Characteristics of the Compton Modified Band

Abstract

The shapes of Compton modified bands have been calculated for all scattering elements from hydrogen to argon. These shapes vary periodically with atomic number, atoms with one-valence electron being characterized by sharp, narrow lines while atoms with completed electron shells produce broadly rounded bands. Experimental results, though incomplete, confirm these variations except as to absolute breadth. Breadths of observed modified bands exceed calculated breadths on the average by 75 percent for carbon scatterers and 140 percent for beryllium. Variation of scattering angle has only a second-order effect upon the observational breadth of wide modified bands. To an accuracy of about 10 percent the intensity ratio of modified to unmodified radiation from carbon (graphite) scatterers is found to agree with predictions based upon the Wentzel-Waller theory of scattering by bound electrons for wavelengths in the range 435 X.U. to 710 X.U. and scattering angles between 27 and 139°. Though previous measurements showed the magnitude of the wave-length shift of the maximum in the modified band to be less than that given by the Compton equation it is now argued that present theory predicts a still smaller shift.