European XFEL Commissions Its Particle Accelerator

The European XFEL has successfully commissioned the particle accelerator that will drive the X-ray laser along its full length. When fully operational, the research facility will produce up to 27,000 X-ray laser flashes per second, each so short and intense that researchers can make pictures of structures and processes at the atomic level. The accelerator’s superconducting technology, developed by an international collaboration led by DESY, is the basis for the facility’s high rate of X-ray laser flashes.

From December into January, DESY engineers cooled the accelerator to -271°C, the operating temperature at which its components have no electrical resistance. The electron injector and first section of the main accelerator then went into operation, comprising altogether 18 of 98 total accelerator modules. Within this section, engineers accelerated and compressed electron bunches three times, down to 10 micrometers, or a thousandth of a millimeter. The team then placed the third section of the accelerator into operation.

Currently, XFEL electrons reach an energy of 12 gigaelectronvolts (GeV), with an energy of up to 17.5 GeV planned for regular operation. “The energy and other properties of the electron bunches are already within the range where they will be during first user operation,” says Winfried Decking, the DESY physicist who leads the commissioning of the European XFEL accelerator.

Accelerated electrons have now passed through the complete 2.1-kilometer length of the accelerator tunnel. In the next step, the energy of the electrons will be raised further, and then sent into 210-meter long magnetic structures called undulators, a magnetic slalom type section that generates the bright X-ray laser light. Researchers have planned the first lasing for May and expect experiments to begin in the fall.

“The European XFEL’s particle accelerator is the first superconducting linear accelerator of this size in the world to go into operation,” says Helmut Dosch, chairman of the DESY Board of Directors. “With the commissioning of this complex machine, DESY and European XFEL scientists have placed the crown on their 20-year engagement in developing and building this large international project. The first experiments are within reach, and I am quite excited about the discoveries ahead of us. I am exceptionally happy about arriving at this milestone and congratulate all involved for the outstanding work and their great tenacity.”

An international consortium led by DESY built the European XFEL superconducting particle accelerator over the last seven years. “The successful commissioning of the accelerator is a very important step that brings us much closer to the start of user operation in the fall,” says Robert Feidenhans, chairman of the European XFEL Management Board. “Under the leadership of DESY, the Accelerator Consortium, comprising 17 research institutes, has done an excellent job in the last years. I thank all colleagues involved for their work, which entailed a great deal of know-how and precision but also much personal commitment. The accelerator is an outstanding example of successful global cooperation, encompassing research facilities, institutes and universities alongside companies that produced certain components.”