The paper examines the possibility of using 3D printing technology to manufacture structural elements of ionizing radiation detectors under low-background conditions. The results of measurements conducted with a scintillation detector housed in a housing made of PETG plastic are presented.

To create a prototype of a detector based on a neodymium-containing liquid organic scintillator for the search for neutrinoless double-beta decay of ^150 Nd, measurements of the spectra of radioactive impurities from various materials used in the manufacture of the detector were carried out using low-background semiconductor gamma spectrometers at the Baksan Neutrino Observatory, Institute of Nuclear Research of the Russian Academy of Sciences. The potential use of 3D printing in low-background conditions was considered. This could potentially allow creating the detector structural elements with a record-low content of radioactive impurities for experiments in neutrino astrophysics, dark matter searches, neutrinoless double-beta decay experiments. The activity of radioactive impurities in plastic parts produced on a 3D printer, which were intended for use in creating a prototype of a detector and its low-background shielding, were measured.

В статье дается краткий обзор детекторов, которые способны регистрировать нейтринную вспышку от сверхновой (СН). Представлен статус эксперимента по регистрации нейтринных вспышек на Баксанском подземном сцинтилля- ционном телескопе ИЯИ РАН. Обсуждается возможная связь нейтрино от СН с экспериментами по поиску легкой темной материи (с массой частиц ≤ МэВ). The article gives a brief overview of the detectors that are capable of registering a neutrino burst from a supernova (SN). The status of the experiment on registration of neutrino bursts at the Baksan underground scintillation telescope of the INR RAS is presented. A possible connection between SN neutrinos and experiments on the search for light dark matter (with a particle mass of ≤ MeV) is discussed

Baksan underground scintillation telescope (BUST) operates under the program of neutrino burst search since the middle of 1980. We report the current status of the experiment and the results associated with analysis of background events and facility operation stability. We demonstrate the BUST potentialities in detecting neutrino bursts from close supernovae. Over the period from 30.06.1980 to 30.06.2021, the observation time is 35.5 years. During this time, not a single candidate for a neutrino burst has been registered. This leads to an upper bound of the mean frequency of gravitational collapses of stars in our Galaxy of 0.065 year–1 at the 90% confidence level.

A large-volume liquid scintillator neutrino detector is proposed to develop at the Baksan Neutrino Observatory of Institute for Nuclear Research of the Russian Academy of Sciences in the North Caucasus. The detector will be located at the depth of 4700 m.w.e. (meter of water equivalent). A target mass of the detector will be 10 kt. This multipurpose detector is being developed to study primarily natural neutrino and antineutrino fluxes namely fluxes of solar neutrinos, geoneutrinos and neutrinos from other astrophysical sources. This project, if implemented, would be a successor of the Borexino experiment and other European projects like LENA. The project is aimed to have a record energy resolution, which along with its location at the large depth and relatively far distance from operating nuclear reactors will allow reaching a record sensitivity to the natural neutrino and antineutrino fluxes. We report in the paper the present status of the project and describe some selective results of the project first stage — the detector prototype with liquid scintillator mass of 0.5 t. Results of R&D for the project second stage with 5 tons of liquid scintillator are presented too.

The results of searching for neutrino events from the blazar PKS 0735+17 at the Baksan Underground Scintillation Telescope (BUST) are presented. A neutrino from the PKS 0735+17 region was detected at BUST on December 4, 2021, during a strong outburst of this object, coinciding with an observed Fermi LAT gamma-ray outburst. The BUST neutrino event preceded the detections of high-energy neutrino events from the PKS 0735+17 region by IceCube, Baikal-GVD, and KM3NeT.

Data from the Baksan Underground Scintillation Telescope were used to search for muon neutrinos and antineutrinos with energies above 1 GeV in coincidence with gravitational-wave events detected by the Advanced LIGO and Advanced Virgo observatories in three observing periods. Limits on the integral fluxes of muon neutrinos and antineutrinos from gravitational wave sources were obtained. A way of searching for neutrino events from LIGO/Virgo alerts is presented. An algorithm for data processing and finding coincidences between neutrino and gravitational-wave events in real time is described.

