2.1.3 Multilayer Samples

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:

CrO on [MgF-Cr] $_{x}$ on TiO $_{2}$ on Si substrate, (`GoldCr')
WO on [MgF-Cr] $_{x}$ on TiO $_{2}$ on Si substrate, (`RedW')
10-15Å Al on 1500Å MgF $_{2}$ on Si substrate
50Å Al on 1500Å MgF $_{2}$ on Si substrate
W on MgF $_{2}$ on TiO $_{2}$ on Si substrate (samples `top' and `bottom')

All these surfaces were tested for use both as start and conversion surfaces. Typical sample sizes were 1 to 2 cm $^{2}$ .

March 2001 - Martin Wieser, Physikalisches Institut, University of Berne, Switzerland