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![Spectrum showing cosmogenic 37 Ar contributions and their decay as discussed in the text. Black: first 100 days of present exposure. Dark blue: last 500 days. Red and cyan show respectively the contributions to the dark blue spectrum from events with only an S2 pulse and from events with a single S1 and a single S2 pulse. Inset: normalized difference of black minus dark blue, showing the two x-ray peaks from 37 Ar decay. the 2.82 keV K-shell x-rays following electron capture in 37 Ar [38-40]. These are clearly visible in the first 100 days spectrum and absent in the remainder of the data set, as expected given the 35.04 d [41] half-life of](profile/Giuseppe-Longo-4/publication/323302735/figure/fig3/AS:596310461788160@1519182901421/Spectrum-showing-cosmogenic-37-Ar-contributions-and-their-decay-as-discussed-in-the-text.png)
Spectrum showing cosmogenic 37 Ar contributions and their decay as discussed in the text. Black: first 100 days of present exposure. Dark blue: last 500 days. Red and cyan show respectively the contributions to the dark blue spectrum from events with only an S2 pulse and from events with a single S1 and a single S2 pulse. Inset: normalized difference of black minus dark blue, showing the two x-ray peaks from 37 Ar decay. the 2.82 keV K-shell x-rays following electron capture in 37 Ar [38-40]. These are clearly visible in the first 100 days spectrum and absent in the remainder of the data set, as expected given the 35.04 d [41] half-life of
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We present the results of a search for dark matter WIMPs in the mass range below 20 GeV/c^2 using a target of low-radioactivity argon. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso (LNGS). The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully effici...
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... 241 AmBe and 241 Am 13 C neutron sources in DarkSide-50 is systematically lower than the ion- ization yield from SCENE and ARIS. The choice of Q y extracted from 241 AmBe and 241 Am 13 C in this analysis leads to a conservative estimate of the ex- clusion limits. Fig. 7 shows the N e − spectrum for the last 500 days (same as blue histogram in Fig. 3) together with the contributions from the individual radiation sources from the simulation, normalized using the detector construction materials radioassay data and radioactivity estimation obtained by fitting gamma lines at high energy, 39 Ar, and 85 Kr spectra. The N e − distribution from the 500 day sample obtained with the present ...
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Citations
... In 2018, DarkSide-50 extended the physics case to lighter dark matter candidates [5,6] by lowering the energy threshold from tens of keV (nuclear recoil equivalent) to few hundreds of eV . This was achieved by using to construct an energy estimator only the ionization signal (S2, which benefits from the multiplication in the gas) as opposed to prompt scintillation signals. ...
... While no quenching fluctuations are considered for the curve labelled NQ, the curve labelled QF assumes a binomial process governing the energy partition between visible (ionization electrons and excitons) and invisible (phonons) quanta. Assuming NQ fluctuations, the most conservative model, DarkSide-50 establishes the current best 90% C.L. limits for dark matter with mass in the range [1.2, 3.6] GeV/c 2 and improves by a factor of ∼10 at 3 GeV/c 2 over previous results [5,12]. ...
... The DarkSide program within the Global Argon Dark Matter Collaboration (GADMC) is searching for dark matter in the form of Weakly Interacting Massive Particles (WIMPs) by using argon dual-phase Time Projection Chambers (TPC) at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN. The experiment DarkSide-50 [1] took data at LNGS until 2018 using a 50-kg Ar TPC. The next generation detector DarkSide-20k [2] features a 50 ton TPC readout by cryogenic Silicon Photomultipliers (SiPMs) and is currently under construction at LNGS. ...
... In this case, the NR energy is as low as a few keV in Ar. As the S1 signal is often too low to be detected, the search for low-mass WIMPs must be performed by using the S2 signal only [3]: being the gain 2 for the S2 signal ∼ 20 photoelectrons (PE) for each extracted electron [1], Ar dual-phase TPCs are potentially sensitive to few-electron signals, i.e. to sub-keV Ar recoils. A dedicated S2-only analysis of the DarkSide-50 data was carried on in Ref. [3] in order to constrain low-mass WIMPs. ...
... The drawback is the reduced background discrimination power due to the absence of scintillation pulse shape and volume fiducialization along the electric field, as the drift time is no longer measurable. Nevertheless, this analysis technique, applied for the first time to a liquid argon experiment, led in 2018 to the improvement of existing limits on WIMP-nucleon and WIMPelectron interactions in the few GeV/c 2 and sub-GeV/c 2 mass ranges, respectively 3,4 . ...
