Speaker
Description
The SLAC experiment 320 (E-320) collaboration is probing Strong-Field QED (SFQED), by colliding a $\sim 10\, \textrm{GeV}$ electron beam, generated by the FACET-II linear accelerator, with $\sim 10\, \textrm{TW}$ NIR laser pulses [1,2]. The main objectives of E-320 are: a) the investigation of the transition from the multiphoton to the strong background-field regime, where the laser can no longer be treated perturbatively, and b) the generation of electron-positron pairs through the nonlinear Breit-Wheeler mechanism in the deep tunneling regime [3,4].
In this talk, we will report our preliminary analysis of the experimental data obtained in the spring of 2024. We have clearly observed a strongly nonlinear Compton signal in the spectra of scattered electrons and an intensity-dependent redshift of the Compton edges, leading to a quasi-continuous, quantum-corrected synchrotron spectrum. Based on our preliminary estimates, we observed collisions with an averaged quantum nonlinearity parameter $\chi$ of at least 0.12, which implies that we have likely observed quantum radiation reaction [4].
[1] V. Yakimenko et al., Phys. Rev. Accel. Beams, 101301 (2019)
[2] S. Meuren (for the E-320 collaboration), talk at FACET-II PAC Meeting(2022)
[3] A. Fedotov et al., Phys. Rep. 1010, 1 (2023)
[4] A. Gonoskov et al., Rev. Mod. Phys. 94, 045001 (2022)
This work was supported by the U.S. Department of Energy under award DE-SC0020076. FACET-II is supported by the U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
