Description of the luminosity evolution for the CERN LHC including dynamic aperture effects. Part II: application to Run 1 data

M Giovannozzi,F.F Van Der Veken

doi:10.1016/j.nima.2018.08.019

M Giovannozzi, F.F Van Der Veken

Open Access

https://doi.org/10.1016/j.nima.2018.08.019

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Abstract

In recent years, modelling the evolution of beam losses in circular proton machines starting from the concept of dynamic aperture its time evolution has been the focus of intense research. Results from single-particle non-linear beam dynamics have been used to build simple models that proved to be in good agreement with beam measurements. These results have been generalised, thus opening the possibility to describe also the luminosity evolution in a circular hadron collider. In a companion paper Giovannozzi and Van der Veken (0000), the derivation of a scaling law for luminosity, which includes both burn off and pseudo-diffusive effects, has been carried out. In this paper, the proposed models are applied to the analysis of the data collected during the CERN Large Hadron Collider (LHC) Run 1. A dataset referring to the proton physics runs for the years 2011 and 2012 has been analysed and the results are proposed and discussed in detail in this paper.

Highlights

The unavoidable non-linear magnetic field errors that plague the dynamics of charged particles of modern superconducting colliders, inducing new and potential harmful effects, require the development of new approaches to perform$Research supported by the HL-Large Hadron Collider (LHC) project ∗Corresponding authorPreprint submitted to Elsevier more powerful analyses and to gain insight in the beam dynamics
The proposed approach is put in action by analysing a selection of luminosity data collected at the LHC during Run 1, in particular for the proton physics runs in the years 2011 and 2012, which is the focus on this paper, where the result of these analyses is discussed in detail
The inaccuracy to reproduce the LHC data using only burn off has been confirmed by the analysis made, while the proposed models showed a remarkable power in reproducing and describing the observed behaviours of luminosity as a function of time and of integrated luminosity

Summary

Introduction

The unavoidable non-linear magnetic field errors that plague the dynamics of charged particles of modern superconducting colliders, inducing new and potential harmful effects, require the development of new approaches to perform. Preprint submitted to Elsevier more powerful analyses and to gain insight in the beam dynamics It is the case of the critical revision of the concept of dynamic aperture (DA) and of its dependence on time [2, 3] for the case of single-particle effects. Such a scaling law was later successfully extended to the case in which weak-strong beam-beam effects are taken into account [4]. The plan of the paper is the following: in section 2 a global overview of the LHC data is presented, including a discussion of the time-dependence of some beam parameters, and the choice made for the data analysis.

General considerations

Integrated luminosity over a physics fill

Optimal physics fill duration

Conclusions