Some embodiments of the present disclosure provide a method that includes colliding a laser with an electron beam to produce backscattered x-rays while the electron beam is traversing a circular arc. This backscattering process is inverse Compton scattering (ICS). ICS x-rays are emitted in the same direction as the electrons. Because this ICS direction is changing as a function of time, the position of the x-ray beam on a detector will change depending on the timing of electron/laser collision. This position change is easily detected and converted to a timing measurement sensitive at the femtosecond scale, converting a very difficult timing measurement of laser pulse, electron pulse, and x-ray pulse synchronization into a simple and robust position measurement.