Solar neutrinos have been pivotal to the discovery of neutrino flavour oscillations and are a unique tool to probe the reactions that keep the Sun shine. Although most of solar neutrino components ...have been directly measured, the neutrinos emitted by the keystone pp reaction, in which two protons fuse to make a deuteron, have so far eluded direct detection. The Borexino experiment, an ultra–pure liquid scintillator detector running at the Laboratori Nazionali del Gran Sasso in Italy, has now filled the gap, providing the first direct real time measurement of pp neutrinos and of the solar neutrino luminosity.
The DarkSide Program Rossi, B.; Agnes, P.; Alexander, T. ...
EPJ Web of conferences,
01/2016, Volume:
121
Journal Article, Conference Proceeding
Peer reviewed
Open access
DarkSide-50 at Gran Sasso underground laboratory (LNGS), Italy, is a direct dark matter search experiment based on a liquid argon TPC. DS-50 has completed its first dark matter run using atmospheric ...argon as target. The detector performances and the results of the first physics run are presented in this proceeding.
We report on the first measurement of
39Ar in argon from underground natural gas reservoirs. The gas stored in the US National Helium Reserve was found to contain a low level of
39Ar. The ratio of
...39Ar to stable argon was measured to be
⩽
4
×
10
-
17
(84% C.L.), less than 5% the value in atmospheric argon (
39
Ar
/
Ar
=
8
×
10
-
16
). The total quantity of argon currently stored in the National Helium Reserve is estimated at 1000
tons.
39Ar represents one of the most important backgrounds in argon detectors for WIMP dark matter searches. The findings reported demonstrate the possibility of constructing large multi-ton argon detectors with low radioactivity suitable for WIMP dark matter searches.
Imaging devices made from an ionization target layer of amorphous selenium (aSe) coupled to a silicon complementary metal-oxide-semiconductor (CMOS) active pixel array for charge readout are a ...promising technology for neutrino physics. The high spatial resolution in a solid-state target provides unparalleled rejection of backgrounds from natural radioactivity in the search for neutrinoless \(\beta\beta\) decay and for electron neutrino (\(\nu_e\)) spectroscopy with \(^{82}\)Se. In this white paper, we summarize the broad scientific program of a large imaging detector with a 10-ton target of \(^{82}\)Se. We review the detector technology, and outline the ongoing research program to realize this experiment.
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.
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}}$.
Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given ...the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the "neutrino floor" (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events. Modeling results are presented for the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). The results show that such a detector could measure the CNO neutrino rate with ~15% precision, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector.
This paper describes the design, fabrication, commissioning and use of a CALibration source Insertion System (CALIS) in the DarkSide-50 direct dark matter search experiment. CALIS deploys radioactive ...sources into the liquid scintillator veto to characterize the detector response and detection efficiency of the DarkSide-50 Liquid Argon Time Projection Chamber, and the surrounding 30 t organic liquid scintillator neutron veto. It was commissioned in September 2014 and has been used successfully in several gamma and neutron source campaigns since then. A description of the hardware and an excerpt of calibration analysis results are given below.
The Sun is fueled by a series of nuclear reactions that produce the energy that makes it shine. The primary reaction is the fusion of two protons into a deuteron, a positron and a neutrino. These ...neutrinos constitute the vast majority of neutrinos reaching Earth, providing us with key information about what goes on at the core of our star. Several experiments have now confirmed the observation of neutrino oscillations by detecting neutrinos from secondary nuclear processes in the Sun; this is the first direct spectral measurement of the neutrinos from the keystone proton-proton fusion. This observation is a crucial step towards the completion of the spectroscopy of pp-chain neutrinos, as well as further validation of the LMA-MSW model of neutrino oscillations.
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