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We report on the degradation of the scintillation yield of single crystal YAG: Ce under He irradiation at low energy. The decrease of the luminescence intensity as a function of fluence can be analyzed by the Birks model. The results indicate that the scintillator degrades fast and exhibits poor scintillation efficiency for low-energy irradiation.A possible degradation mechanism is proposed.

The electron-beam ion trap (EBIT) charge breeder of the ReA post-accelerator, located at the National Superconducting Cyclotron Laboratory (Michigan State University), started on-line operation in September 2015. Since then, the EBIT has delivered many pilot beams of stable isotopes and several rare-isotope beams. An operating aspect of the ReA EBIT is the breeding of high charge states to reach high reaccelerated beam energies. Efficiencies in single charge states of more than 20% were measured with 39 K 15þ , 85 Rb 27þ , 47 K 17þ , and 34 Ar 15þ. Producing high charge states demands long breeding times. This reduces the ejection frequency and, hence, increases the number of ions ejected per pulse. Another operating aspect is the ability to spread the distribution in time of the ejected ion pulses to lower the instantaneous rate delivered to experiments. Pulse widths were stretched from a natural 25 μs up to ∼70 ms. This publication reviews the progress of the ReA EBIT system over the years and presents the results of charge-breeding efficiency measurements and pulse-stretching tests obtained with stable-and rare-isotope beams. Studies performed with high sensitivity to identify and quantify stable-isotope contaminants from the EBIT are also presented, along with a novel method for purifying beams.