Impact of high Q on ILC250 upgrade for record luminosities and path toward ILC380

TL;DR

This paper evaluates the feasibility and costs of upgrading the ILC250 to higher luminosity and energy levels, comparing it with FCC-ee and outlining future upgrade paths.

Contribution

It provides a detailed cost and power analysis for upgrading ILC250 to high luminosity and higher energy, including the impact of quality factor Q on costs.

Findings

ILC250 upgrade cost is approximately 2.2 billion ILCU for high luminosity.

The high luminosity upgrade is cost-effective compared to FCC-ee.

The proposed upgrades are compatible with future energy enhancements.

Abstract

In this paper, we address the possibility of upgrading the ILC250 luminosity to $8.1 \times 10^{34}$, so that with the polarization feature, the effective luminosity will be $2.0 \times 10^{35}$ to compete with the FCC-ee luminosity and two detectors. The additional cost of the higher luminosity option will be about 2.2 B ILCU. The total cost for the ILC high luminosity machine will therefore be about 7.7 B versus FCC-ee 10.5 B. The AC power (267 MW) to operate the ILC luminosity upgrade will also be less than the AC power for FCC-ee (300 MW). Even with a modest quality factor Q of $1 \times 10^{10}$ for SRF cavities, the total cost of the upgrade will be 2.5 B ILCU additional over ILC250 baseline. We expect that, if approved, ILC250 will first be built at the baseline luminosity, operated for many years at this luminosity, and later upgraded to the high luminosity option. A significant part (RF power and cryo-power) of the additional cost for the luminosity upgrade overlaps with the expected additional costs for anticipated energy upgrade paths. A second ILC upgrade discussed in this paper will be to the higher energy Top Factory at 380 GeV. We also estimate the additional cost of this upgrade (1.5 B ILCU).