Observation of X-ray Raman, Compton and plasmon scattering using a position sensitive proportional counter

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Abstract
Using a combination of a curved crystal analyser and a position sensitive detector the authors demonstrate how an energy resolution of a few eV in the energy range of 10 keV can be achieved without suffering a prohibitive loss in the observed intensity. An experimental set-up is described in which spectra from Raman, Compton and plasmon scattering can be collected in a matter of hours using monochromatic CuK alpha 1 radiation from a 1.0 kW X-ray generator. After scattering in either a Be or a graphite target, the X-rays were reflected from the (333) planes of a curved Ge crystal and brought to a focus on a position sensitive proportional counter. The measurements on pyrolitic graphite confirm earlier reports of a striking anisotropy in the spectral distribution of the scattered X-rays, depending upon the direction of the experimental scattering vector relative to the basal planes in this layered crystal. The anisotropy arises from the strong directional dependence of the cross section for plasmon excitation in graphite. Some straightforward improvements to the present apparatus would lead to an increase in the observed intensity by a factor of 40 or more.