  Temporal variation of secondary cosmic rays (SCR) flux was measured during
the several full and new moon and days close to them at Department of Physics,
University of Mumbai, Mumbai (Geomagnetic latitude: 10.6 N), India. The
measurements were done by using NaI (Tl) scintillation detector with energy
threshold of 200 keV. The SCR flux shows sudden enhancement for approximately
about 2 hour in counts during couple of events out of all experimental
observations. The maximum Enhancement SCR flux is about 200% as compared to the
diurnal trend of SCR temporal variations. Weather parameters (temperature and
relative humidity) were continuously monitored during all observation. The
influences of geomagnetic field, interplanetary parameters and tidal effect on
SCR flux have been considered. Summed spectra corresponding to enhancement
duration indicates appearance of atmospheric radioactivity which shows single
gamma ray line. Detail investigation revealed the presence of radioactive Ar 41
. This measurements puts limitations on low energy SCR flux monitoring. This
paper will help many researcher who want to measure SCR flux during eclipses
and motivate to find unknown mechanism behind decrease/ increase during
solar/lunar eclipse.
