Energy reconstruction from PileUp events

An experimental technique is described in the present work capable to identify pileup events and to reconstruct the hidden energy information. The procedure is based on the pulse shape analysis of digitized signals with the help of a high frequency, fast and sensitive flash ADC. The CAEN module V1729A, operating at a maximum sampling rate of 2 GHz has been successfully used in a recent experiment performed at the INFN-LNL EXOTIC facility, Padova, with an incident ⁸B beam near barrier energies (E_L=25-40 MeV) on a three stage Si telescope. The nature of the unstable beam nucleus, which decays in ⁸Be and consequently in two alphas, necessitates the usage of appropriate pileup rejection techniques. The proposed offline algorithmic approach has efficiently identified all the recorded pileup events and in most cases has successfully reconstructed the energy information of the overlapping signals. Details of the applied technique with energy reconstruction examples for normal and pileup events are discussed in the present work.