Proton-Proton Scattering at 3.4, 6.8, and 7.5 Mev

Using a gas target and photographic plates as detectors, absolute differential $p-p$ scattering cross sections in the angular range of 45° to 10° at 6.8 and 7.5 Mev were measured with an accuracy of two percent. The apparatus was checked by obtaining data at 3.4 Mev in the angular range of 15° to 45°. The data obtained at this energy range were in agreement with the precise Van de Graaff data. The 6.8- and 7.5-Mev data show that the $S$-wave cross sections at these energies are consistent with the extrapolation of the precise Van de Graaff data to this energy region. No indication of a $P$-wave effect was observed in either the low or high energy data.