A modular NIM electronics for Pulse Shape method with the large area n-planar silicon detectors of the 4π CHIMERA

A new modular NIM electronics has been developedfor Pulse Shape Discrimination (PSD) of the signalsproduced in silicon (Si) detectors. The main purpose indesign the module was the possibility to achieve Z identificationof light nuclear fragments (Z<15) which arestopped in the active region of a silicon detector, with acharge resolution as good as that one commonly obtainedwith an energy loss AE - E method requiring a two-stagetelescopes. In the present study, a simple PSD methodbased on the rise time measurement of the charge signal isproposed . The method was developed for the silicon detectorsof the 4pi array CHIMERA and, consequently, itwas implemented in a compact NIM module. This implementationallows for charge discrimination of fragmentswith charge Z < 15 and energy threshold as low as4.5MeV/nucleon (for Z=6). This result is the natural followon of a previous work recently done for the large areaplanar silicon detectors of CHIMERA, where the silicondetectors were used in both direct and reverse injection.The good performance of the Constant Fraction Discrimination(CFD) required to trigger a start signal allowedto use this signal for time of flight (TOF) methods.In this way good mass measurements were also achievedfor Isotopic identification.