Polarization at TLEP/FCC-ee: ideas and estimates

TL;DR

This paper explores methods for achieving and estimating the polarization buildup at TLEP/FCC-ee, highlighting the potential of wigglers and Siberian Snakes to reach useful polarization levels within about an hour, depending on energy levels.

Contribution

It provides estimates and ideas for radiative polarization techniques at TLEP/FCC-ee, including the use of wigglers and Siberian Snakes for polarization at various energies.

Findings

Wigglers can achieve ~1 hour polarization buildup at W pair production threshold.

Polarization at Higgs production energies may be challenging in a planar ring.

Siberian Snakes and wigglers could enable polarization within about 1 hour at high energies.

Abstract

I examine various ideas for radiative polarization at TLEP/FCC-ee and formulate some estimates for the polarization buildup time and the asymptotic polarization. Using wigglers, a useful degree of polarization (for energy calibration), with a time constant of about 1 h, may be possible up to the threshold of $W$ pair production. At higher energies such as the threshold of Higgs production, attaining a useful level of polarization may be difficult in a planar ring. With Siberian Snakes, wigglers and some imagination, polarization of reasonable magnitude, with a reasonable time constant (of not more than about 1 h), may be achievable at very high energies.