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 Coordinates Network. The Gamma-ray Coordinates Network is a system for distributing alerts from gamma-ray bursts, transients. Muon neutrinos and antineutrinos with energies above 1 GeV are registered with the Baksan Underground Scintillation Telescope. Ultra-high-energy gamma rays are registered with the ‘‘Carpet-2’’ setup. Registration of events and analysis of alerts occurs in near-real time. Alerts from Swift BAT, Fermi-GBM, Fermi-LAT, INTEGRAL, IceCube, HAWC are used. This work presents the description of the alert processing program and preliminary results.

— The Baksan Underground Scintillation Telescope has been used to search for neutrino bursts since the mid-1980s. We use two parts of the telescope with a total mass of 240 tons as a target. The actual observing time from June 30, 1980, to June 30, 2020, was 34.4 years. No neutrino burst candidate events were detected during this period, placing an upper bound of 0.067 g −1 on the average frequency of core collapse supernovas in the Galaxy at a 90% confidence level.

The core collapse of a massive star in the Milky Way will produce a neutrino burst, which will be detected by the Baksan Underground Scintillation Telescope (BUST). The stable and enough low background at the BUST is a clear asset for searching for neutrino bursts. Now two parts of the facility (with the total mass of 242 tons) are used as independent coinciding detectors. Such approach allows us to increase dependability detection of the neutrino signal and the radius of sensitivity of the BUST. The facility has the potential to see a supernova in the Galaxy independently from other detectors. No burst candidate for the core collapse has been detected during the observation period of June 30, 1980, to June 30, 2019. The actual observation time is 33.477 years. This is the longest observation time of our Galaxy with neutrinos at the same facility. An upper bound on the mean frequency of gravitational collapses in the Galaxy is 6.88 per century (at 90% C.L.).

The experiment on recording neutrino bursts operates since the mid-1980. As a target, we use two parts of the facility with a total mass of 240 tons. The current status of the experiment and some results related to the investigation of background events and the stability of facility operation are presented. Over the period of June 30, 1980 to December 31, 2018, the actual observational time is 33.02 years. No candidate for the stellar core collapse has been detected during the observation period. The corresponding upper bound of the mean frequency of core collapse supernovae in our Galaxy is 0.070 year(-1) (90% CL). (C) 2019 Elsevier B.V. All rights reserved.

The detectors based on the liquid scintillator (LS) monitored by an array of photo-multiplier tubes (PMT) are often used in low energy experiments such as neutrino oscillation studies and search for dark matter. Detectors of this kind operate in an energy range spanning from hundreds of keV to a few GeV providing a few percent resolution at energies above 1 MeV and allowing to observe fine spectral features. This article gives a brief overview of relevant physical processes and introduces a new universal simulation tool LSMC (Liquid Scintillator Monte Carlo) for simulation of LS-based detectors equipped with PMT arrays. This tool is based on the Geant4 framework and provides supplementing functionality for ease of configuration and comprehensive output. The usage of LSMC is illustrated by modeling and optimization of a compact detector prototype currently being built at Baksan Neutrino Observatory.

A current status of the project of a large volume scintillation telescope at the Baksan neutrino observatory is presented. The main research activities of the BLVST are low-energy neutrino physics, astrophysics and geophysics. To detect geoneutrinos, large-scale new-generation scintillator detectors located at large depths in the regions with a low background level from nuclear reactors are required. The Baksan Neutrino Observatory is geographically located in one of these places. Recently resumed R&D activities are aimed at the creation of new-generation telescope with a target mass of 10 kt at a depth of 4800 m.w.e. A small scale prototype is already under construction.

The Baksan Underground Scintillation Telescope (BUST) is located in the North Caucasus in an underground laboratory at an effective depth of 850 m.w.e. The BUST began working in 1977, and the installation is still in operation. The successful design of the BUST allows it to be used to solve a number of problems in astrophysics and particle physics. The new data acquisition system is designed to record and analyze experimental data with greatly improved measurement characteristics of digital and analog signals. The data acquisition system is based on the VME interface and provides complete compatibility with existing low-level BUST recording electronics. The hodoscope of pulse channels was completely redeveloped and implemented on field-programmed gate array (FPGA) and LVDS chips.