From European XFEL: “Entering the realm of attosecond X-ray science”

European XFEL

European XFEL

2018/04/13

New methods for producing and characterizing attosecond X-ray pulses.

Ultrashort X-ray pulses (pink) at the Linac Coherent Light Source ionize neon gas at the center of a ring of detectors. An infrared laser (orange) sweeps the outgoing electrons (blue) across the detectors with circularly polarized light. Scientists read data from the detectors to learn about the time and energy structure of the pulses, information they will need for future experiments. Copyright: Terry Anderson / SLAC National Accelerator Laboratory.

SLAC/LCLS

European XFEL produces unfathomably fast X-ray pulses that are already being used by scientists to explore the unchartered territory of the atomic and molecular cosmos. Intense X-ray pulses lasting only a few femtoseconds – or a few millionths of a billionth of a second – are being used to reveal insights into the dynamics of chemical reactions and the atomic structures of biological molecules such as proteins and viruses. And while there is much more to discover in this femtosecond time range, scientists are already looking to take European XFEL to the next time dimension, exploring reactions and dynamics that occur on an even briefer time scale – the attosecond time regime.

If you leave the shutter of your camera open for too long while photographing a race, the resulting pictures will only be a smear of colour. To capture clear and sharp images of the athletes’ movements you need to make sure the shutter is only open for the shortest time; in fact the best shutter speed to capture a clear snapshot of the runners’ legs frozen in action would be faster than the time the runner needed to move their legs. Good light conditions help too to make sure your photos are sharp and in focus. And so it is as scientists attempt to take snapshots of some of nature’s fastest processes such as the movements of electrons within atoms and molecules. To capture snapshots of these movements in action we need pulses of intense X-rays that reflect the timescale on which these reactions occur – and these reactions can occur even down to the attosecond timescale.

XLEAP

Attosecond X-ray science is expected to allow scientists to delve even deeper into ultrafast chemical and molecular processes and the tiniest details of our world than already possible. But how to produce X-ray flashes that are even shorter than the already ultrafast femtosecond flashes? One of the methods currently being explored by scientists is ‘X-ray Laser-Enhanced Attosecond Pulse generation’ (XLEAP). The method, being developed at the SLAC National Accelerator Laboratory in the USA, is expected to be possible with only moderate modifications to the layout of existing FEL facilities. If successful, the usually chaotic time and energy structure of XFEL (X-ray Free-Electron Laser) pulses, consisting of a sequence of many intensity spikes based on the so-called SASE (Self-Amplification by Spontaneous Emission) principle, can be reliably narrowed down to one single, coherent intensity spike of only few hundreds of attoseconds. In a recent review article in the Journal of Optics, European XFEL scientists propose how the XLEAP method might be implemented at the SASE 3 branch of the facility, eventually providing attosecond pulses for experiments.

European XFEL scientist Markus Ilchen working on the original angle resolving time-of-flight spectrometer at PETRA III, DESY. Copyright: European XFEL

DESY Petra III

DESY Petra III interior

Angular Streaking diagnostics

While the free-electron laser technology is almost ready to provide attosecond pulses, another hurdle is to actually prove and characterize their existence. Experiments to date at XFEL facilities have often relied on indirect measurements and simulations of X-ray pulses to calibrate results. However, only with detailed information from direct measurements of the exact time and energy structure of each X-ray pulse, can X-ray science enter a new era of time resolved and coherence dependent experiments.

With this in mind, a novel experimental approach was conceived as part of an international collaboration including scientists from SLAC, Deutsches Elektronen-Synchrotron (DESY), European XFEL, the Technical University of Munich, University of Kassel, University of Gothenburg, University of Bern, University of Colorado, University of the Basque Country in Spain, and Lomonosov Moscow State University in Russia. In a study published in the journal Nature Photonics, the international groupdemonstrated the capability of a so-called ‘angular streaking’ method to characterize the time and energy structure of X-ray spikes. The scientists used the shortest pulses available at the Linac Coherent Light Source (LCLS) at SLAC in the USA for their experiment. Using the new angular streaking diagnostic method, millions of pulses, each of a few femtoseconds in length, were successfully captured and analyzed. “Being able to get the precise information about the energy spectrum, as well as the time and intensity structure of every single X-ray pulse is unprecedented” explains Markus Ilchen from the Small Quantum Systems group at European XFEL, one of the principal investigators of this work. “This is really one of the holy grails of FEL diagnostics” he adds enthusiastically.

The new angular streaking technique works by using the rotating electrical field of intense circularly polarized optical laser pulses to extract the time and energy structure of the XFEL pulses. Interaction with the XFEL pulse causes atoms to eject electrons which are then strongly kicked around by the surrounding laser field. Information about the electron’s exact time of birth is not only imprinted in the energy of the electron but also in the ejecting angle. This all provides a ‘clock’ by which to sort the resulting experimental data. Pulses generated by the SASE process, as implemented at European XFEL and SLAC, are intrinsically variable and chaotic. Some of the recorded pulses during the experiment at SLAC were, therefore, already single spikes in the attosecond regime which then were fully characterized for their time-energy structure.

Angle resolving time-of-flight spectrometer

An illustration of the ring-shaped array of 16 individual detectors arranged in a circle like numbers on the face of a clock. An X-ray laser pulse hits a target at the center and sets free electrons that are swept around the detectors. The location, where the electrons reach the “clock,” reveals details such as the variation of the X-ray energy and intensity as a function of time within the ultrashort pulse itself. Copyright: Frank Scholz & Jens Buck, DESY.

he underlying spectroscopic method is based on an angle resolving time-of-flight spectrometer setup consisting of 16 individual spectrometers aligned in a plane perpendicular to the XFEL beam. These are used to characterize the X-ray beam by correlating the electrons’ energies and their angle dependent intensities. An adapted version of the spectrometer setup originally developed at the PETRA III storage ring at DESY, was built in the diagnostics group of European XFEL and provided for the beamtime at SLAC.

At European XFEL the diagnostic goal is that scientists will eventually be able to use the method to extract all information online during their experiments and correlate and adjust their data analysis accordingly. Furthermore, although the method has so far only been designed and tested for soft X-rays, Ilchen and his colleagues are optimistic that it could also be used for experiments using hard X-rays. “By reducing the wavelength of the optical laser, we could even resolve the few hundreds of attosecond broad spikes of the hard X-ray pulses here at the SASE 1 branch of European XFEL” Ilchen says.

