\‘olunw 196, number 1 PHYSICS LETTERS B 24 September 1987 zyxwvutsr FIRST OBSERVATION OF yy+op’ ARGUS Collaboration H. ALBRECHT, A.A. ANDAM ‘, U. BINDER, P. BOCKMANN, R. GLkSER, G. HARDER, A. NIPPE, M. SCHb;FER, W. SCHMIDT-PARZEFALL, H. SCHRijDER, H.D. SCHULZ, R. WURTH, A. YAGIL 2.3 DESY, D-2000 Hamburg, Fed. Rep. Germany J.P. DONKER, A. DRESCHER, D. KAMP, H. KOLANOSKI, U. MATTHIESEN, H. SCHECK, B. SPAAN, J. SPENGLER, D. WEGENER Institut fur Physik ‘, Universitat Dortmund, D-4600 Dortmund, Fed. Rep. Germany C. EHMANN, J.C. GABRIEL, T. RUF, K.R. SCHUBERT, J. STIEWE, K. STRAHL, R. WALDI, S. WESELER 5 Institut fur Hochenergiephysik ‘, Universitat Heidelberg, D-6900 Heidelberg, Fed. Rep. Germany K.W. EDWARDS ‘, W.R. FRISKEN ‘, D.J. GILKINSON 9, D.M. GINGRICH 9, H. KAPITZA ‘, P.C.H. KIM 9, R. KUTSCHKE 9, D.B. MACFARLANE lo, J.A. McKENNA 9, K.W. MCLEAN lo, A.W. NILSSON lo, R.S. ORR 9, P. PADLEY 9, J.A. PARSONS 9, P.M. PATEL lo, J.D. PRENTICE 9, H.C.J. SEYWERD 9, J.D. SWAIN 9, G. TSIPOLITIS lo, T.-S. YOON 9, J.C. YUN ’ Institute ofParticle Physics ’ ‘, Canada R. AMMAR, D. COPPAGE, R. DAVIS, S. KANEKAL, N. KWAK University ofKansas , I2 Lawrence, KS 66045, USA B. BOSTJANCIC, G. KERNEL, M. PLESKO Institut J. Stefan and Oddelek zafiziko 13,Univerza v Ljubljani. 611 I I Ljubljana, Yugoslavia L. JijNSSON Institute of Phystcs 14,University oflund, S-22362 Lund, Sweden A. BABAEV, M. DANILOV, B. FOMINYKH, A. GOLUTVIN, I. GORELOV, V. LUBIMOV, V. MATVEEV, V. NAGOVITSIN, V. RYLTSOV, A. SEMENOV, V. SHEVCHENKO, V. SOLOSHENKO, V. TCHISTILIN, I. TICHOMIROV, Yu. ZAITSEV Institute of Theorettcal and Experimental Physics, 1 I7 259 Moscow, USSR R. CHILDERS, C.W. DARDEN, Y. OKU University of South Carolina “, Columbia, SC 29208, USA and H. GENNOW University of Stockholm, S-1 13 46 Stockholm, Sweden Q370-2693/87/$ 03.50 0 Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division) 101