Radiation damage in Mo75Re25 superconducting thin films by He+-particles

The excellent transport properties of superconductors compared to normal conductors make them suitable for a wide range of applications. Low-T(c) metallic-type superconductors, for example, are utilized in the accelerators environment both in bulk and thin film shapes. One of the requirements these materials must satisfy is their radiation hardness with respect to the particles utilized in the accelerators. This work deals with the study of the radiation hardness of superconducting thin films of Mo75Re25, a compound that presents interesting features for its utilization as coating for the accelerating cavities. Two Mo75Re25 superconducting thin-films have been investigated together with a Nb one for comparison. The films have been irradiated by means of 2MeV He+-particles, the Mo75Re25 films with three successive doses, whereas the Nb one with two. The experimental set-up and some preliminary measurements are described, together with a theoretical extimation of the surface resistance of the materials (the most important parameter to be considered for the application to accelerating cavities). The results obtained show a higher radiation hardness of Mo75Re25 films compared to the Nb one for what concerns the degradation of T(c) and of the residual resistivity; also the calculated values of the surface resistance result less sensible to radiation in Mo75Re25 samples than in the Nb one.