New AI-driven tool streamlines experiments

Researchers at the Department of Energy’s SLAC National Accelerator Laboratory have demonstrated a new approach to peer deeper into the complex behavior of materials. The team harnessed the power of machine learning to interpret coherent excitations, collective swinging of atomic spins within a system. 

This groundbreaking research, published recently in Nature Communications, could make experiments more efficient, providing real-time guidance to researchers during data collection, and is part of a DOE-funded project led by Howard University including researchers at SLAC and Northeastern University to use machine learning to accelerate research in materials. 

The team created this new data-driven tool using “neural implicit representations,” a machine learning development used in computer vision and across different scientific fields such as medical imaging, particle physics and cryo-electron microscopy. This tool can swiftly and accurately derive unknown parameters from experimental data, automating a procedure that, until now, required significant human intervention.

Peculiar behaviors

Collective excitations help scientists understand the rules of systems, such as magnetic materials, with many parts. When seen at the smallest scales, certain materials show peculiar behaviors, like tiny changes in the patterns of atomic spins. These properties are key for many new technologies, such as advanced spintronics devices that could change how we transfer and store data. 

To study collective excitations, scientists use techniques such as inelastic neutron or X-ray scattering. However, these methods are not only intricate, but also resource-intensive given, for example, the limited availability of neutron sources. 

Machine learning offers a way to address these challenges, although even then there are limitations. Past experiments used machine learning techniques to enhance the accuracy of X-ray and neutron scattering data interpretation. These efforts relied on traditional image-based data representations. But the team’s new approach, using neural implicit representations, takes a different route. 

Read more on SLAC website

LCLS-II ushers in a new era of science

SLAC fires up the world’s most powerful X-ray laser

With up to a million X-ray flashes per second, 8,000 times more than its predecessor, it transforms the ability of scientists to explore atomic-scale, ultrafast phenomena that are key to a broad range of applications, from quantum materials to clean energy technologies and medicine.

The newly upgraded Linac Coherent Light Source (LCLS) X-ray free-electron laser (XFEL) at the Department of Energy’s SLAC National Accelerator Laboratory successfully produced its first X-rays, and researchers around the world are already lined up to kick off an ambitious science program. 

The upgrade, called LCLS-II, creates unparalleled capabilities that will usher in a new era in research with X-rays. Scientists will be able to examine the details of quantum materials with unprecedented resolution to drive new forms of computing and communications; reveal unpredictable and fleeting chemical events to teach us how to create more sustainable industries and clean energy technologies; study how biological molecules carry out life’s functions to develop new types of pharmaceuticals; and study the world on the fastest timescales to open up entirely new fields of scientific investigation. 

“This achievement marks the culmination of over a decade of work,” said LCLS-II Project Director Greg Hays. “It shows that all the different elements of LCLS-II are working in harmony to produce X-ray laser light in an entirely new mode of operation.”  

Reaching “first light” is the result of a series of key milestones that started in 2010 with the vision of upgrading the original LCLS and blossomed into a multi-year ($1.1 billion) upgrade project involving thousands of scientists, engineers, and technicians across DOE, as well as numerous institutional partners. 

“For more than 60 years, SLAC has built and operated powerful tools that help scientists answer fundamental questions about the world around us. This milestone ensures our leadership in the field of X-ray science and propels us forward to future innovations,” said Stephen Streiffer, SLAC’s interim laboratory director. “It’s all thanks to the amazing efforts of all parts of our laboratory in collaboration with the wider project team.”

Read more on the SLAC website

Image: The newly upgraded Linac Coherent Light Source (LCLS) X-ray free-electron laser (XFEL) at the Department of Energy’s SLAC National Accelerator Laboratory successfully produced its first X-rays. The upgrade, called LCLS-II, creates unparalleled capabilities that will usher in a new era in research with X-rays.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

SLAC researchers take important step toward developing cavity-based X-ray laser technology

Researchers have announced an important step in the development of a next-gen technology for making X-ray free-electron laser pulses brighter and more stable: They used precisely aligned mirrors made of high-quality synthetic diamond to steer X-ray laser pulses around a rectangular racetrack inside a vacuum chamber.

