Future Collider Options for the US

Abstract

The United States has a rich history in high energy particle accelerators and collidersboth lepton and hadron machines, which have enabled several major discoveries in elementary particle physics. To ensure continued progress in the field, U.S. leadership as a key partner in building next generation collider facilities abroad is essential; also critically important is the exploring of options to host a future collider in the U.S. The "Snowmass" study and the subsequent Particle Physics Project Prioritization Panel (P5) process provide the timely opportunity to develop strategies for both. What we do now will shape the future of our field and whether the U.S. will remain a world leader in these areas. In this white paper, we briefly discuss the US engagement in proposed collider projects abroad and describe future collider options for the U.S. We also call for initiating an integrated R&D program for future colliders.

Report of the Snowmass 2021 Collider Implementation Task Force

“…Overview: The "Site Filler" is a proposed circular e + e − collider in a very early development stage to be located on the FNAL site [54]. A schematic is shown below.…”

“…There are several proposals put forward for accelerators on the Fermilab site [54]. Among them is an ambitious idea to build a pp collider that will fit on the existing site.…”

Muon Collider Forum report

“…Currently rough dimensions of the facility have been identified and siting at CERN is being actively explored. An alternative siting at Fermilab is possible and is mentioned in [217].…”

Superconducting radio frequency linear collider HELEN

“…With the accelerating structures about 2 times longer than TESLA cavities, the fill factor of HELEN SRF linac increases to 80.4% and the collider will be 7.5 km long. As it is discussed in [42], there are three possible locations for a linear collider at Fermilab: two 7-km NE-SW orientations fitting diagonally on the site (figure 3 in [42]), and a 12-km footprint with N-S orientation extending outside Fermilab boundary, but with the Interaction Region (IR) remaining on site. Figure 12 show three possible sitings of HELEN collider on Fermilab site for the 250 GeV c.m.e.…”