The European x-ray free electron laser (European XFEL) is an X-ray research laser facility recently inaugurated in Hamburg, Germany.
The international project with 11 participating countries (Denmark, France, Germany, Hungary, Italy, Poland, Russia, Slovakia, Spain, Sweden and Switzerland) is located in the German federal states of Hamburg and Schleswig-Holstein. A free-electron laser generates high-intensity electromagnetic radiation by accelerating electrons to relativistic speeds and directing them through special magnetic structures. The European XFEL is constructed such that the electrons produce x-ray light in synchronisation, resulting in high-intensity x-ray pulses with the properties of laser light and at intensities much brighter than those produced by conventional synchrotron light sources.
The 3.4 km long tunnel for the European XFEL housing the superconducting linear accelerator and photon beamlines will run 6 to 38 m underground from the site of the DESY research center in Hamburg to the town of Schenefeld in Schleswig-Holstein, where the administrative buildings and experimental stations and laboratories will be located.
The German Federal Ministry of Education and Research granted permission to build the facility on 5 June 2007 at a cost of 850 million EUR, under the provision that it should be financed as a European project. Following the 6-year construction period, commissioning of the facility will begin in 2016/2017. In 2007, the European XFEL project was officially launched and the European XFEL GmbH that will build and operate the facility has been founded in 2009. Civil construction of the facility began on 8 January 2009. Construction of the tunnels was completed in summer 2012, and all underground construction was completed the following year. The overall cost for the construction and commissioning of the facility is as of 2015 estimated at 1.22 billion EUR (price levels of 2005).
