Characterization of light particles (Z ≤ 2) discrimination performances by pulse shape analysis techniques with high-granularity silicon detector
Résumé
Pulse shape analysis for light particles () is studied in a 500 μm thick Double-Sided Stripped Silicon Detector (DSSSD) of nTD type with a pitch lower than 500 μm. Good separation between the isotopes is achieved irrespective of the side used for signal pick up with the detector biased at depletion voltage. The low energy threshold for discrimination between isotopes is found to be around 2.5 MeV at depletion voltage and the quality of the separation can be slightly improved by using filtering methods. On the other hand, the discrimination performances are enhanced when lowering the bias of the detector at the expense of energy resolution. At nominal bias (i.e. overdepletion) where the energy resolution is the best, no separation between the three hydrogen isotopes is achieved when using the amplitude of the current signal. Discrimination can still be obtained by acquiring the time over a threshold set at 10% of the amplitude after applying a square bipolar filter to the current signal. Besides, in view of the design of the front-end electronics, the effect of the sampling rate needed for pulse shape analysis has been investigated and shows that below 200 MSa/s, the discrimination quality is strongly reduced.