Director’s Corner

This year is the 90th anniversary of Berkeley Lab. I am honored to be part of ATAP as we carry forward Lawrence’s twin legacies — particle accelerators and the team-science paradigm — into the unknown, but doubtless remarkable, discoveries and inventions yet to come.

In this issue of ATAP News, you can read about a variety of our contributions to the accelerators still to come, including interaction-region focusing magnets for the High-Luminosity Upgrade of the Large Hadron Collider, a novel technique for measuring the electron beams of laser-plasma accelerators, contributions to community-planning processes for plasma accelerators and for fusion energy and plasma science; an innovative superconducting undulator for future free-electron lasers; and applications of machine learning to accelerator control and design.

Thinking of how these achievements involve teamwork (in many cases, with multiple institutions) and directly or indirectly foster discovery science at user facilities — and of the crucial roles played by people at an early stage in their careers — I am sure that Lawrence’s legacy is in good hands at his namesake laboratory as we begin the next 90.


—ATAP, Engineering play key roles in multi-lab magnet program

Based on a story by Leah Hesla of Fermilab

A fully assembled quadrupole magnet

The U.S. Department of Energy has formally approved the High-Luminosity Large Hadron Collider Accelerator Upgrade Project (AUP) to go into series production mode, building and delivering components. Those components prominently include cutting-edge magnets designed and built with the help of ATAP and the Engineering Division.

The approval, known as Critical Decision 3, or CD-3, in DOE’s project-management process, is a milestone in the U.S. contributions to the high-luminosity upgrade of the Large Hadron Collider, or HL-LHC, at the European laboratory CERN. The approval follows a Fermilab Director’s Review in July 2020 and a DOE Review in November 2020.

“The incredible talent across our national laboratories working seamlessly has made this possible.”
— Kathleen Amm, Director, Magnet Division, Brookhaven National Laboratory

This video highlights magnet-making efforts to support the High-Luminosity Large Hadron Collider upgrade at CERN in Europe. Three U.S. Department of Energy national labs — Berkeley Lab, Fermilab, and Brookhaven — are building superconducting magnets that can produce far stronger magnet fields than the magnets now in place at the LHC. This will enable more particle collisions and data to help us learn more about exotic particles and their properties. (Marilyn Sargent/Berkeley Lab)

Fermilab is lead lab in the AUP, in which the U.S. collaborators will contribute 16 magnets to dramatically focus the LHC’s near-light-speed particle beams to a tiny volume before colliding. In an aspect that does not involve Berkeley Lab, the AUP is also contributing eight superconducting radiofrequency cavities.

Berkeley Lab’s contributions, through our Superconducting Magnet Program/Berkeley Center for Magnet Technology (SMP/BCMT), include superconducting cables; insulation of the cables; and magnets (sidebar).

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With CD-3 approval, AUP collaborators can now move full speed ahead on building and delivering crucial components. Fermilab, Brookhaven National Laboratory and Berkeley Lab are currently building the magnet components and plan to begin delivering the first magnet cryoassembly by late 2021 for critical tests. Components will be installed in the HL-LHC from 2025 to early 2027.

“Gaining DOE’s endorsement to move to full production is a huge achievement. Knowing what it means for the future of particle physics — for the new physics that the HL-LHC will reveal and for future accelerators enabled by these technologies — makes it even more gratifying,” said Giorgio Apollinari, Fermilab scientist and HL-LHC AUP project manager. “I congratulate the entire AUP team on the milestone. They have been instrumental in ensuring the development and technical successes of the leading-edge technologies needed for the HL-LHC.”


Magnets By the Numbers

Berkeley Lab’s contributions to the AUP include 104 cables made of superconducting wire to be used in the magnets; the insulation of the cables; and the assembly of 26 four-meter-long quadrupole magnets, designated MQXFA, that will focus the LHC’s particle beams.

The total of 26 magnets includes 16 series-production magnets (the effort set in motion by CD-3 approval), plus a prototype, five pre-series production units, and four that may require reassembly. A net total of 20 magnets will be provided to CERN.

Two of the 20 magnets will go into each of the 10 magnet cryoassemblies — cooling and housing units that enable the magnets’ superconductivity — to be provided by the AUP. Eight of these 10 magnet cryoassemblies will be installed during the upgrade; the other two will serve as spares.

