BPM Resolution Studies at PETRA III

In order to measure the noise level of a BPM system from beam generated orbit data, the correlated beam jitter has tobe removed from the position signals. There exist different ways to extract the BPM noise, as the “three-BPM” correlation method or the model-independent principal components analysis (PCA). Both methods will shortly be reviewed.Based on a PCA, the resolution of the PETRA III LiberaBrilliance based BPM system was measured. The resultsare presented together with first measurements in view ofan updated BPM system for the future PETRA IV project at DESY

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

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

Status of the Radiation Damage on th European XFEL Undulator Systems

The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three movable gap SASE Undulator Systems based on hybrid NdFeB permanent magnet technology were built. Radiation damage due to machine operation affects the magnetic propertiesof the segments and the quality of the SASE process.Dosimeters monitor the absorbed doses in every undulator segment and each SASE system is equipped with a diagnostic undulator (DU). We report on the profile of the absorbed doses seen in the first year of the Undulator Systems operation. Magnetic field degradation higher than 3.5% in the DU is found and associated to absorbed doses up to 4.4 kGy. An initial limit of 55 Gy for the 5-mundulator segments is recommended based on the precise K-parameter determination for beam operation

Commissioning of the New Online-Radiation-Monitoring-System at the New European XFEL Injector with First Tests of the High-Sensitivity-Mode for Intra-Tunnel Rack Surveillance

System, developed for the 17.5 GeV superconducting European XFEL (E-XFEL) that is currently being built between the DESY campus at Hamburg and Schenefeld at Schleswig-Holstein [1,2], has been commissioned in a first system test setup at the E-XFEL Injector. As most of the electronic systems for machine control, diagnostics and safety of the E-XFEL will be located in cabinets inside the accelerator tunnel, the test setup incorporates all system parts like cabinet-internal and -external monitor electronics, infrastructure interface boards, firmware, software, cabling and sensors. Hence the commissioning system setup gives the possibility for first operation of the complete online radiation monitoring system under realistic environmental conditions in terms of irradiation, electro-magnetic interference (EMI) inside the injector tunnel, as well as operational and control system aspects. Commissioning results and measurements based on different internal and external sensor channels will be presented here, together with recent measurements done at different radiation sources using the high-sensibility mode for intra-rack radiation monitoring

Absorbed Radiation Doses on the European XFEL Undulator Systems During Early User Experiments

The European XFEL GmbH (EuXFEL) is a FEL userfacility based on a superconducting accelerator with highduty cycle. Three movable gap SASE Undulator Systems using hybrid NdFeB permanent magnet segments are in operation. We observed in a dedicated diagnostic undulator for radiation damage doses up to 4 kGy and 3% demagnetization effect during the commissioning phase. In this work we present characteristics of the absorbed radiation doses in undulators during photon beam delivery for users. Lower absorbed doses are measured since the startof user operation. While ramping up electron beam parameters and repetition rates, individual segments located at the downstream end of the SASE systems show persistent absorbed doses which are proportional to the transmitted charge. In addition, the dose per charge ratio shows photon energy dependence. Portable magnetic flux measurement systems allow in-situ tunnel assessment of undulator magnetic properties in order to estimate radiation dose limits for future user operation