First light in the SwissFEL Maloja endstation

The first endstation at the SwissFEL Athos soft X-ray branch is rapidly developing and on track for first experiments in 2021.

On Friday June 26th 2020, late in the evening, the intense soft X-ray pulses from the Athos undulator line at SwissFEL have entered the Maloja endstation for the first time. In the following days already electron, ion, and photon spectra could be measured from single and unfocused x-ray pulses. This is a major step towards bringing the SwissFEL Athos branch into operations.

Figure 1: The first X-ray pulses in the Maloja endstation seen on a screen. The beam is focused to a vertical line with the first beam line mirror.

The Athos branch of SwissFEL produced first soft x-ray pulses in December 2019 with only two out of sixteen undulator modules installed. At that time, the Maloja experimental hall was still completely empty and large boxes with equipment started arriving.

In the following months, teams from across PSI poured concrete baseplates for the beamline and endstation optics, laid cables, and installed vacuum systems. Over a hundred meter of beamline and the endstation were on a fast track when a major and unforeseen hurdle developed, the COVID-19 pandemic arrived in Switzerland.

With virtually all of PSI in home office, new concepts needed to be developed. A small number of people continued working onsite, installing the endstation infrastructure and components as well as finished the hundred meters of beamline vacuum and optical systems. Other staff worked remotely on design and engineering of components, developed data analysis routines, and software tools.

Figure 2.: The happy Maloja endstation team. From front to rear Gregor Knopp, Jonas Knurr, Andre Al Haddad, Sven Augustin, Kirsten Schnorr, Zhibin Sun, and Christoph Bostedt. Missing on the photo are Florian Amrein and Simon Tiefenbacher.

The tireless effort of the technical, engineering, and scientific staff across divisions allowed the x-ray pulses to fly closer and closer to the endstation throughout June. At the same time, the instrument team was busy setting up the Maloja endstation and testing their devices in the off-hours. “On Friday late evening everything came nicely together and we were in principle ready for first beam, a few days prior to the scheduled milestone,” said Kirsten Schnorr, a Maloja scientist. “We decided spontaneously to ask the control room if they can deliver x-rays – and they did!” she added.

“It was amazing to see how our systems came to life one after another over the next days” mentioned Andre Al Haddad, another Maloja scientist. “After years of planning, designing, and building the Maloja endstation this was a great moment” both agreed with a big smile.

Of course, the COVID-19 pandemic has also left its mark on the project. For example, the installation of the beamline refocusing optics, a key component for the endstation, was delayed until late summer due to international travel restrictions. But the Athos project teams will also  get these components up and running soon and they anticipate that the Maloja endstation will be ready for first experiments on ultrafast and non-linear soft X-ray sciences  in 2021.


The Maloja endstation is supported with a R’equip grant from the Swiss National Science Foundation. More information about SwissFEL and its scientific capabilities can be found at