Solar and geoneutrinos Ludhova, L; Agostini, M; Altenmüller, K ...
Journal of physics. Conference series,
12/2021, Letnik:
2156, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
Thanks to the progress of neutrino physics, today we are able of exploiting neutrinos as a tool to study astrophysical objects. The latter in turn serve as unique sources of elusive ...neutrinos, which fundamental properties are still to be understood. This contribution attempts to summarize the latest results obtained by measuring neutrinos emitted from the Sun and geoneutrinos produced in radioactive decays inside the Earth, with a particular focus on a recent discovery of the CNO-cycle solar neutrinos by Borexino. Comprehensive measurement of the
pp
-chain solar neutrinos and the first directional detection of sub-MeV solar neutrinos by Borexino, the updated
8
B solar neutrino results of Super-Kamiokande, as well as the latest Borexino and KamLAND geoneutrino measurements are also discussed.
We have measured the speed of muon neutrinos with the Borexino detector using short-bunch CNGS beams. The final result for the difference in time-of-flight between an 〈E〉=17 GeV muon neutrino and a ...particle moving at the speed of light in vacuum is δt=0.8±0.7stat±2.9sys ns, well consistent with zero.
The DarkSide-50 experiment at the Laboratori Nazionali del Gran Sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. Light ...signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (PMTs), 19 above and 19 below the TPC volume inside the argon cryostat. We describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. The electronics include resistive voltage dividers on the PMTs, custom pre-amplifiers mounted directly on the PMT voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). After amplification, the PMT signals are digitized in CAEN waveform digitizers, and CAEN logic modules are used to construct the trigger; the data acquisition system for the TPC is based on the Fermilab artdaq software. The system has been in operation since early 2014.
Borexino is a 300 ton sub-MeV liquid scintillator solar neutrino detector which has been running at the Laboratori Nazionali del Gran Sasso (Italy) since 2007. Thanks to its unprecedented ...radio-purity, it was able to measure the flux of 7Be, 8B, pp, and pep solar neutrinos and to detect geo-neutrinos. A reliable simulation of the detector is an invaluable tool for all Borexino physics analyses. The simulation accounts for the energy loss of particles in all the detector components, the generation of the scintillation photons, their propagation within the liquid scintillator volume, and a detailed simulation of the electronics chain. A novel efficient method for simulating the external background which survives the Borexino passive shield was developed. This technique allows to reliably predict the effect of the contamination in the peripheral construction materials. The techniques developed to simulate the Borexino detector and their level of refinement are of possible interest to the neutrino and dark matter communities, especially for current and future large-volume liquid scintillator experiments.
The cosmic silence of the underground Gran Sasso laboratory together with the exceptional radio purity of the liquid scintillator, has allowed Borexino to investigate the radiogenic heating of the ...Earth’s interior and to contribute to various fields of experimental neutrino astronomy. This contribution is aimed to summarize the results obtained by Borexino on geo-neutrinos and on possible extra-terrestrial sources of antineutrinos such as supernovae explosions and solar flares.
Stars are fuelled by the fusion of hydrogen into helium via two processes: the ‘‘
pp
chain’’ and the ‘‘CNO cycle.’’ Neutrinos emitted in the core of the Sun are the only direct probe for the ...investigation of such processes. The Borexino experiment has performed a complete spectroscopy of the neutrinos from the ‘‘
pp
chain,’’ and has recently reported the first experimental evidence of neutrinos from the CNO cycle, never observed before, being this process subdominant in the Sun (about 1% of the solar energy). This experimental evidence of the CNO neutrinos was obtained using the highly radiopure large-volume liquid-scintillator detector of Borexino. Advances in the thermal stabilization of the detector over the last five years enabled us to exploit a method to constrain the rate of Bi-210 contaminating the scintillator, the main background for such a measurement. Since the CNO cycle is dominant in massive starts, this result proves the evidence of the primary mechanism for the stellar conversion of hydrogen into helium in the Universe.
Borexino, a real-time device for low energy neutrino spectroscopy is nearing completion of construction in the underground laboratories at Gran Sasso, Italy (LNGS). The experiment's goal is the ...direct measurement of the flux of
7
Be solar neutrinos of all flavors via neutrino–electron scattering in an ultra-pure scintillation liquid. Seeded by a series of innovations which were brought to fruition by large-scale operation of a 4-ton test detector at LNGS, a new technology has been developed for Borexino. It enables sub-MeV solar neutrino spectroscopy for the first time. This paper describes the design of Borexino, the various facilities essential to its operation, its spectroscopic and background suppression capabilities and a prognosis of the impact of its results towards resolving the solar neutrino problem. Borexino will also address several other frontier questions in particle physics, astrophysics and geophysics.
DarkSide search for dark matter Alexander, T; Alton, D; Arisaka, K ...
Journal of Instrumentation,
11/2013, Letnik:
8, Številka:
11
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The DarkSide staged program utilizes a two-phase time projection chamber (TPC) with liquid argon as the target material for the scattering of dark matter particles. Efficient background reduction is ...achieved using low radioactivity underground argon as well as several experimental handles such as pulse shape, ratio of ionization over scintillation signal, 3D event reconstruction, and active neutron and muon vetos. The DarkSide-10 prototype detector has proven high scintillation light yield, which is a particularly important parameter as it sets the energy threshold for the pulse shape discrimination technique. The DarkSide-50 detector system, currently in commissioning phase at the Gran Sasso Underground Laboratory, will reach a sensitivity to dark matter spin-independent scattering cross section of 10 super(-45) cm super(2) within 3 years of operation.
Despite the fact that the electric charge conservation law is confirmed by many experiments, search for its possible violation remains a way of searching for physics beyond the Standard Model. ...Experimental searches for the electric charge non-conservation mainly consider electron decays into neutral particles. The Borexino experiment is an excellent tool for the electron decay search due to the highest radiopurity among all the existing experiments, large detector mass, and good sensitivity at low energies. The process considered in this study is a decay into a photon and a neutrino, for which a new lower limit on the electron lifetime is obtained. This is the best electron lifetime limit up to date, exceeding the previous one obtained at the Borexino prototype at two orders of magnitude.
Rare event search experiments, such as those searching for dark matter and observations of neutrinoless double beta decay, require ultra low levels of radioactive background for unmistakable ...identification. In order to reduce the radioactive background of detectors used in these types of event searches, low background photosensors are required, as the physical size of these detectors become increasing larger, and hence the number of such photosensors used also increases rapidly. Considering that most dark matter and neutrinoless double beta decay experiments are turning towards using noble liquids as the target choice, liquid xenon and liquid argon for instance, photosensors that can work well at cryogenic temperatures are required, 165 K and 87 K for liquid xenon and liquid argon, respectively. The Silicon Geiger Hybrid Tube (SiGHT) is a novel photosensor designed specifically for use in ultra low background experiments operating at cryogenic temperatures. It is based on the proven photocathode plus silicon photomultiplier (SiPM) hybrid technology and consists of very few other, but also ultra radio-pure, materials like fused silica and silicon for the SiPM. The introduction of the SiGHT concept, as well as a feasibility study for its production, is reported in this paper.
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