First 6 GHz cavity coated and characterised

This report is on Deliverable D9.3: First 6 GHz cavity coated and characterised. The Report show the results from the morphological and SC characterisation of planar samples coated with material different from niobium such as Nb₃Sn, NbTiN and V₃Si. That results of RF surface resistance on planar samples at 7.8 GHz chocked cavity and on 400 MHz on QPR measurements at 4 K demonstrate that Nb₃Sn is the most suitable material for cavity coatings.

Then first coated 6 GHz cavity was coated with NbTiN an alternative material to niobium and RF tested. The RF results show low Q and Eacc due to lack of suitable deposition targets with required composition. This work to be continued in the future.

The 6 GHz split cavity was deposited with Nb₃Sn in planar configuration. The RF test demonstrated that its performance is limited by cavity geometry rather than the quality of the film. The split cavity geometry has been changed to address this feature and future tests are ongoing.

Based on work performed in Task 9.3, the decision for 1.3 GHz cavity coating material and technology was taken to drive a delivery in Task 9.2.