Time-resolved experiments

During the experiment at SLAC the scientists also showed that it was even possible to use the acquired data to select pulses with exactly two intensity spikes with a variable time delay between them. This demonstrates the capability of FELs to enable time-resolved X-ray measurements attosecond to few femtosecond delay. “By determining the time duration and distance of those two spikes, we can sort our data for matching pulse properties and use them to understand how certain reactions and processes have progressed on an attosecond timescale” explains Ilchen. “Since our method gives us precise information about the pulse structure, we will be able to reliably reconstruct what is happening in our samples by producing a sequence of snapshots, so that much like a series of photographs pasted together makes a moving film sequence, we can make ‘movies’ of the reactions” he adds.

From principle to proof

Due to the limited pulse repetition rate currently available at most XFELs, however, moving from a proof-of-principle experiment to actually using specifically structured pulses for so-called pump-probe experiments requires a large leap of the imagination. European XFEL, however, already provides more pulses per second than other similar facilities, and will eventually provide 27,000 pulses per second, making the dream of attosecond time-resolved experiment a real possibility. “Although, currently, no machine in the world can provide attosecond X-ray pulses with variable time delay below the femtosecond regime in a controlled fashion,” says Ilchen, “the technologies available at European XFEL in combination with our method, could enable us to produce so much data that we can pick the pulse structures of interest and sort the rest out while still getting enough statistics for new scientific perspectives.”

Further reading:

News from SLAC – “Tick, Tock on the ‘Attoclock’: Tracking X-Ray Laser Pulses at Record Speeds”

Overview of options for generating high-brightness attosecond x-ray pulses at free-electron lasers and applications at the European XFEL
S. Serkez et al., Journal of Optics, 9 Jan 2018 doi:10.1088/2040-8986/aa9f4f

See the full article here .

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XFEL Tunnel

XFEL Gun

The Hamburg area will soon boast a research facility of superlatives: The European XFEL will generate ultrashort X-ray flashes—27 000 times per second and with a brilliance that is a billion times higher than that of the best conventional X-ray radiation sources.

The outstanding characteristics of the facility are unique worldwide. Started in 2017, it will open up completely new research opportunities for scientists and industrial users.

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From SLAC: “Tick, Tock on the ‘Attoclock:’ Tracking X-Ray Laser Pulses at Record Speeds”

SLAC Lab

April 4, 2018
Amanda Solliday
Angela Anderson

In this illustration, ultrashort X-ray pulses (pink) at the Linac Coherent Light Source ionize neon gas at the center of a ring of detectors.

SLAC/LCLS

An infrared laser (orange) sweeps the outgoing electrons (blue) across the detectors with circularly polarized light. Scientists read data from the detectors to learn about the time and energy structure of the pulses, information they will need for future experiments. (Terry Anderson / SLAC National Accelerator Laboratory)

When it comes to making molecular movies, producing the world’s fastest X-ray pulses is only half the battle. A new technique reveals details about the timing and energy of pulses that are less than a millionth of a billionth of a second long, which can be used to probe nature’s processes at this amazingly fast attosecond timescale.

To catch chemistry in action, scientists at the Department of Energy’s SLAC National Accelerator Laboratory use the shortest possible flashes of X-ray light to create “molecular movies” that capture the motions of atoms in chemical reactions and reveal new details about the most fundamental processes in nature.

Future experiments at the Linac Coherent Light Source (LCLS), SLAC’s X-ray free-electron laser, will use pulses that last just attoseconds (billionths of a billionth of a second). Such experiments will be even more powerful because they’ll be able to detect the motions of electrons within molecules during chemical reactions. However, to design such ultrafast experiments, researchers need meticulous measurements of the X-ray pulses so they can use that information to interpret the data they collect on the samples they study.

Now an international team, including SLAC scientists, has created an X-ray “attoclock” that lets them analyze X-ray pulses on the attosecond timescale of electron motions.

“Using this method, we can resolve details of the pulses in the attosecond domain for the first time,” says Ryan Coffee, a senior scientist at LCLS and the Stanford PULSE Institute and a principal investigator on the team. “This paves the way for X-ray free-electron laser science at a timescale that is key to understanding physical chemistry.”

The team’s research was published in Nature Photonics on March 5.

Timekeeping in Attoseconds

An illustration of the ring-shaped array of 16 individual detectors arranged in a circle like numbers on the face of a clock. An X-ray laser pulse hits a target at the center and sets free electrons that are swept around the detectors. The location, where the electrons reach the “clock,” reveals details such as the variation of the X-ray energy and intensity as a function of time within the ultrashort pulse itself. (Frank Scholz & Jens Buck / DESY)

The term “attoclock” was coined by Swiss physicist Ursula Keller, who first demonstrated a technique to study attosecond processes with circularly polarized light 10 years ago. However, the LCLS version is the first one designed to measure individual X-ray pulses, one by one.

It consists of a ring of detectors arranged like numbers on the face of a clock. When an X-ray pulse hits a target at the center of the clock, it knocks electrons out of the target’s atoms. Those electrons are hit by circularly polarized laser light that whirls the electrons around the ring before they land on one of the detectors. The position of that detector – the number on the clock face – tells scientists how much energy the X-ray pulse contained and when exactly it hit the target.

“It’s like reading a watch,” Coffee says. “An electron may strike a detector positioned at one o’clock or three o’clock or anywhere around the clock face. We can tell from where it hits exactly when it was generated by the X-ray pulse.”

In an experiment designed to test the technique, the researchers hit neon gas with an attosecond X-ray pulse and then read which of the 16 detectors arrayed around the attoclock the freed electrons hit.

“In coming up with this technique, we combined ideas from different fields,” says principal investigator Wolfram Helml, then a Marie Curie research fellow at SLAC and the Technical University of Munich and now at the Ludwig-Maximilian University of Munich. “For our purposes, it just made sense to combine the circularly polarized light used in the original attoclock with a ring-shaped detector that has been used in other kinds of experiments.”

Finding the True Colors

The technique will be especially important for pump-probe experiments, in which a molecule is first excited with a “pump” pulse and then analyzed by a second “probe” pulse to see how it reacted.

As short as they are, these pulses can contain many different colors or wavelengths. “The color can also vary widely from pulse to pulse, and our technique can sift through the pulses, finding those that are interesting for the experiment,” Coffee says, noting the importance that such sifting will have for the data deluge expected when an upgrade to the X-ray laser, LCLS-II, comes online a couple years from now.

SLAC/LCLS II projected view

With pulses that arrive up to a million times per second, LCLS-II will produce as much data in a few minutes as LCLS currently collects in a month.

“For instance, only a certain color may excite a molecule when it is ‘pumped,’” Helml said. “With the attoclock we can see what part of the pulse is actually exciting the molecule because we know exactly when particular colors of light arrive. This lets us pinpoint more precisely when changes occur in the molecule as a result of the interaction with light.”

What’s more, scientists can potentially excite individual elements in separate parts of the molecule at the same time using different colors of X-rays.

