Pulse-shape analysis for identification of low-energy particles by using a silicon pad detector

We have investigated a pulse-shape analysis method with a silicon pad detector to identify light particles with energies below 5 MeV/A. The silicon pad detector with dimensions of 50 x 50 x 0.995 mm(3) was used to detect the particles and produced current signals that depended on incident particle species. The current signals were integrated and converted into voltage signals with various pulse shapes by using a charge sensitive preamplifier. The pulse shapes were digitized into 14-bit, 40-MHz sampling data and were digitally recorded. We performed a theoretical calculation in order to confirm and quantify the plasma erosion effect influencing the pulse shapes and then attempted to deduce the correlation between the plasma time and the energy of particles. We report on the results obtained for alpha particles emitted from a Ra-226 source and on the feasibility of particle identification by using a pulse shape analysis for low-energy light particles.