Prospects of the search for neutrino bursts from supernovae with Baksan large volume scintillation detector

Observing a high-statistics neutrino signal from the supernova explosions in the Galaxy is a major goal of low-energy neutrino astronomy. The prospects for detecting all flavors of neutrinos and antineutrinos from the core-collapse supernova (ccSN) in operating and forthcoming large liquid scintillation detectors (LLSD) are widely discussed now. One of proposed LLSD is Baksan Large Volume Scintillation Detector (BLVSD). This detector will be installed at the Baksan Neutrino Observatory (BNO) of the Institute for Nuclear Research, Russian Academy of Sciences, at a depth of 4800 m.w.e. Low-energy neutrino astronomy is one of the main lines of research of the BLVSD.     

Search for low-energy neutrino radiation accompanying gamma-ray bursts on the Baksan subterranean scintillation telescope

An analysis aimed at finding possible neutrino radiation accompanying gamma-ray bursts in a 24-h period about them is performed on the basis of the data in the 4B BATSE Gamma-Ray Burst Catalog and data from the Baksan scintillation telescope according to a program for finding neutrinos from collapsing stars. Values significantly exceeding the background are not discovered. A lower bound for the distance to the source is established under the assumption that the anticipated radiation has characteristics similar to the characteristics of collapse neutrinos. It attests to the cosmological origin of gamma-ray bursts with a high degree of probability. Zh. éksp. Teor. Fiz. 114, 1921–1929 (December 1998)     

Twenty years of Galactic observations in searching for bursts of collapse neutrinos with the Baksan underground scintillation telescope

The results of twenty-year-long Galactic observations in neutrino radiation are summarized. Except for the recording of a neutrino signal from the supernova SN 1987A, no Galactic bursts of collapse neutrinos have been detected. An upper bound on the mean frequency of gravitational collapses in our Galaxy was obtained, f _collapse (at 90% confidence) <0.13 yr^?1.     

The search for neutrino bursts from core collapse Supernovae at the Baksan Underground Scintillation Telescope

The current status of the experiment on recording neutrino bursts from core collapse stars is presented. The actual observational time T (from June 30, 1980 until December 31, 2009) is 25.58 years. An upper bound of the mean frequency of gravitational collapse in our Galaxy f _col < 0.090 year^?1 at a 90% confidence level. The results of studying single events at the facility in the case of muon inelastic interaction of cosmic rays with the matter of the detector are presented.     

Neutron flux measurement using activated radioactive isotopes at the Baksan underground scintillation telescope

Preliminary results of a neutron background measurement at the Baksan underground scintillation telescope (BUST) are presented. The external planes of the BUST are fully covered with standard scintillation detectors shielding the internal planes and suppressing thus background events due to cosmogenic and local radioactivity. The shielded internal planes were used as target for the neutron flux registration. The experimental method is based on the delayed coincidences between signals from any of the BUST counters. It is assumed that the first signal is due to inelastic interaction of a neutron with the organic scintillator, while the second signal comes from the decay of an unstable radioactive isotope formed when the fast neutron interacts with the ¹²C nuclei. Using the Monte-Carlo method (GEANT4) we also simulated propagation of neutrons through a layer of scintillator. The experimentally found muon induced neutron flux is j =1.3_-0.3^+0.7 ×10^-10cm^-2s^-1 for neutron energies E ≥ 22MeV, which is in a qualitative agreement with similar measurements of other underground laboratories as well as with predictions of the GEANT4.     

Investigation of the spectrum of high-energy muons by the method of multiple interactions on the basis of data from the Baksan underground scintillation telescope

Experimental data obtained with the aid of the Baksan underground scintillation telescope over a long period of its operation are analyzed with the aim of searches for an excess flux of ultrahigh-energy (≥100 TeV)muons. The multiple-interaction method, which is based on the ideas of the pair-meter technique, is used to analyze the energy spectrum of the muons. The phenomenological parameters of this method and its sensitivity to the shape of the spectrum are discussed. The experimental distributions are compared with the results of calculations for various versions of the muon spectrum. The possibility of separating ultrahigh-energy muons that fly in the vicinity of the axis of extensive air showers is assessed on the basis of the integrated number of recorded and simulated events featuring large energy depositions.     

High energy neutrinos from gamma-ray bursts with precursor supernovae

The high energy neutrino signature from proton-proton and photo-meson interactions in a supernova remnant shell ejected prior to a gamma-ray burst provides a test for the precursor supernova, or supranova, model of gamma-ray bursts. Protons in the supernova remnant shell and photons entrapped from a supernova explosion or a pulsar wind from a fast-rotating neutron star remnant provide ample targets for protons escaping the internal shocks of the gamma-ray burst to interact and produce high energy neutrinos. We calculate the expected neutrino fluxes, which can be detected by current and future experiments.     

