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An Interaction Region for Gamma-Gamma and Gamma-Electron Collisions at TESLA/SBLC

R. Brinkmann, I. Ginzburg, N. Holtkamp, G. Jikia, O. Napoly, E. Saldin, E. Schneidmiller, V. Serbo, G. Silvestrov, V. Telnov, A. Undrus, M. Yurkov

TL;DR

<3-5 sentence high-level summary> The paper analyzes a dedicated photon-collider interaction region for gg and ge collisions at TESLA/SBLC, enabled by laser backscattering to convert electrons into high-energy photons. It compares two collision schemes (with and without magnetic deflection) and optimizes laser parameters, optics, and beam properties to achieve substantial high-energy luminosities while mitigating backgrounds. The study details Higgs and electroweak physics opportunities, top-quark and beyond-Standard-Model searches, and hadron/QCD studies achievable with gg/γe modes, providing ultimate luminosity projections under increasingly favorable emittance and laser-technology scenarios. It also surveys laser technologies (solid-state CPA and FEL) and forward-looking enhancements (multi-stage FEL amplifiers) to realize the required high-power, high-repetition-rate photon beams for a viable photon collider at a linear accelerator.

Abstract

Linear colliders offer unique opportunities to study gamma-gamma (gg), gamma-electron (ge) interactions. Using the laser backscattering method one can obtain gg, ge colliding beams with an energy and luminosity comparable to that in e+e- collisions. This work is a part of the Conceptual Design of TESLA/SBLC linear colliders describing a second interaction region for gg, ge collisions. We consider here possible physics in high energy gg, ge collisions, e -> g conversion, requirements to lasers, collision schemes, attainable luminosities, backgrounds, possible lasers, optics at the interaction region and other associated problems.

An Interaction Region for Gamma-Gamma and Gamma-Electron Collisions at TESLA/SBLC

TL;DR

<3-5 sentence high-level summary> The paper analyzes a dedicated photon-collider interaction region for gg and ge collisions at TESLA/SBLC, enabled by laser backscattering to convert electrons into high-energy photons. It compares two collision schemes (with and without magnetic deflection) and optimizes laser parameters, optics, and beam properties to achieve substantial high-energy luminosities while mitigating backgrounds. The study details Higgs and electroweak physics opportunities, top-quark and beyond-Standard-Model searches, and hadron/QCD studies achievable with gg/γe modes, providing ultimate luminosity projections under increasingly favorable emittance and laser-technology scenarios. It also surveys laser technologies (solid-state CPA and FEL) and forward-looking enhancements (multi-stage FEL amplifiers) to realize the required high-power, high-repetition-rate photon beams for a viable photon collider at a linear accelerator.

Abstract

Linear colliders offer unique opportunities to study gamma-gamma (gg), gamma-electron (ge) interactions. Using the laser backscattering method one can obtain gg, ge colliding beams with an energy and luminosity comparable to that in e+e- collisions. This work is a part of the Conceptual Design of TESLA/SBLC linear colliders describing a second interaction region for gg, ge collisions. We consider here possible physics in high energy gg, ge collisions, e -> g conversion, requirements to lasers, collision schemes, attainable luminosities, backgrounds, possible lasers, optics at the interaction region and other associated problems.

Paper Structure

This paper contains 31 sections, 31 equations, 26 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Physics at $\gamma\gamma$, $\gamma$e collider
  3. Introduction
  4. Higgs boson physics
  5. Measurements of the Higgs boson couplings.
  6. The discovery of the Higgs boson.
  7. Gauge boson physics
  8. Physics of t--quarks
  9. The new physics
  10. Hadron physics and QCD
  11. Conversion region
  12. Optimization of laser parameters, conversion efficiency
  13. Low energy electrons after conversion.
  14. Interaction region
  15. Collision schemes
  16. ...and 16 more sections

Figures (26)

  • Figure 1: Scheme of a $\gamma\gamma$; $\gamma$e collider.
  • Figure 2: The cross sections of some processes in $\gamma\gamma\,$ and $\gamma$e collisions.
  • Figure 3: Comparison of cross sections for charged pair production in e$^+$e$^-$ and $\gamma\gamma$ collisions. The cross section $\sigma =(\pi\alpha^2/M^2)f(x)$, P=S (scalars), F (fermions), W (W-bosons); M is particle mass, $x=W_{p\bar{p}}^2/4M^2$. The functions $f(x)$ are shown.
  • Figure 4: Spectrum of the Compton scattered photons for different polarizations of the laser and electron beams.
  • Figure 5: Mean helicity of the scattered photons.
  • ...and 21 more figures