The AUP magnet cryoassemblies are designated Q1 and Q3. Between them will be the CERN-provided Q2 (in two segments, a and b). Together, Q1, Q2a/b, and Q3 are called an “inner triplet” of quadrupole magnets.

There will be an inner triplet on either side of each of the two major detectors, ATLAS and CMS, to focus the proton beams as they come from opposite directions en route to head-on collisions.

Multi-institutional teamwork in the time of COVID

The AUP is supported by the DOE Office of Science. The AUP team consists of six U.S. laboratories and two universities: Fermilab, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory, and Thomas Jefferson National Accelerator Facility (all DOE national laboratories), along with the National High Magnetic Field Laboratory, Old Dominion University, and the University of Florida. Each brings unique strengths to the challenges of designing and building these advanced magnets.

SMP/BCMT head Soren Prestemon said, “These are very challenging magnets that took excellence in multiple skill sets and a variety of facilities. From conductor through cabling, design and assembly of magnets, and testing, this has been teamwork at its best.”

“As the review committees have noted, the AUP has been notable not only for technical achievement, but also for managerial coordination,” added Interim ATAP Division Director Thomas Schenkel. “A coast-to-coast project for a customer several time zones away is never easy, and especially during the pandemic, when we can’t meet in person, they’ve done a remarkable job of coordinating their efforts.”

The AUP magnets use conductors made of niobium-tin to generate a stronger magnetic field compared to predecessor technology. This type of magnet will make its debut in the HL-LHC: its run will be the first time that niobium-tin magnets will be used in a particle accelerator for particle physics research.

To date, the team at Berkeley has assembled four of the 5 pre-series magnets, and is now gearing up for series production now that the CD-3 approval has been given. “These magnets are a culmination of more than 15 years of technology development, starting with the LARP (LHC Accelerator Research Program) collaboration,” recounts Dan Cheng, who is the Deputy Level-3 Control Account Manager for the Magnet Structures task at LBNL. “That effort was the foundation of what all of our teams have achieved so far, but there are still many challenges ahead of us.”

“It is very exciting to see this cutting-edge magnet technology, which is enabling breakthrough science at the LHC, enter the production phase after the successful test of our first magnet and with the approval of CD-3,” said Kathleen Amm, the Brookhaven representative for the Accelerator Upgrade Project and director of Brookhaven’s Magnet Division. “The incredible talent across our national laboratories working seamlessly has made this possible.”

The LHC AUP magnets and cavities will be positioned near two of the LHC’s collision points — the ones that host the ATLAS and CMS particle detectors. These giant, stories-high underground instruments are also being upgraded to take full advantage of the HL-LHC’s higher rate of collisions.

Over the course of the project the AUP team has seen one success after another, hitting both technological and project milestones according to the schedule established in 2015, says Apollinari. The U.S. collaboration’s first focusing magnet, completed last year in a prototyping phase, met or exceeded specifications.

“Building such an ambitious machine requires not only vision but discipline in carrying it out — tight, transparent, respectful coordination with partners, including with funding agencies and the independent reviewers,” Apollinari said. “The achievement is not only that we received CD-3 approval, but how we got here. We met our goals on a timescale that was put down on paper five years ago. That’s thanks to incredible teamwork of everyone involved.”

Stronger magnets mean more-precise (and possibly new) physics

At the LHC, beams of protons race in opposite directions around the collider’s 17-mile circumference, colliding at high energies at four specific interaction points along the way. Scientists study the collisions to better understand nature’s constituent components and to look for exotic matter, such as dark matter.

The HL-LHC is expected to start operations in 2027 and run through the 2030s. The higher luminosity will enable a tenfold increase in the number of particle collisions, compared to the current LHC. This improvement will enable physicists to study particles such as the Higgs boson in greater detail. The increase in the number of collisions could also uncover rare physics phenomena or signs of new physics.

“HL-LHC is a truly global scientific undertaking that will usher in a new era of research and discovery in particle physics. AUP plays a critical role in making this possible,” said Fermilab Director Nigel Lockyer. “The technologies developed by AUP will be important not only for the operation of HL-LHC, but also for the viability of future hadron colliders and the future of the field of particles — beyond the end of the HL-LHC’s run.”


