Direct Observation and Partial-width Measurement of Gamma-gamma-decay of Charmonium States

C. BAGLIN;S. BAIRD;G. BASSOMPIERRE;G. BORREANI;J. C. BRIENT;C. BROLL;J. M. BROM;L. BUGGE;T. BURAN;J. P. BURQ;A. BUSSIERE;A. BUZZO;R. CESTER;M. CHEMARIN;M. CHEVALLIER;B. ESCOUBES;J. FAY;S. FERRONI;V. GRACCO;J. P. GUILLAUD;E. KHANARONSEN;B. ILLE;K. KIRSEBOM;M. LAMBERT;L. LEISTAM;A. LUNDBY;M. MACRI;F. MARCHETTO;E. MENICHETTI;C. MORCH;B. MOUELLIC;N. PASTRONE;L. PETRILLO;M. G. PIA;J. POOLE;M. POULET;G. RINAUDO;A. SANTRONI;M. SEVERI;G. SKJEVLING;B. STUGU