“With this technique we could look within a single molecule at the interplay between atoms. For example, what’s going on with an oxygen atom and how might that affect the chemical environment surrounding a nearby nitrogen atom?” Helml says. “With that level of detail, we can discern completely new chemical behavior.”

Progress in Motion

The attoclock team is now working on a proposal to build more refined detectors.

“With the next detector, we are aiming to precisely identify a broader spectrum of energies,” Coffee says. “This will be an important feature for our upgraded X-ray laser, LCLS-II, which will produce pulses with an even wider energy range and more multi-color flexibility than our current machine.”

This is one of several ideas being tested at SLAC to give scientists detailed information about attosecond pulses. Two other teams are building similar systems with different types of detectors, including one at LCLS and PULSE that recently published a study in Optics Express.

The international team on the Nature Photonics study also included scientists from Deutsches Elektronen-Synchrotron (DESY) and the European X-ray Free-electron Laser (Eu-XFEL), both in Germany, who also provided the unique ring-shaped detector; University of Kassel in Germany; University of Gothenburg in Sweden; University of Bern in Switzerland; University of Colorado at Boulder; University of the Basque Country in Spain; and Lomonosov Moscow State University in Russia.

LCLS is a DOE Office of Science user facility.

See the full article here .

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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 LBNL: “News Center COSMIC Impact: Next-Gen X-ray Microscopy Platform Now Operational”

Berkeley Lab

March 21, 2018

A next-generation X-ray beamline now operating at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) brings together a unique set of capabilities to measure the properties of materials at the nanoscale.

Called COSMIC, for Coherent Scattering and Microscopy, this X-ray beamline at Berkeley Lab’s Berkeley Lab’s Advanced Light Source (ALS) allows scientists to probe working batteries and other active chemical reactions, and to reveal new details about magnetism and correlated electronic materials.

From left to right: Advanced Light Source scientists Tony Warwick, Sujoy Roy, and David Shapiro at the COSMIC beamline. (Credit: Lori Tamura/Berkeley Lab)

LBNL/ALS

COSMIC has two branches that focus on different types of X-ray experiments: one for X-ray imaging experiments and one for scattering experiments. In both cases, X-rays interact with a sample and are measured in a way that provides, structural, chemical, electronic, or magnetic information about samples.

The beamline is also intended as an important technological bridge toward the planned ALS upgrade, dubbed ALS-U, that would maximize its capabilities.

Now, after a first-year ramp-up during which staff tested and tuned its components, the scientific results from its earliest experiments are expected to get published in journals later this year.

A study published earlier this month in the journal Nature Communications, based primarily on work at a related ALS beamline, successfully demonstrated a technique known as ptychographic computed tomography that mapped the location of reactions inside lithium-ion batteries in 3-D. That experiment tested the instrumentation that is now permanently installed at the COSMIC imaging facility.

A next-generation X-ray beamline now operating at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) brings together a unique set of capabilities to measure the properties of materials at the nanoscale.

Called COSMIC, for Coherent Scattering and Microscopy, this X-ray beamline at Berkeley Lab’s Berkeley Lab’s Advanced Light Source (ALS) allows scientists to probe working batteries and other active chemical reactions, and to reveal new details about magnetism and correlated electronic materials.

COSMIC has two branches that focus on different types of X-ray experiments: one for X-ray imaging experiments and one for scattering experiments. In both cases, X-rays interact with a sample and are measured in a way that provides, structural, chemical, electronic, or magnetic information about samples.

The beamline is also intended as an important technological bridge toward the planned ALS upgrade, dubbed ALS-U, that would maximize its capabilities.

Now, after a first-year ramp-up during which staff tested and tuned its components, the scientific results from its earliest experiments are expected to get published in journals later this year.

A study published earlier this month in the journal Nature Communications, based primarily on work at a related ALS beamline, successfully demonstrated a technique known as ptychographic computed tomography that mapped the location of reactions inside lithium-ion batteries in 3-D. That experiment tested the instrumentation that is now permanently installed at the COSMIC imaging facility.

“This scientific result came out of the R&D effort leading up to COSMIC,” said David Shapiro, a staff scientist in the Experimental Systems Group (ESG) at Berkeley Lab’s ALS and the lead scientist for COSMIC’s microscopy experiments.

That result was made possible by ALS investments in R&D, and collaborations with the University of Illinois at Chicago and with Berkeley Lab’s Center for Advanced Mathematics for Energy Research Applications (CAMERA), he noted.

X-rays strike a scintillator material at the COSMIC beamline, causing it to glow. (Credit: Simon Morton/Berkeley Lab)

“We aim to provide an entirely new class of tools for the materials sciences, as well as for environmental and life sciences,” Shapiro said. Ptychography achieves spatial resolution finer than the X-ray spot size by phase retrieval from coherent diffraction data, and “The ALS has done this with world-record spatial resolution in two and now three dimensions,” he added.

The ptychographic tomography technique that researchers used in this latest study allowed them to view the chemical states within individual nanoparticles. Young-Sang Yu, lead author of the study and an ESG scientist, said, “We looked at a piece of a battery cathode in 3-D with a resolution that was unprecedented for X-rays. This provides new insight into battery performance both at the single-particle level and across statistically significant portions of a battery cathode.”

COSMIC is focused on a range of “soft” or low-energy X-rays that are particularly well-suited for analysis of chemical composition within materials

Ptychographic tomography can be particularly useful for looking at cellular components as well as batteries or other chemically diverse materials in extreme detail. Shapiro said that the X-ray beam at COSMIC is focused to a spot about 50 nanometers (billionths of a meter) in diameter; however, ptychography can enhance the spatial resolution routinely by a factor of 10 or more. The current work was performed with a 120-nanometer beam that achieved a 3-D resolution of about 11 nanometers.

COSMIC’s X-ray beam is also brighter than the ALS beamline that was used to test its instrumentation, and it will become even brighter once ALS-U is complete. This brightness can translate to an even higher nanoscale resolution, and can also enable far more precision in time-dependent experiments.

Making efficient use of this brightness requires fast detectors, which are developed by the ALS detector group. The current detector can operate at a data rate of up to 400 megabytes per second and can now generate a few terabytes of data per day – enough to store about 500 to 1,000 feature-length movies. Next-generation detectors, to be tested shortly, will produce data 100 times faster.

“We are expecting to be the most data-intensive beamline at the ALS, and an important component of COSMIC is the development of advanced mathematics and computation able to quickly reconstruct information from the data as it is collected,” Shapiro said.

To develop these tools COSMIC coupled with CAMERA, which was created to bring state-of-the-art mathematics and computing to DOE scientific facilities.

CAMERA Director James Sethian said, “Building real-time advanced algorithms and the high-performance ptychographic reconstruction code for COSMIC has been a highly successful multiyear effort between mathematicians, computer scientists, software engineers, software experts, and beamline scientists.”