— BELLA Center, UC-Berkeley, Ohio State team develops new diagnostic technique

Glenn Roberts, Jr., Berkeley Lab Strategic Communications

Photo - Sam Barber, left, a research scientist at Berkeley Lab’s BELLA Center, and Jeroen van Tilborg, a staff scientist at the BELLA Center, hold the active plasma lens, right, and dipole magnets used in an electron-beam diagnostic experiment. Combined, the magnets allowed measurements of electron-beam energy, with range and resolution comparable to what is achieved using the multi-ton magnet located behind them. (Marilyn Sargent/LBNL)

Research scientist Sam Barber (l.) and staff scientist Jeroen van Tilborg of the BELLA Center hold the active plasma lens used in an electron-beam diagnostic experiment. The setup enabled measurements of electron-beam energy with range and resolution comparable to what is achieved using the multi-ton dipole magnet located behind them. (Marilyn Sargent/LBNL)

Physicists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) are figuring out new ways to accelerate electrons to record-high energies over record-short distances with a technique that uses laser pulses and exotic matter known as a plasma. But measuring the properties of the high-energy electron beams produced in laser-plasma acceleration experiments has proven challenging, as the high-intensity laser must be diverted without disrupting the electron beam.

Now, a new, compact system has been successfully demonstrated at the Berkeley Lab Laser Accelerator (BELLA) Center to provide simultaneous high-resolution measurements of multiple electron-beam properties.

The new system uses ultrathin liquid-crystal films, developed by Prof. Douglass Schumacher and his team at Ohio State University, to redirect the laser while allowing the electron beam to pass through, largely unaffected. The laser forms a plasma that reflects the bulk of its laser light.

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While each laser pulse destroys the liquid-crystal film, similar to a bubble machine, the liquid-crystal film is replenished by a rotating disc and wiper device after each laser shot. The films formed by this device are just tens of nanometers (billionths of meters) in thickness, about a factor of 1,000 thinner than those in other replenishable plasma mirror systems that use VHS cassette tape, for example. This reduction in thickness serves to preserve the electron beam’s properties.

The deflection of laser light away from the electron beam is essential for producing a precise diagnostic of the electron beam, noted Jeroen van Tilborg, a BELLA Center staff scientist, and it is also crucial for multistage laser-plasma acceleration experiments, in which the laser pulses are refreshed at each stage to provide an additional “kick” of acceleration for the electron beam until it reaches its required acceleration.

The liquid-crystal plasma mirror (LCPM) also enables the use of a gas-filled, 6-centimeter-long strong focusing device for the electron beam, known as an active plasma lens.

This lens allows a compact alternative to a large diagnostic tool called a magnetic spectrometer device, which has bulky magnets that weigh more than a ton and are coupled to a large power supply.

“We were able to replace this with dipole (two-pole) magnets about the size of a sandwich,” said Sam Barber, a research scientist at the BELLA Center in Berkeley Lab’s Accelerator Technology and Applied Physics (ATAP) Division. “Laser plasma accelerators can produce high-energy electrons in compact footprints, but there is still much that can be done to shrink some of the components, including electron beam diagnostics.”

Photo - Sam Barber holds an active plasma lens, left, and dipole magnets used in an electron-beam diagnostic experiment at the BELLA Center. (Credit: Marilyn Sargent/Lawrence Berkeley National Laboratory)

Sam Barber holds an active plasma lens (l.) and dipole magnets used in the electron-beam diagnostic. (Marilyn Sargent/LBNL)

He added, “This is a huge reduction in the scale. We are combining a petawatt (high-power) laser with ultrathin LCPMs and active plasma lenses – all novel technologies that have just recently been developed. We combined all three of them and we got a nice result. We are making big steps forward. There is a whole slew of new applications that this could be used for.”

Barber was the lead author of a study detailing the performance and setup of the new diagnostic tool, published in the journal Applied Physics Letters. Other BELLA Center researchers participated in the study, too, along with researchers from UC Berkeley and Ohio State University.

The development of high energy and high quality electron beams based on laser-plasma acceleration at the BELLA Center is funded primarily by the DOE Office of High Energy Physics and by an Early Career Research Program grant from the Office of Basic Energy Sciences, as well as by LaserNetUS, the recently formed network of high-power laser facilities that is funded by the DOE Office of Fusion Energy Sciences.

