Photon Masks for the ILC Positron Source with 175 and 250 GeV Electron Drive Beam

TL;DR

This paper analyzes photon mask design for the ILC positron source at 175 and 250 GeV electron energies, focusing on power deposition limits to optimize undulator performance.

Contribution

It provides a detailed study of power deposition along photon masks for different ILC energy configurations, aiding in effective mask design.

Findings

Power deposition is within acceptable limits with proper mask placement.

Optimal mask design varies between 350 and 500 GeV configurations.

The study informs the placement and specifications of photon masks for future ILC upgrades.

Abstract

In the future the International Linear Collider (ILC), a helical undulator-based polarized positron source, is expected to be chosen. A high energy electron beam passes through a superconducting helical undulator in order to create circularly polarized photons which will be directed to a conversion target, resulting in electron-positron pairs. The resulting positron beam is longitudinally polarized. Since the photons are produced with an opening angle and pass through a long superconducting helical undulator, some of these photons will strike the undulator walls. Therefore photon masks must be placed along the undulator line in order to keep the power deposited in the undulator walls below the acceptable limit of 1W/m. The baseline design of the ILC is focused on 250 GeV center-of-mass energy and upgrade to center-of-mass energies of 350 and 500 GeV is foreseen. This paper shows a detailed study of the ideal power deposited along the masks for both 350 and 500 GeV center-of-mass energies.