Proton-Proton Scattering at Low Energies

The analyzing power in proton-proton scattering has been measured at bombarding energies of 5.05 and 9.85 MeV to an accuracy of ±5×${10}^{-5\mathrm{}}$. The measurements were combined with existing cross-section data to obtain model-independent $S$- and $P$-wave phase shifts at these energies. In addition, the first experimental determination of the $P$-wave scattering lengths and effective ranges is reported. These are compared to model values and their use in obtaining improved $S$-wave parameters is suggested.