Frequency Sensitivity to Cavity Geometry Errors of HIE-ISOLDE High-Beta QuarterWave Resonator

Quarter-Wave Resonators (QWRs) are to be used in the linac upgrade in the framework of HIE-ISOLDE project. The QWRs are made of copper with niobium sputtered on the RF surface. The resonant frequency of the cavity is 101.28 MHz at 4.5 K. The resonant frequency changes due to cavity geometry variation. Thus the manufacturing tolerance has been set to 0.1 mm for the copper substrate. The frequency sensitivity to different geometry changes has been evaluated in this report.