XCC: an X-ray FEL-based γγ Compton collider Higgs factory

• Published in: Journal of instrumentation 2023-07, Vol.18 (7), p.P07028
• Main Authors: Barklow, T., Emma, C., Huang, Z., Naji, A., Nanni, E., Schwartzman, A., Tantawi, S., White, G.
• Format: Article
• Language: English
• Subjects: Accelerator Subsystems and Technologies; Bosons; Center of mass; Coupling; Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Electron beams; Free electron lasers; Higgs bosons; Laser beams; Particle accelerators
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/18/07/P07028

This report describes the conceptual design of a   γγ Higgs factory in which 62.8 GeV electron beams collide with 1 keV X-ray free electron laser (XFEL) beams to produce colliding beams of 62.5 GeV photons. The Higgs boson production rate is 80,000 Higgs bosons per 10 7 second year, roughly the same as the ILC Higgs rate at √ s = 250 GeV. The electron accelerator is based on cold copper distributed coupling (C 3 ) accelerator technology. Unlike the center-of-mass energy spectra of previous optical wavelength γγ collider designs, the sharply peaked γγ center-of-mass energy spectrum of XCC produces model independent Higgs coupling measurements with precision on par with e + e - colliders. For the triple Higgs coupling measurement, the XCC center-of-mass energy can be upgraded to 380 GeV, where the cross section for   γγ → HH is twice that of   e + e - → ZHH at √ s = 500 GeV. Design challenges are discussed, along with the R&D to address them, including demonstrators.