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

X-ray magnetic circular dichroism studies of magnetic 3d transition-metal s amples require the recording of high-quality absorption scans in high magne tic 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 vac uum. This technique is rendered problematic by the influence of the high ma gnetic field on the motion of the electrons emitted. Detection of the fluor escent X-rays avoids this problem and eases the constraints of sample prepa ration and environment. However, the specifications required for a successf ul X-ray detector are severe, requiring an insensitivity to magnetic fields up to 4 T (for hysteresis curve measurements), a large dynamic range, dete ction of soft X-rays with good efficiency and signal to noise and containme nt of the detector structure within a space of a few cm(3). Such a detector has been developed using gas microstrip technology and tests show that the se requirements can be met.