Elastic scattering of hadrons on protons has been measured at momenta of 50, 100, and 200 GeV/c. The meson-proton scattering is found to be independent of momentum and meson type fort > 0.8 (GeV/c)'.The momentum dependence of the pp dip att = 1.4 (GeV/c)' was investigated. Slope parameters are given.

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A resonance is observed in the diffractively photoproduced two-pion final state with a mass of ~ 1600 MeV and a width of ~ 300 MeV. The four-pion distribution is characterized by a width of ~ 600 MeV and peaks around 1500 MeV.The p'(1600) meson has been observed as an enhancement in the four-pion final state both in e + e~ collisions 1 and in photoproduction experiments. 2 "" 5 Estimates of the mass vary from 1430 to 1620 MeV, while estimates of the width vary from 310 to 650 MeV. A nonresonance interpretation of the photoproduction data as a purely kinematic enhancement in the pmi production amplitude also appears to describe these data adequately. 6 Indications of the existence of the two-pion decay mode have come from two photoproduction experiments 5 ' 7 and from a phase-shift analysis of the reaction n~p -+ir + Ti~n. 8 It has been assumed that the branching ratio of p'(1600) into two pions is small, although no published measurement of this number exists.We report here on a study of high-mass twoand four-pion final states photoproduced in the wide-band neutral beam at Fermilab. 9 Our expo-sure consisted of approximately 6 xlO 11 photons with energies greater than 50 GeV incident on a 2-cm-long (5% of a radiation length) scintillator target. The products of the interactions in the target were detected in the multiparticle spectrometer system described in Ref. 9. Two Cherenkov counters with pion thresholds of 6 and 12 GeV were used for particle indentification. A large lead-glass array detected y rays accompanying the charged particles. Two-pion events were recorded under a trigger designed to accept e + e~ pairs. The trigger had a finite efficiency for 7r + 7r pairs; however, uncertainties in the calculation of this efficiency result in a relatively large uncertainty in the absolute normalization for 77 + 7T states. Four-pion events were recorded under a trigger requiring at least three tracks in the spectrometer and a minimum energy deposition of 40 GeV in the hadron calorics)