Carl Schroeder, a Berkeley Lab senior scientist who is deputy director of the BELLA Center, said that besides its compactness, the new diagnostic technique can collect several electron-beam properties at once, including the detailed energy distribution of the electron beam and the beam’s emittance, on a single-shot basis. Emittance is a critical property of an electron beam that dictates how tightly the beam can be focused. A low emittance means the beam can be focused down to a very small spot, crucial for most accelerator applications like colliders and free-electron lasers.

“Typically, these are multishot diagnostics,” he said, which average the measurements of several beam pulses but don’t measure on a pulse-by-pulse basis – as does the new technique.

In the demonstrated setup, a laser is focused into a gas cell, where it creates and interacts with a plasma, generating and accelerating an electron beam. After passing through this cell, the combined laser beam and electron beam arrive at the LCPM, at which point the laser is deflected while the electron beam is transmitted – with negligible disruption.

The electron beam then passes through the active plasma lens. The lens is used to focus the electron beam into a sequence of small magnets. The magnetic field disperses the electrons according to energy – much like the way light is dispersed by color when passing through a prism.

The dispersed electron beam then passes through a special crystal that produces light as the electron passes through. High-resolution images of the crystal’s light signature enable a precise, sub-percent-resolution mapping of the energy of the electron beam, and simultaneous emittance measurements.

The measurements can ultimately help researchers to troubleshoot, tune, and improve the performance of laser-plasma acceleration experiments, and the setup could potentially be relevant for future collider applications and compact X-ray free-electron lasers, researchers noted, which could have a wide array of applications.

“You want to be able to rapidly characterize these beams and use that as feedback for optimization,” Barber said. “This is useful for the characterization and control of electron-beam properties.”


— Berkeley Lab contributes to community planning process

Glenn Roberts, Jr., Berkeley Lab Strategic Communications

Photo - This 2018 photo shows the BELLA HTT laser system, which enables multipulse, high-energy-density photon sources for LaserNetUS and other experiments. (Credit: Berkeley Lab)

This 2018 photo shows the BELLA Hundred Terawatt Thomson-scattering (HTT) laser system, which enables multipulse, high-energy-density photon sources for LaserNetUS and other experiments. Plasma produced by the laser creates a radial rainbow when the initially almost invisible (infrared) laser pulse is frequency shifted as it ionizes air in the chamber. This shows that the laser is compressed to a short pulse duration on target. (Credit: Berkeley Lab)

The U.S. Department of Energy (DOE) Fusion Energy Sciences Advisory Committee (FESAC) has adopted and endorsed a new report that lays out a strategic plan for fusion energy and plasma science research over the next decade. The report has been two years in the making, gathering an unprecedented level of input and support from across the U.S. fusion and plasma community.

Its strategic plan charts a path for the U.S. as it seeks to develop fusion as a limitless and practical source of energy while also advancing areas of fundamental plasma science.

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Photo - Cameron Geddes (Credit: Berkeley Lab)

Cameron Geddes (Credit: Berkeley Lab)

“The report establishes a strong and coordinated plan for fusion energy and plasma science for the next 10 years and demonstrates exciting opportunities for growth. Berkeley Lab has an important role to play,” said Cameron Geddes, deputy director of the Berkeley Laboratory Laser Accelerator (BELLA) Center who served as a report subcommittee member. “The process required all parts of the community to learn about the whole and plan comprehensively, and it has been an honor to participate.”

Thomas Schenkel, interim director of Berkeley Lab’s Accelerator Technology and Applied Physics Division, added, “From building powerful superconducting magnets for controlled fusion reactions and pioneering novel concepts for inertial fusion, to advanced lasers enabling high-energy-density science and miniature accelerators, to the modeling and simulation of powerful laser beams and plasmas, we have a lot to offer across the entire field of fusion energy sciences.”

He noted the Lab’s ongoing participation in LaserNetUS, a program highlighted in the report that has enabled new capabilities by pairing plasma researchers from the U.S. and around the world with the BELLA Center’s cutting-edge laser capabilities, including a new short-focal-length beamline under construction, and with the capabilities of other centers.

The report comes at an important moment for fusion and plasma science and technology, and recommends three drivers in each area.

In fusion science and technology:

  • Advance the science and technology required to confine and sustain a burning plasma.
  • Develop the materials required to withstand the extreme environment of a fusion reactor.
  • Engineer the technologies required to breed fusion fuel and to generate electricity in a fusion pilot plant by the 2040s.

