Figure 2.

(Top) The basic architecture of an individual channel with N energy thresholds in the ASIC. (Bottom) Each photon incident on a detector will generate a pulse whose height is associated with the photon energy. Quasicoincident photons within the detector deadtime τ are counted as 1 event with different energies from the originals due to pulse pileup effects. The former will result in lost counts and the latter in a distorted recorded energy spectrum.