Setups like these are at the heart of cavity-based X-ray free-electron lasers, or CBXFELs, which scientists are designing to make X-ray laser pulses brighter and cleaner – more like regular laser beams are today.

“The successful delivery of a cavity-based X-ray free-electron laser will mark the start of a new generation of X-ray science by providing a huge leap in beam performance,” said Mike Dunne, director of the Linac Coherent Light Source (LCLS) X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory, where the work was carried out.

“There are still many challenges to overcome before we get there,” he said. “But demonstration of this first integrated step is very encouraging, showing that we have the approach and tools needed to sustain high cavity performance.”

The SLAC research team described their work in a paper published in Nature Photonics. Early results were so encouraging, they said, that the lab is already working with DOE’s Argonne National Laboratory, its longtime collaborator on the subject, to design and install the next, bigger version of the experimental cavity system in the LCLS undulator tunnel.

Despite their name, X-ray laser pulses are not yet fully laser-like. They’re created by making accelerated electrons wiggle through sets of magnets called undulators. This forces them to give off X-rays, which are shaped into powerful pulses for probing matter at the atomic scale. At LCLS, pulses arrive 120 times a second, a rate that will soon increase to a million times per second. 

But because of the way X-ray laser pulses are generated, they vary in intensity and contain an unpredictable mix of wavelengths. This creates what scientists call “noise,” which muddles their view of samples they are probing. 

The introduction of a cavity has been proposed to overcome this problem, adopting the approach used by conventional optical lasers. Cavities increase the coherence of lasers ­by preferentially selecting light of a single wavelength whose peaks and troughs line up with each other. ­But the mirrors that bounce light around in regular laser cavities won’t work for X-ray laser pulses – all you would get would be a smoking hole in your mirror where the X-rays drilled through. 

The idea of using crystals – and, more recently, synthetic diamond crystals – as mirrors to smooth and help amplify X-ray pulses inside a cavity has been around for a long time, said Diling Zhu, who led the experimental team with fellow SLAC scientist Gabriel Marcus.

Read more on SLAC website

Image: A top-down view of one of the cavity vacuum chambers. Two diamond mirrors can be seen in the upper and lower left corners, each one mounted on four motors that control its angle and position. At upper right, the precision diamond grating that brings X-ray pulses into the chamber is mounted on a screen holder. 

Credit: Diling Zhu/SLAC National Accelerator Laboratory

Elusive missing step in the final act of photosynthesis

After decades of effort and help from SLAC’s X-ray laser, scientists have finally seen the process by which nature creates the oxygen we breathe.

Photosynthesis plays a crucial role in shaping and sustaining life on Earth, yet many aspects of the process remain a mystery. One such mystery is how Photosystem II, a protein complex in plants, algae and cyanobacteria, harvests energy from sunlight and uses it to split water, producing the oxygen we breathe. Now researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Lawrence Berkeley National Laboratory, together with collaborators from Uppsala University, Humboldt University, and other institutions have succeeded in cracking a key secret of Photosystem II.

Using SLAC’s Linac Coherent Light Source (LCLS) and the SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan, they captured for the first time in atomic detail what happens in the final moments leading up to the release of breathable oxygen. The data reveal an intermediate reaction step that had not been observed before.

Find out more on the SLAC website

New SLAC-Stanford Battery Center targets roadblocks to a sustainable energy transition

The center at SLAC aims to bridge the gaps between discovering, manufacturing and deploying innovative energy storage solutions. 

The Department of Energy’s SLAC National Accelerator Laboratory and Stanford University today announced the launch of a new joint battery center at SLAC. It will bring together the resources and expertise of the national lab, the university and Silicon Valley to accelerate the deployment of batteries and other energy storage solutions as part of the energy transition that’s essential for addressing climate change.

A key part of this transition will be to decarbonize the world’s transportation systems and electric grids ­– to power them without fossil fuels. To do so, society will need to develop the capacity to store several hundred terawatt-hours of sustainably generated energy. Only about 1% of that capacity is in place today.

