Multiple Scattering of Fast Particles in Photographic Emulsions

The multiple scattering theory of Williams is applied to photographic emulsion techniques, and the "scattering constant" $K$, which is commonly used in determining particle energies from mean scattering deflections, is evaluated for various experimental conditions. For fast particles $K$ varies from 19 to 30 for scattering cell lengths between 10 and ${10}^4$ microns of emulsion. The scattering theories of Snyder and Scott and of Molière are also compared with that of Williams. The theories of Molière and Williams agree closely for both photographic emulsions and pure substances when the Molière $\gamma$-factor, covering the transition from the classical case to the Born approximation case, is introduced into Williams' theory. For fast particles the theory of Snyder and Scott agrees with the other theories within about 1 percent for most cases for the mean scattering angle between tangents.