Photoproduction of phi mesons on liquid hydrogen with polarized and unpolarized bremsstrahlung

Two experiments are reported. The first consists of the measurement of the differential cross sections for the process γp → phi p at photon energies from 6 to 19 GeV at fixed t value, t = -.6 (GeV/c)2, and at t values .2 < parallel bar t parallel bar < 1.2 (GeV/c)2 for a fixed photon energy of 12 GeV. The differential cross section results indicate that the process is very weakly dependent on energy and is consistent with energy independence. The second experiment consists of the measurement of the asymmetry parameter SIGMA for the process γp → phi p K+K- with diamond bremsstrahlung. This provides a test of the diffractive character of the production reaction. The measured asymmetry, SIGMA = +1.01 +- .14 is consistent with the hypothesis that the reaction proceeds diffractively