  We employed two independent methods to study possible damage to the
scintillation mechanism in lead tungstate crystals due to irradiation by a 34
GeV pion beam. First, 10 crystals were irradiated simultaneously over 30 hours
by a narrow beam, so that only a small region of each crystal was affected. We
studied the effect of the irradiation on the light output non-uniformity. If a
localized degradation was observed, it would indicate damage to the
scintillation mechanism. Secondly, we detected light output using two
phototubes attached to sides of a crystal. Since these phototubes detect
scintillation light only from a small localized region, the effect of
transmission loss should be minimal. We did not see any statistically
significant evidence for scintillation mechanism damage with either method. The
effect is consistent with zero, and the upper limit is 0.5% at 95% C.L.

Instrumentation and Detectors;High Energy Physics - Experiment