  The collection efficiency for Cherenkov light incident on a wavelength
shifting plate (WLS) has been determined during a beam test at the Proton
Synchrotron facility located in the National Laboratory for High Energy Physics
(KEK), Tsukuba, Japan. The experiment was conducted in order to determine the
detector's response to photoelectrons converted from photons produced by a
fused silica radiator; this allows for an approximation of the detector's
quality. The yield of the photoelectrons produced through internally generated
Cherenkov light as well as light incident from the radiator was measured as a
function of the momentum of the incident hadron beam. The yield is proportional
to sin$^2$$\theta_c$, where $\theta_{c}$ is the opening angle of the Cherenkov
light created. Based on estimations and results from similarly conducted tests,
where the collection efficiency was roughly 39%, the experimental result was
expected to be around 40% for internally produced light from the WLS. The
results of the experiment determined the photon collection response efficiency
of the WLS to be roughly 62% for photons created in a fused silica radiator and
41% for light created in the WLS.
