engleski

Elastic scattering of charged pions from 3^H and 3^He

We have measured the ratios of normalized yields for the elastic scattering of charged pions from 3H and3He in the backward hemisphere. At Tpi = 180 MeV, we have completed the angular distribution measured earlier, adding six new data points in the angular range from 119° to 169° in the pi-nucleus center of mass. We also measured an excitation function with data points at Tpi = 142, 180, 220, and 256 MeV at the largest angle achievable with our detector?between 160° and 170° in the pi-nucleus center of mass. The data, taken as a whole, show an apparent role reversal of the two charge-symmetric ratios r1 and r2 in the backward hemisphere. For data >=100° we observe a strong dependence of the ratios on ?t, independent of Tpi or thetapi. 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 3H and3He. Comparisons are also made with recent calculations incorporating different wave functions and double-scattering models.

elastic scattering

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