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Bonfini, G.

Publications and source records attributed to Bonfini, G..

33 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

The DarkSide experiment: Present status and future

Here, 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 cm 2 (for a WIMP mass of 100 GeV/c 2 ). Presently the detector is filled with Underground Argon, which is depleted in 39 Ar by a factor of (1.4 ± 0.2)×10 3 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 cm 2 for a WIMP mass of 100 GeV/c 2 . Up to date this is the best limit obtained with an argon target.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

The DarkSide-50 Experiment: a Liquid Argon Target for Dark Matter Particles

The DarkSide-50 experiment, located at the “Laboratori Nazionali del Gran Sasso (INFN)”, is based on low-radioactivity argon double phase time projection chamber, surrounded by an active liquid scintillator veto, designed for the zero background achievement. The liquid argon features sufficient self shielding and easy scalability to multi-tons scale. The impressive reduction of the 39 Ar isotope (compared to the atmospheric argon), along with the excellent pulse shape discrimination, make this technology a possible candidate for the forthcoming generation of multi-ton Dark Matter experiments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

The search for sterile neutrinos with SOX-Borexino

The aim of the SOX-Borexino project is to verify or falsify the existence of eV-scale sterile neutrinos. The existence of sterile neutrinos is suspected because of several anomalies, which were observed in previous experiments. A ~3.7 PBq electron antineutrino source made of {sup 144}Ce will be installed below the Borexino detector at LNGS, Italy, to search for short-baseline oscillations of active-to-sterile neutrinos within the detector volume. Source delivery and beginning of data acquisition is planned for end of 2016, preliminary results are expected already in 2017.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

The electronics and data acquisition system for the DarkSide-50 veto detectors

DarkSide-50 is a detector for dark matter candidates in the form of weakly interacting massive particles. It utilizes a liquid argon time projection chamber for the inner main detector, surrounded by a liquid scintillator veto (LSV) and a water Cherenkov veto detector (WCV). The LSV and WCV act as the neutron and cosmogenic muon veto detectors for DarkSide-50. This paper describes the electronics and data acquisition system used for these two detectors. The system is made of a custom built front end electronics and commercial National Instruments high speed digitizers. The front end electronics, the DAQ, and the trigger system have been used to acquire data in the form of zero-suppressed waveform samples from the 110 PMTs of the LSV and the 80 PMTs of the WCV. The veto DAQ system has proven its performance and reliability. This electronics and DAQ system can be scaled and used as it is for the veto of the next generation DarkSide-20k detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Current Status of the dark matter experiment DarkSide-50

DarkSide-50 is a dark matter direct search experiment at LNGS, searching for rare nuclear recoils possibly induced by WIMPs. It has two nested vetoes and a dual phase liquid argon TPC as dark matter detector. Key features of this experiment are the use of underground argon as radio-pure target and of muon and neutron active vetoes to suppress the background. The first data-taking campaign was running from November 2013 to April 2015 with an atmospheric argon target and a reduced efficiency neutron veto due to internal contamination. However, an upper limit on the WIMP-nucleon cross section of 6.1×10 -44 cm 2 at 90% CL was obtained for a WIMP mass of 100 GeV/c 2 and an exposure of (1422 ± 67) kg·d. At present DarkSide-50 started a 3 years run, intended to be background-free because the neutron veto was successfully recovered and underground argon replaced the atmospheric one. Additionally calibration campaigns for both the TPC and the neutron veto were completed. Thanks to the good performance of the background rejection, the results obtained so far suggest the scalability of DarkSide-50 to a ton-scale detector, which will play a key role into the dark matter search scenario.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

The DarkSide awakens

Here, 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 39 Ar 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 39 Ar by a factor (1.4 ± 0.2) × 10 3 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.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

A first walk on the DarkSide

DarkSide-50 (DS-50) at Gran Sasso underground laboratory (LNGS), Italy, is a direct dark matter search experiment based on a TPC with liquid argon. DS-50 has completed its first dark matter run using atmospheric argon as target. Here, the DS-50 detector performances and the results of the first physics run are reviewed in this proceeding.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Results From the First Use of Low Radioactivity Argon in a Dark Matter Search

Liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. The DarkSide-50 dark matter search here reports the first WIMP search results obtained using a target of low-radioactivity argon. DarkSide-50 is a dark matter detector, using a two-phase liquid argon time projection chamber, located at the Laboratori Nazionali del Gran Sasso. The underground argon is shown to contain Ar39 at a level reduced by a factor (1.4±0.2)×103 relative to atmospheric argon. We report a background-free null result from (2616±43) kg d of data, accumulated over 70.9 live days. When combined with our previous search using an atmospheric argon, the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section, based on zero events found in the WIMP search regions, is 2.0×10-44 cm2 (8.6×10-44 cm2, 8.0×10-43 cm2) for a WIMP mass of 100 GeV/c2 (1 TeV/c2, 10 TeV/c2).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

The veto system of the DarkSide-50 experiment

Nuclear recoil events produced by neutron scatters form one of the most important classes of background in WIMP direct detection experiments, as they may produce nuclear recoils that look exactly like WIMP interactions. In DarkSide-50, we both actively suppress and measure the rate of neutron-induced background events using our neutron veto, composed of a boron-loaded liquid scintillator detector within a water Cherenkov detector. This paper is devoted to the description of the neutron veto system of DarkSide-50, including the detector structure, the fundamentals of event reconstruction and data analysis, and basic performance parameters.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

The DarkSide project

DarkSide is a graded experimental project based on radiopure argon, and is now, and will be, used in direct dark matter searches. The present DarkSide-50 detector, operating at the Gran Sasso National Laboratory, is a dual-phase, 50 kg, liquid argon time-projection-chamber surrounded by an active liquid scintillator veto. It is designed to be background free in 3 years of operation. DS-50 performances, when filled with atmospheric argon, are reported. However DS-50 filled with underground argon, shows impressive reduction of the 39Ar isotope. The application of this powerful technology in a future generation of the DarkSide program is discussed.

Agnes, P.↗
DOE OSTI2015

Neutrino measurements from the Sun and Earth: Results from Borexino

Important neutrino results came recently from Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprecedented radiopurity levels achieved in the core of the detection medium, it is the only experiment in operation able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. The recently achieved breakthrough observation of the fundamental pp flux, the precise measurement of the {sup 7}Be solar neutrino flux, and the results concerning the pep, {sup 8}B and CNO fluxes, together with their physics implications, are described in this work. Moreover, the detector has also provided a clean detection of terrestrial neutrinos, from which they emerge as a new probe of the interior of the Earth.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Geo-neutrinos and Borexino

Geo-neutrinos, electron anti-neutrinos produced in β-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet’s interior. After a brief introduction about the Earth, the geo-neutrinos’ properties and the main aims of their study are discussed. An overview of the latest experimental results obtained by the Borexino collaboration is provided, followed by a short overview of future perspectives of this new inter-disciplinary field.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Solar neutrino with Borexino: Results and perspectives

Borexino is a unique detector able to perform measurement of solar neutrinos fluxes in the energy region around 1 MeV or below due to its low level of radioactive background. It was constructed at the LNGS underground laboratory with a goal of solar {sup 7}Be neutrino flux measurement with 5% precision. The goal has been successfully achieved marking the end of the first stage of the experiment. A number of other important measurements of solar neutrino fluxes have been performed during the first stage. Recently the collaboration conducted successful liquid scintillator repurification campaign aiming to reduce main contaminants in the sub-MeV energy range. With the new levels of radiopurity Borexino can improve existing and challenge a number of new measurements including: improvement of the results on the Solar and terrestrial neutrino fluxes measurements; measurement of pp and CNO solar neutrino fluxes; search for non-standard interactions of neutrino; study of the neutrino oscillations on the short baseline with an artificial neutrino source (search for sterile neutrino) in context of SOX project.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

The DarkSide Multiton Detector for the Direct Dark Matter Search

A wide range of astronomical evidence implies the existence of Dark Matter, but as yet the nature of this major component of the Universe is completely unknown. A leading candidate explanation is that Dark Matter is composed of Weakly Interacting Massive Particles (WIMPs) formed in the early universe and gravitationally clustered together with the standard baryonic matter. Such WIMPs could in principle be detected through their collisions with ordinary nuclei in a sensitive target, producing observable low-energy (<100 keV) nuclear recoils. The predicted collision rates are very low and require ultra-low background detectors with large (0.1 { 10 tons) target masses, located in deep underground sites to reduce the background produced by neutrons from cosmic ray muons [1{4].

Dark Matter↗