Filling the enormous gap between what we have and what we need is one of the biggest challenges in energy research and development. It will require that experts in chemistry, materials science, engineering and a host of other fields join forces to make batteries safer, more efficient and less costly and manufacture them more sustainably from earth-abundant materials, all on a global scale. 

The SLAC-Stanford Battery Center will address that challenge. It will serve as the nexus for battery research at the lab and the university, bringing together large numbers of faculty, staff scientists, students and postdoctoral researchers from SLAC and Stanford for research, education and workforce training. 

 “We’re excited to launch this center and to work with our partners on tackling one of today’s most pressing global issues,” said interim SLAC Director Stephen Streiffer. “The center will leverage the combined strengths of Stanford and SLAC, including experts and industry partners from a wide variety of disciplines, and provide access to the lab’s world-class scientific facilities. All of these are important to move novel energy storage technologies out of the lab and into widespread use.”

Expert research with unique tools

Research and development at the center will span a vast range of systems – from understanding chemical reactions that store energy in electrodes to designing battery materials at the nanoscale, making and testing devices, improving manufacturing processes and finding ways to scale up those processes so they can become part of everyday life. 

“It’s not enough to make a game-changing battery material in small amounts,” said Jagjit Nanda, a SLAC distinguished scientist, Stanford adjunct professor and executive director of the new center, whose background includes decades of battery research at DOE’s Oak Ridge National Laboratory. “We have to understand the manufacturing science needed to make it in larger quantities on a massive scale without compromising on performance.”

Longstanding collaborations between SLAC and Stanford researchers have already produced many important insights into how batteries work and how to make them smaller, lighter, safer and more powerful. These studies have used machine learning to quickly identify the most promising battery materials from hundreds made in the lab, and measured the properties of those materials and the nanoscale details of battery operation at the lab’s synchrotron X-ray facility. SLAC’s X-ray free-electron laser is available, as well, for fundamental studies of energy-related materials and processes. 

SLAC and Stanford also pioneered the use of cryogenic electron microscopy (cryo-EM), a technique developed to image biology in atomic detail, to get the first clear look at finger-like growths that can degrade lithium-ion batteries and set them on fire. This technique has also been used to probe squishy layers that build up on electrodes and must be carefully managed, in research performed at the Stanford Institute for Materials and Energy Sciences (SIMES).

Nanda said the center will also focus on making energy storage more sustainable, for instance by choosing materials that are abundant, easy to recycle and can be extracted in a way that’s less costly and produces fewer emissions.

Read more on the SLAC website

Artificial intelligence deciphers detector “clouds” to accelerate materials research

A machine learning algorithm automatically extracts information to speed up – and extend – the study of materials with X-ray pulse pairs.

X-rays can be used like a superfast, atomic-resolution camera, and if researchers shoot a pair of X-ray pulses just moments apart, they get atomic-resolution snapshots of a system at two points in time. Comparing these snapshots shows how a material fluctuates within a tiny fraction of a second, which could help scientists design future generations of super-fast computers, communications, and other technologies.

Resolving the information in these X-ray snapshots, however, is difficult and time intensive, so Joshua Turner, a lead scientist at the Department of Energy’s SLAC National Accelerator Center and Stanford University, and ten other researchers turned to artificial intelligence to automate the process. Their machine learning-aided method, published October 17 in Structural Dynamics, accelerates this X-ray probing technique, and extends it to previously inaccessible materials.

“The most exciting thing to me is that we can now access a different range of measurements, which we couldn’t before,” Turner said.

Handling the blob

When studying materials using this two-pulse technique, the X-rays scatter off a material and are usually detected one photon at a time. A detector measures these scattered photons, which are used to produce a speckle pattern – a blotchy image that represents the precise configuration of the sample at one instant in time. Researchers compare the speckle patterns from each pair of pulses to calculate fluctuations in the sample.

