Evaluation of Beam Halo from Beam-Gas Scattering at the KEK-ATF

TL;DR

This paper investigates beam halo formation at KEK-ATF caused by beam-gas scattering, combining simulations and experimental measurements to understand the underlying mechanisms and effects on beam quality.

Contribution

It provides the first detailed numerical and experimental analysis of beam-gas scattering as a source of beam halo at KEK-ATF.

Findings

Beam-gas scattering significantly contributes to beam halo formation.

Monte Carlo simulations align with experimental measurements.

Beam halo distribution is influenced by gas pressure and scattering dynamics.

Abstract

In circular colliders, as well as in damping rings and synchrotron radiation light sources, beam halo is one of the critical issues limiting the performance as well as potentially causing component damage and activation. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the available theoretical models. Elastic beam-gas scattering can drive particles to large oscillation amplitudes and be a potential source of beam halo. In this paper, numerical estimation and Monte Carlo simulations of this process at the ATF of KEK are presented. Experimental measurements of beam halo in the ATF2 beam line using a diamond sensor detector are also described, which clearly demonstrates the influence of the beam-gas scattering process on the transverse halo distribution.