Decrement of Secondary Gamma Radiation Flux during Solar Eclipses on January 4, 2011 and December 26, 2019 at Udaipur, India

Abstract

Abstract: The solar eclipses at Udaipur (270 43’ 12.00”N, 750 28’ 48.01”E), India were experimentally observed on January 4, 2011 and December 26, 2019 using a ground-based NaI (Tl) scintillation detector. For the solar eclipse on January 4, 2011, the data files were stored in a computer for a thirty-minute duration from 14.30 IST to 15.00 IST on pre-eclipse normal days as well as on post-eclipse normal days and also on partial eclipse day (January 4, 2011). For solar eclipse on December 26, 2019, cadences of data were collected for three hours from 8 AM to 11 AM on pre-eclipse normal days as well as on post-eclipse normal days and also on eclipse day (December 26, 2019). The analyzed data revealed significant decrement of secondary gamma radiation flux (SGR) on solar eclipse day (January 4, 2011) of about 10 % and on solar eclipse day (December 26, 2019) of about 17 % in the counts of SGR flux on comparison to average counts of normal days. We interpret such decrement of SGR flux on the basis of obstruction effect produced by the Moon during solar eclipses. Keywords: Solar eclipse, Cosmic radiation, Solar radiation, Secondary gamma radiation, Obstruction effect by the Moon.