HZB builds undulator for SESAME in Jordan

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.