Study of lateral density distributions of Cherenkov photons in extensive air showers at primary energy 50 GeV and above

An EAS (extensive air shower) refers to the cascade of secondary particles created from the interactions of high energy primary cosmic ray particles with the air nuclei and subsequent decay of the particles produced. Ultra-relativistic secondary charged particles in the atmosphere produce Cherenkov radiation, which may be detected by ground based detector array. Such an array, HAGAR (High Altitude GAmma Ray) experiment is operating at Hanle, Ladakh, at an energy threshold of about 100 GeV, which will be lowered to 50 GeV using MACE telescope. We have studied the simulations of the distribution patterns of lateral density of Cherenkov photons generated in EAS for different primary particles (γ, p) incident with the fixed primary energy 50 GeV and these are compared with those of 100 GeV showers using the standard CORSIKA code. From our study it has been found that, for all primary particles, the variation of lateral density distribution of Cherenkov photons almost obey the functional relation, ρ_ch (r) = ρ₀ e(−βr). The steepness of the lateral distribution function is found to depend on the primary mass composition. Further a prominent hump is observed in the lateral distribution for gamma shower only. (paper)