Status of simulations and required inputs

Hollow Electron Lenses (HELs) are being considered by the High Luminosity Large Hadron Collider (HL-LHC) upgrade project. Their scope to clean beam tails (e.g. > 3.5 σ) to avoid magnet quenches or permanent damage to primary collimators (TCPs) in case of orbit jitters or crab cavity phase slips is described. This presentation was given at Collimation Upgrade Specification Meeting #122, CERN, Friday 22 Nov 2019