Photon Sources at DESY

During the past 10 years, photon science activities at DESY in Hamburg, Germany, have expanded significantly and this development is expected to continue in the coming years. The soft X-ray free-electron laser (FEL) FLASH has been in user operation for over 10 years and the high-brilliance hard X-ray synchrotron radiation source PETRA III started serving the user community five years ago. Access to both light sources has since been highly demanded by scientists not only from Germany and Europe, but from all over the world. The request for beamtime far exceeded the capacity of available experimental infrastructure at both facilities and, for this reason, it was necessary to add further beamlines and also to broaden the portfolio of techniques. Therefore, new facilities have recently been built to almost double the existing capacity for user beamtime at both sources (Figure 1).     

XRMS 2008 Workshop at DESY

From January 23–24, 2008, the Deutsches Elektronen Synchrotron (DESY) provided a forum for more than 75 scientists from 12 countries to discuss recent developments in the investigation of magnetic solids with synchrotron radiation. The framework for this meeting was the International Workshop for X-ray Spectroscopy of Magnetic Solids (XRMS 2008). The XRMS workshop series was established in 2000 when the first meeting was held at BESSY (Berlin, Germany). It then continued annually or bi-annually, always in conjunction with a users meeting at one of the European synchrotron radiation facilities. In this year, the XRMS workshop preceded the HASYLAB Users Meeting at DESY on January 25.     

First Lasing of FLASH2 at DESY

The free-electron laser FLASH at DESY in Hamburg, Germany, has been extended by a second undulator line in a separate tunnel and a new experimental hall (Figure 1). The existing undulator line, called FLASH1, and the new one, which includes provisions for external seeding to be realized later, called FLASH2, both use the same linear accelerator. They are operated in tandem by separating the pulse train into two sections, which are then directed to the different undulators. The linac energy is determined by the needs of the experiments at FLASH1, whereas the wavelength at FLASH2 can be varied in the limits of the tuning range of the undulators.     

Prompt J/ψ plus photon associated electroproduction at DESY HERA

We study the production of a prompt J/ψ meson in association with a prompt photon in ep deep-inelastic scattering within the factorisation formalism of non-relativistic quantum chromodynamics (NRQCD) and demonstrate that this process provides a clean probe of the colour-octet mechanism at DESY HERA. Our analysis is based on an updated set of non-perturbative NRQCD matrix elements obtained through a joint fit to data on charmonium inclusive hadroproduction from runs I and II at the Fermilab Tevatron. PACS 12.38.-t; 12.38.Bx; 13.85.Fb; 14.40.Gx     

Statistical properties of the radiation from VUV-FEL at DESY (Femtosecond mode of operation)

Present bunch compression scheme at the VUV FEL at DESY is essentially nonlinear and naturally results in the formation of a short, high-current leading peak (spike) in the density distribution that produces FEL radiation. The main feature of the considered mode of operation is the production of short, down to 20 fs radiation pulses with GW-level peak power and contrast of 80%.