Response Of Cooled Pwo Scintillators To Low-Energy Gamma-Rays And Its Importance In Studies Of The H(C) -> Eta(C) + Gamma Transition In Charmonium

Suppression of non-resonant background due to emission of pi(0) increases signal to background ratio in gamma-ray emission studies between the discrete states of charmonium. We demonstrate with Monte-Carlo simulations how pi(0) identification capability increases with decreasing threshold for gamma-ray detection in pi(0) decay. An apparatus has been designed and measurements of the FWHM resolution performed for the three energies 6.13, 12.7 and 16.9 MeV. The trend established in the 50-650 MeV energy range is corroborated.