From Brookhaven National Lab: “NSLS-II Achieves Design Beam Current of 500 Milliamperes”

From Brookhaven National Lab

January 22, 2020
Cara Laasch
laasch@bnl.gov

Accelerator division enables new record current during studies.

The NSLS-II accelerator division proudly gathered to celebrate their recent achievement. The screen above them shows the slow increase of the electron current in the NSLS-II storage ring and its stability.

The National Synchrotron Light Source II (NSLS-II) [below] at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory is a gigantic x-ray microscope that allows scientists to study the inner structure of all kinds of material and devices in real time under realistic operating conditions. The scientists using the machine are seeking answers to questions including how can we built longer lasting batteries; when life started on our planet; and what kinds of new materials can be used in quantum computers, along with many other questions in a wide variety of research fields.

The heart of the facility is a particle accelerator that circulates electrons at nearly the speed of light around the roughly half-a-mile-long ring. Steered by special magnets within the ring, the electrons generate ultrabright x-rays that enable scientists to address the broad spectrum of research at NSLS-II.

Now, the accelerator division at NSLS-II has reached a new milestone for machine performance. During recent accelerator studies, the team has been able to ramp up the machine to 500 milliamperes (mA) of current and to keep this current stable for more than six hours. Similar to a current in a river, the current in an accelerator is a measure of the number of electrons that circulate the ring at any given time. In NSLS-II’s case, a higher electron current opens the pathway to more intense x-rays for all the experiments happening at the facility.

“Since we turned on the machine for the first time in 2014 with 50mA current, we have progressed steadily upwards in current and now – in just five years – we have reached 500mA,” said Timur Shaftan, NSLS-II accelerator division director. “Along the way, we encountered many significant challenges, and it is thanks to the dedication, knowledge, and expertise of the team that we were able to overcome them all to get here.”

All good things come in threes?

On their quest to a higher current, the accelerator division faced three major challenges: an increase in power consumption of the radiofrequency (RF) accelerating cavities, more intense “wakefields,” and the unexpected heating of some accelerator components.

The purpose of the RF accelerating cavities can be compared to pushing a child on a swing – with the child being the electrons. With the correct timing, large amplitudes can be driven with little effort. The cavities feed more and more energy to the electrons to compensate for the energy the electrons lose as they generate x-rays in their trips around the ring.

“The cavities use electricity to push the electrons forward, and even though our cavities are very efficient, they still draw a good amount of raw power,” said Jim Rose, RF group leader. “To reach 500 mA, we monitored this increase closely to ensure that we wouldn’t cross our limit for power, which we didn’t. However, there is another challenge we now have to face: The cavities compress the groups of electrons—we call them bunches—that rush through the machine, and by doing so they increase the heating issues that we face. To fully address this in the future, we will install other cavities of a different RF frequency that would lengthen the bunches again.”

Rose is referring to the issue of “wakefields.” As the electrons speed around the ring, they create so called wakefields—just like when you run your finger through still water and create waves that roll on even though your fingers are long gone. In the same way, the rushing electrons generate a front of electric fields that follow them around the ring.

“Having more intense wakefields causes two challenges: First, these fields influence the next set of electrons, causing them to lose energy and become unstable, and second, they heat up the vacuum chamber in which the beam travels,” said accelerator physicist Alexei Blednykh. “One of the limiting components in our efforts to reach 500mA was the ceramic vacuum chambers, because they were overheating. We mitigated the effect by installing additional cooling fans. However, to fully solve the issue we will need to replace the existing chambers with new chambers that have a thin titanium coating on the inside.”

The accelerator division decided to coat all the new vacuum chambers in house using a technique called direct current magnetron sputtering. During the sputtering process, a titanium target is bombarded with ionized gas so that it ejects millions of titanium atoms, which spray onto the surface of the vacuum chamber to create a thin metal film.

“At first, coating chambers sounds easy enough, but our chambers are long and narrow, which forces you to think differently how you can apply the coating. We had to design a coating system that was capable of handling the geometry of our chambers,” said vacuum group leader Charlie Hetzel. “Once we developed a system that could be used to coat the chambers, we had to develop a method that could accurately measure the thickness and uniformity along the entire length of the chamber.”

For the vacuum chambers to survive the machine at high current, the coatings had to meet a number of demanding requirements in terms of their adhesion, thickness, and uniformity.

The third challenge the team needed to overcome was resolving the unexpected heating found between some of the vacuum flanges. Each of the vacuum joints around the half-mile long accelerator contain a delicate RF bridge. Any errors during installation can result in additional heating and risk to the vacuum seal of the machine.

“We knew from the beginning that increasing the current to 500 mA would be hard on the machine, however, we needed to know exactly where the real hot spots were,” explained accelerator coordination group leader Guimei Wang. “So, we installed more than 1000 temperature sensors around the whole machine, and we ran more than 400 hours of high-current beam studies over the past three years, where we monitored the temperature, vacuum, and many other parameters of the electrons very closely to really understand how our machine is behaving.”

Based on all these studies and many more hours spend analyzing each single study run, the accelerator team made the necessary decisions as to which what parts needed to be coated or changed and, most importantly, how to run the machine at such a high current safely and reliably.

Where do we go from here?

Achieving 500mA during beam studies was an important step to begin to shed light on the physics within the machine at these high currents, as well as to understand the present limits of the accelerator. Equipped with these new insights, the accelerator division now knows that their machine can reach the 500mA current for a short time, but at this point it’s not possible to sustain high current for operations over extended periods with the RF power necessary to deliver it to users. To run the machine at this current, NSLS-II’s accelerator will need additional RF systems both to lengthen the bunches and to secure high reliability of operations, while providing sufficient RF power to the beam to generate x-rays for the growing set of beamlines.

“Achieving 500 mA for the first time is a major milestone in the life of NSLS-II, showing that we can reach the aggressive design current goals we set for ourselves when we first started thinking about what NSLS-II could be all those years ago. This success is due to a lot of hard work, expertise, and dedication by many, many people at NSLS-II and I would like to thank them all very much,” said NSLS-II Director John Hill. “The next steps are to fully understand how the machine behaves at this current and ultimately deliver it to our users. This will require further upgrades to our accelerator systems—and we are actively working towards those now.”

NSLS-II is a DOE Office of Science user facility.

See the full article here .

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From Lawrence Berkeley National Lab: “Milestone in Advanced Light Source Upgrade Project Will Bring in a New Ring”

From Lawrence Berkeley National Lab

January 8, 2020
Glenn Roberts Jr.
geroberts@lbl.gov
(510) 486-5582

Construction of innovative accumulator ring as part of ALS-U project will keep Berkeley Lab at the forefront of synchrotron light source science.