The code the team developed to improve ptychographic imaging at COSMIC, dubbed SHARP, is now available to all light sources across the DOE complex. For COSMIC, the SHARP code runs on a dedicated graphics processing unit (GPU) cluster managed by Berkeley Lab’s High Performance Computing Services.

Besides ptychography, COSMIC is also equipped for experiments that use X-ray photon correlation spectroscopy, or XPCS, a technique that is useful for studying fluctuations in materials associated with exotic magnetic and electronic properties.

COSMIC enables scientists to see such fluctuations occurring in milliseconds, or thousandths of a second, compared to time increments of multiple seconds or longer at predecessor beamlines. A new COSMIC endstation with applied magnetic field and cryogenic capabilities is now being built, with early testing set to begin this summer.

Scientists have already used COSMIC’s imaging capabilities to explore a range of nanomaterials, battery anode and cathode materials, cements, glasses, and magnetic thin films, Shapiro said.

“We’re still in the mode of learning and tuning, but the performance is fantastic so far,” he said. He credited the ALS crew, led by ESG scientist Tony Warwick, for working quickly to bring COSMIC up to speed. “It’s pretty remarkable to get to such high performance in such a short amount of time.”

The ALS is a DOE Office of Science User Facility. Development and deployment of the COSMIC beamline was supported by the DOE Office of Science.

See the full article here .

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

From STFC: “UK joins World Leading X-Ray Laser Facility”

STFC

3.19.18
Jake Gilmore
STFC Media Manager
07970994586

The UK has today become the latest member state of the European XFEL, the international research facility that is home to the world’s largest X-ray laser.

DESY European XFEL

European XFEL

European XFEL

European XFEL Campus

Sited in Germany the European XFEL is capable of generating extremely intense X-ray laser flashes that offer new research opportunities for scientists across the world. Its range of capabilities include enabling researchers to take three-dimensional “photos” of the nanoworld, “film” chemical reactions as they happen and study processes such as those that occur deep inside planets.

In a ceremony at the British Embassy in Berlin, representatives of the UK government and the other contract parties, including the German federal government, signed the documents to join the European XFEL Convention. The UK is European XFEL’s twelfth member state. The UK’s contribution will amount to 26million Euro, or about 2% of the total construction budget of 1.22 billion Euro (both in 2005 prices) and an annual contribution of about 2% to the operation budget. The UK will be represented in European XFEL by the Science and Technology Facilities Council (STFC) as shareholder.

UK Science Minister Sam Gyimah said:

“The incredible XFEL laser will help us better understand life threatening diseases by using one of the world’s most powerful X-ray machines. Working with our international partners, the super-strength laser will help develop new medical treatments and therapies, potentially saving thousands of lives across the world.

“Through our modern Industrial Strategy we are investing an extra £4.7 billion into research and development. I am determined that we continue to secure our position as being a world-leader in science, research and innovation and I can’t wait to see the results that come from our participation in this extraordinary project.”

Although not an official shareholder until today the UK has been involved with XFEL since 2008 through both collaboration on technology and the two XFEL User Consortia. The first advanced detector to be installed at the European XFEL, the Large Pixel Detector (LPD), a cutting-edge X-ray “camera” capable of capturing images in billionths of a second, was developed and built by STFC. The LPD was installed mid-2017 and is now operational at the instrument for Femtosecond X-ray Experiments (FXE) at European XFEL.

In addition the STFC Central Laser Facility, based at Rutherford Appleton Laboratory near Oxford in the UK is currently building a nanosecond high energy laser for the High Energy Density (HED) instrument at European XFEL. This new “Dipole” laser will be used to recreate the conditions found within stars.

Dr Brian Bowsher, Chief Executive of STFC, said:

“As the UK becomes a full member of XFEL it opens up areas of research for British scientists at the atomic, molecular and nanoscale level that are currently inaccessible. This signing today reinforces our continued strategy to ensure UK science remains at the very forefront of global research by collaborating with the best scientists in the world and using the best facilities.

The capabilities offered by XFEL are already opening up entirely new scientific opportunities and this is a very important day for both UK science and STFC. Building on the contributions already made to XFEL by both STFC research and engineering staff and other UK researchers, I look forward with immense interest to see what my fellow UK research colleagues and the XFEL team will discover in the coming years”.

The UK has also developed a training facility at the Diamond Light Source on the Harwell campus in Oxfordshire for British scientists. The UK XFEL life sciences hub will enable users to fully prepare for their experiments with XFELs.

Chair of the European XFEL Council Professor Martin Meedom Nielsen who was present at the signing said:

“All member states are very happy that the United Kingdom now officially joins the European XFEL. The UK science community has been very active in the project since the very beginning, and their contribution of ideas and know-how has always been highly appreciated. Together, we will maintain and develop the European XFEL as a world leading facility for X-ray science.”

See the full article here .

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Helping build a globally competitive, knowledge-based UK economy

We are a world-leading multi-disciplinary science organisation, and our goal is to deliver economic, societal, scientific and international benefits to the UK and its people – and more broadly to the world. Our strength comes from our distinct but interrelated functions:

Universities: we support university-based research, innovation and skills development in astronomy, particle physics, nuclear physics, and space science
Scientific Facilities: we provide access to world-leading, large-scale facilities across a range of physical and life sciences, enabling research, innovation and skills training in these areas
National Campuses: we work with partners to build National Science and Innovation Campuses based around our National Laboratories to promote academic and industrial collaboration and translation of our research to market through direct interaction with industry
Inspiring and Involving: we help ensure a future pipeline of skilled and enthusiastic young people by using the excitement of our sciences to encourage wider take-up of STEM subjects in school and future life (science, technology, engineering and mathematics)

We support an academic community of around 1,700 in particle physics, nuclear physics, and astronomy including space science, who work at more than 50 universities and research institutes in the UK, Europe, Japan and the United States, including a rolling cohort of more than 900 PhD students.

STFC-funded universities produce physics postgraduates with outstanding high-end scientific, analytic and technical skills who on graduation enjoy almost full employment. Roughly half of our PhD students continue in research, sustaining national capability and creating the bedrock of the UK’s scientific excellence. The remainder – much valued for their numerical, problem solving and project management skills – choose equally important industrial, commercial or government careers.

Our large-scale scientific facilities in the UK and Europe are used by more than 3,500 users each year, carrying out more than 2,000 experiments and generating around 900 publications. The facilities provide a range of research techniques using neutrons, muons, lasers and x-rays, and high performance computing and complex analysis of large data sets.

They are used by scientists across a huge variety of science disciplines ranging from the physical and heritage sciences to medicine, biosciences, the environment, energy, and more. These facilities provide a massive productivity boost for UK science, as well as unique capabilities for UK industry.