Search for neutrino emission from supernovae using the Large Volume Detector

The basic task of the Large Volume Detector LVD situated at the underground Gran Sasso National Laboratory (Italy) is the search for neutrino bursts from gravitational stellar collapses in our Galaxy. At present, the algorithm for determining neutrino bursts has been developed. It is based on the identification of event clusters in fixed time intervals, special attention is paid not only to the inverse β decay reaction which has a characteristic signature, but also to the neutrino-iron interaction. The data for of 3.5 years of LVD operation have been processed. No candidates for neutrino bursts are found.     

Search for neutrino radiation from collapsing stars with the Artyomovsk scintillation detector

The current status of an experiment designed to search for neutrino radiation from collapsing stars using the Artyomovsk Liquid Scintillation Detector is described. Observations were conducted from November 1977 to July 2012. The upper limit for the mean rate at which neutrino bursts occur in the Galaxy is found to be f _col < 0.0658 events per year at a 90% confidence level. In 35 years of observations, no supernovae were detected in the Galaxy.     

Data acquisition system for the Baikal-GVD neutrino telescope

The objective of the Baikal-GVD project is the construction of a km³-scale neutrino telescope in Lake Baikal. The Gigaton Volume Detector consists of a large three-dimensional array of photo-multiplier tubes. The first GVD-cluster has been deployed and commissioned in April 2015. The data acquisition system (DAQ) of the detector takes care of the digitization of the photo-multiplier tube signals, data transmission, filtering and storage. The design and the implementation of the data acquisition system are described.     

A search for neutrino oscillations

We present here the final results of experiments searching for neutrino oscillations, carried out by the CHARM Collaboration. The data — taking took place in 1983. The first experiment was performed by exposing two detectors simultaneously to the CERN PS low energyv _µ beam. In the second experiment the full CHARM detector was exposed to the wide-band horn-focusedv _µ beam of the CERN SPS. Complete details of the experiments and data reduction are presented. No statistically significant signals for neutrino oscillations were observed. Our 90% CL limits in the appearance experiment (v _µ→v _e ) exclude Δm ²≧0.19 eV² for complete mixing (sin²2θ=1), and sin²2θ≧0.008 for the region Δm ²≧30 eV². These results, and the limits observed for (v _µ→v _x ) (disappearance of (v _µ), are in agreement with those of most other experiments but exclude part of the region previously reported as a possible indication ofv _µ→v _e oscillations.     

Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.     

A search for heavy neutrino decays in a neutrino beam

A search has been made for the decays of heavy (≈200–500 MeV/c²) neutrinos, ν_H→νμe, in a 23 m long detector, in the wide-band neutrino beam at the Brookhaven AGS. No significant excess of such events was found and limits are set on the neutrino mixing matrix elements, |U_eH|² and |U_μH|². Results of a more general search for anomalous μe events are also reported.     

The search for different neutrino flavors from collapsing stars using the LVD detector

The main goal of the Large Volume Detector (LVD) is to search for neutrino burst from gravitational stellar collapses in our Galaxy. The apparatus is shown to be able to register stellar collapse even if there is none of the antineutrino emission specific to the standard scenario. The data from more than nine years of detector operation have been processed, and no candidate events for neutrino bursts have been detected. This implies the existence of an experimental limit to the galactic stellar collapse rate in those cases where collapse is not accompanied by electron antineutrino emission: less than one event per 4.1 yr at the 90% confidence level.     

Experimental search for gamma-ray bursts from evaporating primordial black holes

The energy spectra and temporal characteristics of high-energy gamma-ray bursts from evaporating primordial black holes have been calculated using various evaporation models. The currently existing theoretical uncertainties in the shape of the evaporated photon spectrum are discussed. The data from the Andyrchy and Carpet-2 arrays of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) obtained in the mode of detection of a single cosmic-ray component are used to search for cosmic gamma-ray bursts with a primary photon energy of about 8 GeV. New upper limits have been obtained for the number density of evaporating black holes in a local region of space with a characteristic size of ～10^?3 pc for various evaporation models.     

New limits on radiative sterile neutrino decays from a search for single photons in neutrino interactions

It has been recently shown that excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino _νh${\nu }_h$ produced in _νμ${\nu }_{\mu }$ neutral-current-like neutrino interactions. If the _νh${\nu }_h$ exist, it would be also produced by the _νμ${\nu }_{\mu }$ beam from the CERN SPS in the neutrino beam line shielding. The _νh${\nu }_h$?s would penetrate the shielding and be observed through the _νh→γν${\nu }_h\to \gamma \nu$ decay followed by the photon conversion into e⁺e⁻$e^{+}{e}^{-}$ pair in the active target of the NOMAD detector. The _νh${\nu }_h$?s could be also produced in the iron of the magnetic spectrometer of the CHORUS detector, located just in front of NOMAD. Considering these two sources of _νh${\nu }_h$?s we set new constraints on _νh${\nu }_h$ properties and exclude part of the LSND/MiniBooNE _νh${\nu }_h$ parameter space using bounds on single photons production in neutrino reactions recently reported by the NOMAD Collaboration. We find that broad bands in the parameter space are still open for more sensitive searches for the _νh${\nu }_h$ in future neutrino experiments.     

