A helicity resolving soft X-ray emission spectrometer for studying magnetic circular dichroism with laboratory excitation sources

We have constructed a helicity resolving soft X-ray emission (SXE) spectrometer. By using the effect of magnetic resonant (anomalous) scattering from an iron interface we achieved helicity sensitivity in the wavelength region around the L-edge. The instrument features a magnetic Codling-slit that replaces the ordinary entrance slit of an already existent SXE grating-spectrometer of proven design retaining high efficiency. A calibration method for the spectral response-curve of the instrument is devised, using the output of circularly polarized X-rays of a storage ring bending magnet. Once the instrument has been calibrated, helicity resolved SXE spectroscopy allows one to study magnetic samples using a laboratory excitation source, e.g. an electron gun.