Calibration of the online dose monitoring system at the free-electron laser SwissFEL

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2024-11, Vol.224, p.112070, Article 112070
• Main Authors: Hohmann, Eike, Galeev, Roman, Harm, Christine, Harzmann, Sophie, Pedrazzi, Lisa, Tisi, Marco, Walter, Nick, Mayer, Sabine
• Format: Article
• Language: English
• Subjects: Free-electron laser facilities; Neutron dose rate; Radiation protection
• ISSN: 0969-806X
• DOI: 10.1016/j.radphyschem.2024.112070

The latest large-scale research facility of the Paul Scherrer Institute, the x-ray free-electron laser SwissFEL, is installed in a 740 m long building. The facility accelerates electrons to a maximal energy of 5.8 GeV with repetition rates up to 100 Hz. The building is integrated in a regional recreation area with shielding of the accelerator vault dimensioned to tolerate temporary beam losses. An online dose monitoring system capable of shutting down SwissFEL ensures compliance with legal requirements. The studies present an overview of the evaluation of calibration factors for this system and results of dedicated benchmark measurements, carried out to verify underlying assumptions and simplifications. •Compliance with legal constraints is ensured by surveying of the neutron dose inside the accelerator tunnel.•Attenuation factors are derived based on a generic beam loss scenario and a detailed geometrical model of the SwissFEL building.•Dedicated measurement campaigns with intentional beam losses confirm the applied method.