E. A. Dobrynina

Single and multiple muons and the generation of neutrons in the LVD experiment

The large geometric factor and good spatial resolution of the Large Volume Detector (LVD) ensures statistically significant and highly accurate measurements of muon trajectories and determination of the multiplicity of muon groups. The developed algorithm allows us to reconstruct 2 × 106 muon events (single muons and muon groups). Characteristics of muon groups are obtained and the specific yield of neutrons produced by single muons, muon groups, and showers is determined.

The energy spectrum of neutrons produced by cosmic ray muons in LVD

The energy spectrum of neutrons produced by cosmic ray muons in the underground detector LVD (3650 m.w.e.) is obtained for the energy range of 30–450 MeV. The spectrum is derived using the energy release spectrum of neutron interaction products in 1.5 m3 scintillation counters.

Measurement of neutron number generated by cosmic-ray muons in iron using the LVD

The experiment to measure the neutrons numbers generated by muons in iron (Fe) and lead (Pb) carried out using LVD. A full Monte Carlo simulation of the actual geometric configuration of the experiment is performed. The first measurement results are obtained. The measured yield of neutrons produced by muons with an energy of 280 GeV in iron is 16 × 10−4 n/μ/(g cm−2).

Analysis of Seasonal Variations of the Cosmic Ray Muon Flux and Neutrons Produced by Muons in the LVD Detector

The Russian-Italian Large Volume Detector (LVD) is located at the Gran Sasso underground laboratory at a depth of 3300 m w.e. To study the seasonal variations of the penetrating component of cosmic rays, the data on cosmic ray muons detected in 2001–2008 was analyzed, along with those associated with neutrons produced by muons since April 2003. One-year periodic variations of muons and neutrons produced by them were found. The maximum intensity is observed in July, in accord with theoretical concepts.

LVD Experiment: 25 Years of Operation

The current status of the LVD (large volume detector) experiment aimed at search for neutrinos from the gravitational collapse of stellar cores is described. Within the period of observations from June 1992 to February 2017, no gravitational collapse was found in the Milky Way Galaxy and Magellanic Clouds, including hidden ones (not ejecting the envelope). The LVD collects data for 99% of the live time. A limit on the frequency of supernova bursts within a distance of 25 kpc was set at a level of 0.1 event/yr. The most recent results obtained by studying the muon component of cosmic rays are presented.

Seasonal variations in the muon-induced neutron flux and background of natural radioactivity at the Gran Sasso Underground Laboratory

Cosmic ray muons at average energies of 280 GeV and muon-induced neutrons are detected by the LVD (Large Volume Detector). An analysis of seasonal variations in the neutron flux, based on data collected over 15 years, is presented. Measuring of the seasonal variations in the specific number of neutrons generated by muons allows us to determine the magnitude of variations in the average energy of the muon flux at the depth of the LVD’s location. The source of the seasonal variations in the total neutron flux is a change in the intensity and average energy of the muon flux. An analysis of the long-term monitoring of the LVD’s low-energy background is also presented.

Joint analysis of experimental data to search for neutrinos from collapsing stars using the LVD and BUST apparata

Preliminary results of the search for neutrino bursts from collapsing stars using the experimental data of two detectors, the INR’s Baksan Underground Scintillation Telescope (BUST) and the Gran Sasso Large Volume Detector (LVD), are presented. The frequency of coincidence of single pulses measured by these detectors made on the bases of the same liquid scintillator is studied using experimental data obtained in 2012. The results can be explained by random pulse coincidences in the LVD and BUST detectors.

Generation of neutrons produced by muons from CERN neutrino beam

Preliminary results of neutron generation by muons, produced in CERN neutrino beam with average energy 17 GeV in LVD experiment are presented for the period 2008–2011 yrs. A Monte Carlo simulation of neutrons produced by horizontal muons was performed using the Geant4 software package. The efficiency of neutron detection in the LVD was calculated. For iron-based and white spirit scintillators, the measured neutron yields prove to be Ysc = (3.6 ± 0.7) × 10−5n/μ (g−1 cm2) and YFe = (23.2 ± 4.6) × 10−5n/μ (g−1 cm2).

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.

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.