In plasma science and technology:

  • Develop a deeper understanding of the plasma universe – plasmas are at the core of most energetic events we observe in the universe.
  • Explore and discover new regimes and exotic states of matter; utilize new experimental capabilities.
  • Unlock the potential of plasmas to transform society.

Image - A rendering of the layout of the iP2 high-intensity focal-point capability, which will enable new regimes in laser-matter interaction and ion acceleration for under LaserNetUS. The target chamber is shown at left. (Credit: Berkeley Lab)

A rendering of the layout of the iP2 high-intensity, short-focal-length beamline, which will enable new regimes in laser-matter interaction and ion acceleration for LaserNetUS experiments. The target chamber is shown at left. (Credit: Berkeley Lab)

Decades of public investment in fusion research have yielded important advances. These include the International Thermonucler Experimental Reactor (ITER_ experiment in France, which is the first fusion experiment that will yield net energy for an extended period – mastering hot plasmas to the point when the total power produced by a fusion plasma surpasses the power injected to heat it.

The U.S. is one of 35 ITER partner countries and a strong supporter of the project, which will start operations in 2025 and passed the 70 percent construction mark this year. Berkeley Lab has participated in R&D in support of the ITER project, and in other concepts that have the potential to advance its performance, such as inertial fusion.

The ultimate goal of both private and public investment is to develop fusion into an economical, essentially inexhaustible source of clean, carbon-free electricity that is available at all hours.

Plasma research has yielded important discoveries that are already benefiting national defense, supporting high-tech manufacturing (such as computer chips, a field where Berkeley Lab has been very active in supporting the development of plasma-based light sources for high-resolution lithography), and helping to develop new cutting-edge materials.

“Plasma-based accelerators and photon sources, driven by a new generation of high-repetition-rate lasers, represent an exciting and timely opportunity that was identified in the report,” noted Geddes.

To explore further…

Powering the Future: Fusion & Plasmas,” Fusion Energy Sciences Advisory Committee report, Feb. 10, 2021


Testing of Niobium-Tin Superconducting Undulator Underway at Argonne

— Predictive quench protection was among Berkeley Lab contributions

Based on a news release by Andre Salles, Argonne National Laboratory

After more than 15 years of work, scientists at three DOE national laboratories have succeeded in creating and testing an advanced, more powerful superconducting magnet made of niobium and tin for use in the next generation of light sources.

The joint ATAP/Engineering Division Berkeley Center for Magnet Technology (BCMT) played important roles. The foundations of the effort build on earlier work by BCMT’s Soren Prestemon, Diego Arbelaez, and colleagues in the use of Nb3Sn in accelerator magnets and in superconducting undulator technology (for technical details, see for example this article in the International Committee for Future Accelerators Beam Dynamics Newsletter). In this project, a team led by Diego Arbelaez designed a state-of-the-art system that uses advanced computing techniques to detect quenches, or sudden transitions out of superconductivity, and protect the magnet.

Nb3Sn undulator prototype

This half-meter-long prototype of a niobium-tin superconducting undulator magnet was designed and built by a team from three U.S. Department of Energy national laboratories. The next step will be to build a meter-long version and install it at the Advanced Photon Source at Argonne. (ANL/Ibrahim Kesgin)

With a powerful enough light, you can see things that people once thought would be impossible. Large-scale light source facilities generate that powerful light, and scientists use it to create more durable materials, build more efficient batteries and computers, and learn more about the natural world.

When it comes to building these massive facilities, space is money. If you can get higher-energy beams of light out of smaller devices, you can save millions on construction costs. Add to that the chance to significantly improve the capabilities of existing light sources, and you have the motivation behind a project that has brought scientists at three U.S. Department of Energy (DOE) national laboratories together.

“If you reduce the size of the device you reduce the size of the tunnel, and if you can do that you can save tens of millions of dollars. That makes a huge difference.”
— Efim Gluskin, Argonne Distinguished Fellow

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This team has just achieved an important milestone that has been in the works for more than 15 years: they have designed, built and fully tested a new state-of-the-art half-meter-long prototype magnet that meets the requirements for use in existing and future light source facilities.

The next step, according to Efim Gluskin, a Distinguished Fellow at DOE’s Argonne National Laboratory, is to scale this prototype up, build one that is more than a meter long, and install it at the Advanced Photon Source (APS), a DOE Office of Science user facility at Argonne. But while these magnets will be compatible with light sources like the APS, the real investment here, he said, is in the next generation of facilities that have not yet been built.

