SLAC -PUB-1707 January 1976 (E) MEASUREMENTS OF EXCLUSIVE PHOTOPRODUCTION PROCESSES AT LARGE VALUES OF t AND u FROM 4 TO 7.5 GeV*

Exclusive photoproduction cross sections have been measured for the processes y p Ir+n, yp ++ +?r’p, -ypdnA , YP’ POP, and Y P at large t and u values at several energies for each process between 4 and 7.5 GeV. These measurements taken together with past data taken at small values of t and u provide complete angular distributions. The data show the usual small t and u peaks and a central region dropping as approximately -‘/ s . The results are discussed within the context of parton or constituent models 0 (Submitted to Phys. Rev. D. ) *Work supported by the U. S. Energy and Research Development Administration. **Present address: CEN Saclay, BP2, 91190, Gif-sur-Yvette, France. ?‘Present address: Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213. f?Present address: U. S. Geological Survey, Menlo Park, California 94025.