Development of a single-particle detector for the dielectronic recombination experiment on HIRFL-CSRm

A single-particle detector, which is designed to detect ions with energies of more than 2 MeV/u, has been built and tested. The detector is operated based on the secondary-electron emission, which are produced by the incident ions impacting on a molybdenum foil with a thickness of about 5 μm. The secondary electrons are deflected and focused onto two microchannel plates with chevron assembly. We simulated the trajectories of the secondary electrons in the electrostatic field and obtained the theoretical detection efficiency, which is greater than 90% and depends on electron yields and diameter of area of the electron emission. The detector was tested by an alpha radioactive source offline and by 86Kr26+ ions (25 MeV/u) from accelerator. The detector can be used under the counting rate up to about 1×107 s−1, which satisfies the requirements of the dielectronic recombination experiment on storage ring CSRm.