This cutaway rendering of the Advanced Light Source dome shows the layout of three electron-accelerating rings. A new approval step in the ALS Upgrade project will allow the installation of the middle ring, known as the accumulator ring. (Credit: Matthaeus Leitner/Berkeley Lab)

An upgrade of the Advanced Light Source (ALS) at the U.S. Department of Energy’s (DOE’s) Lawrence Berkeley National Laboratory (Berkeley Lab) has passed an important milestone that will help to maintain the ALS’ world-leading capabilities.

LBNL ALS

On Dec. 23 the DOE granted approval for a key funding step that will allow the project to start construction on a new inner electron storage ring. Known as an accumulator ring, this inner ring will feed the upgraded facility’s main light-producing storage ring, and is a part of the upgrade project (ALS-U).

This latest approval, known as CD-3a, authorizes an important release of funds that will be used to purchase equipment and formally approves the start of construction on the accumulator ring. This approval is an essential step in a DOE “critical decision” process that involves in-depth reviews at several key project stages.

“It’s exciting to finally be able to start construction and see all our hard work come to fruition and to get one step closer to having a next-generation light source,” said David Robin, director of the ALS-U project.

The ALS produces ultrabright light over a range of wavelengths, from infrared to high-energy X-rays, by accelerating electrons to nearly the speed of light and guiding them along a circular path.

Powerful arrays of magnets bend the beam of electrons, causing it to emit light that is channeled down dozens of beamlines for experiments in a wide range of scientific areas – from physics, medicine, and chemistry to biology and geology. More than 2,000 scientists from around the world conduct experiments at the facility each year.

Brighter, more laser-like beams, and ‘recycled’ electrons

In addition to installing the accumulator ring, the upgrade project will replace the existing main storage ring with a next-generation storage ring that will reduce the size of the light beams at their source from around 100 microns (millionths of a meter) to below 10 microns.

This illustration shows components of the accumulator ring (top) and new storage ring (bottom) that will be installed as a part of the ALS-U project. (Credit: Berkeley Lab)

The combination of the accumulator ring and upgraded main storage ring will enable at least 100 times brighter beams at key energies, and will make the beams more laser-like by enhancing a property known as coherence. This will make it possible to reveal nanometer-scale features of samples, and to observe chemical processes and the function of materials in real time.

Today, electrons at the ALS are first accelerated by a linear (straight) accelerator and a booster ring before they are transferred to the storage ring that feeds light to the beamlines. After the upgrade, electrons from the booster ring will instead go to the accumulator ring, which will reduce the size and spread of the electron beam and accumulate multiple batches or “injections” of electron bunches from the booster ring before transferring bunches to the storage ring.

Shrinking the beam profile in the accumulator ring, together with an innovative technique for swapping electron bunches between ALS rings – and the use of improved magnetic devices called undulators that wiggle the electrons and help to narrow the path of the light they emit – will enable the higher brightness of the upgraded ALS.

This rendering shows a sector of accumulator ring equipment along an inner wall at the Advanced Light Source. (Credit: Scott Burns/Berkeley Lab)

The accumulator ring will also “recycle” incoming electron bunches – via a transfer line from the main storage ring – that have a depleted charge. It will restore them to a higher charge and feed them back into the storage ring.

This electron-bunch recycling, known as “bunch train swap-out,” is a unique design feature of the upgraded ALS that could also prove useful if adopted at other accelerator facilities around the globe. It will reduce the number of lost electrons, in turn reducing the workload for the facility’s production of electrons.

To allow precisely timed electron bunch-train exchanges between the accumulator ring and the booster and storage rings, three transfer lines are needed.

One of these transfer lines will deliver bunches of electrons from the booster ring to the accumulator ring, where the size of the bunches will be reduced and the charge progressively increased, before delivering them via another transfer line to the main storage ring. A third transfer line will allow excess electrons that would otherwise be discarded to reenter the accumulator ring for reuse.

This silicon-based device is one of eight stages of an inductive voltage adder, which is used to drive a “kicker” that kicks electrons from one path to another. (Credit: Marilyn Sargent/Berkeley Lab)

“Every upgrade project should contribute to accelerator technology and push the field forward in some way,” Robin said. “Recent state-of-the art facilities and upgrades in Europe and the U.S. have implemented technology that we are making use of. Using an accumulator with bunch train swap-out injection is one of our main contributions.”

At the leading edge of ‘soft’ and ‘tender’ X-ray science

Robin credited Christoph Steier, who is the Accelerator Systems Lead for the ALS-U project, and his team for developing the bunch train swap-out technique and related technologies that are critical for the facility’s enhanced performance.

The ALS-U project will keep the facility at the forefront of research using “soft” X-rays, which are well-suited to studies of the chemical, electronic, and magnetic properties of materials. Soft X-rays can be used in studies involving lighter elements like carbon, oxygen, and nitrogen, and have a lower energy than “hard” X-rays that can penetrate deeper into samples.

It will also expand access to “tender” X-rays, which occupy an energy range between hard and soft X-rays and can be useful for studies of earth, environmental, energy, and condensed-matter sciences.

But achieving this performance is a tricky feat, noted Daniela Leitner, who is responsible for accelerator removal and installation for the ALS-U project. The main storage ring is housed in thick concrete tunnels designed to fit one ring, and now the upgrade requires that a second ring be squeezed in.

Accumulator ring to function as a mini ALS, will boost performance of new storage ring

“We need to build a ‘mini ALS,’” Leitner said, in the form of the accumulator ring. The accumulator ring will measure about 600 feet in circumference while the main storage ring will be about 640 feet in circumference. It must be installed about 6 1/2 feet above the floor, just 7 inches below the ceiling height in some places – and fit snugly around an inner wall to allow workers to safely navigate the ALS’ tunnels.

Robin noted, “This is a complicated logistical ‘dance.’ It is a very confined space, and there is equipment in the existing tunnel that has to be moved to make room.”

The accumulator ring is designed to be compact, with a reduced weight, footprint, and power consumption compared to the existing storage ring.

The accumulator ring installation – which is enabled by the CD-3a release of funds – will also be carefully orchestrated to minimize disruptions to ALS operations, with installation work fit into regularly scheduled downtimes over the next few years. The ALS typically runs 24/7 outside of scheduled maintenance downtimes.

