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Author(s): Shannon, S.R.; Anderson, L.; Bridgewater, A.; Chaffee, R.; Chamberlain, O.; Dahl, O.; Fuzesy, R.; Gorn, W.; Jaros, J.; Johnson, R.; Kenney, R.; Nelson, J.; O'Keefe, G.; Oliver, W.; Papp, J.; Pollard, D.; Pripstein, M.; Robrish, P.; Shapiro, G.; Steiner, H.; Wahlig, M.

Further work below the meson threshold using both protons and deuterons as targets is reported. Experimental and theoretical cross sections for scattering of photons bv hydrogen are plotted as a function of lab energy at a c.m. angle of 90 deg . The conclusions are: (1) the observed scattering of photons by protons at 9O deg c.m. over the energy range 0 to 300 Mev is described well by a model of the proton as a Dirac particle plus strong pion interactions giving the well-known 3/2, 3/2/sup +/ and 1/2, 3/2-- resonances, provided the half life of the no meson is greater than 10/sup -18/ second; (2) the scattering of photons by deuteron; below meson threshold is more than expected. (A.C.)

Data from two flights of a new superconducting magnetic spectrometer are reported. This instrument was capable of a direct matter-antimatter separation in the cosmic rays. Antimatter events would appear in the spectrometer as trajectories which curve in the opposite direction to common matter, because of their negative charge. A brief description of the equipment and of the characteristics of the instrument is presented, along with the data processing techniques used. A new upper limit on the amount of antimatter in primary cosmic rays has been established. The limits are considerably lower than those for any previous experiment.

This paper describes the design, calibration, and operation of a magnetic spectrometer for particle astronomy. The spectrometer consists of a superconducting magnet, optical spark chambers, scintillation detectors, and associated electronics. The instrument has been flown in a balloon gondola to 4.8 g/cm2 residual atmosphere, where it was used to analyze the charge and differential rigidity spectra of primary nuclei from 5 to 100 GeV/c.

The differential cross section for the reaction π − p→n π ° has been measured with high statistics at six incident beam momenta between 1.0 and 2.4 GeV/ c . The results are compared with predictions of recent phase shift analyses and forward dispersion relations.

A spark chamber consisting of eight coaxial cylindrical gaps around a liquid hydrogen target has been built and used. The sparks are viewed by a single camera looking axially up into the chamber. Stereo information is provided in the same view by reflections of the sparks from tilted mirrors at the top of the chamber.

The scattering of negative and positive pions by hydrogen in the laboratory energy range 470 to 1200 Mev was investigated in order to clarify the broad resonance occurring near 900 Mev. The target was five feet of liquid hydrogen. The experimental setup is described. and results are given. (W.D.M.)

The f/sup 0/ yields 2 pi /sup 0/ decay mode was observed in the reaction pi /sup -/ + p yields f/sup 0/ + n at an incident momentum of 10 Bev/ c. It is concluded that the f/sup 0/ has even spin and positive parity. (C.E.S.)

An upper limit of 0.50 (90% confidence level) is set for the branching ratio $\frac{(\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}+\ensuremath{\gamma}+\ensuremath{\gamma})}{(\ensuremath{\eta}\ensuremath{\rightarrow}\ensuremath{\gamma}+\ensuremath{\gamma})}$ in a spark-chamber experiment measuring ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}(n+4\ensuremath{\gamma} \mathrm{and} n+2\ensuremath{\gamma})$ at 10 BeV/c. This disagrees with a recent measurement of 0.90\ifmmode\pm\else\textpm\fi{}0.10 for the same ratio.