Contributions to a conference proceedings

The diffraction limited synchrotron light source envisioned for the PETRA IV project will require strong focusing to produce the small emittances in both planes. The large natural chromaticity together with small dispersion will require very strong sextupoles [...]

Mode-locked lasers provide extremely low jitter optical pulse trains for a number of applications ranging from sampling of RF-signals and optical frequency combs to microwave and optical signal synthesis. Integrated versions have the advantage of high reliability, low cost and compact. [...]

Electron beams of high quality, e.g., low emittance, are of crucial importance for cutting-edge scientific instruments, such as x-ray free electron lasers (XFELs) and ultrafast electron diffraction (UED) setups. A velocity-map-imaging (VMI) spectrometer was implemented to characterize the intrinsic root-mean-square (rms) normalized emittance from photocathodes. [...]

We present a staged Terahertz accelerator composed of a compressor and accelerator stage. Preliminary experiments are described demonstrating >30 keV energy gain and compression of electrons down to 100 fs for 55 keV electron bunches from a DC-gun [...]

Wire scanners are used usually to measure the profile of the core of the beam. Especially at high beam currents the wire has to flip very fast through the beam, otherwise it will burn This is not true for the tails of the beam where the wire can be moved very slowly (or even stay stationary). [...]

PETRA III is a 6 GeV hard X-ray synchrotron radiation source at DESY in Hamburg (Germany) and is in user operation since 2010. The natural emittance of PETRA III is extremely low with 1.3 nm·rad and the coupling is typically less than 1 %. [...]

The recent measurement of bunch length versus current indicated that the longitudinal impedance (Z/n) is 0.15 Ohm in close agreement with the impedance model [1]. Naïve application of Keil-Schnell criteria predicts that the threshold of microwave instability at 0.25 mA. [...]

Working on a coupling resonance is a usual way of producing round beams in a synchrotron. The beam dynamics in this regime is however more complicated, and the emittance is sensitive to the working point, coupling correction, and bunch current drop with time, which complicates the operation. [...]

The FLASH free-electron laser (FEL) at DESY is currently operated in self-amplified spontaneous emission (SASE) mode in both beamlines FLASH1 and FLASH2. Seeding offers unique properties for the FEL pulse, such as full coherence, spectral and temporal stability [...]

The axion not only solves the strong CP puzzle, but it also may be the main constituent of cold dark matter. We review the axion dark matter predictions for the case that the Peccei-Quinn symmetry is restored after inflation..