Our two Campuses are based around our Rutherford Appleton Laboratory at Harwell in Oxfordshire, and our Daresbury Laboratory in Cheshire – each of which offers a different cluster of technological expertise that underpins and ties together diverse research fields.

The combination of access to world-class research facilities and scientists, office and laboratory space, business support, and an environment which encourages innovation has proven a compelling combination, attracting start-ups, SMEs and large blue chips such as IBM and Unilever.

We think our science is awesome – and we know students, teachers and parents think so too. That’s why we run an extensive Public Engagement and science communication programme, ranging from loans to schools of Moon Rocks, funding support for academics to inspire more young people, embedding public engagement in our funded grant programme, and running a series of lectures, travelling exhibitions and visits to our sites across the year.

Ninety per cent of physics undergraduates say that they were attracted to the course by our sciences, and applications for physics courses are up – despite an overall decline in university enrolment.

From LLNL: “Earth’s core metals react well to electrons”

Lawrence Livermore National Laboratory

March 1, 2018

Anne M Stark
stark8@llnl.gov
925-422-9799

LLNL scientists discovered that at the thermodynamic conditions in Earth’s core, metals such as iron and nickel become electronegative and attract electrons. Image by Adam Connell/TID.

At temperatures and pressures found on Earth’s surface, metallic elements are electropositive and lose their valence electrons to form positively charged cations. Metals have free electrons that naturally form compounds with electronegative elements. For example, iron reacts with oxygen to form Fe2O3 – commonly referred to as rust.

In contrast, noble gas elements (NGEs), such as argon, neon and xenon — considered the most chemically inert elements – show very little reactivity with other elements.

However, in the Earth’s core, the reaction of metals with NGEs is quite different. Lawrence Livermore National Laboratory (LLNL) scientists, in collaboration with researchers at the University of Saskatchewan (UoS), the Carnegie Geophysical Laboratory (GL) and the University of Chicago, challenged this basic chemical phenomenon by examining the possible reaction between iron and nickel with xenon at thermodynamic conditions like those found in Earth’s core. Using synchrotron X-ray diffraction and Raman spectroscopy diagnostics in concert with first principles calculations, they discovered that it is possible to create stable xenon iron/nickel intermetallic compounds at Earth-core thermodynamic conditions. The experimental team used a natural iron meteorite, which fell on the Sikhote-Alin mountains in Russia, as a proxy to Earth’s core composition.

The research is published in the Feb. 28 edition of Physical Review Letters.

“We targeted iron/nickel-xenon reactions at pressures greater than 2 million times Earth’s atmospheric (surface) pressure and temperatures above 2000 Kelvin to simulate thermodynamic conditions representative of Earth’s core. Our aim was to solve the missing xenon paradox, that is xenon depletion in Earth’s atmosphere,” explained lead author, Elissaios (Elis) Stavrou, an LLNL physicist.

“In spite of our intentions, Elis and I were floored when, at the X-ray beamline [Advanced Photon Source, beamline GSECARS.], a clear signature of a reaction between iron and nickel with xenon was signaled by the diffraction pattern,” added LLNL physical chemist Joe Zaug.

ANL/APS

Heavy NGEs like xenon are known to react with strong electronegative elements, such as halogens; however, as Stavrou added: “This is the first experimental evidence of a noble gas element reacting with a metal.”

If this discovery were not enough, a transformative process was found to attribute the process where xenon reacted with metallic elements. Calculations by UoS and GL theorists Yansun Yao and Hanyu Liu revealed that at these conditions, iron and nickel metals become extraordinarily electronegative and attracted electrons away from xenon.

“Amazing,” Zaug said, “The metals effectively became halogen-like under the Earth-core conditions we created in the laboratory.”

The results indicate the changing chemical properties of elements under extreme conditions where elements, which are electropositive at ambient conditions, become electronegative. “A novel periodic table is needed to understand the changing chemical properties of elements under extreme thermodynamic conditions. There are many more systems and paradoxes to resolve. We look forward to writing new chapters about extreme physicochemical phenomena,” Stavrou said.

Researchers contributing to the work include Yansun Yao of University of Saskatchewan, Alexander Goncharov, Sergey Lobanov and Hanyu Liu of Geophysical Laboratory and Vitali Prakapenka and Eran Greenberg of the Advanced Photon Source/ University of Chicago.

This work was partially funded by a Laboratory Directed Research and Development Program project.

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Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

LLNL/NIF

From European XFEL: “European XFEL starts operation of second X-ray light source”

European XFEL

European XFEL

2018/02/09

Another important milestone achieved in the development of the facility.

Image of the first X-ray laser beam in the tunnel from the European XFEL’s SASE3 undulator. SASE3 generates X-rays with a wavelength similar to the width of an atom. Those X-rays will be used to study subjects such as the formation and breaking of chemical bonds and the emergence of special properties such as semiconductivity in materials.

The second X-ray light source has successfully been taken into operation at European XFEL, the world’s largest X-ray laser located in the Hamburg metropolitan region. The X-ray light source SASE3 successfully produced X-ray laser light flashes in one of the underground tunnels. SASE3 will serve two experiment stations scheduled to begin user operation at the end of the year. Since the start of operation in September 2017, 340 scientists from across the globe have already used the facility for their research. The successful start of operation of the new SASE 3 source will enable the facility to increase the number of users further.

European XFEL Managing Director Prof. Robert Feidenhans’l said: “The construction and commissioning of the new light source are complex processes, for which we and our DESY colleagues have been preparing intensely for these last weeks and months. We are very happy that the commissioning of this second light source SASE 3 has also run so smoothly, and that both sources, SASE1 and SASE3, produce light simultaneously. For this I would like to thank all those involved, in particular the accelerator team from DESY. We continue to be on schedule to start operation at all four experiment stations currently under construction, beginning with the first two instruments in November. The remaining two will start operation at the beginning of 2019. This will increase our current capacity threefold by mid 2019.”

The new X-ray light source SASE3 uses electrons that have first passed through the light source SASE1 where they have already produced laser light. SASE3 provides laser light that will provide X-ray light for the experiment stations SQS and SCS, which are currently under construction. The SQS instrument (Small Quantum Systems) is specialized for the study of fundamental processes such as how chemical bonds break in molecules, or what happens on the atomic level when materials absorb many photons at the same time. The SCS instrument (Spectroscopy and Coherent Scattering) will focus on the investigation of fast changes in material properties, such as within magnetic materials, materials that withstand extreme temperatures, superconducting materials, and also biological samples. The research at these two stations has relevance for basic research but also for the development of new materials in the fields of IT, medicine, energy research, and catalysts, among others.

