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The Center for Bright Beams, A National Science Foundation Science and Technology Center

First Experimental Demonstration of Optical Stochastic Cooling

an image showing OSC, description in caption
Optical Stochastic Cooling uses a system of two undulators to cool a particle beam. The "Hot" beam, enters the pickup undulator where each particle emits a pulse of undulator radiation. The beam is passed through a chicane while the radiation travels straight through where it is focused and delayed. The two meet again in the kicker undulator where the radiation is reabsorbed by the particle in just the right way to reduce the momentum deviation. Over many turns around the ring, this effect builds up and cools the beam.

Stochastic Cooling (SC) has been used in storage rings for decades to produce smaller, brighter beams for collision experiments. Optical Stochastic Cooling (OSC) builds on the traditional microwave stochastic cooling by using shorter wavelengths. This could cool beams much faster than SC, because the cooling rate is related to the bandwidth, but is harder to realize because overlapping the shorter (optical) wavelengths with the beam requires much more precise control over the beam and the radiation. This paper outlines the technical requirements to successfully implement OSC and demonstrates many of the basic dynamics. The setup used in this experiment shows an increase in bandwidth ~2000x greater than traditional SC and also demonstrates a successful cooling scheme for all three (horizontal, vertical, longitudinal) degrees of freedom.

This is the first time Stochastic Cooling has been experimentally extended to the optical regime. Optical Stochastic Cooling promises faster cooling rates than traditional stochastic cooling but is more challenging to 
implement due, in part, to the shorter operating wavelength. This experiment shows that it is experimentally possible and lays the groundwork for a future amplified OSC experiment.

What overall goal of CBB does this result advance?

One major goal of the CBB is to increase the brightness of beams at the beam's final destination. OSC could help achieve this by reducing emittance and fighting intra-beam scattering. 

What potential applications could benefit from this advancement?  
OSC increases the quality of beams in storage rings. It can decrease the emittance of beams, producing brighter beams for light sources or colliders. It could also be used to increase beam lifetime by fighting different diffusive and scattering effects.

Citation:

J. Jarvis, V. Lebedev, A. Romanov, D. Broemmelsiek, K. Carlson, S. Chattopadhyay, A. Dick, D. Edstrom, I. Lobach, S. Nagaitsev, H. Piekarz, P. Piot, J. Ruan, J. Santucci, G. Stancari, and A. Valishev, “First Experimental Demonstration of Optical Stochastic Cooling,” arXiv:2203.08899 [physics], Mar. 2022, doi: 10.48550/arXiv.2203.08899. [Online]. Available: http://arxiv.org/abs/2203.08899