Measurements of Beam Backgrounds in SuperKEKB Phase 2
physics.ins-det
/ Authors
Zachary J. Liptak, Antonio Paladino, Luka Santelj, Jeffery Schueler, Slavomira Stefkova, Hikaru Tanigawa, Noritsugu Tsuzuki, Alberto Aloisio, Patrick Ahlburg, Philip Bambade
and 59 more authors
Giovanni Bassi, Matthew Barrett, Jerome Baudot, Thomas Browder, Giulia Casarosa, Giuseppe Cautero, David Cinabro, Gilles Claus, Daniel Cuesta, Francesco Di Capua, Salvatore Di Carlo, John Flanagan, Ariane Frey, Bryan Fulsom, Yoshihiro Funakoshi, Miroslav Gabriel, Raffaele Girodano, Dario Giuressi, Mathieu Goffe, Koji Hara, Oskar Hartbrich, Michael Hedges, Daniel Heuchel
/ Abstract
The high design luminosity of the SuperKEKB electron-positron collider will result in challenging levels of beam-induced backgro\ unds in the interaction region. Understanding and mitigating these backgrounds is critical to the success of the Belle~II experi\ ment. We report on the first background measurements performed after roll-in of the Belle II detector, a period known as SuperKE\ KB Phase 2, utilizing both the BEAST II system of dedicated background detectors and the Belle II detector itself. We also repor\ t on first revisions to the background simulation made in response to our findings. Backgrounds measured include contributions f\ rom synchrotron radiation, beam-gas, Touschek, and injection backgrounds. At the end of Phase 2, single-beam backgrounds origina\ ting from the 4 GeV positron Low Energy Ring (LER) agree reasonably well with simulation, while backgrounds from the 7 GeV elect\ ron High Energy Ring (HER) are approximately one order of magnitude higher than simulation. We extrapolate these backgrounds for\ ward and conclude it is safe to install the Belle II vertex detector.