XFEL: Light at the end of the last tunnel

During the afternoon and evening hours of Friday 5 October, the DESY accelerator team and the European XFEL photon commissioning team worked together to guide the first X-ray light through the last of the facility’s initial three X-ray beamlines, SASE2, and towards the last of the currently planned European XFEL instruments, the High Energy Density (HED) and Materials Imaging and Dynamics (MID) instruments.

At about midday on Friday, the X-ray light entered the photon tunnel leading to the SASE 2 instruments. To get there, the beam had to pass through a 12 mm horizontal aperture of the shutter collimator about 264 m from the source. In order to make this possible, alignment and vacuum system experts from the DESY accelerator group worked together during the last few months to precisely align the undulator section that generates X-ray laser light from accelerated electrons. This work was based on data obtained during the initial commissioning done in May 2018.

Once in the tunnel the beam was guided over a series of mirrors before reaching the last part of the MID branch during the evening of the 5 October and the HED branch the following day. At the end of the tunnel, the X-ray light was 937 m from the undulator.

The SASE2 instruments HED and MID will be the last of the currently planned instruments to start user operation, completing the initial configuration of the European XFEL.

The HED scientific instrument will be able to generate matter under extreme conditions of pressure, temperature, or electric fields using a combination of the European XFEL, high energy optical lasers, or pulsed magnets. These types of experiments will enable scientists to acquire insights into how planets and stars are formed. The first user experiment is planned for late spring 2019.

The MID instrument will focus on the determination of the structure of disordered materials as well as dynamics at the nanoscale, helping to understand, for example, how glassy states of matter form and how magnetism works, while also giving insights into the structure of biological cells and viruses. First experiments are scheduled for early 2019.