Scattering of 3.7-25 Mev Positive Pions by Hydrogen

The Columbia University hydrogen bubble chamber was used to investigate the ${\pi }^{+}-p$ scattering cross section in a laboratory energy range from 3.7 to 25 Mev. A total of 950 events were measured, of which 338 were caused by incident pions that would have come to rest in the chamber. Treating the small $p$-wave and large Coulomb contributions as known, the $s$-wave phase shift is found to deviate from a linear dependence on momentum only by one and a half standard deviations.