The plan is to install and test the accumulator ring prior to a planned yearlong shutdown – with the potential to test the new ring even during regular ALS operations. The shutdown period, known as “dark time,” will allow the removal of the existing storage ring and installation of the new storage ring.

Installing the accumulator ring in advance allows the project team to minimize the shutdown period, which will require the removal and replacement of 400 tons of equipment. This final stage of the project is slated to begin in a few years.

This powerful magnetic device is a prototype for 84 “main bend” magnets that will be installed as a part of the new main storage ring. An additional 24 bend magnets will have a different design. The poles are constructed of precision-machined cobalt-iron. The device weighs 1 ton. (Credit: Marilyn Sargent/Berkeley Lab)

The accumulator ring will bring about 80 tons of new equipment into the facility, with construction expected to begin in the summer of 2020. There are dozens of major pieces of equipment to install, including specialized magnetic devices that help to bend and focus the electron beam. These magnetic devices are part of an array of seven pieces that must be installed in each of the 12 ALS sectors and connected by vacuum tubes.

The accumulator ring installation will take an estimated 53,000 worker-hours and requires the placement of thousands of cables.

Prototypes and simulations to ease assembly, installation, troubleshooting

The ALS-U project team has built and acquired prototypes for key components of the accumulator ring, and has constructed models of some of the accumulator ring equipment at their designed height to find the best installation methods. Project crews will also build out fully equipped sections of the accumulator ring to measure their alignment and test the integrated hardware prior to installation to help speed up the process.

Leitner said that about 80 percent of the installation can be assisted by an overhead crane that will lift heavy equipment into the tunnels, but there are also plans for elevated platforms to ease the installation, and customized lifts to enable installation where the crane cannot be used.

Steier said that technical improvements in accelerator simulations should help to troubleshoot and negate potential problems ahead of time that may arise with the commissioning of the accumulator ring and storage ring. The algorithms account for misaligned magnets and power-supply fluctuations, for example, that are common with constructing large accelerator facilities.

“In general, we simulate everything beforehand, and over time these simulations have become more accurate,” he said, to the point that the simulations can actually guide design choices for the accelerator equipment, and could speed up the ALS-U startup process.

Robin said, “I’m really proud of what the team has accomplished over the last few years.”

The Advanced Light Source is a DOE Office of Science User Facility.

See the full article here .

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From Optics & Photonics: “Lasers Extend Study of Matter at Extremes”

From Optics & Photonics

12.27.19
Stewart Wills

Researchers at the Gemini Laser Facility, Central Laser Facility, U.K. The laser was used to drive the creation, through laser wakefield acceleration, of X-rays that can potentially be used to probe processes in solid matter at extremely high temperatures, relevant to fusion energy and studies of planetary interiors. [Image: STFC]

The dynamics of high-energy density (HED) matter—“warm, dense matter,” with the density of a solid but at temperatures as high as 10,000 °C—hold potential insights in domains ranging from studies of planetary interiors to efforts for fusion energy. But getting a grip on those ephemeral, femtosecond-scale processes in these piping-hot materials has been tough.

An international team led by researchers at Imperial College London (ICL), U.K., now reports that it has developed a practical platform for study of these ultrafast HED-matter processes [Physical Review Letters].

The secret lies in tricking out a laser-wakefield accelerator (LWFA) to deliver single-shot, broadband X-ray fluxes that are reportedly 100 times greater than previous measurements—and that pack enough energy to get the job done.

Difficult environment for study

In principle, researchers interested in atomic-scale dynamics in HED matter have a number of options for peering into the maelstrom. But none are perfect. X-ray scattering, for example, reportedly falls short for studying non-equilibrium processes, and the extremely small scattering cross-sections require hefty, high-brightness sources such as X-ray free-electron lasers (XFELs) to get any meaningful result.

A potentially better and more flexible route to studying HED-matter processes is X-ray absorption, which overcomes some of the experimental limitations of scattering techniques. But performing single-shot experiments that could capture the ultrafast dynamics at work requires a combination—high-brightness, broadband X-rays with multi-keV photon energy—that been elusive in practice. Behemoth lasers like the U.S. National Ignition Facility, for example, can supply plenty of photon energy, but in pulses on the scale a hundred picoseconds or even longer. Synchrotron sources also lack ultrashort duration, while XFEL pulses, though short enough, lack the required broadband operation.

Realizing the LWFA advantage

LWFAs, which use laser-driven plasmas to accelerate electrons and create by-product X-rays through betatron radiation, could potentially circumvent these problems. That’s because LWFAs are, according to the researchers behind the new study, “the only currently available sources that provide bright bursts of broadband X-rays on the femtosecond timescale.”

But heretofore, the source fluxes and photon energies available in LWFAs have required integration across many shots to achieve the energy needed to study warm dense matter. Getting a true, femtosecond-scale view of electron dynamics in HED matter would require an LWFA that could pack sufficient energy into a single, ultrafast broadband pulse.

In the setup for generating ultrashort X-ray bursts, the driving laser passes through a gas cell (left), accelerating electrons and creating a plasma wakefield that gives rise to high-energy X-rays that exit through a pinhole (right). [Image: Brendan Kettle]

The ICL-led team, helmed by Stuart Mangles and by first author Brendan Kettle, sought to achieve just that, with a novel setup. The setup begins with an extremely powerful driving laser, the 200-TW Gemini Laser at the U.K.’s Central Laser Facility at Rutherford Appleton Laboratory.

STFC Rutherford Appleton Laboratory at Harwell in Oxfordshire, UK

The laser’s 800-nm-wavelength beam is focused into a helium gas cell, where it strips electrons from the gas and creates an electron plasma wave in the laser’s wake. The high laser fields subsequently accelerate the electrons to GeV-scale energies, forcing out high-energy betatron X-rays. A sacrificial length of polyimide plastic tape absorbs the surplus laser energy and allows the X-rays to pass through to the sample.

In measurements with their setup, the researchers found that the use of the powerful Gemini Laser to drive an LWFA allowed the creation of single shots with energies in the 5-keV range, and with photon flxes on the order of 1.2 million per eV. The team was able to use those pulses to perform X-ray absorption near-edge structure experiments on a piece of room-temperature titanium foil. And numerical simulations by the team suggest that it should work as a platform for ultrafast electron processes in HED matter as well.

Higher-intensity lasers ahead

The team believes that such experiments will become increasingly viable as new and even higher-intensity driving lasers (such as those at the European Extreme Light Infrastructure) come online. The researchers envision setups in which these LWFA-driving lasers are deployed in tandem with XFELs or other high-energy lasers that are used to push the samples to HED states, which are then probed with the LWFA-generated X-rays in ultrafast and brilliant single shots.

