A New Carbon based VUV Mirror of High Radiation Length for the HADES RICH*
S. Winkler, J. Friese, R. Gernhauser, P. Maier-Komor. B. Sailer
April 4, 2002
The VUV Cherenkov photons radiated by electrons and positrons in the gaseous
C4F10 radiator of the HADES RICH are focused by a spherical mirror of 1.5 m diameter and 0.78 m radius of curvature to the padplane of the MWPC photon detector. To match the requirements of maximum radiation length we have produced a mirror based on a novel pure carbon substrate of 2 mm thickness and very high stiffness. The mirror system is segmented into 18 panels mounted on a light weight support structure with a sixfold narrow spoke geometry. The panels are produced from glassy carbon substrates, individually polished and coated with VUV reflective
* supported by BMBF (6TM970I) and CSI (TM-FR1).