Optical Stochastic Cooling at Fermilab's IOTA Ring

Stochastic cooling (SC) constitutes one of the greatest conceptual and technological achievements in particle beam cooling. Numerous SC systems have been built in the microwave regime and used to extend the science reach of accelerator facilities worldwide. The ability to sense and correct the particle ensemble using high-bandwidth feedback systems is at the core of the concept. Here we describe the first realization of SC at optical frequencies and bandwidths. The demonstration was recently carried out at Fermilab’s Integrable Optics Test Accelerator (IOTA) storage ring using the transit-time method of Optical Stochastic Cooling (OSC) and achieved an integrated system bandwidth of approximately 20 THz, which is more than 2,000-times that of conventional SC systems. This demonstration establishes the foundation for more advanced OSC experiments with high-gain amplification, currently underway at Fermilab, and the eventual application of OSC to colliders and other accelerator facilities.