'PhD Thesis Prize' of the Association of the Friends and Sponsors of DESY for Sebastien Couet and Michael Röhrs (May 2009)

DESY Price 2009

From left: Dr. Sebastien Couet, DESY Director Professor Helmut Dosch, Dr. Michael Röhrs

This year’s PhD thesis prize of the Association of the Friends and Sponsors of DESY is shared by Dr. Sebastien Couet (Measurement of magnetic and structural properties of iron oxide at DESY and the ESRF) and Dr. Michael Röhrs (Investigation of the Phase Space Distribution of Electron Bunches at FLASH) , both from the University of Hamburg. The annual PhD thesis prize from the Association of the Friends and Sponsors of DESY acknowledges the best doctoral thesis on DESY physics every year.

Sebastien Couet receives the prize for his excellent thesis on “The structural and magnetic properties of Fe/native oxide systems resolved by X-ray scattering and spectroscopy methods”. Couet’s work deals with the oxidation of iron, which is especially undesirable when it leads to corroding of the material. Thin oxide layers, however, can also lend the iron completely new properties. To study this, Couet produced sandwich-layered systems consisting of alternating layers of iron and its natural oxide, and observed their growth using synchrotron radiation. His analyses show that the magnetic alignment of the individual iron layers is not parallel, but rather perpendicular to one another. This is due to the structure of the oxide between the iron layers. The results of Couzet’s thesis point out a new way of stabilizing novel magnetic structures in the nanocosmos. His research was carried out jointly at the Deutsches Elektronen-Synchrotron and the ESRF (at ID 18).

Michael Röhrs receives the prize for his thesis on the “Investigation of the Phase Space Distribution of Electron Bunches at the FLASH Linac Using a Transverse Deflecting Structure”. His work covers high-resolution beam diagnostics at the free-electron laser FLASH. The electron bunches used in FLASH have to be strongly compressed in the longitudinal direction in order to reach the peak currents of several thousand Ampere required for the FEL. The extremely complex phenomena occurring during this compression can be modelled only inadequately in theoretical models. Röhrs analysed the compressed electron bunches with a measuring device corresponding to an oscillograph with a time resolution enhanced by a factor of thousand. He used methods of computed tomography to determine the spatial and temporal structure of the electron bunches with unprecedented precision. Michael Röhrs’ results have been widely recognized throughout the international community. At the FEL conference 2008 in Korea, he was awarded the “Young Investigator FEL Prize” for his achievements.

(From DESY News 20 May 2009)