A New Carbon based VUV Mirror of High Radiation Length for the HADES RICH*
S. Winkler, J. Friese, R. Gernhauser, P. Maier-Komor. B.
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 Al-MgF2 layers.
* supported by BMBF (6TM970I) and CSI (TM-FR1).
You can download the presentation in PDF format