A CRYSTAL MONOCHROMATOR FOR A LINEARLY POLARIZED X-RAY SOURCE UTILIZING CHANNELING RADIATION

The performance of a high transmission crystal monochromator to be use d as part of a source of linearly polarized X-rays of moderately narro w bandwidth in the energy regime of 10-50 keV has been investigated us ing channeling radiation produced by 86 MeV electrons from the superco nducting linear accelerator S-DALINAC at the Technische Hochschule Dar mstadt. Best results on monochromatic photon yields have been obtained with cylindrically bent silicon monocrystals in Laue and with planar mosaic crystals in Bragg geometry, respectively. At energies between 2 0 and 30 keV monochromatized X-ray intensities of up to 1.5 x 10(10) p hotons/(s sr mu A) have been obtained for axial channeling radiation f rom a 13 mu m thick silicon radiator crystal. The measured yields of n arrow band X-rays are such that an intense source of highly polarized planar channeling radiation could well serve to calibrate the linear p olarization sensitivity of a CCD polarimeter.