In situ estimation of the maximum secondary electron yield in the LHC Vacuum Pilot Sector beam pipe via electron cloud measurements and numerical simulations
Abstract
The maximum secondary electron yield, δ max , is a key parameter governing electron cloud buildup in high-intensity proton accelerators, yet its direct determination under operational conditions remains challenging. This paper presents a novel method to estimate δ max in the Large Hadron Collider (LHC) using electron cloud measurements performed in the Vacuum Pilot Sector. The approach exploits the characteristic evolution of electron cloud intensity during beam injection, in particular the transition from an initial build-up regime to a linear scaling of electron flux with the number of injected bunches. Electron cloud currents measured with dedicated electron pickups are compared with PyECLOUD simulations performed for varying δ max values. The threshold number of injected bunches required to reach the linear regime provides a robust observable from which δ max can be extracted with limited sensitivity to other surface-emission parameters. The method is applied to multiple LHC fills and surface materials. For conditioned copper liners, δ max values between approximately 1.16 and 1.30 are obtained, in agreement with independent analyses and literature values. Applying the technique over extended operation periods enables the reconstruction of surface conditioning curves as a function of cumulative electron dose. These curves show a rapid initial decrease in δ max before approaching an apparent plateau, which may lie below the detection limit of the method depending on the beam pipe material and location. The method is compatible with routine LHC operation and enables systematic monitoring of vacuum-surface conditioning.
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BibTeX
@article{duong2026situ,
title = {{In situ estimation of the maximum secondary electron yield in the LHC Vacuum Pilot Sector beam pipe via electron cloud measurements and numerical simulations}},
author = {Quentin Duong and Vincent Baglin and Gaël Sattonnay},
journal = {Phys.Rev.Accel.Beams},
year = {2026},
month = sep,
doi = {10.1103/6hvz-l89v},
url = {https://hal.science/hal-05735429v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - In situ estimation of the maximum secondary electron yield in the LHC Vacuum Pilot Sector beam pipe via electron cloud measurements and numerical simulations
AU - Quentin Duong
AU - Vincent Baglin
AU - Gaël Sattonnay
PY - 2026
DA - 2026/09/02
JO - Phys.Rev.Accel.Beams
DO - 10.1103/6hvz-l89v
UR - https://hal.science/hal-05735429v1
AB - The maximum secondary electron yield, δ max , is a key parameter governing electron cloud buildup in high-intensity proton accelerators, yet its direct determination under operational conditions remains challenging. This paper presents a novel method to estimate δ max in the Large Hadron Collider (LHC) using electron cloud measurements performed in the Vacuum Pilot Sector. The approach exploits the characteristic evolution of electron cloud intensity during beam injection, in particular the transition from an initial build-up regime to a linear scaling of electron flux with the number of injected bunches. Electron cloud currents measured with dedicated electron pickups are compared with PyECLOUD simulations performed for varying δ max values. The threshold number of injected bunches required to reach the linear regime provides a robust observable from which δ max can be extracted with limited sensitivity to other surface-emission parameters. The method is applied to multiple LHC fills and surface materials. For conditioned copper liners, δ max values between approximately 1.16 and 1.30 are obtained, in agreement with independent analyses and literature values. Applying the technique over extended operation periods enables the reconstruction of surface conditioning curves as a function of cumulative electron dose. These curves show a rapid initial decrease in δ max before approaching an apparent plateau, which may lie below the detection limit of the method depending on the beam pipe material and location. The method is compatible with routine LHC operation and enables systematic monitoring of vacuum-surface conditioning.
ER -