“We will now be able to probe warm dense matter much more efficiently, and in unprecedented resolution,” first author Kettle said in an ICL press release accompanying the work. That, he suggested, “could accelerate discoveries in fusion experiments and astrophysics, such as the internal structure and evolution of planets including the Earth itself.”

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From Imperial College London and STFC: “Ultrashort x-ray technique will probe conditions found at the heart of planets”

From Science and Technology Facilities Council

and

From Imperial College London

19 December 2019
Hayley Dunning

Working with the Gemini Laser. Credit: STFC

Combining powerful lasers and bright x-rays, Imperial and STFC researchers have demonstrated a technique that will allow new extreme experiments.

The new technique would be able to use a single x-ray flash to capture information about extremely dense and hot matter, such as can be found inside gas giant planets or on the crusts of dead stars.

The same conditions are also found in fusion experiments, which are trying to create a new source of energy that mimics the Sun.

______________________________________
We will now be able to probe warm dense matter much more efficiently and in unprecedented resolution.
Dr Brendan Kettle
______________________________________

The technique, reported this week in Physical Review Letters, was developed by a team led by Imperial College London scientists working with colleagues including those at the UK’s Central Laser Facility at the Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory [below], and was funded by the European Research Council.

The researchers wanted to improve ways to study ‘warm dense matter’ – matter that has the same density as a solid, but is heated up to 10,000?C. Researchers can create warm dense matter in the lab, recreating the conditions in the hearts of planets or crucial for fusion power, but it is difficult to study.

Accelerating discoveries

The team used the Gemini Laser, which has two beams – one which can create the conditions for warm dense matter, and one which can create ultrashort and bright x-rays to probe the conditions inside the warm dense matter.

STFC Gemini Laser

Previous attempts using lower-powered lasers required 50-100 x-ray flashes to get the same information that the new technique can gain in just one flash. The flashes last only femtoseconds (quadrillionths of a second), meaning the new technique can reveal what is happening within warm dense matter across very short timescales.

First author Dr Brendan Kettle, from the Department of Physics at Imperial, said: “We will now be able to probe warm dense matter much more efficiently and in unprecedented resolution, which could accelerate discoveries in fusion experiments and astrophysics, such as the internal structure and evolution of planets including the Earth itself.”

The technique could also be used to probe fast-changing conditions inside new kinds of batteries and memory storage devices.

Answering key questions

In the new study, the team used their technique to examine a heated sample of titanium, successfully showing that it could measure the distribution of electrons and ions.

Lead researcher Dr Stuart Mangles, from the Department of Physics at Imperial, said: “We are planning to use the technique to answer key questions about how the electrons and ions in this warm dense matter ‘talk’ to each other, and how quickly can energy transfer from the electrons to the ions.”

The Central Laser Facility’s Gemini Laser is currently one of the few places the right conditions for the technique can be created, but as new facilities start operating around the world, the team hope the technique can be expanded and used to do a whole new class of experiments.

Dr Rajeev Pattathil, Gemini Group Leader at the Central Laser Facility, said: “With ultrashort x-ray flashes we can get a freeze-frame focus on transient or dynamic processes in materials, revealing key new fundamental information about materials here and in the wider Universe, and especially those in extreme states.”

See the full article here .

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From SLAC National Accelerator Lab: “Scientists discover how proteins form crystals that tile a microbe’s shell”

From SLAC National Accelerator Lab

December 17, 2019
Glennda Chui

In this illustration, protein crystals join six-sided ’tiles’ forming at top left and far right, part of a protective shell worn by many microbes. A new study zooms in on the first steps of crystal formation and helps explain how microbial shells assemble themselves so quickly. Credit: Greg Stewart/SLAC National Accelerator Laboratory

A new understanding of the nucleation process could shed light on how the shells help microbes interact with their environments, and help people design self-assembling nanostructures for various tasks.

Many microbes wear beautifully patterned crystalline shells, which protect them from a harsh world and can even help them reel in food. Studies at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have revealed this food-reeling process and shown how shells assemble themselves from protein building blocks.

Now the same team has zoomed in on the very first step in microbial shell-building: nucleation, where squiggly proteins crystallize into sturdy building blocks, much like rock candy crystallizes around a string dipped into sugar syrup.

The results, published today in the Proceedings of the National Academy of Sciences, could shed light on how the shells help microbes interact with other organisms and with their environments, and also help scientists design self-assembling nanostructures for various tasks.

Jonathan Herrmann, a graduate student in Professor Soichi Wakatsuki’s group at SLAC and Stanford, collaborated with the structural molecular biology team at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) on the study.

SLAC/SSRL

They scattered a powerful beam of X-rays off protein molecules that were floating in a solution to see how the atomic structures of the molecules changed as they nucleated into crystals. Meanwhile, other researchers made a series of cryogenic electron microscope (cryo-EM) images at various points in the nucleation process to show what happened over time.

They found out that crystal formation takes place in two steps: One end of the protein molecule nucleates into crystal while the other end, called the N-terminus, continues to wiggle around. Then the N-terminus joins in, and the crystallization is complete. Far from being a laggard, the N-terminus actually speeds up the initial nucleation step ­– although exactly how it does this is still unknown, the researchers said – and this helps explain why microbial shells can form so quickly and efficiently.

Some of the X-ray data was collected at Lawrence Berkeley National Laboratory’s Advanced Light Source, which like SSRL is a DOE Office of Science user facility.

LBNL ALS

Researchers from the University of British Columbia and from Professor Lucy Shapiro’s laboratory at Stanford also contributed to this work, funded in part by the National Institute of General Medical Sciences and the Chan Zuckerberg Biohub. Work in Wakatsuki’s labs at SLAC and Stanford was funded by a Laboratory Directed Research and Development grant from SLAC, the DOE Office of Science’s Office of Biological and Environmental Research, and Stanford’s Precourt Institute for Energy.

See the full article here .

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SLAC/LCLS

SLAC/LCLS II projected view

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
The scientists used special software, designed by van den Bedem, that is highly sensitive to identifying protein movement from X-ray crystallography data to interpret the results, revealing never-before-seen motions that play a key role in catalyzing complex reactions, such as breaking down antibiotics. Next, the researchers hope to use LCLS to obtain room temperature structures of other enzymes to get a better look at how the motions occurring within them help move along reactions.
SSRL and LCLS are DOE Office of Science user facilities. This work was funded by the DOE Office of Science and the National Institutes of Health, among other sources.

