Escape probability of 511Â keV annihilation photons from HPGe detectors

The escape probability of 511keV annihilation photons from a HPGe detector is presented with a third order polynomial which depends on the total photon cross section and average chord length of the sensitive volume of the detector. Theoretical results agree with the experiment within 3%. It is shown that equations describing neutron escape probability from an absorbing medium, approximates photon escape from a germanium detector.