  The energy resolution of PWO crystals and their dependence on the incoming
energy has been investigated. The crystals used were first prototype crystals
of a new generation, characterized by a higher light yield. Two crystal types
with different shape and light yield, manufactured by suppliers in China and
Russia, were used. An experiments were performed on two cooled arrays of 3x3
crystals. Photon beams of eight different energies, ranging from 64 MeV to 715
MeV, were directed into the center crystals. Photo Multiplier Tubes were used
to read out the response of the scintillators. The energy resolution was
calculated using three different methods - FWHM, a two gaussian fit and a right
side fit. The two Gaussian method delivered the lowest sigma value and also the
lowest energy resolution. The obtained energy resolution for the Russian
crystals was 1.61%/sqrt(E)+0.73% and similarly 1.58%/sqrt(E)+4.25% for the
Chinese crystals.