“The real scale of this technology is for future free-electron laser facilities,” Gluskin said. “If you reduce the size of the device, you reduce the size of the tunnel, and if you can do that you can save tens of millions of dollars. That makes a huge difference.”

That long-term goal brought Gluskin and his Argonne colleagues into collaboration with scientists from Lawrence Berkeley National Laboratory and Fermi National Accelerator Laboratory, both DOE labs. Each lab has been pursuing superconducting technology for decades, and has in recent years focused research and development efforts on an alloy that combines niobium with tin.

This material remains in a superconducting state — meaning it offers no resistance to the current running through it — even as it generates high magnetic fields, which makes it perfect for building what are called undulator magnets. Light sources like the APS generate beams of photons (particles of light) by siphoning off the energy given off by electrons as they circulate inside a storage ring. The undulator magnets are the devices that convert that energy to light, and the higher a magnetic field you can generate with them, the more photons you can create from the same size device.

There are a few superconducting undulator magnets installed at the APS now, but they are made of a niobium-titanium alloy, which for decades has been the standard. According to Soren Prestemon, senior scientist at Berkeley Lab, niobium-titanium superconductors are good for lower magnetic fields — they stop being superconducting at around 10 Tesla. (That’s about 8,000 times stronger than your typical refrigerator magnet.)

Niobium-3 tin is a more complicated material,” Prestemon said, ​but it is capable of transporting current at a higher field. It is superconductive up to 23 Tesla, and at lower fields it can carry three times the current as niobium-titanium. These magnets are kept cold at 4.2 Kelvin, which is about –450 degrees Fahrenheit, to keep them superconducting.”

Prestemon has been at the forefront of Berkeley’s niobium-3 tin research program, which began back in the 1980s. The new design developed at Argonne built off of the previous work of Prestemon and his colleagues.

This is the first niobium-3 tin undulator that has both met the design current specifications and been fully tested in terms of magnetic field quality for beam transport,” he said.

Fermilab started working with this material in the 1990s, according to Sasha Zlobin, who initiated and led the niobium-3 tin magnet program there. Fermilab’s niobium-3 tin program has centered on superconducting magnets for particle accelerators, like the Large Hadron Collider at CERN in Switzerland and the upcoming PIP-II linear accelerator, to be built on the Fermilab site.

We’ve demonstrated success with our high-field niobium-3 tin magnets,” Zlobin said. ​We can apply that knowledge to superconducting undulators based on this superconductor.”

Part of the process, according to the team, has been learning how to avoid premature quenches in the magnets as they approach the desired level of magnetic field. When the magnets lose their ability to conduct current without resistance, the resulting backlash is called a quench, and it eliminates the magnetic field and can damage the magnet itself.

The team will report in IEEE Transactions on Applied Superconductivity that their new device accommodates nearly twice the amount of current with a higher magnetic field than the niobium-titanium superconducting undulators currently in place at the APS.

The project drew on Argonne’s experience building and operating superconducting undulators and Berkeley and Fermilab’s knowledge of niobium-3 tin. Fermilab helped to guide the process, advising on the selection of superconducting wire and sharing recent developments in their technology. Berkeley designed a state-of-the-art system that uses advanced computing techniques to detect quenches and protect the magnet.

At Argonne, the prototype was designed, fabricated, assembled and tested by a group of engineers and technicians under the guidance of Project Manager Ibrahim Kesgin, with contributions in the design, construction and testing by members of the APS superconducting undulator team led by Yury Ivanyushenkov.

Co-authors on the paper include Matt Kasa, Steve MacDonald and Quentin Hasse from Argonne; Emanuela Barzi and Daniele Turrioni from Fermilab; and Diego Arbelaez from Berkeley Lab.

The research team plans to install their full-sized prototype, which should be finished next year, at Sector 1 of the APS, which makes use of higher-energy photon beams to peer through thicker samples of material. This will be a proving ground for the device, showing that it can operate at design specifications in a working light source. But the eye, Gluskin says, is on transferring both technologies, niobium titanium and niobium-3 tin, to industrial partners and manufacturing these devices for future high-energy light source facilities.

