High-energy high-luminosity e+e− collider using energy-recovery linacs

Abstract

In this paper we present alternative approach for Future Circular electron-positron Collider. Current 100 km circumference design with the top CM energy of 365 GeV (182.5 GeV beam energy) is based on two storage rings to circulate colliding beams [1][2]. One of the ring-ring design shortcomings is enormous power consumption needed to compensate for 100 MW of the beam energy losses for synchrotron radiation. We propose to use energy recovery linac located in the same tunnel to mitigate this drawback. We show in this paper that our approach would allow a significant -up to an order of magnitude -reduction of the beam energy losses while maintaining high luminosity in this collider at high energies. Furthermore, our approach would allow to extend CM energy to 500 GeV (or above), which is sufficient for double-Higgs production.Introduction. The current ring-ring design of the Future Circular electron-positron Collider (FCC ee) (see [1][2][3]6] and references therein) aims to achieve the top CM energy of 365 GeV with a luminosity of 1.5-3x10 34 cm -2 s -1 using 100 MW of RF power compensating for the synchrotron radiation of the electron and position beams, which likely would result in a wall-plug AC power of 200MW. At lower energies, with the same level of RF power, the FCC ee luminosity would grow approximately as E -3.6 . While the ring-ring FCC ee promises a very high luminosity of 4.5x10 36 cm -2 s -1 at CM energy of 91.3 GeV, it drops more than two orders of magnitude to 3x10 34 cm -2 s -1 at CM energy of 365 GeV.

Prospects for direct CP tests of hqq interactions

“…e + e − collider [25] that would produce five times the instantaneous luminosity of the FCCee and would run for the same duration as the FCC-hh. With the resulting 200 ab −1 of integrated luminosity in each of four detectors, and the e + e − → Zh cross section of 200 fb [24], a similar number of Higgs bosons would be produced as for the FCC-hh h ν and h processes.…”

Higgs Physics

“…At FCC, the current baseline strategy to access to double Higgs production is to not upgrade the energy FCC-ee to 500 GeV, but to move to proton-proton collisions at the much higher energy of 100 TeV (see Section 3.2). It has been recently realised, however, that FCC-ee could be, as an intermediate step towards FCC-hh, upgraded with the Energy-Recovery Linacs (ERL) technology, to reach an energy of 600 GeV with a luminosity 5 to 50 ab −1 in 10 years of operation with one interaction point [89]. With such a luminosity, up to ten times that expected at a linear collider at the same energy, a measurement of the Higgs self-coupling with a 10% precision can be contemplated as well.…”

Accelerators for HEP: Challenges and R&D

“…Many innovative accelerator concepts are now under active exploratory studies. Among them are: i) Energy Recovery Linac (ERL) based FCCee [34] assumes 100 km long 240 GeV cme + − collider, that brings particles' energies up in just several turns employing 60 GeV per turn SRF accelerating sections and promises some 3-10 times less RF power per ab −1 of luminosity than the FCCee; main challenges of such approach are the need for generation and control of very small beam emittances as well as strong beam-beam effects; ii) ERL-based LHeC (or FCCeh) [35] also seeks acceleration of electrons in three turns to 30-60 GeV by SC RF sections in a new 6 km tunnel to collide with the LHC/FCCpp protons and deliver (1 ab −1 ) of luminosity at 1.2/3.2 TeV c.m.e. ; extensive tests of the ERL technology are planned at the PERLE facility at Orsay; iii) − Higgs Factories [36] require collisions of only 80 GeV − for the Higgs production, but require further R&D on the design of such recirculating linear accelerator facilities, on the high power lasers, etc; iv) in the Gamma-Factory concept [37] collision of high intensity laser with the LHC ions results in generation of (1 GeV) 's, positrons and muons; following recent proof-of-principle demonstration, possibilities of significantly higher fluxes are being considered.…”