A Monte-Carlo simulation of the equilibrium beam polarization in ultra-high energy electron (positron) storage rings

TL;DR

This paper presents a Monte-Carlo simulation method for predicting equilibrium beam polarization in ultra-high energy electron-positron storage rings, crucial for future collider designs and understanding spin dynamics at these energies.

Contribution

It introduces a simulation approach based on PTC to evaluate beam polarization and compares different spin resonance crossing regimes at ultra-high energies.

Findings

Simulation results align with the hypothesis of regime transition from correlated to uncorrelated spin resonance crossing.

The study provides insights into spin dynamics relevant for next-generation colliders.

The simulation framework can be used to optimize polarization strategies at ultra-high energies.

Abstract

With the recently emerging global interest in building a next generation of circular electron-positron colliders to study the properties of the Higgs boson, and other important topics in particle physics at ultra-high beam energies, it is also important to pursue the possibility of implementing polarized beams at this energy scale. It is therefore necessary to set up simulation tools to evaluate the beam polarization at these ultra-high beam energies. In this paper, a Monte-Carlo simulation of the equilibrium beam polarization based on the Polymorphic Tracking Code(PTC) (Schmidt et al., 2002 [1]) is described. The simulations are for a model storage ring with parameters similar to those of proposed circular colliders in this energy range, and they are compared with the suggestion (Derbenev et al., 1978 [2]) that there are different regimes for the spin dynamics underlying the polarization of a beam in the presence of synchrotron radiation at ultra-high beam energies. In particular, it has been suggested that the so-called "correlated" crossing of spin resonances during synchrotron oscillations at current energies, evolves into "uncorrelated" crossing of spin resonances at ultra-high energies.