Beam Losses and Collimators in Transfer Lines

Designs of future high-power accelerators are facing a major challenge in terms of minimizing uncontrolled primary beam losses in areas aiming at hands-on maintenance of accelerator components. At the European Spallation Source (ESS), the canonical <1 W/m loss rate corresponds to an unprecedented <200 ppb relative loss (at 5 MW). Transport sections offer the possibility of installing collimator systems to convert some of the downstream uncontrolled losses to localized controlled losses. The collimators can potentially also mask sensitive regions or components and mitigate non-nominal beam conditions. The challenges and benefits of a collimator system at beam energies of a few GeV are believed to be relevant and somewhat common to many high-power facilities.