Dr. Winni Decking, responsible for the operation of the European XFEL accelerator at DESY, explained: “The first X-ray laser light at SASE3 is a special moment for the technicians, engineers, and scientists who, over many years, have contributed to the construction of the facility with great care and precision. The fact that we have achieved this milestone so soon after the first round of user operation also shows how well the operation teams from DESY and European XFEL work together.”

The European XFEL X-ray laser light is extremely intense and million times brighter than current synchrotron light sources. With the European XFEL, up to 27 000 light flashes per second can be produced, making the facility unique worldwide. In order to accomplish this, the superconducting accelerator technology developed at DESY is used at European XFEL. The X-ray light flashes are produced in the tunnels from bunches of electrons that have been accelerated to nearly the speed of light and have a lot of energy. These bunches are repeated regularly at extremely short time intervals. Up to 200m long magnetic structures, so-called undulator systems, send the accelerated electrons on a tight slalom course. At every turn, the electron bunches send out X-ray light pulses that build on one another.

SASE3 is one of currently three undulator systems at European XFEL. SASE1 produced the first-ever X-ray light at European XFEL in May 2017. Now SASE3 follows on schedule. The first lasing from SASE2 is planned for the middle of 2018. SASE1 and SASE2 are 200 m long, very similar in their construction and produce extremely short-wavelength X-ray light. SASE3, which sits behind SASE1, is, at 120 m, somewhat shorter and produces longer-wavelength X-ray light.

The wavelengths attainable with SASE1 and SASE2 correspond to roughly the size of an atom. This, therefore, enables the capturing of pictures and films of the nano-cosmos in atomic resolution, such as of biomolecules that are important for the development of disease or for novel medication.

At the first lasing, SASE3 produced X-ray light with a wavelength of 1.4 nanometre (900 eV), about 600 times shorter than that of visible light. The start-up of operation began with 20 pulses per second; later this will increase to 27 000.

As a world first, the accelerated electrons are first used to produce laser light in SASE1 and then used in SASE3 to produce X-ray light a few hundred meters further downstream. The light sources, therefore, produce X-rays for different instruments in the experiment hall at the end of the tunnel at the same time. The planned simultaneous operation of several light sources and the experiment stations is a further unique characteristic of European XFEL and of particular importance due to the high international demand for experiment time.

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XFEL Tunnel

XFEL Gun

The Hamburg area will soon boast a research facility of superlatives: The European XFEL will generate ultrashort X-ray flashes—27 000 times per second and with a brilliance that is a billion times higher than that of the best conventional X-ray radiation sources.

The outstanding characteristics of the facility are unique worldwide. Started in 2017, it will open up completely new research opportunities for scientists and industrial users.

From CERN Courier: “EU project lights up X-band technology”

CERN Courier

Nov 10, 2017

A CLIC X-band prototype structure built by PSI using Swiss FEL technology. (Image credit: M Volpi)

Advanced linear-accelerator (linac) technology developed at CERN and elsewhere will be used to develop a new generation of compact X-ray free-electron lasers (XFELs), thanks to a €3 million project funded by the European Commission’s Horizon 2020 programme. Beginning in January 2018, “CompactLight” aims to design the first hard XFEL based on 12 GHz X-band technology, which originated from research for a high-energy linear collider. A consortium of 21 leading European institutions, including Elettra, CERN, PSI, KIT and INFN, in addition to seven universities and two industry partners (Kyma and VDL), are partnering to achieve this ambitious goal within the three-year duration of the recently awarded grant.

X-band technology, which provides accelerating-gradients of 100 MV/m and above in a highly compact device, is now a reality. This is the result of many years of intense R&D carried out at SLAC (US) and KEK (Japan), for the former NLC and JLC projects, and at CERN in the context of the Compact Linear Collider (CLIC). This pioneering technology also withstood validation at the Elettra and PSI laboratories.

XFELs, the latest generation of light sources based on linacs, are particularly suitable applications for high-gradient X-band technology. Following decades of growth in the use of synchrotron X-ray facilities to study materials across a wide spectrum of sciences, technologies and applications, XFELs (as opposed to circular light sources) are capable of delivering high-intensity photon beams of unprecedented brilliance and quality. This provides novel ways to probe matter and allows researchers to make “movies” of ultrafast biological processes. Currently, three XFELs are up and running in Europe – FERMI@Elettra in Italy and FLASH and FLASH II in Germany, which operate in the soft X-ray range – while two are under commissioning: SwissFEL at PSI and the European XFEL in Germany (CERN Courier July/August 2017 p18), which operates in the hard X-ray region. Yet, the demand for such high-quality X-rays is large, as the field still has great and largely unexplored potential for science and innovation – potential that can be unlocked if the linacs that drive the X-ray generation can be made smaller and cheaper.

This is where CompactLight steps in. While most of the existing XFELs worldwide use conventional 3 GHz S-band technology (e.g. LCLS in the US and PAL in South Korea) or superconducting 1.3 GHz structures (e.g. European XFEL and LCLS-II), others use newer designs based on 6 GHz C-band technology (e.g. SCALA in Japan), which increases the accelerating gradient while reducing the linac’s length and cost. CompactLight gathers leading experts to design a hard-X-ray facility beyond today’s state of the art, using the latest concepts for bright electron-photo injectors, very-high-gradient X-band structures operating at frequencies of 12 GHz, and innovative compact short-period undulators (long devices that produce an alternating magnetic field along which relativistic electrons are deflected to produce synchrotron X-rays). Compared with existing XFELs, the proposed facility will benefit from a lower electron-beam energy (due to the enhanced undulator performance), be significantly more compact (as a consequence both of the lower energy and of the high-gradient X-band structures), have lower electrical power demand and a smaller footprint.

Success for CompactLight will have a much wider impact: not just affirming X-band technology as a new standard for accelerator-based facilities, but advancing undulators to the next generation of compact photon sources. This will facilitate the widespread distribution of a new generation of compact X-band-based accelerators and light sources, with a large range of applications including medical use, and enable the development of compact cost-effective X-ray facilities at national or even university level across and beyond Europe.

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THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

From SLAC: “Q&A: Alan Heirich and Elliott Slaughter Take On SLAC’s Big Data Challenges”

SLAC Lab

January 9, 2018
Manuel Gnida

Members of SLAC’s Computer Science Division. From left: Alex Aiken, Elliott Slaughter and Alan Heirich. (Dawn Harmer/SLAC National Accelerator Laboratory)

As the Department of Energy’s SLAC National Accelerator Laboratory builds the next generation of powerful instruments for groundbreaking research in X-ray science, astronomy and other fields, its Computer Science Division is preparing for the onslaught of data these instruments will produce.

The division’s initial focus is on LCLS-II, an upgrade to the Linac Coherent Light Source (LCLS) X-ray laser that will fire 8,000 times faster than the current version. LCLS-II promises to provide completely new views of the atomic world and its fundamental processes. However, the jump in firing rate goes hand and in hand with an explosion of scientific data that would overwhelm today’s computing architectures.

