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The NMR signals of the nuclei 2 H, 35 C1, 37 C1, 79 Br and 81 Br have been investigated in aqueous solutions. The concentration dependence of the NMR si gnal s of 35 C1 and 81 Br has been determined in solutions of alkali hal i des and alkali Perchl orates in H20 and D20 and the l arge solvent isotope effect on the chemi cal shift has been established. The ratios of the Larmor frequencies of the halide nuclei relative to 2 H have been measured with high accuracy. Using the concentration dependence, the ratios of the Larmor frequencies of the hal i de nuclei for infinite dilution relative to 2 H in pure D20 are given. From these ratios, magneti c moments for the halide nuclei have been derived.

The pion-proton differential scattering cross sections have been measured at 150 and 170 Mev. Measurements were made at eight angles using scintillation counters and a liquid hydrogen target. Statistical errors are of the order 5 percent or less. Phase shift analyses of the data have been made on the assumption that the total isotopic spin is conserved and that only .? and p waves are appreciably scattered. The angular distributions give no positive indication of any d-wave scattering.

External meson beams, ranging in energy from 135 Mev to 260 Mev for the ir~, and 135 Mev to 198 Mev for the 7r + , have been used for the measurement of total cross sections by an attenuation experiment using liquid hydrogen as well as CH2 and C as absorbers. Possible errors introduced by contamination of the ir + beam by protons have been eliminated by use of time-of-flight and pulse-height discrimination. The corrected cross sections for iT mesons in hydrogen rise from 47 mb at 133 Mev to a maximum of about 66 mb near 180 Mev and fall thereafter to 38 mb at 258 Mev, with typical uncertainties of ±5 percent. The cross sections for ir + mesons rise from 122 mb at 128 Mev to around 200 mb between 170 Mev and 196 Mev, with accuracy comparable to that for the ir~ mesons except for the very high energies where the beams are of low intensity. The ir + cross sections follow very well the curve representing three times the total ir~ cross section, indicating that in the measured energy range the dominant interaction between pion and nucleon occurs for total isobaric spin 7=f. Comparison of the ir~ cross section with (8/3)7rX 2 supports the idea that the particular angular momentum state /= §, L-1 (for /= f) is especially prominent in the scattering.The total cross sections for TT + and if~ mesons interacting with deuterium have also been measured by comparing the transmissions of D 2 0 and H2O cells. Within the accuracy, the TT + and x~ total cross sections are equal, consistent with the principle of charge symmetry. The total scattering cross section of deuterium is less than but of the same order of magnitude as the sum of the hydrogen cross sections for TT + and ir~. DEFLECTING MAGNET SCALE IN FEETFIG.

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