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.     

On the possibilities of studying supernova neutrinos at Baksan

We consider the possibilities of studying a supernova collapse neutrino burst at Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) using the proposed 5-kt target-mass liquid scintillation spectrometer. Attention is given to the influence of mixing angle ? ₁₃ on the expected rates and spectra of neutrino events.     

Searching for Neutrino and Ultra-High-Energy Gamma-Ray Counterparts of the GCN Alerts

Physics of Atomic Nuclei - The Baksan Neutrino Observatory setups are currently performing search for neutrino and ultra-high-energy gamma-ray counterparts of the events on the Gamma-ray...     

Neutrino geophysics at Baksan I: Possible detection of georeactor antineutrinos

J.M. Herndon in the 1990s proposed a natural nuclear fission georeactor at the center of the Earth with a power output of 3–10 TW as an energy source to sustain the Earth magnetic field. R. S. Raghavan in 2002 pointed out that, under certain conditions, antineutrinos generated in such a georeactor can be detected using massive scintillation detectors. We consider the underground Baksan Neutrino Observatory (4800 m.w.e.) as a possible site for developments in geoneutrino physics. Here, the intrinsic background level of less than 1 event/yr in a liquid scintillation ～1000-t target detector can be achieved and the main source of background is the antineutrino flux from power reactors. We find that this flux is ～10 times lower than at the KamLAND detector site and two times lower than at the Gran Sasso laboratory and thus at Baksan the georeactor hypothesis can be conclusively tested. We also discuss possible searches for the composition of georeactor burning nuclear fuel by analysis of the antineutrino energy spectrum.     

Atmospheric neutrino flux at INO,South Pole and Pyhäsalmi

We present the calculation of the atmospheric neutrino fluxes for the neutrino experiments proposed at INO, South Pole and Pyhäsalmi. Neutrino fluxes have been obtained using ATMNC, a simulation code for cosmic ray in the atmosphere. Even using the same primary flux model and the interaction model, the calculated atmospheric neutrino fluxes are different for the different sites due to the geomagnetic field. The prediction of these fluxes in the present Letter would be quite useful in the experimental analysis.     

Simulation of natural radioactivity backgrounds in the JUNO central detector

The Jiangmen Underground Neutrino Observatory(JUNO) is an experiment proposed to determine the neutrino mass hierarchy and probe the fundamental properties of neutrino oscillation.The JUNO central detector is a spherical liquid scintillator detector with 20 kton fiducial mass.It is required to achieve a 3%/E(MeV)~(1/2) energy resolution with very low radioactive background,which is a big challenge to the detector design.In order to ensure the detector performance can meet the physics requirements,reliable detector simulation is necessary to provide useful information for the detector design.A simulation study of natural radioactivity backgrounds in the JUNO central detector has been performed to guide the detector design and set requirements for the radio-purity of the detector materials.The accidental background induced by natural radioactivity in the JUNO central detector is 1.1/day.The result is satisfied for the experiment.     

Modernization and Methods of Maintaining the Operating Mode of the OGRAN (Optoacoustic Gravity Antenna) Setup

Physics of Atomic Nuclei - An upgraded version of the combined optoacoustic gravitational radiation detector OGRAN is considered. This underground setup located at the Baksan Neutrino Observatory...     

ORLANDO - Oak Ridge large neutrino detector

We discuss a proposal for construction of an Oak Ridge LArge Neutrino DetectOr (ORLANDO) to search for neutrino oscillations at the Spallation Neutron Source (SNS). A 4 MW SNS is proposed to be built at the Oak Ridge National Laboratory with the first stage to be operative around 2006. It will have two target stations, which makes it possible with a single detector to perform a neutrino oscillation search at two different distances. Initial plans for the placement of the detector and the discovery potential of such a detector are discussed.     

ORLaND_— Oak Ridge Laboratory for Neutrino Detectors

The proposed Oak Ridge Laboratory for Neutrino Detectors (ORLaND), to be located adjacent to the Spallation Neutron Source (SNS), is described. ORLaND will take advantage of the fact that the SNS will be the world’s best intermediate-energy pulsed neutrino source in the world. A broad range of neutrino measurements is contemplated by means of a number of detectors, including the large CoNDOR detector. Specifics of neutrino oscillation investigations, and of the possible impact of certain neutrino measurements on our understanding of supernova explosions, are discussed.     

Pulsations of the geomagnetic field associated with variations in cosmic ray intensity during thunderstorms

It was discovered that strong variations in the intensity of secondary cosmic rays observed during thunderstorms and earlier interpreted as a consequence of the cyclic generation of electrons and positrons in a strong electric field are accompanied in some cases by well-pronounced pulsations of the geomagnetic field. An experiment was performed with the CARPET array for studying extensive air showers of cosmic rays. This array, located in the Baksan Valley (North Caucasus), was used as a particle detector. Magnetic measurements were made using a high-precision magnetic variation station located deep underground in a tunnel of the Baksan Neutrino Observatory at a distance of about 4 km from the CARPET array.     

Measurement of the activity of an artificial neutrino source based on 37Ar

The activity of an artificial neutrino source based on ³⁷Ar was measured by a specially developed method of directly counting ³⁷Ar decays in a proportional counter. This source was used to irradiate the target of the SAGE radiochemical gallium—germanium neutrino telescope at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences, Moscow), whereupon the measurements were performed at the Institute of Reactor Materials (Zarechny, Sverdlovsk oblast, Russia). The method used to prepare gaseous samples for measurements in proportional counters and the counting procedure are described. The measured activity of the ³⁷Ar neutrino source is 405.1 ± 3.7 kCi (corrected for decays that occurred within the period between the instant of activity measurement and the commencement of the irradiation of Ga target at 04:00 Moscow time, 30.04.2004).     

