DEWAR TESTING OF BETA = 0.085 QUARTER WAVE RESONATORS AT MSU*

Michigan State University is developing quarter wave resonators (QWRs) for a superconducting linac to reaccelerate exotic ions to 3 MeV per nucleon or higher (ReA3). Eight QWRs with an optimum velocity of β = v/c = 0.085 and a resonant frequency of 80.5 MHz are required for the third cryomodule, which will complete the first stage of the reaccelerator linac. Approximately 100 additional β = 0.085 QWRs of similar design will be required for the Facility for Rare Isotope Beams (FRIB). This paper covers Dewar testing of the QWRs, performance issues observed in the tests, and design improvements to mitigate these issues.