BIW2012 - List of Authors (Tiessen, H.)

Paper	Title	Page
MOPG007	XFEL Beam Loss Monitor System	35
	A. Kaukher, I. Krouptchenkov, D. Nölle, H. Tiessen, K. Wittenburg DESY, Hamburg, Germany
	The European XFEL will have a sophisticated Machine Protection System, including Beam Loss Monitors (BLMs). The monitors will detect losses of electron beam to protect the components of the XFEL from damage and excessive activation. For protection of undulators, BLMs with a scintillator rod will be used. BLMs at places with high radiation load will be equipped with fused silica rods. Beam dumps of the XFEL will be instrumented with glass-fiber BLMs. The BLMs were tested with an electron test-beam facility at DESY, as well as at FLASH. Due to large amounts of light produced by scintillator, no optical grease is needed, while the cathode potential of the R5900 PMT is 500-600 volt. Comparable signal from a prototype with a quartz glass was obtained with typically 150 volt higher cathode potential than that in the prototype with a scintillator. Unexpectedly slower rise and fall time of the signal has been observed, presumably due to radio-luminescence in the used quartz glass rod. Good operation of all three types of BLMs prototypes was obtained. We also plan to use the same types of BLMs for the FLASH II project. The current status of the XFEL BLM system development will be presented.

Paper

Title

Page

XFEL Beam Loss Monitor System

35

A. Kaukher, I. Krouptchenkov, D. Nölle, H. Tiessen, K. Wittenburg
DESY, Hamburg, Germany

The European XFEL will have a sophisticated Machine Protection System, including Beam Loss Monitors (BLMs). The monitors will detect losses of electron beam to protect the components of the XFEL from damage and excessive activation. For protection of undulators, BLMs with a scintillator rod will be used. BLMs at places with high radiation load will be equipped with fused silica rods. Beam dumps of the XFEL will be instrumented with glass-fiber BLMs. The BLMs were tested with an electron test-beam facility at DESY, as well as at FLASH. Due to large amounts of light produced by scintillator, no optical grease is needed, while the cathode potential of the R5900 PMT is 500-600 volt. Comparable signal from a prototype with a quartz glass was obtained with typically 150 volt higher cathode potential than that in the prototype with a scintillator. Unexpectedly slower rise and fall time of the signal has been observed, presumably due to radio-luminescence in the used quartz glass rod. Good operation of all three types of BLMs prototypes was obtained. We also plan to use the same types of BLMs for the FLASH II project. The current status of the XFEL BLM system development will be presented.