文摘
We have developed a new approach to characterize betatron X-ray radiation that is excited by the wiggling of relativistic electrons inside laser wakefield driven cavities. This approach can measure the average critical energy, E c , of the betatron radiation by using the reflection off a grazing incidence mirror (ROGIM). This technique relies on the reflectivity change of a high-Z-coated mirror with the grazing angle of incidence for the betatron X-rays. The average E c measured with this approach is in agreement with the one measured with a photon-counting X-ray CCD. This approach suggests that grazing incidence mirrors coupled to X-ray detectors can be used as online monitors of E c in betatron applications.