Studying the Energy Spectra of Background Gamma Radiation Increases
Several detectors have been integrated into a single system for monitoring the electromagnetic component of secondary cosmic rays (SCRs) at the Cosmic Ray Laboratory of the Polar Geophysical Institute (Apatity). The system includes a differential gamma-ray spectrum detector based on a NaI(Tl) crystal. One gamma-ray spectrum is collected in 30 min. The energy range is 0.2–8 MeV. It should be noted that like other detectors, the spectrometer was precalibrated using known lines. Background gamma radiation increases during precipitation. More than 1500 such events have been detected since the detector became operational. A number of long-term measurements have been made thus far, which make it possible to study in detail the energy parameters of increase events. The main aim of the study is to compare the characteristics between the spectra in clear weather and under different types of precipitation. Particular attention is given to radiation analysis of samples collected during the rain. The results show there is no pollution of water with radionuclides. It is concluded that the observed effect is due to purely atmospheric effects. A preliminary interpretation of the phenomenon is the creation of a model for the acceleration of charged particles of SCRs in the electromagnetic fields of nonthunderstorm rain clouds. The results from calculations are presented, and their consistency with the experimental data is shown.