In the game, he finds a cure for the Hulk by using the gamma orb, which draws out the gamma energy that created the Hulk.
On its own, it may be unable to distinguish between radioisotopes that have similar gamma energies.
Both cobalt-60 and caesium-137 have only a few gamma energies, which makes them close to monochromatic.
This effect is predominant at low gamma energies and is known as the photoelectric effect.
This effect predominates at higher gamma energies and is known as the Compton effect.
The process requires more energy than can be generated with the technology of 1930, so the Daleks plan to use gamma energy from a solar flare.
On the other side of the decay energy range, there is effectively no lower limit to gamma energy derived from radioactive decay.
The full decay chain, along with half-lives and relevant gamma energies, is:
Gammadroid - An android that is powered by a combination of gamma energies and cosmic energies.
Determination of half life and gamma energies, International Journal of Applied Radiation Isot., 26, 403 405.
