Development of Beam Halo Monitors for the  European XFEL using radiation hard sensors and demonstration of the technology at FLASH

Ignatenko, Alexandr

Report/Dissertation / PhD Thesis

PUBDB-2014-04146

Development of Beam Halo Monitors for the European XFEL using radiation hard sensors and demonstration of the technology at FLASH

Ignatenko, A. (Corresponding Author)DESY*

2015
Verlag Deutsches Elektronen-Synchrotron

Verlag Deutsches Elektronen-Synchrotron, DESY-THESIS 109 pp. (2015) [10.3204/DESY-THESIS-2015-016] = Brandenburgische Technische Universität Cottbus-Senftenberg, Diss., 2015

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Please use a persistent id in citations: doi:10.3204/DESY-THESIS-2015-016

Report No.: DESY-THESIS-2015-016

Abstract: The European X-Ray Free-Electron Laser (E-XFEL), currently under construction in Hamburg, Germany, is intended to be an international linear accelerator (linac) based user facility. Its electron beam can carry maximal average power of 600 kW. A beam with such a high power needs to be carefully transmitted through the machine and safely dumped after utilization. This is supported by various diagnostics tools. A Beam Halo Monitor (BHM) based on synthetic diamond and sapphire sensors has been designed. Diamond sensors are developed by the company element6 for the detection of ionizing radiation and used previously elsewhere. Sapphire sensors are in this thesis applied for the first time. The BHM concept has been applied already at the Free-electron Laser in Hamburg (FLASH). A module with four diamond and four sapphire sensors was designed, installed inside the beam pipe, commissioned, calibrated and has been successfully operated for 4 years. The system contributed significantly to safe and efficient operation of FLASH. Both types of the sensors for the BHM were characterized. Measurements of radiation tolerance are done in a 10 MeV electron beam for polycrystalline CVD (pCVD) diamond sensors for the first time up to a dose of 10 MGy and for sapphire sensors up to 5 MGy. The charge collection efficiency (CCE) drops as a function of the absorbed dose, is however still sufficient for application as a BHM. To improve a main sensor characteristic, the charge collection efficiency, for sapphire sensors the impurity concentration was reduced and different growth techniques were compared. Finally, charge collection efficiency of about 5 % for a bias voltage of 500 V was reached. The BHM concept for the XFEL is designed and in the construction phase.

Keyword(s): Dissertation

Note: Brandenburgische Technische Universität Cottbus-Senftenberg, Diss., 2015

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