Time evolution of the luminosity of colliding heavy-ion beams in BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider

Abstract

We have studied the time evolution of the heavy ion luminosity and bunch intensities in the Relativistic Heavy Ion Collider (RHIC), at BNL, and in the Large Hadron Collider (LHC), at CERN. First, we present measurements from a large number of RHIC stores (from Run 7), colliding 100 GeV/nucleon 197 Au 79+ beams without stochastic cooling. These are compared with two different calculation methods. The first is a simulation based on multi-particle tracking taking into account collisions, intrabeam scattering, radiation damping, and synchrotron and betatron motion. In the second, faster, method, a system of ordinary differential equations with terms describing the corresponding effects on emittances and bunch populations is solved numerically. Results of the tracking method agree very well with the RHIC data. With the faster method, significant discrepancies are found since the losses of particles diffusing out of the RF bucket due to intrabeam scattering are not modeled accurately enough. Finally, we use both methods to make predictions of the time evolution of the future 208 Pb 82+ beams in the LHC at injection and collision energy. For this machine, the two methods agree well. PACS numbers: 29.20.db, • Multi-particle tracking: This method, described in Sec. III, is rather direct and accurate but slow. We use an extended version of the code introduced in Refs. [12][13][14], motivated by the fact that the longi-

Compare 100 GeV/n Au Run 2010 with Run 2007

“…A complete luminosity model for heavy ion runs at both RHIC and LHC is presented in [3]. With tracking and/or solving ODEs (ordinary differential equations), the results agree well with the RHIC Au runs, and the model can be used to predict the luminosity of the LHC lead runs.…”

“…The decay patterns of the luminosity and the beam intensity are quite different [3]. Moreover, the luminosity decays in 2007 and 2010 are different, and also the intensity decays with and without longitudinal cooling are different.…”

“…is almost all caused by the burn-off, and the Blue decay is mostly due to the longitudinal IBS caused leakage from the RF bucket, which can be well formulated in a tracking [3]. 3.…”

A luminosity model of RHIC gold runs

“…For example, the longitudinal and transverse damping time due to the radiation mechanism is 825 hour and 1650 hour, respectively. This is compared with LHC at store, 6.3 hour and 12.6 hour, respectively [8].…”

Heavy-Ion Operation of HL-LHC

“…The next stage of the modelling is to look at the evolution over a fill using the Collider Time Evolution simulation program [16][17][18], a multi-particle simulation that includes the effects of IBS, luminosity burn-off, radiation damping, etc. Here again, of course, the spread in bunch parameters differentiates the rate of intensity and luminosity decay along the bunch train.…”