From SLAC National Accelerator Lab: “Researchers reveal how enzyme motions catalyze reactions”

From SLAC National Accelerator Lab

December 16, 2019
Ali Sundermier

What they learned could lead to a better understanding of how antibiotics are broken down in the body, potentially leading to the development of more effective drugs.

This illustration shows how an enzyme moves and changes as it catalyzes complex reactions and breaks down organic compounds. (10.1073/pnas.1901864116)

In a time-resolved X-ray experiment, researchers uncovered, at atomic resolution and in real time, the previously unknown way that a microbial enzyme breaks down organic compounds.

The team, led by Mark Wilson at the University of Nebraska Lincoln (UNL) and Henry van den Bedem at the Department of Energy’s SLAC National Accelerator Laboratory (now at Atomwise Inc.), published their findings last week in the Proceedings of the National Academy of Sciences. What they learned about this enzyme, whose structure is similar to one that is implicated in neurodegenerative diseases such as Parkinson’s, could lead to a better understanding of how antibiotics are broken down by microbes and to the development of more effective drugs.

Previously, the researchers used SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) to obtain the structure of the enzyme at very low temperatures using X-ray crystallography.

SLAC/SSRL

In this study, Medhanjali Dasgupta, a UNL graduate student who was the study’s first author, used the Linac Coherent Light Source (LCLS), SLAC’s X-ray laser, to watch the enzyme and its substrate within the crystal move and change as it went through a full catalytic cycle at room temperature.

SLAC/LCLS

The scientists used special software, designed by van den Bedem, that is highly sensitive to identifying protein movement from X-ray crystallography data to interpret the results, revealing never-before-seen motions that play a key role in catalyzing complex reactions, such as breaking down antibiotics. Next, the researchers hope to use LCLS to obtain room temperature structures of other enzymes to get a better look at how the motions occurring within them help move along reactions.

SSRL and LCLS are DOE Office of Science user facilities. This work was funded by the DOE Office of Science and the National Institutes of Health, among other sources.

See the full article here .

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SLAC/LCLS

SLAC/LCLS II projected view

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

From University of British Columbia: “New laser technique images quantum world in a trillionth of a second”

From University of British Columbia

MengXing Na and Andrea Damascelli at UBC’s Stewart Blusson Quantum Matter Institute (SBQMI). Credit: Research2Reality

Dec 10, 2019
Sachi Wickramasinghe
UBC Media Relations
Tel: 604-822-4636
sachi.wickramasinghe@ubc.ca

For the first time, researchers have been able to record, frame-by-frame, how an electron interacts with certain atomic vibrations in a solid. The technique captures a process that commonly causes electrical resistance in materials while, in others, can cause the exact opposite—the absence of resistance, or superconductivity.

“The way electrons interact with each other and their microscopic environment determines the properties of all solids,” said MengXing Na, a University of British Columbia PhD student and co-lead author of the study, published last week in Science. “Once we identify the dominant microscopic interactions that define a material’s properties, we can find ways to ‘turn up’ or ‘down’ the interaction to elicit useful electronic properties.”

Controlling these interactions is important for the technological exploitation of quantum materials, including superconductors, which are used in MRI machines, high-speed magnetic levitation trains, and could one day revolutionize how energy is transported.

At tiny scales, atoms in all solids vibrate constantly. Collisions between an electron and an atom can be seen as a ‘scattering’ event between the electron and the vibration, called a phonon. The scattering can cause the electron to change both its direction and its energy. Such electron-phonon interactions lie at the heart of many exotic phases of matter, where materials display unique properties.

Ultrafast pulses of extreme ultraviolet light are created in a gas jet (white plasma), and are visible as blue dots on a phosphor screen as well as yellow beams from oxygen fluorescence. Credit: Research2Reality

With the support of the Gordon and Betty Moore Foundation, the team at UBC’s Stewart Blusson Quantum Matter Institute (SBQMI) developed a new extreme-ultraviolet laser source to enable a technique called time-resolved photoemission spectroscopy for visualizing electron scattering processes at ultrafast timescales.

“Using an ultrashort laser pulse, we excited individual electrons away from their usual equilibrium environment,” said Na. “Using a second laser pulse as an effective camera shutter, we captured how the electrons scatter with surrounding atoms on timescales faster than a trillionth of a second. Owing to the very high sensitivity of our setup, we were able to measure directly—for the first time—how the excited electrons interacted with a specific atomic vibration, or phonon.”

The researchers performed the experiment on graphite, a crystalline form of carbon and the parent compound of carbon nanotubes, Bucky balls and graphene. Carbon-based electronics is a growing industry, and the scattering processes that contribute to electrical resistance may limit their application in nanoelectronics.

The approach leverages a unique laser facility conceived by David Jones and Andrea Damascelli, and developed by co-lead author Arthur Mills, at the UBC-Moore Centre for Ultrafast Quantum Matter. The study was also supported by theoretical collaborations with the groups of Thomas Devereaux at Stanford University and Alexander Kemper at North Carolina State University.

“Thanks to recent advances in pulsed-laser sources, we’re only just beginning to visualize the dynamic properties of quantum materials,” said Jones, a professor with UBC’s SBQMI and department of Physics and Astronomy.

“By applying these pioneering techniques, we’re now poised to reveal the elusive mystery of high-temperature superconductivity and many other fascinating phenomena of quantum matter,” said Damascelli, scientific director of SBQMI.

The work was supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative, the Natural Sciences and Engineering Research Council, Canada Foundation for Innovation, the B.C. Knowledge Development Fund, and the Canada First Research Excellence Fund.

See the full article here .

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The University of British Columbia is a global centre for research and teaching, consistently ranked among the 40 best universities in the world. Since 1915, UBC’s West Coast spirit has embraced innovation and challenged the status quo. Its entrepreneurial perspective encourages students, staff and faculty to challenge convention, lead discovery and explore new ways of learning. At UBC, bold thinking is given a place to develop into ideas that can change the world.

From D.O.E. Office of Science via Brookhaven National Lab: “The Big Questions: José Rodriguez on Catalysts”

Brookhaven National Lab

December 4, 2019
José Rodriguez

Distinguished Scientists Fellow José Rodriguez from Brookhaven Lab worked with fellow chemist Ping Liu to characterize structural and mechanistic details of a low-temperature catalyst for producing hydrogen gas from water and carbon monoxide.
Image courtesy of Brookhaven National Laboratory.

