GBS Elektronik MCA-527 How to do an optimum setup - Manual (Page 10)

Example for trigger filter threshold set too low. At the low energy end of the spectrum a noise peak can be seen
and count rate is higher than expected.
Pile-up rejector
By default this is on.
Should be switched off only with preamplifier signals which exhibit ringing or otherwise are misinterpreted as
double pulse. For the function of the pile-up rejector, press Cntrl-F during a measurement to see the pile-up
rejector statistics and time resolution.
Statistical distribution of pile-up rejector times, here typical as expected for a NaI-detector