GUIDING HARD X-RAYS WITH GLASS POLYCAPILLARY FIBER

X rays can be guided through a polycapillary fiber by multiple total r eflections from the smooth channel walls of the fiber. Using monochrom atic synchrotron radiation at energies of 22 and 44 keV, we measured t he efficiency of transmission of X rays through polycapillary fibers w ith channel diameters of about 13 mum. Efficiencies of 57.3 and 54.5% for 22 and 44 keV X rays, respectively, were obtained with a 120-mm-lo ng straight polycapillary fiber aligned with the incident beam. These values are close to the open fraction of the fiber, which is about 60% . In addition, transmission efficiency was measured as a function of t he tilt angle between the incident beam and the axis of the fiber. We also measured the transmission efficiency as a function of the deflect ion angle for a 114-mm-long curved polycapillary fiber. The measuremen ts are compared with a ray-tracing simulation.