Giuseppe Maruccio, Antonella Lorusso, M. Panareo, Esteban Broitman, Alessio Perrone, Anna Grazia Monteduro, F. Gontad, GONTAD FARIÑA, FRANCISCO JOSÉ, Lorusso, Antonella, Panareo, Marco, Monteduro, ANNA GRAZIA, Maruccio, Giuseppe, Broitman, E, and Perrone, Alessio
We report a design of photocathode, which combines the good photoemissive properties of lead (Pb) and the advantages of superconducting performance of niobium (Nb) when installed into a superconducting radio-frequency gun. The new configuration is obtained by a coating of Nb thin film grown on a disk of Pb via pulsed laser deposition. The central emitting area of Pb is masked by a shield to avoid the Nb deposition. The nanomechanical properties of the Nb film, obtained through nanoindentation measurements, reveal a hardness of 2.8±0.3 GPa, while the study of the electrical resistivity of the film shows the appearance of the superconducting transitions at 9.3 K and 7.3 K for Nb and Pb, respectively, very close to the bulk material values. Additionally, morphological, structural and contamination studies of Nb thin film expose a very low droplet density on the substrate surface, a small polycrystalline orientation of the films and a low contamination level. These results, together with the acceptable Pb quantum efficiency of 2×10−5 found at 266 nm, demonstrate the potentiality of the new concept photocathode. Funding agencies: Italian National Institute of Nuclear Physics (INFN); Italian MIUR through the Project FIRB Futuro in Ricerca [RBFR12NK5K]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]