“However, every photon creates an explosion of electrical charge on the detector,” Turner said. “If there are too many photons, these charge clouds merge together to create an unrecognizable blob.” This cloud of noise means the researchers must collect tons of scattering data to yield a clear understanding of the speckle pattern.

“You need a lot of data to work out what’s happening in the system,” said Sathya Chitturi, a Ph.D. student at Stanford University who led this work. He is advised by Turner and coauthor Mike Dunne, director of the Linac Coherent Light Source (LCLS) X-ray laser at SLAC. 

Read more on the SLAC website

Image: A speckle pattern typical of the sort seen at LCLS’s detectors

Credit: Courtesy Joshua Turner

Researchers resolve decades-long debate about shock-compressed silicon with unprecedented detail

They saw how the material finds a path to contorting and flexing to avoid being irreversibly crushed.


Silicon, an element abundant in Earth’s crust, is currently the most widely used semiconductor material and is important in fields like engineering, geophysics and plasma physics. But despite decades of studies, how the material transforms when hit with powerful shockwaves has been a topic of longstanding debate.

“One might assume that because we have already studied silicon in so many ways there is nothing left to discover,” said Silvia Pandolfi, a researcher at the Department of Energy’s SLAC National Accelerator Laboratory. “But there are still some important aspects of its behavior that are not clear.”

Now, researchers at SLAC have finally put this controversy to rest, providing the first direct, high-fidelity view of how a single silicon crystal deforms during shock compression on nanosecond timescales. To do so, they studied the crystal with X-rays from SLAC’s Linac Coherent Light Source (LCLS) X-ray laser. The team published their results in Nature Communications on September 21st. What they learned could lead to more accurate models that better predict what will happen to certain materials in extreme conditions.

“This is a great example of an experiment that’s necessary to better understand certain materials,” said SLAC scientist Arianna Gleason, who was the principal investigator. “You have to start simple, with single crystals, to know what you’re tracking and understand it in really detailed ways before you can build up complexity to give way to, say, the next semiconductor of the 21st Century that will allow the electronics industry to continue the remarkable progress seen in the past 50 years.”

Read more on the SLAC website

‘Diamond rain’ on giant icy planets could be more common than previously thought

Researchers at SLAC found that oxygen boosts this exotic precipitation, revealing a new path to make nanodiamonds here on Earth.

A new study has found that “diamond rain,” a long-hypothesized exotic type of precipitation on ice giant planets, could be more common than previously thought. 

In an earlier experiment, researchers mimicked the extreme temperatures and pressures found deep inside ice giants Neptune and Uranus and, for the first time, observed diamond rain as it formed.

Investigating this process in a new material that more closely resembles the chemical makeup of Neptune and Uranus, scientists from the Department of Energy’s SLAC National Accelerator Laboratory and their colleagues discovered that the presence of oxygen makes diamond formation more likely, allowing them to form and grow at a wider range of conditions and throughout more planets.

The new study provides a more complete picture of how diamond rain forms on other planets and, here on Earth, could lead to a new way of fabricating nanodiamonds, which have a very wide array of applications in drug delivery, medical sensors, noninvasive surgery, sustainable manufacturing, and quantum electronics.

“The earlier paper was the first time that we directly saw diamond formation from any mixtures,” said Siegfried Glenzer, director of the High Energy Density Division at SLAC. “Since then, there have been quite a lot of experiments with different pure materials. But inside planets, it’s much more complicated; there are a lot more chemicals in the mix. And so, what we wanted to figure out here was what sort of effect these additional chemicals have.”

The team, led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Rostock in Germany, as well as France’s École Polytechnique in collaboration with SLAC, published the results today in Science Advances

Read more on the SLAC website

Introducing Stephen Streiffer

After decades of experience in the DOE lab system and as director of a leading synchrotron light source, he’s back to where he earned his PhD – with a much bigger mission.

Thirty years after earning his PhD at Stanford University, materials scientist Stephen Streiffer will be back on campus next week – this time with an outsized role to play. As Stanford’s new vice president for the Department of Energy’s SLAC National Accelerator Laboratory, he’ll play a key part in advising and supporting the lab as it carries out its scientific mission.

