title: Spectrometer for shot-to-shot photon energy characterization in the multi-bunch mode of the free electron laser at Hamburg.
abstract: The setup and first results from commissioning of a fast online photon energy spectrometer for the vacuum ultraviolet free electron laser at Hamburg (FLASH) at DESY are presented. With the use of the latest advances in detector development, the presented spectrometer reaches readout frequencies up to 1 MHz. In this paper, we demonstrate the ability to record online photon energy spectra on a shot-to-shot base in the multi-bunch mode of FLASH. Clearly resolved shifts in the mean wavelength over the pulse train as well as shot-to-shot wavelength fluctuations arising from the statistical nature of the photon generating self-amplified spontaneous emission process have been observed. In addition to an online tool for beam calibration and photon diagnostics, the spectrometer enables the determination and selection of spectral data taken with a transparent experiment up front over the photon energy of every shot. This leads to higher spectral resolutions without the loss of efficiency or photon flux by using single-bunch mode or monochromators.
authors.affiliation: Institute for Experimental Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Palutke
authors.affiliation: Institute for Experimental Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: N C
authors.initials: NC
authors.lastname: Gerken
authors.affiliation: Institute for Experimental Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Mertens
authors.affiliation: Institute for Experimental Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Klumpp
authors.affiliation: Paul Scherrer Institute (PSI), Ch-5232 Villigen, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Mozzanica
authors.affiliation: Paul Scherrer Institute (PSI), Ch-5232 Villigen, Switzerland.
authors.forename: B
authors.initials: B
authors.lastname: Schmitt
authors.affiliation: Deutsches Elekronen Synchrotron (DESY), Notkestraße 85, D-22607 Hamburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Wunderer
authors.affiliation: Deutsches Elekronen Synchrotron (DESY), Notkestraße 85, D-22607 Hamburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Graafsma
authors.affiliation: Institute for Physics, University of Rostock, Universitätsplatz 3, D-18051 Rostock, Germany.
authors.forename: K-H
authors.initials: KH
authors.lastname: Meiwes-Broer
authors.affiliation: Institute for Experimental Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Wurth
authors.affiliation: Institute for Experimental Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Martins