Taming the complex

Project plan

Superconducting magnets from Spain, accelerator elements from Germany and Italy ready for assembly in France, cryostats from China, absorbers from Poland and beam transport magnets as well as vacuum systems from Russia – this non-exhaustive enumeration shows: the accelerator of the European XFEL will be truly international. Partners from all over the world have joined together to build a state-of-the-art accelerator that will be the world champion of superconducting linear accelerators in parameters like beam quality and repetition rate.

The accelerator complex is an integral part of the European XFEL. It will boost bunches of electrons to high energies at which they will generate X-ray flashes of outstanding brilliance. More than a dozen institutes from nine countries form the so-called Accelerator Consortium that is in charge of the construction of the accelerator complex.

“We are building an outstanding accelerator, and it’s a great task”, says Hans Weise, freshly appointed leader of the Consortium. He is the conductor of an orchestra of specialists. His job is to make sure that the result not only sounds good, but is world-class. For that, correct timing is essential.

“Our goal was to develop one common schedule with all the necessary links between the work packages. Now we have to see that this schedule is complied with. It looks very good so far”, Weise says. To accomplish this daunting task, he is not only supported by project management software, but also by a team of four people plus the leaders of all the work packages the workload of the Accelerator Consortium is divided into. His office is located at DESY in Hamburg, which is the leading contributor to the complex and acts as the coordinator of the consortium.

Hans Weise—In July 2007 Hans Weise was appointed leader of the project that is in charge of DESY’s contribution to the construction of the European XFEL. He also took over the coordination of the Accelerator Consortium for the X-ray free-electron laser. The accelerator scientist joined DESY in 1993. He lives in Hamburg with his wife and two children.

European XFEL GmbH

Hans Weise almost grew up with accelerators: “My diploma and PhD theses were on that topic already. Then in Darmstadt, we developed Germany’s first free-electron laser.” A machine of which he knew all the components by heart. After his PhD, he was asked by DESY to bring his expertise to the TESLA project: the idea of a large accelerator for particle physics and photon science, of which the European XFEL is an offspring.

What makes the accelerator of the European XFEL so special are its superconducting accelerating elements. These operate at around two degrees above absolute zero and make the outstanding beam quality and high repetition rate possible in the first place. One of Weise’s first jobs as Consortium Leader was to organize the commissioning of two industry partners with the production of 640 of these cavities. From 2012 on, the delivered cavities will be put through their paces in a custom-built test hall at DESY. The cavities will then be sent to France to be put together to accelerator modules, each comprising a string of eight superconducting cavities. The completed modules will then be brought back to Hamburg to be tested again before final assembly in the tunnel. “To ensure that the sensitive modules will survive the transport, we have already test-transported modules from Hamburg to Saclay and back. All went pretty well”, Hans Weise says.

Since summer he has been project leader of the Accelerator Consortium and is now in charge of the second biggest item of the European XFEL construction budget – after civil construction. That’s a lot of responsibility, but Hans Weise is relaxed, can build on the strong teams at all contributing institutions and has no sleepless nights. “I have no nightmares. What we are doing is what we have been wanting to do for many many years. We are very well prepared.”

Author: Dirk Rathje