Development and Evaluation of an Alternative Sensor Lifetime Enhancement Technique Used with the Online-Radiation-Monitoring System (DosiMon) at the European XFEL at DESY, Hamburg

Abstract

The European XFEL (E-XFEL), that started operation in September 2017 at the DESY/XFEL site in Hamburg/Germany uses a single-tunnel concept, forcing all frontend machine devices and electronics to be located inside the accelerator tunnel. Electro-magnetic showers,mainly produced by gun dark-current, RF cavity field emission and beam-losses expose these devices to damaging irradiation. The new Online-Radiation-Monitoring-System (DosiMon) is mainly used for surveillance of radiation sensitive permanent magnet structures, diagnostic devices and rack-housed electronics. The integrated dose from Gamma- and optional future Neutron-radiation measurements can be monitored online by the DosiMonsystem. Safety limits ensure the correct function of monitored devices, provided by lifecycle estimations as measures for on time part exchange, to prevent significant radiation damage. A first expansion state currently enables more than 500 gamma measuring points. The development of a new sensor lifetime enhancement technique for the utilized RadFet sensors is presented together with corresponding evaluation measurements