The Big Questions series features perspectives from the five recipients of the Department of Energy Office of Science’s 2019 Distinguished Scientists Fellows Award describing their research and what they plan to do with the award.

Contributing Author Credit: José Rodriguez is a senior chemist at Brookhaven National Laboratory.

How can we use some of the world’s brightest and strongest sources of synchrotron light to better understand the catalysts that speed up chemical reactions?

Catalysts reduce the energy needed to make a chemical reaction take place. They’re essential in industry, used for making everything from fabric to synthetic plants. Catalysts are used in the production of many chemicals and fuels.

Over the years, people have tried to understand how catalysts work in hopes of making them even better. To understand how a catalyst works, you need to see what happens at its active sites during chemical transformations. This is a very complex thing. You need a lot of tools to see how the catalyst changes over time, especially under harsh environmental conditions like high pressures and temperatures. Synchrotrons – incredibly powerful sources of light that produce X-rays – can provide a unique look into how these catalysts work.

When I first arrived at the Department of Energy’s Brookhaven National Laboratory (BNL) 29 years ago, scientists were for the first time seriously proposing the use of a synchrotron to study catalysts. At that time, there was a lot of activity in the National Synchrotron Light Source (NSLS), a DOE Office of Science user facility.

BNL NSLS

At the end of my job interview, the head of BNL’s Chemistry Department asked, “How much money do you need to do this kind of science?” I said, “This is a very complex science. I need $750,000.” As a physical inorganic chemist, $50,000 was a lot of research money for him. But despite the price tag, he looked at me and said, “Okay, we’ll see what we can do.” He called up the person at DOE in charge of the catalysis program and said, “The young man looks very promising; we want to go into this new area. He needs $750,000.”

With that funding, my team and I used NSLS to study catalysts in very controlled environments. We created these environments by putting the catalysts in specialized ultra-high vacuum chambers originally developed by NASA in the 1960s. After setting the inside of the chambers to the conditions we wanted, we put them in the synchrotron. The hard and soft X-rays from the synchrotron made it possible to study the structural, electronic, and chemical properties of the catalytic material as well as how those changed during the reaction process.

There is still a big interest in the DOE Office of Science in understanding these catalytic materials. Since then, the NSLS has been replaced by its successor NSLS-II [below], which is also a DOE Office of Science user facility. With NSLS-II, we can use a high-intensity beam to do ultra-fast measurements. Now, we can make in-situ measurements of samples with highly diluted elements in times as short as milliseconds (a thousandth of a second). With this speed, we can now monitor catalysts’ properties during reactions very quickly. In catalysis research, the faster you can go, the better.

With this fellowship, I’m going to expand the work we’re doing at the NSLS-II to better understand catalysts’ properties and how they change during reactions. While we’ve been working on this project for about five years, this new funding will help us move it forward. This work will involve not just the NSLS-II, but also researchers at BNL’s Center for Functional Nanomaterials (a DOE Office of Science user facility), the University of Kansas, Stony Brook University, and Columbia University. In the spirit of this fellowship, any equipment we develop will remain at the NSLS-II, where it will be available for the entire catalysis community to use.

I think this project has the potential to make a big contribution to the field and I appreciate the opportunity the DOE’s Office of Science has provided me to lead it.

See the full article here .

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BNL Center for Functional Nanomaterials

BNL NSLS-II

BNL NSLS II

BNL RHIC Campus

BNL/RHIC Star Detector

BNL RHIC PHENIX

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

From SLAC National Accelerator Lab: “SLAC scientists invent a way to see attosecond electron motions with an X-ray laser”

From SLAC National Accelerator Lab

December 2, 2019
Manuel Gnida
mgnida@slac.stanford.edu
(650) 926-2632

Called XLEAP, the new method will provide sharp views of electrons in chemical processes that take place in billionths of a billionth of a second and drive crucial aspects of life.

Researchers at the Department of Energy’s SLAC National Accelerator Laboratory have invented a way to observe the movements of electrons with powerful X-ray laser bursts just 280 attoseconds, or billionths of a billionth of a second, long.

A SLAC-led team has invented a method, called XLEAP, that generates powerful low-energy X-ray laser pulses that are only 280 attoseconds, or billionths of a billionth of a second, long and that can reveal for the first time the fastest motions of electrons that drive chemistry. This illustration shows how the scientists use a series of magnets to transform an electron bunch (blue shape at left) at SLAC’s Linac Coherent Light Source into a narrow current spike (blue shape at right), which then produces a very intense attosecond X-ray flash (yellow). (Greg Stewart/SLAC National Accelerator Laboratory)

SLAC/LCLS

The technology, called X-ray laser-enhanced attosecond pulse generation (XLEAP), is a big advance that scientists have been working toward for years, and it paves the way for breakthrough studies of how electrons speeding around molecules initiate crucial processes in biology, chemistry, materials science and more.

The team presented their method today in an article in Nature Photonics.

“Until now, we could precisely observe the motions of atomic nuclei, but the much faster electron motions that actually drive chemical reactions were blurred out,” said SLAC scientist James Cryan, one of the paper’s lead authors and an investigator with the Stanford PULSE Institute, a joint institute of SLAC and Stanford University. “With this advance, we’ll be able to use an X-ray laser to see how electrons move around and how that sets the stage for the chemistry that follows. It pushes the frontiers of ultrafast science.”

Studies on these timescales could reveal, for example, how the absorption of light during photosynthesis almost instantaneously pushes electrons around and initiates a cascade of much slower events that ultimately generate oxygen.

“With XLEAP we can create X-ray pulses with just the right energy that are more than a million times brighter than attosecond pulses of similar energy before,” said SLAC scientist Agostino Marinelli, XLEAP project lead and one of the paper’s lead authors. “It’ll let us do so many things people have always wanted to do with an X-ray laser – and now also on attosecond timescales.”

A leap for ultrafast X-ray science

One attosecond is an incredibly short period of time – two attoseconds is to a second as one second is to the age of the universe. In recent years, scientists have made a lot of progress in creating attosecond X-ray pulses. However, these pulses were either too weak or they didn’t have the right energy to home in on speedy electron motions.

Over the past three years, Marinelli and his colleagues have been figuring out how an X-ray laser method suggested 14 years ago [Physical Review Accelerators and Beams] could be used to generate pulses with the right properties – an effort that resulted in XLEAP.

