Search for Violation of Time-Reversal Invariance in Inelastice−pScattering

Abstract

Electrons have been scattered inelastically from a hydrocarbon target containing protons polarized normal to the scattering plane. Scattered electrons with energies corresponding to the production of the $\Delta \mathrm{}\left(1236\right)\mathrm{}$, $N\left(1512\right)\mathrm{}$, and $N\left(1688\right)\mathrm{}$ pion-nucleon resonances were observed. A search was made for changes in the cross section as the target polarization was reversed. Any changes would have been evidence of a violation of time-reversal invariance in the electromagnetic interactions of the hadrons. No such changes were observed. With the maximum time-reversal-violating effect possible, the asymmetry would be 10 times the upper limit of this experiment. Early attempts at a coincidence-polarization experiment are described in an appendix.