When the observed count rate increases the gain of the detector becomes depressed and the position that the photons from a given channel are recorded at (in SCA space) slips to lower values. As a consequence, the perceived energy distribution of the photons can move relative to the energy window defined by the lower and upper level discriminators and some photons may be rejected as being out of limits. This effect has made it difficult to reject the photons caused by Ge fluorescence when the count rates are high.