Energy Dependence of Backwardπ+pElastic Scattering from 2 to 6 GeV/c

The energy dependence of backward ${\pi }^{+}p$ elastic scattering has been measured for incident $\pi$ momenta 2.0-6.0 GeV/c in steps of typically 100 MeV/c. Values are presented for both the differential cross section extrapolated to 180° and the slope of the backward peak as a function of momentum. In the $s$ channel we see the effects of the established ${\Delta }^{++}$ resonances and evidence for the $\Delta \mathrm{}\left(3230\right)\mathrm{}$. Also, the data show the existence of a negative-parity $\Delta$ resonance with mass ∼2200 MeV/${\mathit{c}}^2$.