Streiffer comes to Stanford and SLAC after 24 years at Argonne National Laboratory, where he did research at the lab’s Advanced Photon Source, directed APS for eight years and most recently served as chief research officer and deputy lab director for science and technology.

So he’s more than familiar with both the national lab system and the importance of DOE Office of Science user facilities, like APS and SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) and Linac Coherent Light Source (LCLS), for both fundamental research and experiments with more immediate practical value.

Read Glennda Chui’s Q & A interview with Stephen on the SLAC website

Image: Stephen Streiffer, the new Stanford vice president for SLAC National Accelerator Laboratory

Credit: Mark Lopez, Argonne National Laboratory

Superconducting X-ray laser reaches operating temperature colder than outer space

The facility, LCLS-II, will soon sharpen our view of how nature works on ultrasmall, ultrafast scales, impacting everything from quantum devices to clean energy.

Nestled 30 feet underground in Menlo Park, California, a half-mile-long stretch of tunnel is now colder than most of the universe. It houses a new superconducting particle accelerator, part of an upgrade project to the Linac Coherent Light Source (LCLS) X-ray free-electron laser at the Department of Energy’s SLAC National Accelerator Laboratory.

Crews have successfully cooled the accelerator to minus 456 degrees Fahrenheit – or 2 kelvins – a temperature at which it becomes superconducting and can boost electrons to high energies with nearly zero energy lost in the process. It is one of the last milestones before LCLS-II will produce X-ray pulses that are 10,000 times brighter, on average, than those of LCLS and that arrive up to a million times per second – a world record for today’s most powerful X-ray light sources.

“In just a few hours, LCLS-II will produce more X-ray pulses than the current laser has generated in its entire lifetime,” says Mike Dunne, director of LCLS. “Data that once might have taken months to collect could be produced in minutes. It will take X-ray science to the next level, paving the way for a whole new range of studies and advancing our ability to develop revolutionary technologies to address some of the most profound challenges facing our society.”

With these new capabilities, scientists can examine the details of complex materials with unprecedented resolution to drive new forms of computing and communications; reveal rare and fleeting chemical events to teach us how to create more sustainable industries and clean energy technologies; study how biological molecules carry out life’s functions to develop new types of pharmaceuticals; and peek into the bizarre world of quantum mechanics by directly measuring the motions of individual atoms.

A chilling feat

LCLS, the world’s first hard X-ray free-electron laser (XFEL), produced its first light in April 2009, generating X-ray pulses a billion times brighter than anything that had come before. It accelerates electrons through a copper pipe at room temperature, which limits its rate to 120 X-ray pulses per second.

Read more on the SLAC website

An abundance of talents within the light source community

Monday Montage – Talents!

Our #LightSourceSelfies campaign has uncovered a wealth of talents among staff and users at light source facilities around the world. From skating to sculpting and painting to perennials, this Monday Montage illustrates the many hobbies and interests that those in our community enjoy in their spare time. With contributions from the ESRF, SESAME, LCLS and the European XFEL, this montage highlights the variety of activities that help people maintain a healthy work/life balance.

Advancing materials science with the help of biology and a dash of dish soap

High-speed X-ray free-electron lasers have unlocked the crystal structures of small molecules relevant to chemistry and materials science, proving a new method that could advance semiconductor and solar cell development.

Compounds that form tiny crystals hold secrets that could advance renewable energy generation and semiconductor development. Revealing the arrangement of their atoms has already allowed for breakthroughs in materials science and solar cells. However, existing techniques for determining these structures can damage sensitive microcrystals.

Now scientists have a new tool in their tool belts: a system for investigating microcrystals by the thousands with ultrafast pulses from an X-ray free-electron laser (XFEL), which can collect structural information before damage sets in. This approach, developed over the past decade to study proteins and other large biological molecules at the Department of Energy’s SLAC National Accelerator Laboratory, has now been applied for the first time to small molecules that are of interest to chemistry and materials science.

