Abstract
Several transverse noise sources, such as power supply ripples, can potentially act as an important limiting mechanism for the luminosity production of the Large Hadron Collider (LHC) and its future High-Luminosity upgrade (HL-LHC). In the presence of non-linearities, depending on the spectral components of the power supply noise and the nature of the source, such a mechanism can increase the diffusion of the particles in the distribution through the excitation of sideband resonances in the vicinity of the ones driven by the lattice non-linearities. For the HL-LHC, due to the reduction of the beam size in the Interaction Points (IP) of the high luminosity experiments (IP1 and 5), increased sensitivity to noise effects is anticipated for the quadrupoles of the inner triplets. The modulation that may arise from the power supply ripples will be combined with the tune modulation that intrinsically emerges from the coupling of the transverse and longitudinal plane for off-momentum particles through chromaticity. To this end, the aim of this paper is to study the impact of tune modulation effects on the transverse beam motion resulting from the interplay between quadrupolar power supply ripples and synchro-betatron coupling. A power supply noise threshold for acceptable performance is estimated with single-particle tracking simulations by investigating the impact of different modulation frequencies and amplitudes on the Dynamic Aperture. The excitation of sideband resonances due to the modulation is demonstrated with frequency maps and the higher sensitivity to specific modulation frequencies is explained. Finally, a power supply noise spectrum consisting of several tones is considered in the simulations to determine whether the presence of power supply ripples in the quadrupoles of the inner triplet will limit the luminosity production in the HL-LHC era.
Highlights
In order to optimize the performance of a high-energy particle collider such as the Large Hadron Collider (LHC) [1] and its future High-Luminosity upgrade (HL-LHC) [2], a thorough understanding of all the phenomena that can degrade the luminosity is required
It is important to investigate whether the combination of the tune modulation induced by power supply ripple and synchro-betatron coupling will pose a limitation to the luminosity production of the HL-LHC, as well as other present and future hadron colliders such as Relativistic Heavy Ion Collider (RHIC), the Electron-Ion Collider (EIC) [27] and the Future Circular Collider (FCC) [28]
The increase of the β-functions in the HL-LHC inner triplets, resulting from the decrease of the beam size at the two interaction points (IP), and the presence of strong nonlinearities, combined with the new hardware that is currently being developed, motivates the need to perform a complete analysis on the repercussions of power supply ripple in future operation
Summary
In order to optimize the performance of a high-energy particle collider such as the Large Hadron Collider (LHC) [1] and its future High-Luminosity upgrade (HL-LHC) [2], a thorough understanding of all the phenomena that can degrade the luminosity is required. The present paper investigates the implications of power supply ripple in the quadrupoles located at the high β-function regions of the accelerator These magnetic field fluctuations ΔB induce a modulation in the normalized focusing strength of the quadrupoles Δk. Reach the tune footprint, thereby acting as a diffusion mechanism for the particles in the distribution in addition to the resonances driven by the lattice nonlinearities [15] In the latter case, the existence of such resonances critically limits the available space in frequency domain for an optimized, resonance-free working point. It is important to investigate whether the combination of the tune modulation induced by power supply ripple and synchro-betatron coupling will pose a limitation to the luminosity production of the HL-LHC, as well as other present and future hadron colliders such as RHIC, the Electron-Ion Collider (EIC) [27] and the Future Circular Collider (FCC) [28]. The two tune modulation sources considered in the present paper, power supply ripple and chromatic tune modulation, are first, studied individually and their combined impact is estimated
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