeV for α induced events and 0.07 ± 0.01 keV/MeV for β / γ events, both measured at 1 MeV. The unusual luminescence behavior, i.e. more light being produced under irradiation by α particles warrants further investigation, particularly due to its potential to enhance sensitivity to low-energy nuclear recoils from light dark matter scattering.

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.

COSINUS will be among the first underground experiments to operate Transition Edge Sensors in a dry dilution refrigerator, measuring temperature changes on the order of μ K. A pulse tube cryocooler is used to cool down to 3K, trading simplified handling, by not using liquid noble gases, for an increased vibration noise level in the acoustic frequency range. As the signals measured with a TES are in the same frequency region, it is necessary to decouple the detectors from all possible noise sources. In COSINUS, a two-level passive decoupling system was developed and tested using piezo-based accelerometers. At the first level, the refrigerator is mechanically isolated from all external noise sources. For the second level an internal spring-based system was developed and tested on a mockup system. On the first level a reduction of the vibrational background up to a factor 4 below 10 Hz could be measured. On the second level a resonance frequency of 1.2 Hz with damping of higher frequencies was achieved.

In the field of direct Dark Matter search, a variety of experiments have been developed over the past decades aiming at detecting Weakly Interactive Massive Particles (WIMPs) via their scattering in a detector medium and, in the last years, several experimental efforts are concentrated on the directionality approach: the observation of the incoming apparent direction of WIMPs would in fact provide a new and unambiguous signature and the proof of the galactic origin of Dark Matter. Furthermore the directionality appears as the only way to overcome the neutrino background that is expected to finally prevent standard techniques to further lower cross-section limits. The NEWSdm experiment has been proposed to measure the direction of WIMP-induced nuclear recoils by using a novel emulsion technology with improved spatial resolution. In this paper we will present the status of the experiment, the performances of the newly developed read-out systems reaching sub-micrometric resolution and we will discuss the expected sensitivity and discovery potential.

Background Two main minimal access adrenalectomy techniques are available: laparoscopic transperitoneal (LTA) and posterior retroperitoneoscopic adrenalectomy (PRA). This study aims to compare these approaches in an updated meta-analysis of randomised controlled (RCT) and non-randomised comparative (NRT) trials. Methods A systematic search of comparative LTA and PRA studies was performed. Standard demographic and surgical data were recorded. Outcome measures compared included: operative time, estimated blood loss (EBL), conversion to open, post-operative pain, time to oral intake and ambulation, early morbidity, hospital length of stay (HLOS) and mortality. Quality of RCTs and NRTs was assessed using Cochrane and ROBINS-I, respectively, and heterogeneity using the I 2 test. Dichotomous and continuous variables were compared using odds ratios and mean/standard difference. Studies were then combined using the Mantel–Haenszel method. Meta-analysis was performed by fixed- and random-effect models. Results Following exclusions, 12 studies were included in the analysis: 3 RCTs and 9 NRTs. These reported a total of 775 patients: 341 (44%) PRA and 434 (56%) LTA. Demographics were similar except for tumour size which was smaller (by 0.78 cm) in PRA ( p  = 0.003). Significant differences in outcome were seen in EBL (18 mls less in PRA, p  = 0.006), time to oral intake (3.4 h sooner in PRA p  = 0.009) and HLOS (shorter in PRA by 0.84 day, p  = 0.001). Conclusions This analysis demonstrates that while PRA tends to be performed for smaller tumours it allows for less EBL, earlier post-operative oral intake and shorter hospital stays. In appropriately selected patients, it represents an invaluable tool in the endocrine surgeon’s armamentarium.

COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) is an experiment employing cryogenic calorimeters, dedicated to direct dark matter search in underground laboratories. Its goal is to cross-check the annual modulation signal the DAMA collaboration has been detecting for about 20 years (Bernabei et al. in Nucl Part Phys Proc 303–305:74–79, 2018. https://doi.org/10.1016/j.nuclphysbps.2019.03.015 ) and which has been ruled out by other experiments in certain dark matter scenarios. COSINUS can provide a model-independent test by the use of the same target material (NaI), with the additional chance of discriminating β / γ events from nuclear recoils on an event-by-event basis, by the application of a well-established temperature sensor technology developed within the CRESST collaboration. Each module is constituted by two detectors: the light detector, that is a silicon beaker equipped with a transition edge sensor (TES), and the phonon detector, a small cubic NaI crystal interfaced with a carrier of a harder material (e.g. CdWO 4 ), also instrumented with a TES. This technology had so far never been applied to NaI crystals because of several well-known obstacles, and COSINUS is the first experiment which succeeded in operating NaI crystals as cryogenic calorimeters. Here, we present the COSINUS project, describe the achievements and the challenges of the COSINUS prototype development and discuss the status and the perspectives of this NaI-based cryogenic frontier.

Over almost three decades the TAUP conference has seen a remarkable momentum gain in direct dark matter search. An important accelerator were first indications for a modulating signal rate in the DAMA/NaI experiment (today DAMA/LIBRA) reported in 1997. Today the presence of an annual modulation observed by DAMA, which matches in period and phase the expectation for dark matter, is doubtless and supported at > 9σ confidence. Despite the positive evidence from the DAMA experiment the underlying nature of dark matter is still considered an open and fundamental question of nowadays particle physics. No other direct dark matter search experiment could confirm the DAMA claim up to now; moreover, numerous null-results are in clear contradiction with DAMA under so-called standard assumptions for the dark matter halo and the interaction mechanism of dark with ordinary matter. As both bear a dependence on the target material, resolving this controversial situation will convincingly only be possible with an experiment using sodium iodide (NaI) as target, just like DAMA. COSINUS aims to even go a step further by combining NaI with a novel detection approach. DAMA and all other NaI experiments solely measure the scintillation light created by a particle interaction in the NaI crystal. COSINUS aims to operate NaI as a cryogenic calorimeter reading scintillation light and phonon/heat signal. Two distinct advantages arise from this approach, a substantially lower energy threshold for nuclear recoils and particle identification on an event-by-event basis. These key benefits will allow COSINUS to clarify a possible nuclear recoil origin of the DAMA signal with comparatively little exposure of O(100kg days) and, thereby, answer a long-standing question of particle physics. Today COSINUS is in R&D phase; in this contribution we show results from the 2nd prototype, albeit the first one of the final foreseen detector design. The key finding of this measurement is that pure, undoped NaI is a truly excellent scintillator at low temperatures: We measure 13.1% of the total deposited energy in the NaI crystal in the form of scintillation light (in the light detector).

The OPERA experiment at the Gran Sasso underground laboratory was designed to study νμ → ντ oscillations in appearance mode in the CNGS neutrino beam. In this paper we report the detection of the 5th ντ candidate event found in the analysis of an enlarged data sample. Given the number of analysed events and the low background, νμ → ντ oscillations have been established with a significance of 5.1σ. The analysis of the present electron neutrino sample in the framework of the 3 + 1 sterile model is also presented. Finally the analysis of the muon charge ratio in the cosmic ray sample is discussed.

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.