Brian Schaap (UCLA): Superradiant Inverse Compton Scattering: Theory, Experiment, and Future Frontiers

Monday 2 Mar 2026, 12:45 → 14:00 US/Eastern

D-122 (SBU Physics building)

Elizabeth Worcester, Valerio Dao (Stony Brook University)

Compact light sources offering high-brightness radiation in the X-ray spectral range regime are highly desired for a wide range of scientific and technological applications. A promising approach is Inverse Compton Scattering (ICS) from relativistic electrons colliding with a laser pulse, which allows for the use of university-scale accelerators. Unfortunately, the brightness of typical Compton sources remains small compared to large-scale facilities due to the small cross-section and the large opening angle of the emission. This seminar presents novel pathways to overcome these limitations.

First, utilizing a shallow-angle scattering geometry, instead of a conventional head-on collision, increases brightness with spectral control independent of electron beam energy. Recent experimental breakthroughs at the UCLA Pegasus laboratory, including the demonstration of shallow-angle ICS and the observation of the relativistic Brewster effect will be discussed.

Building upon the flexibility of geometric tuning, the source can be driven into the superradiant regime by spatially structuring the electron beam at the scale of radiation wavelength. The realization of superradiant ICS, scaling quadratically with the number of electrons, promises an orders-of-magnitude increase in photon yield. Efforts to demonstrate superradiance at UCLA by compressing electron bunches to sub-femtosecond timescales are presented, highlighting the advanced longitudinal phase-space diagnostics developed to measure them. Then, the experimental roadmap for employing inverse free electron laser bunching to generate attosecond extreme ultraviolet pulses at the BNL Accelerator Test Facility is outlined.

Finally, I will briefly discuss research frontiers, including nonlinear superradiant Compton scattering, generalized superradiance, and quantum collective effects.  

Schaap_seminar_SBU.pdf

Videorecording (SBU-internal)

12:45 → 13:30 TBC