Guidance on Selection of Radiation Type

Average Energy of Emitted Photons

If E_g,i and I_g,i denote the energy and intensity of the ith photon in the spectrum of photons, including gamma rays and x rays, emitted in decay of a radionuclide, the average energy is given by:

E_g,avg = [SE_g,i x I_g,i] / [SI_g,i]

Photon spectra in decay of radionuclides are given, for example, in refs. [1] and [2].

References:

1. International Commission on Radiological Protection (ICRP), Radionuclide Transformations: Energy and Intensity of Emissions, ICRP Publication 38, Ann. ICRP 11-13, Pergamon Press, Oxford, U.K. (1983).
2. D. C. Kocher, Radioactive Decay Data Tables, DOE/TIC-11026, U.S. Department of Energy, Oak Ridge, Tennessee (available through National Technical Information Service, Springfield, Virginia) (1981).