MEASUREMENT OF THE ELECTRIC AND MAGNETIC POLARIZABILITIES OF THE PROTON

The Compton scattering cross section on the proton has been measured a t laboratory angles of 90 degrees and 135 degrees using tagged photons in the energy range 70-100 MeV and simultaneously using untagged phot ons in the range 100-148 MeV. With the aid of dispersion relations, th ese cross sections were used to extract the electric and magnetic pola rizabilities, <(alpha)over bar> and <(beta)over bar> respectively, of the proton. We find <(alpha)over bar> + <(beta)over bar>=(15.0 +/-2.9/-1.1+/-0.4)x10(-4) fm(3), in agreement with a model-independent dispe rsion sum rule, and <(alpha)over bar> - <(beta)over bar>=(10.8+/-1.1+/ -1.4+/-1.0)X10(-4) fm(3), where the errors shown are statistical, syst ematic, and model-dependent, respectively. A comparison with previous experiments is given and global values for the polarizabilities are ex tracted.