Elastic Scattering Of Charged Pions From H-3 And He-3

We have measured the ratios of normalized yields for the elastic scattering of charged pions from H-3 and(3)He in the backward hemisphere. At T-pi=180 MeV, we have completed the angular distribution measured earlier, adding six new data points in the angular range from 119degrees to 169degrees in the pi-nucleus center of mass. We also measured an excitation function with data points at T-pi=142, 180, 220, and 256 MeV at the largest angle achievable with our detector-between 160degrees and 170degrees in the pi-nucleus center of mass. The data, taken as a whole, show an apparent role reversal of the two charge-symmetric ratios r(1) and r(2) in the backward hemisphere. For data greater than or equal to100degrees we observe a strong dependence of the ratios on -t, independent of T-pi or theta(pi). The superratio R data match very well with calculations based on the forward-hemisphere data that predict the value of the difference between the even-nucleon radii of H-3 and(3)He. Comparisons are also made with recent calculations incorporating different wave functions and double-scattering models.