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Time series of gamma-ray photons from natural radioactivity measured with the Large Volume Detector (LVD) at the Gran Sasso underground laboratory (Laboratori Nazionali del Gran Sasso, Italy) have been analyzed. The instrument is used to detect neutrinos from gravitational collapses of stellar cores in the Galaxy. The background of the experiment is due to neutrons and gamma-ray photons from the decays of daughter nuclei of uranium and thorium. An analysis of periodic variations of the number of gamma-ray photons caused by the radon concentration in the underground laboratory has shown the presence of diurnal, weekly, monthly, and annual modulations. Data collected from 2004 to 2021, including a period of low activity in the hall of the Gran Sasso laboratory during the COVID-19 pandemic, have been reported. [ABSTRACT FROM AUTHOR]

Experimental data obtained using three scintillation detectors are analyzed. The characteristics of cosmogenic neutrons in underground experiments their analytic dependences are considered. The behavior of background counting rate for the LVD detector for two measuring thresholds (0.5 and 5 MeV) are discussed. [ABSTRACT FROM AUTHOR]

Using the Geant4 code, we have performed a full-scale simulation of the LSD response to the neutrino burst from SN 1987A. The neutrino flux parameters were chosen according to one of the models: the standard collapse model or the rotational supernova explosion model. We showed that, depending on the chosen parameters, one can either obtain the required number of pulses in the detector or reproduce their energy spectrum, but not both together. The interaction of neutrino radiation both with LSD itself and with the material of the surrounding rock was taken into account in our simulation. We also explored the hypothesis that the entire unique LSD signal at 2:52 UT was produced by neutrino fluxes from the surrounding granite. However, this hypothesis was not confirmed by our simulation. The results obtained provide a rich material for possible interpretations. [ABSTRACT FROM AUTHOR]

Sources of seasonal temperature variations in the average energy of the muon flux detected in the LVD experiment have been discussed. It has been shown that variations are due to the processes of generation of muons in upper layers of the atmosphere and the passage of muons through a thick rock layer. [ABSTRACT FROM AUTHOR]