We present the latest results from the search for light dark matter particle interactions with the DarkSide-50 dual-phase liquid argon time projection chamber. This analysis, based on the ionization signal only, improves the existing limits for spin-independent WIMP-nucleon interactions in the $[1.2, 3.6]$ GeV/c$^2$ mass range. The sensitivity is extended down to 40 MeV/c$^2$ by assuming the Migdal effect, responsible for an additional ionization signal from the recoiling atom. Finally, we set new constraints to interactions of dark matter particles with electrons in the final state, namely WIMPs, galactic axions, dark photons, and sterile neutrinos.
... The second category on the other hand is focused on spin-dependent (SD) DM particles, which couple preferentially to the nuclei spin, going in favour of detector targets made of highly polarised material. Leading experiments are for instance XENON1T [67], PandaX [68], DarkSide-50 [69] or IceCube [70]. ...
Trotz der zahlreichen astrophysikalisch und kosmologisch überzeugenden Beweise für Dunkle Materie bleibt ihre wahre Natur unbekannt. Eine Motivation für die Suche nach Dunkler Materie am Large Hadron Collider (LHC) und insbesondere mit dem ATLAS-Experiment ist die besonders vielversprechende Möglichkeit, dass Wechselwirkungen zwischen gewöhnlicher Materie und Dunkler Materie durch neue Spin-0-Teilchen vermittelt werden. Solche Teilchen würden das Standardmodell um einen potentiellen Dunklen Sektor erweitern, zu dem die Teilchen der Dunklen Materie gehören. ähnlich wie das Higgs-Boson interagieren diese neuen Mediatoren am stärksten mit den schwersten Teilchen über Kopplungen vom Yukawa-Typ, wodurch sie empfänglicher für die damit verbundene Produktion durch Quarks mit schwerem Flavour werden. Diese Dissertation präsentiert die Ergebnisse der statistischen Kombination von zwei Suchen, die auf die mit Dunkler Materie verbundene Produktion von einem Top-Quark-Paar oder einem einzelnen Top-Quark, jeweils zwei geladenen Leptonen im Endzustand, abzielen. Diese beiden Kanäle weisen komplementäre Eigenschaften auf, und eine Kombination kann die Empfindlichkeit gegenüber Dunkle-Materie-Signalen erheblich verbessern. Diese Kombination wird unter Verwendung von 139 fb-1 pp-Kollisionsdaten durchgeführt, die bei einer Schwerpunktsenergie von 13 TeV erzeugt und vom ATLAS-Detektor am LHC aufgezeichnet wurden. Die Ergebnisse der Kombination werden in Bezug auf vereinfachte Modelle für Dunklen Materie mit einem skalaren oder pseudoskalaren Spin-0-Mediator interpretiert. Die statistische Kombination weitet die bei einem Konfidenzniveau von 95% ausgeschlossenen Massen auf bis zu 350 GeV sowohl für skalare als auch für pseudoskalare Mediatoren aus. Die beobachteten Ausschlu{\ss}grenzen des Wirkungsquerschnitts werden für den ska\-laren (pseudoskalaren) Mediator um 20%(30%) gegenüber dem Besten des einzelnen Kanals verbessert.
... The rest mass of the neutrino is manifested as a deficit of events in the region of the decay spectrum near the Q-value. 1 63 Ho is particularly attractive because of its low Q-value of 2.833 keV and its reasonable half-life of 4570 years [171]. The ECHO collaboration has demonstrated decay spectra with 275,000 counts using a small array of magnetic microcalorimeters [148] and is presently analyzing data corresponding to a spectrum with about 10 8 counts. ...
We discuss here future neutrino detectors with physics goals ranging from the eV to the EeV scale. The focus is on future enabling technologies for such detectors, rather than existing detectors or those under construction. The report includes methodologies across the broad spectrum of neutrino physics: liquid noble and other cryogenic detectors, includin LAr and LXe TPCs; photon-based detectors including technologies enabling hybrid Cherenkov/scintillation detectors; low-threshold detectors which use a wide variety of technologies to probe physics like coherent neutrino-nucleus scattering or detection of cosmic background neutrinos; and ultra-high energy detectors including optical and radio detectors, as well as tracking detectors for use at the forward physics facility of the LHC
... The neutrino floor (dashed line) is also shown for a Xenon target [58]. The source of each experimental limit: DAMIC (blue) [53], NEWS-G (brown) [50], CDMSliteR3 (red) [44], EDELWEISS-III (orange) [59], CRESST-III (pink) [46], DarkSide-50 (purple) [60,61], XENON1T (light aquamarine, dark aquamarine) [47,62], LUX (light green) [63], PandaX-II (dark green) [49]. Note that this plot does not included the recent results (July 2022) from the LZ experiment, which placed the most stringent exclusion limits for WIMP masses above 9 GeV [48]. ...
