MASS RESOLUTION OF RECOIL FRAGMENT DETECTOR TELESCOPES FOR 0.05-0.5-A MEV HEAVY RECOILING FRAGMENTS

The factors governing the mass resolution for 0.05-0.5 A MeV recoil nuclei have been investigated for detector telescopes in which carbon-foil time zero detectors and ion-implanted silicon detectors are used to determine the time of flight and energy respectively. Experimentally determined second moments of the mass distribution have been compared with theoretical estimates based on literature data. The experimental mass resolution is in reasonably good absolute agreement with theoretical estimates. For low energy (< 0.3 A MeV) particles the mass resolution is dominated by the contribution from the silicon detector and thus largely independent of timed flight length. In fact for detection of very low energy (0.1 A MeV) recoil nuclei timed flight lengths of less than 0.22 m are sufficient.