Transmission properties of the X-ray window for the SIXA spectrometer

The ultrathin X-ray entrance window for the spaceborne spectrometer SIXA was characterised using synchrotron radiation. X-ray absorption fine structure near the absorption edges of the constituting elements (aluminium, carbon, oxygen and nitrogen) was measured. Large scale positional variations were also studied. In addition, the opacity of the window was tested by observing the effect of photocurrent in the detector generated by light leaked through the window.