DAMIC-M (Dark Matter in CCDs at Modane) is a near-future experiment that aims at searching for low-mass dark matter particles through their interactions with silicon atoms in the bulk of charge-coupled devices(CCDs). Pioneer in this technique was the DAMIC experiment at SNOLAB. Its successor, DAMIC-M, will have a detector mass 17 times larger and will employ a novel CCD technology (skipper amplifiers) to achieve sub-electron readout noise. Strengthened by these characteristics, DAMIC-M will reach unmatched sensitivity to the dark matter candidates of the so-called hidden sector. A challenging requirement is to control the radiogenic background down to the level of a fraction of events perkeV per kg-day of target exposure. To meet this condition, Geant4 based simulations are being utilized to optimize the detector design, drive the material selection and handling, and test background rejection techniques. Furthermore, precise measurements were carried out with skipper CCDs to characterize the spectrum of Compton scattered electrons, which represent a dominant source of environmental background at low energy. This thesis focuses on the explored detector designs, the corresponding predicted background, and the strategies implemented for its mitigation and characterization.
... Also in 2018, an analysis exploiting the s 2 only signal allowed to reach the best sensitivity between 1.8 and 6 GeV/c 2 [101]. As we will show in Chapter III, a part of this thesis was devoted to a more refined analysis of calibration and different backgrounds allowed improving these limits [96] and additional dark matter candidates were studied. ...
... Additional external calibration of the liquid argon response was performed thanks to two external experiments, SCENE [111] [112] and ARIS [110]. They allowed to determine nuclear recoil energy scale and ionization yields [101]. Both were as well used for measuring scintillation yield and scintillation nuclear and electronic recoil response for low mass analyses [101] [110]. ...
... They allowed to determine nuclear recoil energy scale and ionization yields [101]. Both were as well used for measuring scintillation yield and scintillation nuclear and electronic recoil response for low mass analyses [101] [110]. The advantage of external experiments using a neutron beam is that it is possible to calibrate the liquid argon response to a recoil of a known energy while in in-situ calibration for nuclear recoil relies on spectral shapes that need additional Monte-Carlo simulations to model them. ...
Astrophysical observations and cosmological measurements have raised the existence of an invisible missing mass in the Universe that has been called Dark Matter. Current main candidates for this unknown matter are WIMPs, Weakly Interacting Massive Particles, ALPs, Axion-Like Particles, and sterile neutrinos between 7 and 36 keV/c 2; The DarkSide experiment has for aim direct detection of dark matter particles using a double-phase liquid argon time projection chamber. The actual main detector, DarkSide-50 with 50 kg of active mass, has allowed raising the best detection limits at low mass. The next one, DarkSide-20k with 20 ton of fiducial mass, is in preparation with notably several prototypes testing new technologies or methods of detection to perform successfully the change in scale. Proto-0 and ReD are two of these prototypes; Proto-0 is testing new technologies while ReD is meant for testing the possibility of directionality measurements. In this work, we will first look at some improvements in the background contribution and energy scales of DarkSide-50. This contributed to refining the overall limits on WIMPs with and without the Migdal effect. We will also study additional dark matter models, solar and galactic ALPs and sterile neutrinos in the 7 to 36 keV/c 2 mass range. Limits found for ALPs and sterile neutrinos are not competitive with already existing work. Secondly, we will look at the data reconstruction software developed with Proto-0 and ReD data and with DarkSide-20k simulations. Finally, this data reconstruction will allow us to assess the stability of the gas pocket thickness inside the ReD experiment, to study the impact of several configurations and parameters of the design of DarkSide-20k on the pulse shape discrimination and thus on its sensitivity to dark matter, to reconstruct the position of the scintillation signal inside DarkSide-20k and to assess the performance in associating the scintillation and ionisation signals in DarkSide-20k.
... For experiments with thresholds of ∼20 eV or higher, the noble liquid detectors described in the previous section are again an attractive technology, particularly by focusing exclusively on the ionization channel in which individual electrons can be detected with high efficiency. Achieving such thresholds comes with drawbacks, including the loss of discrimination between ERs and NRs, loss of time resolution, and a class of pathological single-and few-electron backgrounds that dominate the lowest energy bins [343][344][345]. Still, this class of detector has the lowest demonstrated background rate per unit target mass, even in S2only mode, allowing the most stringent DM cross-section limits to date over a wide range of DM masses and interaction models. ...
