A double sided silicon strip detector as an end detector for the DRAGON recoil mass separator



The DRAGON electromagnetic recoil mass separator located at TRIUMF-ISAC in Vancouver, Canada was built to study resonant radiative proton and α-particle capture reactions relevant to nuclear astrophysics. In DRAGON experiments, a stable or radioactive ion beam in the energy range 0.15 MeV/amu to 1.5 MeV/amu from ISAC impinges on a differentially pumped, windowless gas target of hydrogen or helium. Recoiling reaction products are separated electromagnetically from beam ions and detected in the final focal plane, typically with a double sided silicon strip detector. A bench test facility for testing and improvement of the double sided silicon strip detectors and related systems has been assembled. The facility has been used to measure the efficiency and energy resolution of the detectors using an α-particle source, and to assess the effects of radiation damage on the detectors. The pulse height defect and the effect when particles pass through the gap between strips have been measured. Data from α-particle tests have been compared with data from stable beam experiments in the mass range A = 12 to A = 25, and used to predict detector performance in future DRAGON experiments. A 1 MeV/amu 16O beam has been used to measure timing resolution. DRAGON has used this detector system successfully in measurements of the resonance strengths of several astrophysically relevant resonances in the 21Na(p,γ)22Mg reaction with a radioactive beam of 21Na. A hybrid thermoelectric/liquid cooling system has been designed, built and tested with the purpose of cooling the double sided silicon strip detectors and improving their performance. The future possibility of using silicon detectors for particle identification by pulse-shape discrimination has been researched.

Author: Wrede, C. L. H.