IPAC2021 - List of Authors (Freund, W.)

Paper	Title	Page
MOPAB018	SASE Gain-Curve Measurements with MCP-Based Detectors at the European XFEL	96
	E. Syresin, O.I. Brovko, A.Yu. Grebentsov JINR, Dubna, Moscow Region, Russia W. Freund, J. Grünert, J. Liu, Th. Maltezopoulos, D. Mamchyk EuXFEL, Schenefeld, Germany M.V. Yurkov DESY, Hamburg, Germany
	Radiation detectors based on microchannel plates (MCP) are used for characterization of the Free-Electron Laser (FEL) radiation and measurements of the Self-amplified spontaneous emission (SASE) gain curve at the European XFEL. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. There is one MCP-based detector unit installed in each of the three photon beamlines downstream of the SASE1, SASE2, and SASE3 undulators. MCP detectors operate in a wide dynamic range of pulse energies, from the level of spontaneous emission up to FEL saturation. Their wavelength operation range overlaps with the whole range of radiation wavelengths of SASE1 and SASE2 (from 0.05 nm to 0.4 nm), and SASE3 (from 0.4 nm to 5 nm). In this paper we present results of SASE gain-curve measurements by the MCP-based detectors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB018
About •	paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 23 August 2021
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THPAB080	Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator	3953
	F. Brinker DESY, Hamburg, Germany S. Casalbuoni, W. Freund EuXFEL, Schenefeld, Germany
	Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. A crucial condition for the lasing process is the spatial overlap of the electrons with the electromagnetic field. Well-established electron beam-based procedures allow finding a straight trajectory for the electrons defined by the beam position monitors (BPM) between the undulators. A bending of the trajectory in between the BPMs cannot be seen by these methods. A general field offset inside the undulators has the effect that the synchrotron radiation is emitted at a different angle at the beginning and the end of the undulator which can result in a degradation of the FEL-gain especially for very short wavelengths. We report on how the spectral and spatial characteristics of the monochromatized radiation of a single undulator can be used to minimize the field offset in situ with the help of correction coils.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB080
About •	paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 12 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

SASE Gain-Curve Measurements with MCP-Based Detectors at the European XFEL

96

E. Syresin, O.I. Brovko, A.Yu. Grebentsov
JINR, Dubna, Moscow Region, Russia
W. Freund, J. Grünert, J. Liu, Th. Maltezopoulos, D. Mamchyk
EuXFEL, Schenefeld, Germany
M.V. Yurkov
DESY, Hamburg, Germany

Radiation detectors based on microchannel plates (MCP) are used for characterization of the Free-Electron Laser (FEL) radiation and measurements of the Self-amplified spontaneous emission (SASE) gain curve at the European XFEL. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. There is one MCP-based detector unit installed in each of the three photon beamlines downstream of the SASE1, SASE2, and SASE3 undulators. MCP detectors operate in a wide dynamic range of pulse energies, from the level of spontaneous emission up to FEL saturation. Their wavelength operation range overlaps with the whole range of radiation wavelengths of SASE1 and SASE2 (from 0.05 nm to 0.4 nm), and SASE3 (from 0.4 nm to 5 nm). In this paper we present results of SASE gain-curve measurements by the MCP-based detectors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB018

About •

paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 23 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB080

Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator

3953

F. Brinker
DESY, Hamburg, Germany
S. Casalbuoni, W. Freund
EuXFEL, Schenefeld, Germany

Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. A crucial condition for the lasing process is the spatial overlap of the electrons with the electromagnetic field. Well-established electron beam-based procedures allow finding a straight trajectory for the electrons defined by the beam position monitors (BPM) between the undulators. A bending of the trajectory in between the BPMs cannot be seen by these methods. A general field offset inside the undulators has the effect that the synchrotron radiation is emitted at a different angle at the beginning and the end of the undulator which can result in a degradation of the FEL-gain especially for very short wavelengths. We report on how the spectral and spatial characteristics of the monochromatized radiation of a single undulator can be used to minimize the field offset in situ with the help of correction coils.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB080

About •

paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 12 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)