A collimated beam of 200 keV gamma radiation delivers an incident energy flux of 2 J m^-2 s^-1 to a lead shield 1 g cm^-2 thick.
a. What is the incident photon flux in photons cm^-2 s^-1?
b. What is the rate of energy absorption in the shield in both erg g^-1 s^-1, J kg^-1 s^-1 and Gy s^-1