First measurement of a NbTi RF cavity

The first measurement of a NbTi superconducting accelerating cavity at 4.5 GHz is reported. As a first step of a R&D project for the study of new promising superconducting materials for future applications to RF accelerating structures, a NbTi cavity was built using the same technique developed for niobium cavities. The cavity was electron beam welded, chemical polished, and rinsed with high purity water. A first test has shown very good agreement between measured and computed RF surface resistance down to 1.8 K. The authors used the Halbritter´s code for RF loss computation in superconductors to obtain from measured data information about the coherence length, the penetration depth, the mean free path, and the strong coupling coefficient of the material.<>