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Institute for Materials Research

Partial Institute Materials Physics

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The Beamline Scientist: Jörg Hammel

How to look after a ninety-metre microscope

Dr. Jörg Hammel

Illustration: SCHUMACHER; background: HZG/C. Schmid, Portrait: HZG/B. Peters; graphic elements: iStock/ODV; the-lightwrite; naqiewei; Vijay kumar

Dr Jörg Hammel works in the Division for X-ray Imaging with Synchrotron Radiation at the Institute of Materials Research.

Petra III, sector 4, P05 – we are at the brightest storage ring X-ray source in the world. It’s noon on a Thursday. Dr Jörg Hammel worked until two in the morning yesterday. He nevertheless seems completely euphoric as he discusses his work at the beamline.

In this room with us are five work stations, all outfitted with several computer screens. Experiments can be controlled and observed from here, and it is here that the data is displayed and everything is checked.

Jörg Hammel is a beamline scientist. Together with his colleagues he maintains the P05 beamline, which is connected to the PETRA III storage ring in Hamburg. The entire facility is located on the DESY campus, and the beamline belongs to the HZG.

“We’re virtually working with a ninety-metre long microscope to look at miniscule samples – it's crazy!"

The samples are of the most varying kind. Hammel says, “We’ve already investigated the melting of magnesium alloys, the formation of a corrosion layer on biodegradable implants, the connection of the human Achilles tendon to the bone, sand-lime brick deposits, and shark bones – and those are just a sampling of what we've studied.” Emitted from the ring is an X-ray beam that is focussed on the sample to be examined. “We have a field of view measuring seven by seven millimetres. If we want to examine larger samples, we need to take various measurements and then add those together.”

Jörg Hammel grew up in Schwäbisch Hall, near Stuttgart, where the scientist, who is now thirty-eight years old, studied technical biology. “I quickly noticed that basic research is what motivates me. It’s so exciting when you can pursue new ideas.” He then attained his doctorate at the Friedrich-Schiller-University in Jena in the field of zoology. The topic of his dissertation: marine sponges. “These are the simplest multi-celled organisms that we know of – they have neither nerves nor muscles. They can nevertheless react to neuroactive substances and can move on their own. They were extremely exciting objects to research,” he says.

“What lies hidden behind things had already piqued my interest back then. How does it work? Why is it like that? And how can we make even more improvements in how we study it?”

Today he lives with his wife and two children in Hamburg. “The proximity to the water offsets the lack of mountains,” he says with a smile.

While we’re talking, a colleague enters with a quick request. Hammel turns toward the monitor, where we can glimpse around seven different windows with numbers and commands. What the monitor also shows is what the camera is recording at the beamline. “Right now we’re studying the respiratory organs of insects. Here you can see the organs from a type of cricket,” he explains to me. A few clicks and his colleague is satisfied. Things can proceed.

During his graduate studies, Hammel had already forged connections to P05 and the scientists working there. The beamline itself was set up in 2009 and he was amongst the users when the first experiments were carried out. “The high-quality technology here had fascinated me even back then,” he says. “There are so many possibilities for further development – and we have the opportunity to drive this development forward, which is terrific!” After short research stays in Amsterdam and Jena, the scientist seized his chance when a position opened in 2014. “They were searching for someone who was familiar with the facility and who came from the field of life sciences. It fit me perfectly.”

The measuring time at the beamline is heavily regimented. Eighty per cent is assigned to external users. These users can submit requests, which then go through an assignment system and an expert committee. The applicants receive a maximum of one week at the beamline. That time is fully utilised: those granted only seventy-two hours for their project will sleep as little as possible. Jörg Hammel and his colleagues look after the external projects and also remain on call. “Fortunately we can manage a lot from home through the PC, as calls at 2:30 in the morning are not unusual,” he points out. The remaining twenty per cent of the operational time is assigned internally. This time is used for starting up the facilities, further development and their own projects.

“We’re working at the limit of feasibility here”

“Soon we’ll have a weekend with measuring time just for us – my colleagues and I are ecstatically looking forward to it! We're working on time-resolved measurements at the moment, basically 4D. It’s like 3D but the temporal evolution is also included. We can then observe dynamic processes and movements,” says Hammel. At the moment, they're managing to create twenty-second recordings in very high quality using the technology. This, however, only works with good teamwork. Four scientists cooperate with engineers here. There is a great deal of collaboration with the HZG’s Central Technology Department. “Much of the equipment is not at all standard; we are, after all, undertaking cutting-edge research.”

Author: Gesa Seidel (HZG)
Published in the in2science #7 (December 2018)