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Laboratory Tests of Laser Control of Electron Beams for Future Colliders

Claire Munting, Peter Kicsiny, Edoardo Barbi, Noe Gonzalez, Spencer Gessner, Illya Drebot

TL;DR

The work addresses active control of electron-beam intensity and halo in future colliders through laser-based Compton backscattering (CBS) and laser collimation. It combines modeling with CAIN-XSuite integration to predict CBS interactions and scaling for FCC-ee, and describes the E344 experimental configuration at FACET-II, including laser parameters, optics, and diagnostics (electron-energy spectrometer, gamma-ray CBS diagnostics, and Beam Halo Monitor). The results outline expected energy losses and event yields, and establish a path to validate intensity control at the part-per-mille level, while laying groundwork for annular-laser colliders and future WarpX PIC simulations to guide collider design. This work provides a practical validation roadmap for non-destructive beam control techniques that could significantly improve luminosity stability in FCC-ee-like machines.

Abstract

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser-beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.

Laboratory Tests of Laser Control of Electron Beams for Future Colliders

TL;DR

The work addresses active control of electron-beam intensity and halo in future colliders through laser-based Compton backscattering (CBS) and laser collimation. It combines modeling with CAIN-XSuite integration to predict CBS interactions and scaling for FCC-ee, and describes the E344 experimental configuration at FACET-II, including laser parameters, optics, and diagnostics (electron-energy spectrometer, gamma-ray CBS diagnostics, and Beam Halo Monitor). The results outline expected energy losses and event yields, and establish a path to validate intensity control at the part-per-mille level, while laying groundwork for annular-laser colliders and future WarpX PIC simulations to guide collider design. This work provides a practical validation roadmap for non-destructive beam control techniques that could significantly improve luminosity stability in FCC-ee-like machines.

Abstract

Laser-driven Compton backscattering (CBS) has been proposed as method for controlling the intensity of colliding bunches in the FCC-ee so as to avoid the flip-flop instability caused by intensity asymmetry in colliding bunches. Laser-based collimation has also been proposed as an indestructible collimator for high-intensity electron beams. We have initiated a laboratory-based test program of these concepts with the E344 experiment at FACET-II. In this paper, we describe simulations of laser-beam interactions at FACET-II and the relevant scaling for FCC-ee. We also describe the experimental setup and diagnostics that will be used to make the measurements at FACET-II.
Paper Structure (6 sections, 3 equations, 4 figures, 1 table)

This paper contains 6 sections, 3 equations, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Compton Back Scattering
  3. Modeling in CAIN and XSuite
  4. Experimental Configuration
  5. Diagnostics
  6. Conclusion

Figures (4)

  • Figure 1: Top: $\beta_x$ and $\beta_y$ functions for this lattice section. Bottom: part of the final focusing section indicating the laser IP (black) and downstream OTR camera (red, "wdsotr").
  • Figure 2: Energy and horizontal (x) position after interaction with a $100\m\Joule$ laser after propagation through the FACET-II lattice. Energy is represented as a fractional deviation from the reference energy $p_0c=10\text{ GeV}$.
  • Figure 3: Schematic showing the E320 experimental layout inside the "picnic basket" chamber at FACET-II. The electron beam enters from the left and passes by the electro-optical sampling (EOS) crystal which provides femtosecond-scale timing information for beam-laser synchronization. The main laser pulse enters from the top left and is directed by mirrors M1 and M2 onto the electron beam trajectory. The laser pulse is back-reflected onto the electron beam by the off-axis parabola (OAP) mirror. The OAP assembly is retractable and shown in the "out" position in this schematic.
  • Figure 4: The BHM setup in the FACET-II tunnel at the WDSOTR location.