The European XFEL is going to be the world's biggest X-ray laser when it launches in September, but the science team is already celebrating as the device just completed its last major test, shining its powerful X-ray beam for the first time. 

"This is an important moment that our partners and we have worked towards for many years. The European XFEL has generated its first X-ray laser light,” European XFEL Managing Director Prof. Robert Feidenhans'l said in a statement. “We can now begin to direct the X-ray flashes with special mirrors through the last tunnel section into the experiment hall, and then step by step start the commissioning of the experiment stations. I very much look forward to the start of international user operation, which is planned for September."

The facility is 3.4 kilometers (2.1 miles) long and produces X-rays through the acceleration of electrons, the so-called synchrotron radiation. The tiny particles are first pushed to almost the speed of light in a 2.1-kilometer (1.3-mile) accelerator tunnel and then 17,290 permanent magnets with alternating poles get them on a slalom course, forcing them to release short X-ray bursts.

These X-rays have a wavelength of 0.8 nanometers, about the width of an atom and 500 times smaller than visible light. Their size makes the European XFEL an important instrument, as it can create pictures and movies with atomic resolution. Powerful X-ray lasers around the world have already been used to look at biological and chemical reactions, peering futher and further into the nano world.

^{The detected first laser light at the European XFEL. DESY}

“The first laser light produced today with the most advanced and most powerful linear accelerator in the world marks the beginning of a new era of research in Europe," added Helmut Dosch, chairman of the DESY (Deutsches Elektronen-Synchrotron) Directorate, where the laser is located. "The European XFEL will provide us with the most detailed images of the molecular structure of new materials and drugs and novel live recordings of biochemical reactions."

“I congratulate all those involved in the research, development, and construction of this facility with passion and commitment: the employees of DESY, European XFEL, and international partners. They have achieved outstanding results and demonstrated impressively what is possible in international cooperation.”

The facility will open its doors to external scientists in early September, with researchers able to use the first two (of the eventual six) scientific instruments.