Panofsky Ratio for Negative Pions Absorbed in Hydrogen

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Abstract
The ratio of mesonic to radiative capture of stopped negative pions in hydrogen, i.e., the Panosfky ratio, provides a useful link in analyzing the results of photoproduction of pions and pion-nucleon scattering. Previous measurements of the Panofsky ratio indicate possible systematic errors in the experimental techniques. The ratio has been remeasured using (a) a lead glass Čerenkov counter of improved resolution to measure the total energy of the gamma rays (±16% for the 129-Mev gamma rays measured in this experiment), (b) time-of-flight measurement of the 180 degree recoil neutrons to determine the shape of the pulse-height spectrum of the high-energy gamma ray, and (c) a collimator of variable dimensions to test the possible effect of degradation of the high-energy gamma rays in the collimator. The value obtained for the ratio is 1.46±0.10, in good agreement with the Liverpool experiments.