Linear array detector for online diagnostics of spectral distributions at MHz repetition rates1

• Published in: Journal of synchrotron radiation 2019-09, Vol.26 (Pt 5), p.1514-1522
• Main Authors: Gerth, Christopher, Brenner, Günter, Caselle, Michele, Düsterer, Stefan, Haack, Daniel, Makowski, Dariusz, Mielczarek, Aleksander, Palutke, Steffen, Rota, Lorenzo, Rybnikov, Vladimir, Schmidt, Christian, Steffen, Bernd, Tiedtke, Kai
• Format: Article
• Language: English
• Subjects: Research Papers
• ISSN: 0909-0495; 1600-5775
• DOI: 10.1107/S1600577519007835

The novel line detector KALYPSO has been developed for the measurement of one-dimensional profiles at high-repetition-rate free-electron lasers (FELs) and synchrotron radiation facilities. The current version has 256 pixels with a continuous data readout at a maximum frame rate of 2.7 MHz. At FLASH, KALYPSO has been utilized as photon diagnostics for monitoring pulse-resolved FEL spectra at a repetition rate of 1.0 MHz. KALYPSO is a collaborative effort between the Karlsruhe Institute of Technology (KIT), Paul Scherrer Institut (PSI), Lodz University of Technology (TUL-DMCS) and Deutsches Elektronen-Synchrotron (DESY). Free-electron lasers (FELs) based on superconducting accelerator technology and storage ring facilities operate with bunch repetition rates in the MHz range, and the need arises for bunch-by-bunch electron and photon diagnostics. For photon-pulse-resolved measurements of spectral distributions, fast one-dimensional profile monitors are required. The linear array detector KALYPSO (KArlsruhe Linear arraY detector for MHz-rePetition rate SpectrOscopy) has been developed for electron bunch or photon pulse synchronous read-out with frame rates of up to 2.7 MHz. At the FLASH facility at DESY, a current version of KALYPSO with 256 pixels has been installed at a grating spectrometer as online diagnostics to monitor the pulse-resolved spectra of the high-repetition-rate FEL pulses. Application-specific front-end electronics based on MicroTCA standard have been developed for data acquisition and processing. Continuous data read-out with low latency in the microsecond range enables the integration into fast feedback applications. In this paper, pulse-resolved FEL spectra recorded at 1.0 MHz repetition rate for various operation conditions at FLASH are presented, and the first application of an adaptive feedback for accelerator control based on photon beam diagnostics is demonstrated.