DarkSide is a multi-stage program devoted to direct searches of Dark Matter particles with detectors based on double phase liquid Argon Time Projection Chamber. The DarkSide-50 setup is running ...underground at the Laboratori Nazionali del Gran Sasso. First it was operated with Atmospheric Argon and during that run (1422 ± 67) kg×d of truly background-free exposure has been accumulated. Obtained data made it possible to set a 90% C.L. upper limit on the WIMP-nucleon cross section of 6.1 × 10−44 cm2 (for a WIMP mass of 100 GeV/c2). Presently the detector is filled with Underground Argon, which is depleted in 39Ar by a factor of (1.4 ± 0.2)×103 with respect to Atmospheric Argon. Acquired so far (2616 ± 43) kg×d (71 live days) in combination with the data from the Atmospheric Argon run give us the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section of 2.0×10−44 cm2 for a WIMP mass of 100 GeV/c2. Up to date this is the best limit obtained with an argon target.
The DarkSide awakens Agnes, P; Agostino, L; M Albuquerque, I F ...
Journal of physics. Conference series,
05/2016, Letnik:
718, Številka:
4
Journal Article
Recenzirano
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The DarkSide program at LNGS aims to perform background-free WIMP searches using two phase liquid argon time projection chambers, with the ultimate goal of covering all parameters down to the ...so-called neutrino floor. One of the distinct features of the program is the use of underground argon with has a reduced content of the radioactive 39Ar compared to atmospheric argon. The DarkSide Collaboration is currently operating the DarkSide-50 experiment, the first such WIMP detector using underground argon. Operations with underground argon indicate a suppression of 39Ar by a factor (1.4 ± 0.2) × 103 relative to atmospheric argon. The new results obtained with DarkSide-50 and the plans for the next steps of the DarkSide program, the 20t fiducial mass DarkSide-20k detector and the 200 t fiducial Argo, are reviewed in this proceedings.
The DarkSide experiment is designed for the direct detection of Dark Matter with a double phase liquid Argon TPC operating underground at Laboratori Nazionali del Gran Sasso. The TPC is placed inside ...a 30 tons liquid organic scintillator sphere, acting as a neutron veto, which is in turn installed inside a 1 kt water Cherenkov detector. The current detector is running since November 2013 with a 50 kg atmospheric Argon fill and we report here the first null results of a Dark Matter search for a (1422 ± 67) kg.d exposure. This result correspond to a 90% CL upper limit on the WIMP-nucleon cross section of 6.1 × 10-44 cm2 (for a WIMP mass of 100 GeV c2) and it's currently the most sensitive limit obtained with an Argon target.
The DarkSide-50 outer detectors Westerdale, S; Agnes, P; Agostino, L ...
Journal of physics. Conference series,
05/2016, Letnik:
718, Številka:
4
Journal Article
Recenzirano
Odprti dostop
DarkSide-50 is a dark matter detection experiment searching for Weakly Interacting Massive Particles (WIMPs), in Gran Sasso National Laboratory. For experiments like DarkSide-50, neutrons are one of ...the primary backgrounds that can mimic WIMP signals. The experiment consists of three nested detectors: a liquid argon time projection chamber surrounded by two outer detectors. The outermost detector is a 10 m by 11 m cylindrical water Cherenkov detector with 80 PMTs, designed to provide shielding and muon vetoing. Inside the water Cherenkov detector is the 4 m diameter spherical boron-loaded liquid scintillator veto, with a cocktail of pseudocumene, trimethyl borate, and PPO wavelength shifter, designed to provide shielding, neutron vetoing, and in situ measurements of the TPC backgrounds. We present design and performance details of the DarkSide-50 outer detectors.
This paper evaluates alternative approaches to management of interstate water resources in the United States (U.S.), including interstate compacts, interstate associations, federal‐state ...partnerships, and federal‐interstate compacts. These governance structures provide alternatives to traditional federalism or U.S. Supreme Court litigation for addressing problems that transcend political boundaries and functional responsibilities. Interstate compacts can provide a forum for ongoing collaboration and are popular mechanisms for allocating water rights among the states. Federal‐interstate compacts, such as the Delaware River Basin Compact and federal‐state partnerships, such as the National Estuary Program, are also effective and complementary approaches to managing water resources. However, all of these approaches can only make modest improvements in managing water resources given the complicated and fragmented nature of our federalist system of government.
