HZB builds undulator for SESAME in Jordan
The APPLE II UE56 double undulator generates brilliant light with variable polarization. © HZB
The Helmholtz-Zentrum Berlin is building an APPLE II undulator for the SESAME synchrotron light source in Jordan. The undulator will be used at the Helmholtz SESAME beamline (HESEB) that will be set up there by five Helmholtz Centres. The Helmholtz Association is investing 3.5 million euros in this project coordinated by DESY.
SESAME stands for "Synchrotron Light for Experimental Science and Applications in the Middle East" and provides brilliant X-ray light for research purposes. The third-generation synchrotron radiation source became operational in 2017. Egypt, Iran, Israel, Jordan, Pakistan, the Palestinian Authority, Turkey, and Cyprus are cooperating on this unique project to provide scientists from the Middle East with access to one of the most versatile tools for research.
New beamline for soft x-rays
Thus far, SESAME has four beamlines and will now receive a fifth meant to generate "soft" X-ray light in the energy range between 70 eV and 1800 eV. This X-ray light is particularly suitable for investigating surfaces and interfaces of various materials, for observing certain chemical and electronic processes, and for non-destructive analysis of cultural artefacts. The new beamline will be constructed as the Helmholtz SESAME Beamline (HESEB) by the Helmholtz Centres DESY (coordinating Centre), Forschungszentrum Jülich, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Helmholtz-Zentrum Berlin (HZB) as well as the Karlsruhe Institute of Technology (KIT).
Undulator made by HZB
The team headed Dr. Johannes Bahrdt at the HZB has assumed the task of constructing and commissioning an undulator for the new beamline. Undulators consist of two opposing arrays of magnets that force the ultrafast electron bunches into wave-like motion. At each reversal point of the wave, the electron bunches emit light that superposes itself on the previously emitted light to produce a coherent, laser-like beam – synchrotron light.
APPLE II UE56 provides polarized light
Johannes Bahrdt has already developed several types of undulators, including the APPLE II UE56 undulator that has been used very successfully at BESSY II for almost 20 years. The APPLE II UE56 double undulator generates brilliant light with variable polarization. This can be used, for example, to study magnetic nanostructures. For SESAME, a UE56 module will now be completely rebuilt, equipped with new magnets and brought up to the state of the art. The undulator team will train their SESAME colleagues and later support them via remote maintenance.
SESAME and HZB
SESAME has a long history with the HZB: at the heart of SESAME are also some accelerator components from BESSY I that were dismantled in 1998. The Helmholtz Association is supporting the Helmholtz SESAME Beamline project (HESEB) with a total of 3.5 million euros. The project will start at the beginning of 2019 and should be completed in four years.
- Ultrafast demagnetisation - Thinner iron, stronger effectThe thinner an iron film, the more easily it can be demagnetised by a laser pulse. Researchers at the University of Duisburg-Essen, working with Helmholtz-Zentrum Berlin and other partners, have discovered why: the key lies in the magnetic order at the material's interfaces. In the long term, these findings could contribute to the development of new technologies for magnetic data storage. The results have been published in the scientific journal Advanced Science.
- Blind spot for the arrangement of atomsArtificial intelligence is increasingly being used to predict the properties of new materials. A research team from Jena and the United States now shows in a study published in the journal Nature Computational Science that when language models are used for this purpose, they reliably identify which types of atoms a material contains. However, they make insufficient use of information about how those atoms are arranged in space. Neither larger models nor additional training data resolve this weakness. For material properties that depend strongly on structure, AI models specifically designed to process spatial relationships are therefore the more reliable choice. (DOI: 10.1038/s43588-026-01045-2)
- Patterns of polar vortices in lead-free superlattices on siliconA team at HZB has, for the first time, reported polar vortices in (BaTiO3/SrTiO3)10 superlattices on silicon. These results expand the range of materials and substrates on which polar topological textures can occur and open up new options for incorporating complex ferroelectric states into silicon-based technologies.