Can Low-Energy Electrons Affect High-Energy Physics Accelerators?

TLDR

Accelerator performance may be limited by the electron cloud effect, whose formation and evolution depend on the vacuum chamber wall surface properties. The study aims to predict how low‑energy electron measurements influence electron cloud production and surface heat load in the Large Hadron Collider. Researchers measured secondary electron yield and energy distributions as functions of incident energy, emphasizing primaries below 20 eV, and then applied state‑of‑the‑art EC simulation codes to evaluate the impact on LHC electron cloud dynamics. The measurements show that the secondary electron yield approaches unity and the reflected electron component dominates as the primary incident energy approaches zero.

Abstract

Present and future accelerators' performances may be limited by the electron cloud (EC) effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. We present measurements of the total secondary electron yield (SEY) and the related energy distribution curves of the secondary electrons as a function of incident-electron energy. Particular attention has been paid to the emission process due to very low-energy primary electrons ($<20\text{ }\text{ }\mathrm{e}\mathrm{V}$). It is shown that the SEY approaches unity and the reflected electron component is predominant in the limit of zero primary incident electron energy. Motivated by these measurements, we have used state-of-the-art EC simulation codes to predict how these results may impact the production of the electron cloud in the Large Hadron Collider, under construction at CERN, and the related surface heat load.