The scintillation time response of liquid argon has a key role in the discrimination of electronic backgrounds in dark matter search experiments. However, its extraordinary rejection power can be ...affected by various detector effects such as the delayed light emission of TetraPhenyl Butadiene, the most commonly used wavelength shifter, and the electric drift field applied in Time Projection Chambers. In this work, we characterized the TetraPhenyl Butadiene delayed response and the dependence of the pulse shape discrimination on the electric field, exploiting the data acquired with the ARIS, a small-scale single-phase liquid argon detector exposed to monochromatic neutron and gamma sources at the ALTO facility of IJC Lab in Orsay.
Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the ...liquid phase. The "standard" EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms ("neutral bremsstrahlung", NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The amplitude yield and position resolution were measured for these readout techniques, which allowed to assess the detection threshold for electron and nuclear recoils in two-phase argon detectors for dark matter searches. To the best of our knowledge, this is the first practical application of the NBrS effect in detection science.
We reanalize data collected with the DarkSide-50 experiment and recently used to set limits on the spin-independent interaction rate of weakly interacting massive particles (WIMPs) on argon nuclei ...with an effective field theory framework. The dataset corresponds to a total (16660 \(\pm\) 270) kg d exposure using a target of low-radioactivity argon extracted from underground sources. We obtain upper limits on the effective couplings of the 12 leading operators in the nonrelativistic systematic expansion. For each effective coupling we set constraints on WIMP-nucleon cross sections, setting upper limits between \(2.4 \times 10^{-45} \, \mathrm{cm}^2\) and \(2.3 \times 10^{-42} \, \mathrm{cm}^2\) (8.9 \(\times 10^{-45} \, \mathrm{cm}^2\) and 6.0 \(\times 10^{-42} \, \mathrm{cm}^2\)) for WIMPs of mass of 100 \(\mathrm{GeV/c^2}\) (1000 \(\mathrm{GeV/c^2}\)) at 90\% confidence level.
Large liquid argon detectors offer one of the best avenues for the detection of galactic weakly interacting massive particles (WIMPs) via their scattering on atomic nuclei. The liquid argon target ...allows exquisite discrimination between nuclear and electron recoil signals via pulse-shape discrimination of the scintillation signals. Atmospheric argon (AAr), however, has a naturally occurring radioactive isotope, \(^{39}\)Ar, a \(\beta\) emitter of cosmogenic origin. For large detectors, the atmospheric \(^{39}\)Ar activity poses pile-up concerns. The use of argon extracted from underground wells, deprived of \(^{39}\)Ar, is key to the physics potential of these experiments. The DarkSide-20k dark matter search experiment will operate a dual-phase time projection chamber with 50 tonnes of radio-pure underground argon (UAr), that was shown to be depleted of \(^{39}\)Ar with respect to AAr by a factor larger than 1400. Assessing the \(^{39}\)Ar content of the UAr during extraction is crucial for the success of DarkSide-20k, as well as for future experiments of the Global Argon Dark Matter Collaboration (GADMC). This will be carried out by the DArT in ArDM experiment, a small chamber made with extremely radio-pure materials that will be placed at the centre of the ArDM detector, in the Canfranc Underground Laboratory (LSC) in Spain. The ArDM LAr volume acts as an active veto for background radioactivity, mostly \(\gamma\)-rays from the ArDM detector materials and the surrounding rock. This article describes the DArT in ArDM project, including the chamber design and construction, and reviews the background required to achieve the expected performance of the detector.
We report measurements of the charged daughter fraction of \(^{218}\)Po as a result of the \(^{222}\)Rn alpha decay, and the mobility of \(^{218}\)Po\(^+\) ions, using radon-polonium coincidences ...from the \(^{238}\)U chain identified in 532 live-days of DarkSide-50 WIMP-search data. The fraction of \(^{218}\)Po that is charged is found to be 0.37\(\pm\)0.03 and the mobility of \(^{218}\)Po\(^+\) is (8.6\(\pm\)0.1)\(\times\)10$^{-4}$$\frac{\text{cm}^2}{\text{Vs}}$.
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