Lead Alloys for Superconducting Cavities

For the superconducting separated orbit cyclotron Tritron six large, wedge shaped cavities for simultaneous acceleration of 19 parallel ions beams are needed. The indirectly cooled superconducting cavities with frequencies of ~170 MHz ± 3 % will be made of copper electroplated with lead alloy. With PbSn and PbBi as superconductor stable surfaces without chemical polishing can be obtained. The results of measurements on a 500 MHz test cavity (PbSn) are reported.