Fine Structure in the Compton Effect

Abstract

This is a continuation of two crystal analyses of fine structure in scattered radiation. The displaced scattered radiation from carbon (pure graphite) and beryllium was investigated. A special x-ray tube was constructed with the scattering element near the target. The tube was mounted so that the scattering angle $\ensuremath{\theta}$ was large. The tube operated at 3200 watts.Fine structure in the displaced scattered radiation from carbon.---The angle of scattering $\ensuremath{\theta}$ was 155\ifmmode^\circ\else\textdegree\fi{}. The displaced radiation has fine structure as follows going toward long wave-lengths: A relatively strong line 0.0421A from Mo $K{\ensuremath{\alpha}}_{1}$ position, and three weaker lines at 0.0012A, 0.002A and 0.0109A from the strong line. These agree closely with fine structure lines previously found by Bergen Davis and D. P. Mitchell. The two pictures are alike, but the displaced one is shifted 0.0421 from the undisplaced. The displacement is less than is to be expected from $d\ensuremath{\lambda}=0.0243(1\ensuremath{-}cos\ensuremath{\theta})$. Our results give $d\ensuremath{\lambda}=0.022(1\ensuremath{-}cos\ensuremath{\theta})$. This is 9 percent less than is to be expected from theory. Errors could not be so great as this.Fine structure in the displaced scattered radiation from beryllium.---Displaced scattering investigated at $\ensuremath{\theta}=163\ifmmode^\circ\else\textdegree\fi{}$. A strong main line was found at 0.0446A=0.0228 ($1\ensuremath{-}cos\ensuremath{\theta}$) from Mo $K{\ensuremath{\alpha}}_{1}$ position. A line at 0.0051A toward the long wave-lengths from this main line. This displacement is near the value to be expected from Be $K$ energy level. A weak line at 0.0009A toward short wave-lengths from main line. These two lines were found by D. P. Mitchell in the undisplaced scattering from beryllium and were ascribed to the $K$ and ${L}_{1}$ energy levels of Be. The ${L}_{1}$ line, however, was shifted 0.00058A, which is much less than the 0.0009A found here in the displaced spectrum.