In experiments carried out just before crews began work on a major upgrade of SLAC’s Linac Coherent Lightsource (LCLS) X-ray laser, the XLEAP team demonstrated that they can produce precisely timed pairs of attosecond X-ray pulses that can set electrons in motion and then record those movements. These snapshots can be strung together into stop-action movies.

Linda Young, an expert in X-ray science at DOE’s Argonne National Laboratory and the University of Chicago who was not involved in the study, said, “XLEAP is a truly great advance. Its attosecond X-ray pulses of unprecedented intensity and flexibility are a breakthrough tool to observe and control electron motion at individual atomic sites in complex systems.”

X-ray lasers like LCLS routinely generate light flashes that last a few millionths of a billionth of a second, or femtoseconds. The process starts with creating a beam of electrons, which are bundled into short bunches and sent through a linear particle accelerator, where they gain energy. Travelling at almost the speed of light, they pass through a magnet known as an undulator, where some of their energy is converted into X-ray bursts.

The shorter and brighter the electron bunches, the shorter the X-ray bursts they create, so one approach for making attosecond X-ray pulses is to compress the electrons into smaller and smaller bunches with high peak brightness. XLEAP is a clever way to do just that.

Making attosecond X-ray laser pulses

At LCLS, the team inserted two sets of magnets in front of the undulator that allowed them to mold each electron bunch into the required shape: an intense, narrow spike containing electrons with a broad range of energies.

Schematic of the XLEAP experiment at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser. LCLS sends bunches of high-energy electrons (green) through an undulator magnet, where electron energy gets converted into extremely bright X-ray pulses (blue) of a few femtoseconds, or millionths of a billionth of a second. In the XLEAP configuration, electron bunches pass two additional sets of magnets (wiggler and chicane) that shape each electron bunch into an intense, narrow spike containing electrons with a broad range of energies. The spikes then produce attosecond X-ray pulses in the undulator. The XLEAP team also developed a customized pulse analyzer (right) to measure the extremely short pulse lengths. (Greg Stewart/SLAC National Accelerator Laboratory)

“When we send these spikes, which have pulse lengths of about a femtosecond, through the undulator, they produce X-ray pulses that are much shorter than that,” said Joseph Duris, a SLAC staff scientist and paper co-first-author. The pulses are also extremely powerful, he said, with some of them reaching half a terawatt peak power.

To measure these incredibly short X-ray pulses, the scientists designed a special device in which the X-rays shoot through a gas and strip off some of its electrons, creating an electron cloud. Circularly polarized light from an infrared laser interacts with the cloud and gives the electrons a kick. Because of the light’s particular polarization, some of the electrons end up moving faster than others.

“The technique works similar to another idea implemented at LCLS, which maps time onto angles like the arms of a clock,” said Siqi Li, a paper co-first-author and recent Stanford PhD. “It allows us to measure the distribution of the electron speeds and directions, and from that we can calculate the X-ray pulse length.”

Next, the XLEAP team will further optimize their method, which could lead to even more intense and possibly shorter pulses. They are also preparing for LCLS-II, the upgrade of LCLS that will fire up to a million X-ray pulses per second – 8,000 times faster than before. This will allow researchers to do experiments they have long dreamed of, such as studies of individual molecules and their behavior on nature’s fastest timescales.

The XLEAP team included researchers from SLAC; Stanford University; Imperial College, UK; Max Planck Institute for Quantum Optics, Ludwig-Maximilians University Munich, Kassel University, Technical University Dortmund and Technical University Munich in Germany; and DOE’s Argonne National Laboratory. Large portions of this project were funded by the DOE Office of Science and through DOE’s Laboratory Directed Research and Development (LDRD) program. LCLS is a DOE Office of Science user facility.

See the full article here .

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SLAC/LCLS

SLAC/LCLS II projected view

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

From Lawrence Berkeley National Lab: “Machine Learning Enhances Light-Beam Performance at the Advanced Light Source”

From Lawrence Berkeley National Lab

November 8, 2019
Glenn Roberts Jr.

Successful demonstration of algorithm by Berkeley Lab-UC Berkeley team shows technique could be viable for scientific light sources around the globe.

Some members of the team that developed the machine-learning tool for the Advanced Light Source (ALS) are pictured in the ALS control room. Top row, from left: Changchun Sun, Simon Leemann, and Alex Hexemer. Bottom row, from left: Hiroshi Nishimura, C. Nathan Melton, and Yuping Lu. (Credit: Marilyn Chung/Berkeley Lab)

Synchrotron light sources are powerful facilities that produce light in a variety of “colors,” or wavelengths – from the infrared to X-rays – by accelerating electrons to emit light in controlled beams.

Synchrotrons like the Advanced Light Source at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) allow scientists to explore samples in a variety of ways using this light, in fields ranging from materials science, biology, and chemistry to physics and environmental science.

LBNL Advanced Light Source

LBNL Advanced Light Source

This image shows the profile of an electron beam at Berkeley Lab’s Advanced Light Source synchrotron, represented as pixels measured by a charged coupled device (CCD) sensor. When stabilized by a machine-learning algorithm, the beam has a horizontal size dimension of 49 microns (root mean squared) and vertical size dimension of 48 microns (root mean squared). Demanding experiments require that the corresponding light-beam size be stable on time scales ranging from less than seconds to hours to ensure reliable data. (Credit: Lawrence Berkeley National Laboratory)

Researchers have found ways to upgrade these machines to produce more intense, focused, and consistent light beams that enable new, and more complex and detailed studies across a broad range of sample types.

But some light-beam properties still exhibit fluctuations in performance that present challenges for certain experiments.

Addressing a decades-old problem

Many of these synchrotron facilities deliver different types of light for dozens of simultaneous experiments. And little tweaks to enhance light-beam properties at these individual beamlines can feed back into the overall light-beam performance across the entire facility. Synchrotron designers and operators have wrestled for decades with a variety of approaches to compensate for the most stubborn of these fluctuations.

And now, a large team of researchers at Berkeley Lab and UC Berkeley has successfully demonstrated how machine-learning tools can improve the stability of the light beams’ size for experiments via adjustments that largely cancel out these fluctuations – reducing them from a level of a few percent down to 0.4 percent, with submicron (below 1 millionth of a meter) precision.

The tools are detailed in a study published Nov. 6 in the journal Physical Review Letters.

