Volume 100B, number 5 PHYSICS LETTERS 16 April 1981 A SEARCH FOR THE S(1936) IN 100 GeV pBe INTERACTIONS The ACCMOR Collaboration C. DAUM, L.O. HERTZBERGER, W. HOOGLAND, R. JONGERIUS, J.C. KLUYVER, G. POLOK 1, W. SPIERENBURG, H. T1ECKE and L. WlGGERS NIKHEF.H, Amsterdam, The Netherlands D.G. BARDSLEY, J. MALOS, R.J. TAPPER and R.J. WHYLEY University of Bristol, Bristol, England M. BOSMAN, M. CERRADA, V. CHABAUD, B. HYAMS, J. VERMEULEN, P. WEILHAMMER and A. WYLIE CERN, Geneva, Switzerland A. DWURAZNY, Z. HAJDUK, M. R()ZA/(ISKA, K. RYBICKI and M. TURALA Institute of Nuclear Physics, Cracow, Poland G. BLANAR, W. BLUM, H. DIETL, W. FAISSLER 2, L. GORLICH, R. KLANNER, E. LORENZ, G. LUTJENS, G. LUTZ, W. M,~NNER, A. PUGL, T. SANFORD and U. STIERLIN Max-Planck-lnstitut far Physik und Astrophysik, Munich, Fed. Rep. Germany R. BAILEY, C. DAMERELL, D. GIDDINGS, A. GILLMAN, C. HARDWICK 3, P. SHARP and F. WICKENS Rutherford Laboratory, Chilton, England Received 12 February 1981 A search for the S (1936) has been made in the invariant mass spectrum of ~p-pairs produced inclusively in proton- beryllium interactions at 100 GeV incident momentum. No enhancement is observed, giving a 3 standard deviation upper limit on the cross section of 220 nb/nucleon for production of a narrow 15p state around ~ 1940 MeV in the XF range 0.18 < x F < 0.48. 1. Introduction. In a previous experiment [ 1 ], with the WA 3 spectrometer, a narrow enhancement (P ~< 10 MeV) was observed at 1940 MeV in the invariant mass spectrum of 15p-pairs produced inclusively in the reac- tion 1 On leave from the Institute of Nuclear Physics, Cracow, Poland. z On leave from North Eastern University, Boston, USA. 3 Now at NIKHEF-H, Amsterdam, The Netherlands. pp ~ 15p + X. The incident beam momentum was 93 GeV; the range in Feynman x (x F = 2PL/X/~ ) 0.18 < x F < 0.48. The enhancement seen was about a 40 effect, the mass and narrow width suggested that it might be identified with the S(1936), a structure seen in various tSp-formation experiments [2] and a strong candidate for "baryonium". In view of the great interest in this possible exotic 0 031-9163/81/0000-0000/$ 02.50 © North-Holland Publishing Company 439