Characterization of Losses and Emittance Growth for Ion Beams on the SPS Injection Plateau

A Saa Hernandez,F Antoniou,H Bartosik,A Huschauer

doi:10.1088/1742-6596/1067/6/062019

A Saa Hernandez, F Antoniou + Show 2 more

Open Access

https://doi.org/10.1088/1742-6596/1067/6/062019

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Abstract

Losses and transverse emittance growth in the Super Protron Synchrotron (SPS) impose presently the main performance limitation on the Large Hadron Collider (LHC) ion injector chain. In this paper we present the measurements performed in 2016 with Pb82+ ions and the analysis to characterize the observations of beam degradation during the long injection plateau. Residual gas scattering, intrabeam scattering (IBS) and resonance excitation have been studied.

Highlights

The Large Hadron Collider (LHC) Injectors Upgrade project (LIU) aims at consolidating and upgrading the existing accelerator chain at CERN in view of the increased beam performance required for the High-Luminosity LHC (HL-LHC) project
A strong degradation of the Pb-ion beam is observed during the long injection plateau of the Super Protron Synchrotron (SPS), consisting of a significant reduction of the transmission and a transverse emittance blow-up
The nominal working point was optimized for beam transmission

Summary

INTRODUCTION

The LHC Injectors Upgrade project (LIU) aims at consolidating and upgrading the existing accelerator chain at CERN in view of the increased beam performance required for the High-Luminosity LHC (HL-LHC) project. The nominal LIU bunch intensity is 3.6×108 Pb ions at SPS injection [2]. Further injections were avoided in order to enable direct measurements of emittance and intensity evolution along the FB. A bunch length reduction of around 15 % was observed for intensity losses along the FB of the order of 35 %, as shown in Fig. 2 (top). To understand if the excitation of nearby resonances could cause the intensity losses, and to search for alternative WPs with a higher transmission and lower emittance blow-up, we explored the resonance diagram around the nominal WP by performing dynamic and static tune scans. We dynamically scanned the tune diagram while measuring the loss rate as a function of the working point in the absence of RF.

STUDIES OF BEAM DEGRADATION

Residual Gas Scattering

Collective Effects

Findings

CONCLUSIONS