  A scheme for exploring photon number amplification and discrimination is
presented based on the interaction of a large number of two-level atoms with a
single mode radiation field. The fact that the total number of photons and
atoms in the excited states is a constant under time evolution in Dicke model
is exploited to rearrange the atom-photon numbers. Three significant
predictions emerge from our study: Threshold time for initial exposure to
photons, time of perception (time of maximum detection probability), and
discrimination of first few photon states.
