The mirror material test programme at the Daresbury SRS

The present generation of high flux electron storage rings, purpose-built as synchrotron radiation sources, presents new problems in optical design, particularly where reflections other than in grazing incidence are required. A mirror test programme, in collaboration with the Photon Factory, Japan, has been under way on the Sychrotron Radiation Source at Daresbury Laboratory for two years. Many samples, ranging from glasses, through ceramics to metals such as molybdenum, have been exposed to radiation densities up to 70 W/cm2, and long term changes in their optical properties measured. Considerable effort has been devoted towards developing a cooled mount satisfactory for use in an ultra high vacuum environment. Recommendations are made for the most suitable materials for future use based on the results of this test programme, bearing in mind the even greater intensities that will be available from undulator and multipole wigglers in the future. Finally, a programme for more detailed measurements on the effect of high density heating and radiation on the optical performance of mirrors is described. (orig.)