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Hahn, U.

Paper Title Page
WEBAU03 Performance Tests of the Photon Monochromator for Self-seeding at FLASH 306
 
  • H. K. Bechtold, J. Hartvig, H. Juul, V. Toft
    Aarhus University, Aarhus
  • R. Follath, G. Reichardt, F. Senf, F. Siewert
    BESSY GmbH, Berlin
  • U. Hahn, J. Viefhaus, R. Treusch
    DESY, Hamburg
  • S. V. Hoffmann
    ISA, Aarhus
  • Ch. Knoechel
    LBNL, Berkeley, California
  • R. Reininger
    UW-Madison/SRC, Madison, Wisconsin
 
  A single pass FEL amplifier can produce extremely intense and fully coherent radiation at short wavelengths if it is seeded by a coherent light beam resonant with the magnetic structure and collinear with the electron beam. Since at the present time a single pass SASE FEL is the only source of sufficiently intense, tunable radiation in the soft X-ray region, it has been proposed to use such a source in combination with a narrow-band monochromator for seeding an FEL amplifier*. By means of such a "Self-Seeding", the soft X-ray free electron laser FLASH at DESY will be modified so that it can provide coherent radiation in space and time in a wavelength range from about 60-6nm (~20-200eV). In this presentation, we will focus on the performance of the photon monochromator beamline which was setup and tested at the synchrotron radiation storage ring ASTRID in Aarhus, Denmark. The optical, mechanical and vacuum design will be described along with results on the resolving power of the monochromator which have been obtained scanning across rare gas resonance lines at various energies. Based on these results we will conclude that the monochromator is mechanically very stable and reproducible and behaves according to its specifications with resolving powers between 10000 and 20000, i.e. bandwidths of a few meV only.

* J. Feldhaus, E. L. Saldin, J. R. Schneider, E. A. Schneidmiller, and M. V. Yurkov, Opt. Commun. 140, 341 (1997)

 
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WEPPH007 MCP-based Photon Detector with Extended Wavelength Range for FLASH 334
 
  • O. I. Brovko, D. Kharlamov, E. A. Matyushevskiy, A. V. Shabunov
    JINR/LHE, Moscow
  • J. Feldhaus, U. Hahn, M. Hesse, U. Jastrow, V. Kocharyan, P. Radcliffe, E. Saldin, E. Schneidmiller, K. I. Tiedtke, R. Treusch, M. V. Yurkov, N. von Bargen, L. Bittner
    DESY, Hamburg
  • V. I. Lokhmatov, E. Syresin
    JINR, Dubna, Moscow Region
 
  Experimental experience gained at the extreme ultraviolet SASE FEL FLASH (DESY, Hamburg) has shown that successful operation of the facility strongly depends on the quality of the radiation detectors. Here key issues are: wide wavelength range (6 to 100 nm for FLASH), wide dynamic range (from the level of spontaneous emission to the saturation level), and high relative accuracy of measurements which is crucial for detection of a signature of amplification and characterization of statistical properties of the radiation. In this report we describe MCP-based radiation detector for FLASH which meets these requirements. Key element of the detector is wide dynamic range micro-channel plate (MCP) which detects scattered radiation from a target. With five different targets and MCPs in combination with optical attenuators present detector covers operating wavelength range from 6 to 100 nm, and dynamic range of the radiation intensities, from the level of spontaneous emission up to the saturation level of SASE FEL.