Neutral particles, mostly photons ,
can also produce hits
in the Cerenkov detector by
production near
the sensitive detector volume. If a photon
with energy
GeV converts to a
pair somewhere in the DC region, then
these particles
will not enter the detector if the magnetic field is
sufficiently high.
Therefore, materials near the detector are
largely responsible
for photon conversions and
subsequent detection of
or
.
Fig. 22 shows the probability for the detection
of photons in the energy range
GeV, as a function of the segment number.
The mean detection probability is about
for most of the effective region, and
for the small
angle sections, where the material thickness is relatively
large.
