A collimated gamma ray beam consists of equal numbers of 0.1 MeV and
1.0 MeV photons. If the beam enters a 15 cm thick concrete shield, what
is the relative portion of 1 MeV photons to 0.1 MeV photons in the
A beam consist of photons of different energies incident and obstacle. The ratio of photons in the emerging beam is calculated.