Researchers from the University of Connecticut, SLAC, DOE’s Lawrence Berkeley National Laboratory and other institutions developed the new process, called small molecule serial femtosecond X-ray crystallography or smSFX, to determine the structures of three compounds that form microcrystal powders, including two that were previously unknown. The experiments took place at SLAC’s Linac Coherent Light Source (LCLS) XFEL and the SACLA XFEL in Japan.

Read more on the SLAC website

Image: Artist’s rendition of the X-ray beam illuminating a solution of powdered metal-organic materials called chalcogenolates.

Credit: Ella Maru Studios

Science that just can’t wait until morning!

We know by now that coffee ranks highly on the list of things that help get light source users through their night shifts. This #LightSourceSelfie also include insights on positive thinking that can provide a much needed boost to get you through to the morning. These insights are brought to you from staff scientists at LCLS and NSLS-II in the USA and Diamond in the UK.

Someday you will get to play with those electrons!

Razib Obaid is a project scientist at the Linac Coherent Light Source (LCLS) at SLAC in California. LCLS is one of 7 free electron lasers in the collaboration. The facility takes X-ray snapshots of atoms and molecules at work, providing atomic resolution detail on ultrafast timescales to reveal fundamental processes in materials, technology and living things. Its snapshots can be strung together into “molecular movies” that show chemical reactions as they happen.

In Razib’s #LightSourceSelfie, he takes you into the Near Experimental Hall and describes the stunning equipment that is used to undertake the experiments, the science it enables and the possibilities for new science with the upgrade to LCLSII. Razib says, “The best thing about working at a light source is the ability as a user to tap into the enormous scientific resources and experience that exists among the staff and scientists. Not to mention the state of the art instrumentation that you have access to, to realise your science. To my younger self, I would say, keep studying quantum mechanics, someday you will get to play with those electrons.”

To learn more about LCLS, visit

Beginning your light source journey

Scientists who use synchrotrons such as the Advanced Light Source in California and CHESS at Cornell University, along with staff scientists at Free Electron Lasers in South Korea (the PAL-XFEL) and California (LCLS at SLAC), reflect on how they felt the first time they used a light source facility to conduct research experiments.  The expertise available from the staff scientists who work on the beamlines is also highlighted in this #LightSourceSelfie video.

Secrets of skyrmions revealed

Why skyrmions could have a lot in common with glass and high-temperature superconductors

Spawned by the spins of electrons in magnetic materials, these tiny whirlpools behave like independent particles and could be the future of computing. Experiments with SLAC’s X-ray laser are revealing their secrets.

Scientists have known for a long time that magnetism is created by the spins of electrons lining up in certain ways. But about a decade ago, they discovered another astonishing layer of complexity in magnetic materials: Under the right conditions, these spins can form little vortexes or whirlpools that act like particles and move around independently of the atoms that spawned them.

The tiny whirlpools are called skyrmions, named after Tony Skyrme, the British physicist who predicted their existence in 1962. Their small size and sturdy nature – like knots that are hard to undo – have given rise to a rapidly expanding field devoted to understanding them better and exploiting their strange qualities.

“These objects represent some of the most sophisticated forms of magnetic order that we know about,” said Josh Turner, a staff scientist at the Department of Energy’s SLAC National Accelerator Laboratory and principal investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC.

Read more on the SLAC website

Images: Top: Images based on simulations show how three phases of matter, including skyrmions – tiny whirlpools created by the spins of electrons – can form in certain magnetic materials. They are stripes of electron spin (left); hexagonal lattices (right); and an in-between phase (center) that’s a mixture of the two. In this middle, glass-like state, skyrmions move very slowly, like cars in a traffic jam – one of several discoveries made in recent studies by scientists at SLAC, Stanford, Berkeley Lab and UC San Diego. Bottom: Patterns formed in a detector during experiments that explored fundamentals of skyrmion behavior at SLAC’s Linac Coherent Light Source X-ray free-electron laser.

Credit: Esposito et al., Applied Physics Letters, 2020