The portion of the total analyzing time that is actually spent processing (mesuring) X-rays because during the time that each X-ray pulse is being measured, the system can not mesure another X-ray that may enter the detector and is, therefore, said to be "dead". In an actual analysis, the total analyzing time is extended by the equipment so that the analyzing time (e.g. 100 seconds) set on the controls is the live time - the time spent waiting for the x-ray photons. Figure 1 shows relationship between output and input count rates.


Figure 1: Relationship of output and input count rates for
a generalized EDS spectrum for three different values of pulse
width.