  In the absence of a standard source of gamma rays or hadrons of known energy
one has to study the details of production of \v Cerenkov light at the
observation level only through detailed simulation studies. Recently such
studies have become all the more important in view of the various techniques
resulting from such studies, to distinguish between gamma ray initiated events
from those generated by much more abundant hadronic component of cosmic rays.
We have carried out a detailed simulation studies using the CORSIKA package in
order to study the Cerenkov photon density fluctuations at various core
distances both for photon and proton primaries incident vertically at the top
of the atmosphere. It is found that the density fluctuations are significantly
non-statistical. Such fluctuations are much more pronounced in the case of
proton primaries as compared to photon primaries at all energies. Several
statistical parameters have been computed some which might lead to a technique
in distinguishing photon primaries.

Astrophysics