Progress in neutrino oscillation searches and their implications

Neutrino oscillation, in which a given flavor of neutrino transforms into another is a powerful tool for probing small neutrino masses. The intrinsic neutrino properties involved are neutrino mass squared difference Δm ² and the mixing angle in vacuum θ. In this paper I will summarize the progress that we have achieved in our search for neutrino oscillation with special emphasis on the recent results from the Sudbury Neutrino Observatory (SNO) on the measurement of solar neutrino fluxes. I will outline the current bounds on the neutrino masses and mixing parameters and discuss the major physics goals of future neutrino experiments in the context of the present picture.     

Measurement of gamow-teller strength for 176Yb --> 176Lu and the efficiency of a solar neutrino detector

We report a 0 degrees 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine Gamow-Teller (GT) matrix elements relative to the model independent Fermi matrix element. The data show that there is an isolated concentration of GT strength in the low-lying 1(+) states making the proposed Low Energy Neutrino Spectroscopy detector (based on neutrino captures on 176Yb) sensitive to pp and 7Be neutrinos and a promising detector to resolve the solar neutrino problem.     

Investigating hadronic cores of exstensive air showers at the CARPET-2 array

Characteristics of the hadronic component of exstensive air shower (EAS) trunks are investigated at the CARPET-2 array of the Baksan Neutrino Observatory, Institute for Nuclear Research, Russian Academy of Sciences. In this work, we study showers with axes that located within its muon detector (MD). We discuss the procedure for selecting such showers in our experiment. The relationship between the number of thermal neutrons detected by heat detectors installed in the muon detector’s tunnel and the total energy of a cascade generated by hadrons in the magnetic detector’s absorbent matter is presented.     

Neutrino geophysics and astronomy at Baksan Neutrino Observatory: Potential of the spectroscopy of natural antineutrino sources

Prospects for studying, at the Baksan Neutrino Observatory, geoneutrinos, as well as neutrinos from supernovae, by means of a scintillation spectrometer having a target mass of 5000 t are considered. It is shown that the geographical location, a deep position (4800 mwe), and a modest background of antineutrinos from nuclear reactors makes the Baksan Neutrino Observatory one of the best places for performing such investigations. Particular attention is given to the derivation of information about the nature of neutrinos, the possibility of detecting relic neutrinos from supernovae, and the discovery of a hypothetical georeactor.     

Technique for direct eV-scale measurements of the Mu and tau neutrino masses using supernova neutrinos

Early black hole formation in a core-collapse supernova will abruptly truncate the neutrino fluxes. The sharp cutoff can be used to make model-independent time-of-flight neutrino mass tests. Assuming a neutrino luminosity of 10(52) erg/s per flavor at cutoff and a distance of 10 kpc, Super-Kamiokande can detect an electron neutrino mass as small as 1.8 eV, and the proposed OMNIS detector can detect mu and tau neutrino masses as small as 6 eV. We present the first technique with direct sensitivity to eV-scale mu and tau neutrino masses.     

Search for Electron Neutrinos from Gravitational Wave Events at the Baksan Underground Scintillation Telescope

In the data obtained at the Baksan underground scintillation telescope (BUST), electron neutrinos and antineutrinos with energies above 21 MeV have been sought in coincidence with the GW150914, GW151226, GW170104, GW170608, GW170814, and GW170817 gravitational wave events. No neutrino signals from gravitational wave events have been detected in the interval of ±500 s at the Baksan underground scintillation telescope. Bounds on the fluxes of low-energy electron neutrinos and antineutrinos from astrophysical sources of gravitational bursts have been obtained.     

Cryogenic Model of the Gravitational Antenna OGRAN

The optoacoustic gravitational-wave antenna (OGRAN) located in the underground laboratory of the Baksan Neutrino Observatory has a limited sensitivity sufficient only to detect gravitational radiation from astronomical objects at a distance of 100 kpc. In order to cover sources in the zone with a radius of up to 15 Mpc, it is proposed to economically upgrade the antenna and cool down the body of the acoustic detector to a temperature of liquid nitrogen of ~78 K [1]. In this case, the spectral density of the Brownian noise of the detector decreases owing to temperature and also owing to the subsequent increase in its acoustic Q factor by one and a half to two orders of magnitude. This paper presents the results of an experiment for testing these ideas on the cryo-OGRAN prototype while preserving the optical detection scheme used for the uncooled antenna.     

Neutrons in extensive air showers

The first results of measurements of the thermal-neutron flux in extensive air showers (EASs) using an unshielded scintillation thermal-neutron detector in the Multicom prototype array at the Baksan Neutrino Observatory of the Institute for Nuclear Research are reported. The operating capacity of the new method for studying the EAS hadron component via detection of thermal neutrons and good prospects of this method are demonstrated.     

Neutrons in extensive air showers

The main properties of the so-called neutron bursts produced by the passage of extensive air showers (EASs) through a detector array and the properties of these EASs are considered using the experiments that are being or have been carried out previously with the Carpet-2 array at Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences, and at Cosmic-Ray Station of UNAM in Mexico as examples. We show that no exotic processes are required to explain the nature of neutron bursts. Based on a working prototype of the previously proposed MULTICOM array, we also show that this phenomenon can be successfully used in studying the EAS hadronic component and that adding special thermal neutron detectors can improve significantly the capabilities of the array for EAS study.