CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors

We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multitelescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10-14 mum Si detector, a second 300 mum (or possibly 500 pm) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 mum Si detector. The telescopes provide full charge separation up to Z = 17 and mass resolution up to A = 9 in the energy range 0.7-60A MeV. The thin p-i-n diode detector, etched out from a 280 mum Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution less than or equal to 8%, while the standard 300 mum detectors have less than or equal to 2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10(10) alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm, gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented. (C) 2003 Elsevier Science B.V. All rights reserved.