For higher UV suppression on the start surface multilayer surfaces
were tested. The idea was to have an UV transparent top layer with
a high secondary electron yield. Photo electrons would be released
in the solid and not on the surface. These electrons would have a
very short free path length and would not be able to escape to the
surface producing false start events. Six of the tested surfaces fall
into this category:
All these surfaces were tested for use both as start and conversion
surfaces. Typical sample sizes were 1 to 2 cm.
- CrO on [MgF-Cr] on TiO on Si substrate,
- WO on [MgF-Cr] on TiO on Si substrate, (`RedW')
- 10-15Å Al on 1500Å MgF on Si substrate
- 50Å Al on 1500Å MgF on Si substrate
- W on MgF on TiO on Si substrate (samples `top'
March 2001 - Martin Wieser, Physikalisches Institut, University of Berne, Switzerland