This chart shows how vertical beam-size stability greatly improves when a neural network is implemented during Advanced Light Source operations. When the so-called “feed-forward” correction is implemented, the fluctuations in the vertical beam size are stabilized down to the sub-percent level (see yellow-highlighted section) from levels that otherwise range to several percent. (Credit: Lawrence Berkeley National Laboratory)

Machine learning is a form of artificial intelligence in which computer systems analyze a set of data to build predictive programs that solve complex problems. The machine-learning algorithms used at the ALS are referred to as a form of “neural network” because they are designed to recognize patterns in the data in a way that loosely resembles human brain functions.

In this study, researchers fed electron-beam data from the ALS, which included the positions of the magnetic devices used to produce light from the electron beam, into the neural network. The neural network recognized patterns in this data and identified how different device parameters affected the width of the electron beam. The machine-learning algorithm also recommended adjustments to the magnets to optimize the electron beam.

Because the size of the electron beam mirrors the resulting light beam produced by the magnets, the algorithm also optimized the light beam that is used to study material properties at the ALS.

Solution could have global impact

The successful demonstration at the ALS shows how the technique could also generally be applied to other light sources, and will be especially beneficial for specialized studies enabled by an upgrade of the ALS known as the ALS-U project.

That’s the beauty of this,” said Hiroshi Nishimura, a Berkeley Lab affiliate who retired last year and had engaged in early discussions and explorations of a machine-learning solution to the longstanding light-beam size-stability problem. “Whatever the accelerator is, and whatever the conventional solution is, this solution can be on top of that.”

Steve Kevan, ALS director, said, “This is a very important advance for the ALS and ALS-U. For several years we’ve had trouble with artifacts in the images from our X-ray microscopes. This study presents a new feed-forward approach based on machine learning, and it has largely solved the problem.”

The ALS-U project will increase the narrow focus of light beams from a level of around 100 microns down to below 10 microns and also create a higher demand for consistent, reliable light-beam properties.

An exterior view of the Advanced Light Source dome that houses dozens of beamlines. (Credit: Roy Kaltschmidt/Berkeley Lab)

The machine-learning technique builds upon conventional solutions that have been improved over the decades since the ALS started up in 1993, and which rely on constant adjustments to magnets along the ALS ring that compensate in real time for adjustments at individual beamlines.

Nishimura, who had been a part of the team that brought the ALS online more than 25 years ago, said he began to study the potential application of machine-learning tools for accelerator applications about four or five years ago. His conversations extended to experts in computing and accelerators at Berkeley Lab and at UC Berkeley, and the concept began to gel about two years ago.

Successful testing during ALS operations

Researchers successfully tested the algorithm at two different sites around the ALS ring earlier this year. They alerted ALS users conducting experiments about the testing of the new algorithm, and asked them to give feedback on any unexpected performance issues.

“We had consistent tests in user operations from April to June this year,” said C. Nathan Melton, a postdoctoral fellow at the ALS who joined the machine-learning team in 2018 and worked closely with Shuai Liu, a former UC Berkeley graduate student who contributed considerably to the effort and is a co-author of the study.

Simon Leemann, deputy for Accelerator Operations and Development at the ALS and the principal investigator in the machine-learning effort, said, “We didn’t have any negative feedback to the testing. One of the monitoring beamlines the team used is a diagnostic beamline that constantly measures accelerator performance, and another was a beamline where experiments were actively running.” Alex Hexemer, a senior scientist at the ALS and program lead for computing, served as the co-lead in developing the new tool.

The beamline with the active experiments, Beamline 5.3.2.2, uses a technique known as scanning transmission X-ray microscopy or STXM, and scientists there reported improved light-beam performance in experiments.

The machine-learning team noted that the enhanced light-beam performance is also well-suited for advanced X-ray techniques such as ptychography, which can resolve the structure of samples down to the level of nanometers (billionths of a meter); and X-ray photon correlation spectroscopy, or XPCS, which is useful for studying rapid changes in highly concentrated materials that don’t have a uniform structure.

Other experiments that demand a reliable, highly focused light beam of constant intensity where it interacts with the sample can also benefit from the machine-learning enhancement, Leemann noted.

“Experiments’ requirements are getting tougher, with smaller-area scans on samples,” he said. “We have to find new ways for correcting these imperfections.”

He noted that the core problem that the light-source community has wrestled with – and that the machine-learning tools address – is the fluctuating vertical electron beam size at the source point of the beamline.

The source point is the point where the electron beam at the light source emits the light that travels to a specific beamline’s experiment. While the electron beam’s width at this point is naturally stable, its height (or vertical source size) can fluctuate.

Opening the ‘black box’ of artificial intelligence

“This is a very nice example of team science,” Leemann said, noting that the effort overcame some initial skepticism about the viability of machine learning for enhancing accelerator performance, and opened up the “black box” of how such tools can produce real benefits.

“This is not a tool that has traditionally been a part of the accelerator community. We managed to bring people from two different communities together to fix a really tough problem.” About 15 Berkeley Lab researchers participated in the effort.

“Machine learning fundamentally requires two things: The problem needs to be reproducible, and you need huge amounts of data,” Leemann said. “We realized we could put all of our data to use and have an algorithm recognize patterns.”

The data showed the little blips in electron-beam performance as adjustments were made at individual beamlines, and the algorithm found a way to tune the electron beam so that it negated this impact better than conventional methods could.

“The problem consists of roughly 35 parameters – way too complex for us to figure out ourselves,” Leemann said. “What the neural network did once it was trained – it gave us a prediction for what would happen for the source size in the machine if it did nothing at all to correct it.

“There is an additional parameter in this model that describes how the changes we make in a certain type of magnet affects that source size. So all we then have to do is choose the parameter that – according to this neural-network prediction – results in the beam size we want to create and apply that to the machine,” Leemann added.

The algorithm-directed system can now make corrections at a rate of up to 10 times per second, though three times a second appears to be adequate for improving performance at this stage, Leemann said.

The search for new machine-learning applications

The machine-learning team received two years of funding from the U.S. Department of Energy in August 2018 to pursue this and other machine-learning projects in collaboration with the Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory. “We have plans to keep developing this and we also have a couple of new machine-learning ideas we’d like to try out,” Leemann said.

SLAC/SSRL

Nishimura said that the buzzwords “artificial intelligence” seem to have trended in and out of the research community for many years, though, “This time it finally seems to be something real.”

The Advanced Light Source and Stanford Synchrotron Radiation Lightsource are DOE Office of Science User Facilities. This work involved researchers in Berkeley Lab’s Computational Research Division and was supported by the Department of Energy’s Basic Energy Sciences and Advanced Scientific Computing Research programs.

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Bringing Science Solutions to the World
In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

A U.S. Department of Energy National Laboratory Operated by the University of California.