Experiments on the Wave-lengths of Scattered X-Rays

Abstract

Intensity distribution of scattered x-rays as a function of wave-length.—(1) Molybdenum rays. Specially built tubes enabled the radiators to be placed only 1.6 cm from the target, so that reliable measurements were obtained from small radiators. An ionization spectrometer (methyl iodide) with a calcite crystal was used. For Li and Al, curves are given for various scattering angles. The results are similar to those obtained by previous observers for carbon, the shift of the maximum intensity of the modified band agreeing with the theory of A. H. Compton. Simultaneous irradiation by two x-ray tubes permitted scatterers to be employed that were small enough to allow a fairly accurate estimate of the width of the modified band. This width (for lithium) was thus found to be greater than that permitted by Compton's equation. The curves obtained show that the intensity of the unshifted line relative to the general radiation is less in the scattered spectrum than when obtained direct from the target of the tube. Less detailed experiments with Be, C, Na, NaCl, Mg and S are in agreement with the theory as far as shift is concerned and show that the relative intensity of the modified band decreases as atomic number increases. (2) Tungsten rays. In this case the radiator could not be placed nearer than 10 cm, so less reliable results were obtained. However the shifts are in general agreement with theory.