SLAC/LCLS

SLAC/LCLS II projected view

In this Q&A, SLAC computer scientists Alan Heirich and Elliott Slaughter talk about their efforts to develop new computing capabilities that will help the lab cope with the coming data challenges.

Heirich, who joined the lab last April, earned a PhD from the California Institute of Technology and has many years of experience working in industry and academia. Slaughter joined last June; he’s a recent PhD graduate from Stanford University, where he worked under the guidance of Alex Aiken, professor of computer science at Stanford and director of SLAC’s Computer Science Division.

What are the computing challenges you’re trying to solve?

Heirich: The major challenge we’re looking at now is that LCLS-II will produce so much more data than the current X-ray laser. Data rates will increase 10,000 times, from about 100 megabytes per second today to a terabyte per second in a few years. We need to think about the computing tools and infrastructure necessary to take control over that enormous future data stream.

Slaughter: Our development of new computing architectures is aimed at analyzing LCLS-II data on the fly, providing initial results within a minute or two. This allows researchers to evaluate the quality of their data quickly, make adjustments and collect data in the most efficient way. However, real-time data analysis is quite challenging if you collect data with an X-ray laser that fires a million pulses per second.
How can real-time analysis be achieved?

Slaughter: We won’t be able to do all this with just the computing capabilities we have on site. The plan is to send some of the most challenging LCLS-II data analyses to the National Energy Research Scientific Computing Center (NERSC) at DOE’s Lawrence Berkeley National Laboratory, where extremely fast supercomputers will analyze the data and send the results back to us within minutes.

Our team has joined forces with Amedeo Perazzo, who leads the LCLS Controls and Data Systems Division, to develop the system that will run the analysis. Scientists doing experiments at LCLS will be able to define the details of that analysis, depending on what their scientific questions are.

Our goal is to be able to do the analysis in a very flexible way using all kinds of high-performance computers that have completely different hardware and architectures. In the future, these will also include exascale supercomputers that perform more than a billion billion calculations per second – up to a hundred times more than today’s most powerful machines.

Is it difficult to build such a flexible computing system?

Heirich: Yes. Supercomputers are very complex with millions of processors running in parallel, and we need to figure out how to make use of their individual architectures most efficiently. At Stanford, we’re therefore developing a programming system, called Legion, that allows people to write programs that are portable across very different high-performance computer architectures.

Traditionally, if you want to run a program with the best possible performance on a new computer system, you may need to rewrite significant parts of the program so that it matches the new architecture. That’s very labor and cost intensive. Legion, on the other hand, is specifically designed to be used on diverse architectures and requires only relatively small tweaks when moving from one system to another. This approach prepares us for whatever the future of computing looks like. At SLAC, we’re now starting to adapt Legion to the needs of LCLS-II.

We’re also looking into how we can visualize the scientific data after they are analyzed at NERSC.

NERSC Cray XC40 Cori II supercomputer

LBL NERSC Cray XC30 Edison supercomputer

The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

NERSC PDSF

PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

The analysis will be done on thousands of processors, and it’s challenging to orchestrate this process and put it together into one coherent visual picture. We just presented one way to approach this problem at the supercomputing conference SC17 in November.

What’s the goal for the coming year?

Slaughter: We’re working with the LCLS team on building an initial data analysis prototype. One goal is to get a first test case running on the new system. This will be done with X-ray crystallography data from LCLS, which are used to reconstruct the 3-D atomic structure of important biomolecules, such as proteins. The new system will be much more responsive than the old one. It’ll be able to read and analyze data at the same time, whereas the old system can only do one or the other at any given moment.
Will other research areas besides X-ray science profit from your work?

Slaughter: Yes. Alex is working on growing our division, identifying potential projects across the lab and expanding our research portfolio. Although we’re concentrating on LCLS-II right now, we’re interested in joining other projects, such as the Large Synoptic Survey Telescope (LSST). SLAC is building the LSST camera, a 3.2-gigapixel digital camera that will capture unprecedented images of the night sky. But it will also produce enormous piles of data – millions of gigabytes per year. Progress in computer science is needed to efficiently handle these data volumes.

Heirich: SLAC and its close partnership with Stanford Computer Science make for a great research environment. There is also a lot of interest in machine learning. In this form of artificial intelligence, computer programs get better and more efficient over time by learning from the tasks they performed in the past. It’s a very active research field that has seen a lot of growth over the past five years, and machine learning has become remarkably effective in solving complex problems that previously needed to be done by human beings.

Many groups at SLAC and Stanford are exploring how they can exploit machine learning, including teams working in X-ray science, particle physics, astrophysics, accelerator research and more. But there are very fundamental computer science problems to solve. As machine learning replaces some conventional analysis methods, one big question is, for example, whether the solutions it generates are as reliable as those obtained in the conventional way.

LCLS and NERSC are DOE Office of Science user facilities. Legion is being developed at Stanford with funding from DOE’s ExaCT Combustion Co-Design Center, Scientific Data Management, Analysis and Visualization program and Exascale Computing Project (ECP) as well as other contributions. SLAC’s Computer Science Division receives funding from the ECP.

See the full article here .

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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 SLAC: “Magnetic Trick Triples the Power of SLAC’s X-Ray Laser”

SLAC Lab

January 31, 2018
Mark Shwartz

The new technique will allow researchers to observe ultrafast chemical processes previously undetectable at the atomic scale.

Scientists at the Department of Energy’s SLAC National Accelerator Laboratory have discovered a way to triple the amount of power generated by the world’s most powerful X-ray laser. The new technique, developed at SLAC’s Linac Coherent Light Source (LCLS), will enable researchers to observe the atomic structure of molecules and ultrafast chemical processes that were previously undetectable at the atomic scale.

SLAC/LCLS

From left, SLAC’s Yauntao Ding and Marc Guetg discuss their work at the lab’s Accelerator Control Room where beams that feed the X-ray laser are monitored.(Dawn Harmer/SLAC)

The results, published in a Jan. 3 study in Physical Review Letters (PRL), will help address long-standing mysteries about photosynthesis and other fundamental chemical processes in biology, medicine and materials science, according to the researchers.

“LCLS produces the world’s most powerful X-ray pulses, which scientists use to create movies of atoms and molecules in action,” said Marc Guetg, a research associate at SLAC and lead author of the PRL study. “Our new technique triples the power of these short pulses, enabling higher contrast.”

The research team, from left: back row, Yuantao Ding, Matt Gibbs, Nora Norvell, Alex Saad, Uwe Bergmann, Zhirong Huang; front row, Marc Guetg and Timothy Maxwell. (Dawn Harmer/SLAC)

Magnetic Wiggles

The X-ray pulses at LCLS are generated by feeding beams of high-energy electrons through a long array of magnets. The electrons, which travel near the speed of light, wiggle back and forth as they pass along the magnets. This wiggling motion causes the electrons to emit powerful X-ray pulses that can be used for nanoscale imaging.

