Speaker
Description
Photon-photon (γγ) Compton colliders offer compelling, high-efficiency pathways to explore the fundamental building blocks of matter without the technological bottlenecks associated with high-intensity positron sources and plasma-based positron acceleration. Furthermore, γγ Compton colliders operating in a narrow-band energy configuration can offer, in many circumstances, additional advantages for precision measurements and energy-frontier discovery. This presentation outlines the design concepts, advanced accelerator technologies, and physics capabilities of narrow band γγ colliders spanning precision Higgs factories to 10 TeV in the center-of-mass.
First, we review the conceptual design of the X-ray Free-Electron Laser (XFEL)-based γγ Compton collider (XCC) Higgs factory. Driven by cold copper distributed coupling (C$^3$) accelerator technology, XCC collides 62.8 GeV electron beams with 1 keV XFEL pulses to generate colliding beams of 62.5 GeV photons. The resulting sharply peaked γγ luminosity spectrum produces 75,000 Higgs bosons per 10$^7$ s year, yielding Higgs coupling measurements comparable in precision to $e^+ e^-$ colliders, with an upgrade path to 280 GeV for triple Higgs coupling studies. Issues of beamline layout, the machine-detector interface and backgrounds are addressed.
Extending the narrow-band approach to the 10 TeV frontier, we evaluate a high-geometric-luminosity configuration of a plasma wakefield $e^-e^-$ collider ($L_{e^- e^-}^{geo} =60\times 10^{35} $ cm$^{-2}$ s$^{-1}$) utilizing short-wavelength, 1 keV scattering lasers paired with 5 TeV electron beams. While optical/UV scattering ($\hbar\omega_0=2.5$ eV) leads to severe primary interaction region electromagnetic fields up to $6\times 10^{16}$ V/m that induce heavy beamstrahlung and coherent pair production, the 1 keV laser configuration mitigates these fields by over two orders of magnitude. This yields a clean, highly peaked luminosity spectrum with a partial 1.5% γγ luminosity of $L_{\gamma\gamma}^{1.5\%}=0.33\times 10^{35}$ cm^{-2} s$^{-1}$ and low pileup ($\langle\mu\rangle_{pileup}\approx 3.3$). Together, these designs demonstrate the unique physics and accelerator advantages of X-ray-driven Compton colliders from 125 GeV to 10 TeV.