Prospects for future asymmetric collisions in the LHC

Marc Andre Jebramcik,John M Jowett

doi:10.1088/1742-6596/1350/1/012003

Abstract

The proton-lead runs of the LHC in 2012, 2013 and 2016 provided luminosity far beyond expectations in a diversity of operating conditions and led to important new results in high-density QCD. This has permitted the scope of the future physics programme to be expanded in a recent review. Besides further high-luminosity proton-lead (p–Pb) collisions, lighter nuclei are also under consideration. A short proton-oxygen run, on the model of the 2012 p-Pb run, would be of interest for cosmic-ray physics. Collisions of protons with argon, other noble gases and nuclei of lighter metals are also discussed. We provide an overview of the operational strategies and potential performance of various options. Potential performance limits from moving beam-beam encounters at injection and various beam-loss mechanisms are evaluated in the light of our understanding of the LHC to date.

Highlights

The simultaneous acceleration of two different particle species were not considered in the initial design of the LHC
The slightly different velocities of the two beams lead to moving long-range beam-beam encounters in the interaction regions (IRs) and can cause fast beam losses and emittance blow-up [4]
A filling pattern foreseen for Pb–Pb operations [14] is used to estimate the potential performance for all ion species

Summary

Introduction

It included preliminary performance estimates for a variety of A–A collisions at beam energies of E = 7 Z TeV showing that lighter species could yield higher integrated nucleon-nucleon luminosities than Pb–Pb. A potential proton-oxygen (p–O) pilot run, similar to the 2012 p–Pb [5] or 2017 xenon–xenon pilot run [10], is envisaged for Run 3 of the LHC to enhance the understanding of cosmic rays [9]. MOPMP024 other lighter ion species are considered for future asymmetric collisions with protons in full intensity one-month runs. Main parameter defining the shift size is the charge-to-mass ratio difference between the protons and the respective ion species.

Results

Conclusion