“When you image an atomic structure, you have a race going on,” said study co-author Uwe Bergmann, a distinguished staff scientist at SLAC. “You need an X-ray pulse strong enough to get a good image, but that pulse will destroy the very structure that you’re trying to measure. However, if the pulse is short enough, about 10 femtoseconds, you can outrun the damage. You can take the snapshot before the patient feels the pain.”

One femtosecond is one millionth of a billionth of a second. Generating high-power X-ray pulses that last only 10 femtoseconds has been a major challenge.

“The trick is to have the electrons packed together as tightly as possible when they start wiggling around,” Guetg explained. “It’s difficult to do, because electrons don’t like each other. They’re all negatively charged, so they repel one another. It’s a battle. We’re constantly trying to force them to together, and they’re constantly trying to move apart.”

To win the battle, Guetg and his SLAC colleagues used a special combination of magnets designed to bring the electrons closer together before they start emitting X-rays.

“One problem when you compress electrons is that they start kicking each other,” Guetg said. “As a result, the electron beam gets tilted, which impairs the light production and therefore the power of the X-ray pulses.”

In previous studies, Guetg had theorized that correcting the tilt would compress the electrons and produce shorter, more powerful bursts of X-rays.

“The electron beam is shaped like a banana,” said co-author Zhirong Huang, an associate professor at SLAC and at Stanford University. “We corrected the curvature of the banana to make it a straight, pencil-like beam.”

Dramatic Results

The results were dramatic. Straightening the beam increased the power of the X-ray pulses by 300 percent, and each pulse lasted only 10 femtoseconds.

“In an ingenious way, Marc and his colleagues were able to compress these electrons like a pancake before they drifted apart,” Bergmann said. “That allowed them to create very short X-ray pulses that are about 1,000 times more powerful than if you focused all the sunlight that hits the Earth onto one square centimeter. It’s an incredible power.”

Bergmann has already used the new technique to create nanoscale images of transition metals such as manganese, which is essential for splitting water to form oxygen molecules (O2) during photosynthesis.

“By pushing the frontier of laser science we can now see more and hopefully learn more about chemical reactions and molecular processes,” he said.

The SLAC team hopes to build on their results in future experiments.

“We want to make the new technique operational and robust so that anyone can use it,” Huang said. “We also want to keep improving the power with this technique and others. I would not call this the final limit.”

The study is co-authored by SLAC staff scientists Alberto Lutman, Yuantao Ding, Timothy Maxwell and Franz-Josef Decker. Financial support was provided by the Department of Energy’s Office of Science. LCLS is a DOE Office of Science user facility.

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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 SLAC: “SLAC Scientists Investigate How Metal 3-D Printing Can Avoid Producing Flawed Parts”

SLAC Lab

January 30, 2018
Kimber Price

A metal 3-D printed sample the team used for experiments. (Johanna Nelson Weker/SLAC)

Video – 3-D printing of a metal sample inside an X-ray chamber

This video shows the 3-D printing of a metal sample inside an X-ray characterization chamber at Lawrence Livermore National Laboratory before the chamber was dismantled, transported to SLAC and rebuilt. At SLAC the glass windows were replaced with X-ray transparent beryllium windows. The chamber allows researchers to observe metal 3-D printing in real time. No video credit.

This video shows the 3-D printing of a metal sample inside an X-ray characterization chamber at Lawrence Livermore National Laboratory before the chamber was dismantled, transported to SLAC and rebuilt. At SLAC the glass windows were replaced with X-ray transparent beryllium windows. The chamber allows researchers to observe metal 3-D printing in real time. No video credit.

SLAC staff scientist Johanna Nelson Weker, front, leads a study on metal 3-D printing at SLAC’s Stanford Synchrotron Radiation Lightsource with researchers Andrew Kiss and Nick Calta, back. (Dawn Harmer/SLAC).

SLAC/SSRL

Pits Among the Layers

In metal 3-D printing, a thin layer of powdered metal, such as titanium alloys, steel, aluminum alloys, or copper, is distributed on a platform and selectively melted by a high-powered laser beam. Then the platform is lowered, a new layer of metal powder is applied and the process is repeated until the object is fully formed.

This process often results in the formation of pits, or weak spots, when the metal cools and hardens unevenly while building up the layers. In the SLAC X-ray experiments, scientists are analyzing every aspect of the process ­– the kind of metal used, the level of heat from the laser, the speed at which the metal heats and cools – to find the best combination for eliminating pits, controlling the microstructure, and manufacturing strong metal parts.

“We are providing the fundamental physics research that will help us identify which aspects of metal 3-D printing are important,” says Chris Tassone, a staff scientist in SSRL’s Materials Science Division. It’s practical information, he says, that could eventually lead to writing recipes for 3-D printer laser settings that manufacturers can use to produce sturdy parts.

Diving in for a Better View

Until recently, researchers watched from above as layers were being added to form a part. Because they couldn’t see below the surface of the metal, it was impossible to tell how deeply the laser was melting the layers as each one was applied. They tried imaging the growing layers with thermal radiation, or heat, but this did not give them enough information about what was causing the weak spots. X-rays, however, give researchers an excellent tool to see and record what’s happening inside the part as it’s being built.

The scientists are using two X-ray methods to see what happens during metal 3-D printing. With one type of X-ray light, they create micron-resolution images of what happens as the layers of metal build up. The second method bounces X-rays off the atoms in the material to analyze its atomic structure as it changes from solid to liquid and back to solid form during the melting and cooling process.

Thus far, the group has been looking at lasers hitting layers of metal powder, but they also plan to investigate another approach called “directed energy deposition.” In this process, a laser beam hits and melts metal powder or wire as it is being laid down, allowing creation of more complex geometric forms. This sort of 3-D printing is especially useful in making repairs.

They also want to incorporate a high-speed camera into their experimental setup so they can collect photographs and video of the manufacturing process and correlate what they see with their X-ray data.

This is important to manufacturers and other researchers who use cameras to observe the process but don’t have access to an X-ray synchrotron, Nelson Weker says: “We want people to be able to connect what they see on their cameras with what we are measuring here so they can infer what’s happening below the surface of the growing metal material. We want to put meaning to those signatures.”

Other researchers on the metal 3-D printing project include Kevin Stone, Anthony Fong, Andrew Kiss and Vivek Thampy. SSRL is a DOE Office of Science user facility. The research was funded by the DOE Office of Energy Efficiency and Renewable Energy’s Advanced Manufacturing Office.

See the full article here .

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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.