A search for high-energy cosmic gamma-ray bursts

Summary A search has been made for excesses of cosmic-ray counting rates at primary energiesE ₀₁>5 GeV andE ₀₄>2·10⁴ GeV over the time scalet=(1÷100) ms. The measurement was performed by means of a small extensive air shower array operating at mountain altitude (3500 m a.s.l.). During the running time 111 cosmic gamma-ray bursts were detected by satellites; 10 of them certainly (55 probably) above the horizon of the detector. No significant counting rate excess has been recorded out of the statistical fluctuations. Also the search for correlations with satellite events has given a negative result. The upper limit for high-energy cosmic gamma-ray flux in bursts isϕ ₁(E>E ₀₁)<4·10⁻⁵ (t = time scale in ms),ϕ ₄(E>E ₀₄)<1.6·10⁻⁵erg/cm². Paper presented at the 2^o Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.     

High energy neutrino flashes from far-ultraviolet and x-ray flares in gamma-ray bursts

The recent observations of bright optical and x-ray flares by the Swift satellite suggest these are produced by the late activities of the central engine. We study the neutrino emission from far-ultraviolet and x-ray flares under the late internal shock model. We show that the efficiency of pion production in the highest energy is comparable to or higher than the unity, and the contribution from such neutrino flashes to a diffuse very high energy neutrino background can be larger than that of prompt bursts if the total baryonic energy input into flares is comparable to the radiated energy of prompt bursts. These signals may be detected by IceCube and are very important because they have possibilities to probe the nature of flares (the baryon loading, the photon field, the magnetic field and so on).     

Search for neutrino bursts from collapsing stars on the basis of the BUST till 2006

Search for neutrino bursts from collapsing stars with the Baksan underground scintillation telescope has been carried out since 1980. In this study, the experimental data obtained during the period from 2001 to 2005 inclusive are analyzed. The upper limit of the mean frequency of collapses in the Galaxy over the entire period of observations (the total live time is 21.83 yr) was found to be 0.105 yr^?1.     

High-energy neutrino astronomy with ?small? underground detectors

Summary High-energy (E _ν>(10÷30) GeV) neutrino sources which can be detected by underground detectors with areaS∼100 m² are discussed in this paper. It is shown that the horizon of these detectors is limited to our Galaxy. The main process to detect neutrino sources,i.e. production of high-energy muons in ν_μ N → μX scattering is studied in detail. Single sources (young supernova shells and supergiants fed by an active pulsar) and binary sources (young pulsar and giant, supernova explosion in a binary system, etc. …) are found to be able to produce a detectable neutrino flux. Special attention is given to Cyg X-3. Finally, it is shown that the possibility to detect neutrinos from solar flares on the opposite side of the Sun can be ruled out on the grounds of γ-rays observations.

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Riassunto Si discutono in questo lavoro le sorgenti di neutrini di alta energia (E _ν>(10÷30) GeV) che possono essere rivelate con rivelatori sotterranei di areaS∼100 m². Si mostra come l'orizzonte di questi rivelatori sia limitato alla nostra Galassia. Il processo principale di rivelazione di sorgenti cosmiche di neutrini, cioè la produzione di muoni di alta energia attraverso lo scattering ν_μ N → μX, è discusso in dettaglio. Si ottiene che sorgenti singole (gusci di suprenovae giovani e supergiganti con una pulsar attiva al loro interno) e sorgenti binarie (pulsar giovane e stella gigante, esplosione supernova in un sistema binario, ecc.…) sono in grado di produrre un flusso di neutrini rivelabili a Terra con rivelatori di piccole dimensioni. Si discute in particolare il sistema Cyg X-3. Infine, si dimostra che la possibilità di rivelare neutrini da flares solari sulla superficie del Sole opposta alla Terra deve essere scartata sulla base delle osservazioni di raggi γ.

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Резюме В этой статье обсуждаются источники нейтрино высоких энергий (E _ν>(10÷30) ГэВ), которые могут быть зарегистрированы с помощью подземных детекторов с площадьюS∼100 м². Показывается, что горизонт этих детекторов ограничен нашей Галактикой. Подробно исследуется основной процесс детектирования нейтринных источников, т.е. образование высокоэнергетичных мюонов при рассеянии ν_μ N → μX. Получено, что изолированные источники (оболочки молодых сверхновых и супергиганты с активным пульсаром внутри) и бинарные источники (молодой пульсар и гигант, взрыв сверхновой в бинарной системе и т.д.) могут генерировать детектируемые потоки нейтрино. Особое внимание уделяется источнику Лебедь X-3. В заключение, показывается, что возможность детектирования нейтрино от солнечных вспышек на противоположной Солнца должна быть исключена на основе наблюдений γ-лучей.