BESSY II launches New Filling Pattern in User Mode

The new filling pattern consists of a Hybrid (or Camshaft) bunch at 4 mA (Chopper) in the center of the 200 ns wide ion clearing gap followed by the so-called PPRE-bunch of variable transverse excitation at 3 mA and 84 ns later. Together with the usual multibunch filling and the 3 slicing bunches on top of the multibunch train, now 302 out of 400 possible buckets in the storage ring are filled and topped up.

The new filling pattern consists of a Hybrid (or Camshaft) bunch at 4 mA (Chopper) in the center of the 200 ns wide ion clearing gap followed by the so-called PPRE-bunch of variable transverse excitation at 3 mA and 84 ns later. Together with the usual multibunch filling and the 3 slicing bunches on top of the multibunch train, now 302 out of 400 possible buckets in the storage ring are filled and topped up. © HZB

Since July 2015 BESSY II has been providing a new bunch filling pattern in Top-Up mode. It will open new opportunities especially for research teams dealing with time-resolved x-ray experiments. It is of significant importance for us and the community anticipating BESSY VSR.

Apart from ultrafast experiments at the Femtoslicing facility (slicing bunches) and x-ray pump-probe applications with the hybrid (or camshaft) bunch, now also time-of-flight experiments with the ARTOF and other instruments that use the pulse selection of the MHz-Chopper [1]  can be carried out in normal mode.

The new additional bunch in the dark gap arriving 84 ns after the chopper bunch can be transversally excited to support time-resolved Photoelectron- and X-ray spectroscopy based on the PPRE-technique [2]. Having such time-resolved methods at hand in the regular usermode we are even now able to take a glimpse into future operation modes at BESSY VSR.

red.

  • Copy link

You might also be interested in

  • Surprising insights into the chemistry of hydroxyl radicals at BESSY II
    Science Highlight
    09.04.2026
    Surprising insights into the chemistry of hydroxyl radicals at BESSY II
    How do radicals form in aqueous solutions when exposed to UV light? This question is important for health research and environmental protection, for example with regard to the overfertilisation of water bodies by intensive agriculture. A team at BESSY II has now developed a new method of investigating hydroxyl radicals in solution. By using a clever trick, the scientists gained surprising insights into the reaction pathway.
  • Kick-off for a new data and AI centre in Berlin
    News
    27.03.2026
    Kick-off for a new data and AI centre in Berlin
    By establishing a new data and AI centre in Berlin, the Zuse Institute Berlin (ZIB) and the Helmholtz-Zentrum Berlin (HZB) are laying the foundations for a scalable and sovereign data infrastructure in the capital. The project strengthens the scientific capabilities of Berlin’s research community whilst making an important contribution to research security, resilience and technological independence.

  • Protein crystallography at BESSY II: faster, better and more and more automatic
    Interview
    04.03.2026
    Protein crystallography at BESSY II: faster, better and more and more automatic
    Many diseases are linked to malfunctions of proteins in the organism. The three-dimensional architecture of these molecules is often highly complex, but it can provide valuable insights into biological processes and the development of drugs. X-ray diffraction at the MX beamlines of BESSY II can be used to decipher the 3D structure of proteins. To date, more than 5000 structures have been solved at the three MX beamlines. Here, we present a review and an outlook with  Manfred Weiss, head of the research group for macromolecular crystallography.