Resonance identification and compensation studies to minimize losses for high intensity beams in the PSB

Abstract

The CERN Proton Synchrotron Booster (PSB) is the first synchrotron in the injection chain ofthe Large Hadron Collider (LHC). Operating at 160 MeV, it is strongly affected by space charge,causing a large tune spread. This results in resonance overlap at injection, leading to emittance increase and particle loss due to the interaction with excited resonances, ultimately limiting the beambrightness. As particles are accelerated, the tune spread decreases and is shifted to a resonance-freezone for extraction, requiring crossing high-order resonances, causing further blow-up and losses.This study focuses on identifying and compensating 3rd and 4th order resonances individually and globally in the PSB. The compensation strategy involves blowing up low-intensity beams at injection, crossing individual resonances, and measuring the induced losses. Using corrector magnets,the losses can be altered and in the right configuration, full compensation for all individual resonances was achieved. Based on these individual compensation settings, a global compensationscheme was then identified and the induced losses when crossing all excited resonances can be minimized globally, with the average remnant losses of all rings being below 4%.