Dancing BESSY-VSR
Paul Goslawski from Godehard Wüstefeld's team was the initiator of this project: Why not demonstrate in vivid form, what the future project BESSY-VSR is all about? With novel cavities to be introduced in synchrotron storage ring BESSY II, the new BESSY-VSR is supposed to compress some of the stored electron buckets. So it is possible to produce brilliant light pulses with variable length: short and long pulses in one ring. The user is able to choose what kind of pulse he needs for his experiment. But the team still has to solve some tricky problems.
Two short movies are now produced to show how BESSY-VSR works and what remains to be solved: The principle as well as the difficulties are now being performed with a dance!
To realize his project, Paul quickly found enthusiastic volunteers: 24 colleagues took part, among them two heads of institutes. Most of them danced in a circle (the storage ring) as "electron buckets", while the "cavities" provided some drive to the system. With the help of a few more colleagues, the shooting of the videos itself only took one afternoon, whereas Paul spent some weekends editing the final film.
But it was worth the effort! Now, the two short films are available in the HZB media centre and on youtube, both in german and english language. "They could even be of good use in presentations", Paul says. Because only motion pictures can illustrate complex physics in an easy way.
- BESSY II: New sample environment allows glimpse into thermocatalytic processesA novel measurement cell allows, for the first time, soft and hard X-ray investigations under high pressures of up to 20 bar and temperatures of up to 400°C. This provides new insights into thermocatalytic processes, such as the Fischer-Tropsch synthesis for producing synthetic fuels. The development of the measurement cell is considered a significant achievement within the Care-O-Sene project.
- Magnetic imaging: Micro-flowers increase the local magnetic fieldMaterials with magnetic nanostructures have many potential applications such as in spintronics. To explore such materials, nanoscale magnetic-sensitive imaging techniques are very useful, but up to now only weak magnetic fields could be applied during the imaging process. Now an international collaboration led by Dr. Sergio Valencia, HZB, has developed an approach that overcomes this limitation. The team designed tiny magnetic flux concentrators (MFCs), into which the sample is placed. The geometry of the MFCs resembles a flower with a number of petals which focus the applied magnetic field into its center. This greatly expands the magnetic field range available during imaging, and so the range of magnetic systems that can be investigated. The micro-flowers, enhancing magnetic fields locally, can find application in different nanometric magnetic microscopy techniques.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.