Summary of Discussion Question 4: Energy Expandability of a Linear Collider

TL;DR

This paper reviews the potential for increasing the energy reach of linear colliders from 500 GeV up to multi-TeV levels, discussing hardware designs, upgrade plans, and innovative acceleration techniques.

Contribution

It provides a comprehensive synthesis of current plans and technological options for expanding the energy capabilities of linear colliders beyond initial designs.

Findings

Current designs reach 500 GeV

Plans to upgrade to 800-1000 GeV

Two-beam acceleration approach for multi-TeV energies

Abstract

We report on Discussion Question 4, in Sub-group 1 (`TeV-class') of the Snowmass Working Group E3: `Experimental Approaches: Linear Colliders', which addresses the energy expandability of a linear collider. We first synthesize discussions of the energy reach of the hardware of the 500 GeV designs for TESLA and NLC/JLC. Next, we review plans for increasing the energy to 800-1000 GeV. We then look at options for expanding the energies to 1500 GeV and sketch the two-beam accelerator approach to achieving multi-TeV energies.