A gas microstrip X-ray detector for application in magnetic circular dichroism experiments

X-ray magnetic circular dichroism studies of magnetic 3d transition-metal samples require the recording of high-quality absorption scans in high magnetic fields using circularly polarized soft X-rays of energies in the range 0.5-1 keV. Normally this is performed by electron yield measurements in vacuum. This technique is rendered problematic by the influence of the high magnetic field on the motion of the electrons emitted. Detection of the fluorescent X-rays avoids this problem and eases the constraints of sample preparation and environment. However, the specifications required for a successful X-ray detector are severe, requiring an insensitivity to magnetic fields up to 4 T (for hysteresis curve measurements), a large dynamic range, detection of soft X-rays with good efficiency and signal to noise and containment of the detector structure within a space of a few cm³. Such a detector has been developed using gas microstrip technology and tests show that these requirements can be met.