Lns activity report 2009 126 test of fazia prototypes at lns

The response of a few silicon-silicon-CsI(Tl) and silicon-silicon telescopes with high quality detectors developed within the FAZIA collaboration [1] is tested in this work. The silicon detectors were manufactured from “random cut” wafers to avoid channeling effects and are characterized by a high dopant homogeneity. One siliconsilicon telescope was mounted on a rotating platform to compare its response in case of front and rear injection. Another silicon detector was mounted on a motorized support, sliding to angles very close to the beam (~0.5°), in order to measure the effects of radiation damage on energy resolution and PSA. Beams of Kr and Xe at 35A MeV, impinging on targets of Ni, Nb, Sn and Au, produced fragments over a large range of charge, mass and energy. The aim was to explore the capabilities of various solutions exploiting the digital techniques of Pulse Shape Analisys (PSA) for the Z and A identification of stopped ions. It has been found that PSA is able to fully discriminate the charge of stopped ions up to the maximum available Z (that of the beam, Z=54). The !E-E correlations of the first two silicon detectors can separate all the nuclides up to Z~25 and no difference in resolution between front and rear injection is observed. The experimental data also provide some preliminary information about the effects of radiation damage on energy resolution and PSA for high fluences of heavy ions.