This report summarizes the findings of the CF1 Topical Subgroup to Snowmass 2021, which was focused on particle dark matter. One of the most important scientific goals of the next decade is to reveal the nature of dark matter (DM). To accomplish this goal, we must delve deep, to cover high priority targets including weakly-interacting massive particles (WIMPs), and search wide, to explore as much motivated DM parameter space as possible. A diverse, continuous portfolio of experiments at large, medium, and small scales that includes both direct and indirect detection techniques maximizes the probability of discovering particle DM. Detailed calibrations and modeling of signal and background processes are required to make a convincing discovery. In the event that a candidate particle is found through different means, for example at a particle collider, the program described in this report is also essential to show that it is consistent with the actual cosmological DM. The US has a leading role in both direct and indirect detection dark matter experiments -- to maintain this leading role, it is imperative to continue funding major experiments and support a robust R\&D program.
... 12 It is seen in the figure that the strength of the signal is well below the future sensitives, as well as the present constraint. 12 The most stringent constraint on the SI scattering cross-section at present is obtained from CDEX [62] for m χ 0.1 GeV, DarkSide-50 [63] for 2 GeV m χ 3 GeV, and XENON1T [64][65][66] for other regions, respectively, where the Migdal effect plays an important role in low m χ regions [67]. On the other hand, the most sensitive projection in the future will be from NEWS-G [68] for m χ 0.5 GeV, SuperCDMS [69] for 0.5 GeV m χ 1.5 GeV, CYGNUS [70] for 1.5 GeV m χ 5 GeV, and DARWIN [71] for m χ 5 GeV, respectively. ...
We study a minimal model for a light scalar dark matter, requiring a light scalar mediator to address the core-cusp problem and interact with the standard model particles. We analyze the model comprehensively by focusing on the Breit-Wigner resonance for dark matter annihilation and self-scattering channels, considering the thermal relic abundance condition that includes the early kinetic decoupling effect, as well as the present and future constraints from collider, direct, and indirect dark matter detections. We found that the scalar dark matter with the mass of 0.3-2 GeV remains uncharted, which will be efficiently tested by the near future MeV gamma-ray observations.
... A typical dark matter experiment focuses on nuclear recoils from a few keV to tens of keV, and thus the detection of reactor CEvNS requires the detector thresholds to be further reduced. Several experimental efforts have been launched to advance the low-energy sensitivity of detector technologies including Si and Ge ionization detectors [204,205,240,242], liquid argon and xenon scintillation/ionization detectors [203,210,212,214,239,243], and cryogenic bolometers [90,213,244,245]. Up to date, energy thresholds in the range of tens of eV to hundreds of eV have been demonstrated in bolometers and ionization detectors. ...
... Right: Integrated CEvNS event rate in 1 kg of Si/Ar/Ge/Xe as a threshold of detector energy threshold, with the same assumption on reactor parameters as for the left figure. detectors such as liquid argon and xenon Time Projection Chambers (TPCs) are limited to an energy threshold of hundreds of eV [239,243,247]. Ongoing R&D efforts are currently pursuing substantial improvements in these directions [248][249][250][251]. ...
... In addition to detector threshold and active mass, another important aspect to consider in reactor CEvNS detection experiments is the excess backgrounds observed in the low energy regions of different detectors [239,243,[252][253][254], which operate at very different temperatures and have different signal readout schemes. Such backgrounds often manifest themselves as a fast rising event rate as the energy approaches the detector threshold, and can vary drastically in rate, temporal behavior, and other characteristics. ...
Nuclear reactors are uniquely powerful, abundant, and flavor-pure sources of antineutrinos that continue to play a vital role in the US neutrino physics program. The US reactor antineutrino physics community is a diverse interest group encompassing many detection technologies and many particle physics topics, including Standard Model and short-baseline oscillations, BSM physics searches, and reactor flux and spectrum modeling. The community's aims offer strong complimentary with numerous aspects of the wider US neutrino program and have direct relevance to most of the topical sub-groups composing the Snowmass 2021 Neutrino Frontier. Reactor neutrino experiments also have a direct societal impact and have become a strong workforce and technology development pipeline for DOE National Laboratories and universities. This white paper, prepared as a submission to the Snowmass 2021 community organizing exercise, will survey the state of the reactor antineutrino physics field and summarize the ways in which current and future reactor antineutrino experiments can play a critical role in advancing the field of particle physics in the next decade.
