Single Shot Bunch Length Monitoring, Based on Interferometer and Novel THz Sensing

With the recent development of advanced photoinjector accelerators and next generation light sources, the progression towards high-current, ultra-short beams is very important. The knowledge of the longitudinal profile and bunch length of the short pulses is necessary for performance optimization and benchmarking to computational models. Thus, in order to achieve successful beam operation, it will be essential to measure these short pulses in a single-shot, in real time, and with sub-picosecond time resolution. This project will develop a real-time bunch-length interferometer utilizing a novel beam autocorrelation technique. In this approach, the interference of the beam with itself takes place on the plane of a terahertz detector array; the spatial interference is correlated to the horizontal position along the array. Phase I consisted of theoretical calculations and modeling of coherent radiation sources typical of accelerator facilities, and the design of an interferometer scheme efficient in the terahertz regime. Laboratory testing and a detector survey also were conducted. Commercial Applications and Other Benefits as described by the awardee: The real-time interferometer would be of great use to the accelerator community. In addition, the real time interferometer could be incorporated into a feedback loop to lock the bunch length of the beam, thus guaranteeing consistent parameter sets for Free Electron Laser, Compton Scattering, and collider facilities. Finally, the technology should have numerous applications in the growing field of terahertz radiation creation and imaging.