Pile-up

When pile-up (English for stacking ) of the case is referred to that in a particle or radiation detector two detection events occur within a time which is shorter than the width of each electrical pulse generated.

With pile-up, only one event is registered instead of two, so there is a loss of counting similar to that caused by dead time . If the pulse height is also measured for the purpose of spectroscopy , the two original pulses are missing at their correct points in the spectrum; instead, a bogus "event" occurs at a higher pulse height.

In order to avoid falsification of the measurement result through pile-up, a pile-up rejector is often inserted into the apparatus. This device recognizes the falsified impulse by its shape - e.g. B. due to the excessive rise time or the occurrence of two maxima in the signal - and prevents it from being passed on, for example to the analog-to-digital converter of the multi-channel analyzer .

literature

• Glenn F. Knoll: Radiation detection and measurement. 2nd ed. Wiley, New York 1989, ISBN 0-471-81504-7 .