Review of halo measurements at the Large Hadron Collider with collimator scans

A good modeling of the beam distribution is essential in order to understand limitiations from overpopulated tails in high-power particle accelerators and find the best strategy to clean particles in the tails, that may cause damage to the accelerator components. Therefore the beam profile in the transverse plane at the Large Hadron Collider (LHC) using collimator scans was measured, analysed and discussed. Two models, Double Gaussian and Lèvy Student, were investigated in order to understand which one fits better the shape of the beam reconstructed from the signal of the Beam Loss Monitor (BLM) during beam scraping with LHC collimaotr and through the Beam Wire Scanner (BWS). A series of Python-based scripts were developed to analyse measurements data, to fit the obtained profiles and to compare the parameters obtained from the fit with both models and to evaluate the particles content in the tail region. This work demonstrated that is possibile to use these two models to represent the beam profile in the vertical and horizontal planes respectivley. A set of reference fit paramters was collected, that allows to model the LHC transverse beam distributions in the cases considerated. A systematic analysis for various measurements performed at the LHC was carried out and is also presented.