50 years later, Wilson Lab stays cutting edge

October 2018 marks the 50th anniversary of the dedication of the Wilson Synchrotron Laboratory.

Initially built for $11million and promising to deliver cutting-edge research in elementary particle physics, it was the NSF’s largest project at that time. Fifty years later, the lab is going through its biggest upgrade in decades.
Chris Conolly looks at the concrete floor of Wilson Lab, eyeing up the numerous holes drilled by one of the contractors for the upgrade project. These one-inch holes pockmark the 10,000sf experimental hall of the Wilson Synchrotron Laboratory. In a way, these holes represent the numerous experiments conducted over the past 50 years.

There are a lot of holes. 652 to be exact, as the CHESS X-ray Technical Director and CHESS-U beamline project manager easily points out.
“It’s almost like being an archaeologist”, says Conolly, as he walks through the maze of newly constructed hutches in the experimental hall. He stops near the sector II hutches, “especially this spot here,” he says, presenting a repeating pattern of drilled holes arcing across the floor. The pattern spans a total of about 25 feet, and Chris, who has been with CHESS for the past 18 years, has no idea what was held down by the bolts marked in the floor.

>Read more on the Cornell High Energy Synchrotron Source website

Image: Robert Wilson, right, was the architect behind Wilson Lab, as well as many of the subsequent experiments. Wilson later went over to Fermilab to design their famed building. 

2018 ALS User Meeting Highlights

Past, present, and future converged at the ALS User Meeting, held October 2–4, 2018. About 480 registrants helped celebrate the 25th anniversary of first light at the ALS and the announcement of CD-1 approval for the ALS Upgrade project (ALS-U), a major federal milestone. Users’ Executive Committee (UEC) Chair Will Chueh kicked things off by acknowledging the organizers—UEC members Jennifer Ciezak-Jenkins, Alex Frañó, and Michael Jacobs—and thanking the ALS for its support. He also explained the organizing principle behind the program: to engage student and young-scientist users and strengthen interactions between users in general. Jeff Neaton, Berkeley Lab’s Associate Laboratory Director for Energy Sciences, then extended an official welcome to attendees. He noted that it’s been an exciting year for the ALS, which gained a new director, Steve Kevan, in addition to CD-1 approval for ALS-U.

>Read more on the Advanced Light Source website

Image: Plenary session, Day 1.
Credit: Peter DaSilva/Berkeley Lab

Light at the end of the last tunnel

X-rays reach instruments HED and MID

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.

>Read more on the European XFEL website

Image: Screenshot of the first light.

First-year operational results of the MAX IV 3 GeV ring

If you fly over MAX IV right now and look down, you’ll see a large circular building. The reason for this size and shape is the 528-meter-long 3GeV storage ring which precisely guides bunches of electrons traveling at velocities approaching the speed of light. As the electrons pass through arrays of magnets called insertion devices, they produce bright X-rays which are then used by beamline scientists to do many different types of experiments.

In an article published this month in the Journal of Synchrotron Radiation, the 3 GeV ring team led by Pedro Tavares describe the results for the first year of operation. This important milestone in the MAX IV project provides validation for many of the brand-new concepts that were implemented in the MAX IV design in order to improve the performance of the machine and reduce downtime.

>Read more on the MAX IV Laboratory website


Linac team has reached major milestones

A big milestone was reached for the MAX IV linear accelerator end of May 2018.

The electron bunches accelerated in the linac was compressed to a time duration below 100 femtoseconds (fs). That means that they were shorter than 1*10^-13s. In fact, we could measure a pulse duration as low as 65 fs FWHM.

The RMS bunch length was then recorded at 32 fs. These results were achieved using only the first of the 2 electron bunch compressors in the MAX IV linac and shows not only that we can deliver short electron bunches, but also that the novel concept adopted in the compressors is working according to theory and simulations.

The ultra-short electron pulses are used to create X-ray pulses with the same short time duration in the linac based light source SPF (Short Pulse Facility). These bursts of X-rays can then be used to make time resolved measurements on materials, meaning you can make a movie of how reactions happen between parts of a molecule.

>Read more on the MAX IV Laboratory website

Picture: Linac team at MAX IV.

Diamond celebrates publication of its 7000th paper

A paper in PNAS by an international scientific collaboration from the UK, Germany and Switzerland is the 7000th to be published as a result of innovative research conducted at Diamond Light Source, the UK’s Synchrotron.

This new paper reveals details of the 3D spin structure of magnetic skyrmions, and will be of key importance for storing digital information in the development of next-generation devices based on spintronics.

Laurent Chapon, Diamond’s Physical Sciences Director, explains the significance of these new findings:  “A skyrmion is similar to a nanoscale magnetic vortex, made from twisted magnetic spins, but with a non-trivial topology that is ‘protecting them’. They are therefore stable, able to move, deform and interact with their environment without breaking up, which makes them very promising candidates for digital information storage in next-generation devices. For years, scientists have been trying to understand the underlying physical mechanisms that stabilise magnetic skyrmions, usually treating them as 2D objects. However, with its unique facilities and ultra-bright light, Diamond has provided researchers the tools to study skyrmions in 3D revealing significant new data.”

As spintronic devices rely on effects that occur in the surface layers of materials, the team was investigating the influence of surfaces on the twisted spin structure. It is commonly assumed that surface effects only modify the properties of stable materials within the top few atomic layers, and investigating 3D magnetic structures is a challenging task. However, using the powerful circularly polarised light produced at Diamond, the researchers were able to use resonant elastic X-ray scattering (REXS) to reconstruct the full 3D spin structure of a skyrmion below the surface of Cu2OSeO3.

>Read more on the Diamond Light Source website

Image: (extract) Illustration of a ‘Skyrmion tornado’. The skyrmion order changes from Néel-type at the surface to Bloch-type deeper in the sample. On the right hand side, the corresponding stereographic projections of these two boundary skyrmion patterns are shown. Full image and detailed article here.