FACED ISSUES IN REA3 QUARTER-WAVE RESONATORS AND THEIR SUCCESSFUL RESOLUTION*

The 80.5 MHz, beta=0.085 QWR production cavities for the ReA3 project at MSU have initially shown puzzling behaviour and unexpected lack of performance. This was due to a combination of design problems and subtle mechanical effects, which have been pointed out during a brief but intense testing campaign made by the FRIB SRF group. The same cavities could be eventually refurbished and brought to performance well above original specifications. This work will be presented with emphasis to the technical problems encountered, their diagnosis and the adopted solutions.