The key has been steady and persistent work, supported by the labs and DOE research and development funds,” Gluskin said. ​It has been incremental progress, step by step, to get to this point.”

ATAP’s Bernhard Ludewigt Named in Secretary of Energy’s Achievement Award

— Member of team studying nondestructive assay of spent fuel

Bernhard Ludewigt

Bernhard Ludewigt of ATAP’s Ion Beam Technology Program is part of a team that won a Secretary of Energy’s Achievement Award for work on nondestructive assay of spent nuclear fuel in support of nuclear safeguards and nonproliferation.

The awards formally recognize the outstanding achievements of individuals and teams who have gone above and beyond in fulfilling the Department’s mission and serving the Nation, and are bestowed upon groups or teams of DOE employees and contractors who together accomplished significant achievements on behalf of the Department. Twenty-four teams were honored in this manner in 2020.

The award was given to the Spent Fuel Nondestructive Assay (NDA) Project Team. The 57-member team, led by Holly Trellue of Lawrence Livermore National Laboratory, drew upon experts at eight of the DOE national laboratories.

Bernhard’s contributions included the investigation of neutron generators and their application to nondestructive assay, as well as a study, “Nuclear Resonance Fluorescence for Pu Mass Determination in Spent Fuel,” conducted jointly with Brian Quiter, deputy head of the Applied Nuclear Physics Program in the Lab’s Nuclear Science Division. Bernhard also engaged in a delayed-gamma study, with colleagues from Pacific Northwest National Laboratory and Lawrence Livermore National Laboratory, that he later headed as a separate project.

In recognition of the successful completion of the Spent Fuel Nondestructive Assay (NDA) Project. A grand challenge in the safeguarding of nuclear material is characterizing commercial spent fuel assemblies. These assemblies are not only extremely radioactive and require large instrumentation to handle, but they are also associated with complex operating histories. The multi-Laboratory Spent Fuel NDA Team, together with international partners, made key technical and programmatic contributions to this important nuclear safeguards challenge by researching 14 possible techniques, then building, field testing, and analyzing results from a series of major nondestructive assay instruments through measurement campaigns at foreign partner facilities. Results from this project greatly improved previous technical understanding of the viability of various neutron and gamma measurement approaches for characterizing properties of Light Water Reactor spent fuel for nuclear safeguards purposes. The team successfully completed this extremely challenging nonproliferation effort because of their innovative thinking, complementary technical skills, on-the-spot problem solving, and exceptional dedication.

Advanced Accelerator Concepts Workshop Seminar Series is a Virtual Success

AAC Seminar Series logo and Web header

Fostering online exchange in advanced accelerators

When the 2020 Advanced Accelerator Concepts Workshop, which was being put together by the Berkeley Lab Laser Accelerator Center, had to be cancelled due to the pandemic, its organizers set up the virtual Advanced Accelerator Concepts Seminar Series.

The Seminar Series consisted of nine half-day sessions on Wednesday mornings, November 18 through February 3, with holiday breaks. The first session gave an introduction to the format, followed by deep-dive tutorials, and attracted 390 participants. After that, a topical session was devoted to each of the eight AAC eight working groups.

Several sessions were shared on Twitter and LinkedIn by Axel Huebl of ATAP’s Accelerator Modeling Program as well.

There were a lot of excellent talks, and I’d like to thank the organizers and the Working Group leaders. I think everyone did a great job — and all the participants,” said general chair Eric Esarey. “Hopefully for the next AAC we can all get together in person.”

Videos of the oral sessions, as well as posters, are available at


Welcome to 3Q4, in which we put three questions to someone from our staff to help get to know the people behind the science. In this issue, we meet Marlene Turner, a BELLA Center postdoctoral researcher, as well as Simon Leemann, a staff scientist in the Advanced Light Source Accelerator Physics Program.

Marlene Turner

Marlene Turner

A personal and technical journey from car projects and robot battles to laser plasma accelerators

With interests rooted in both particle physics and accelerator science and technology, Marlene is a postdoctoral scholar with ATAP’s Berkeley Lab Laser Accelerator Center (BELLA). A native of Austria, she earned a master’s degree in engineering physics and applied physics at the Technical University of Graz.

Her relationship with CERN began with summer internships and eventually became a PhD program. Her interests turned toward accelerator science and technology, and for her doctoral studies, she worked on AWAKE, their proton-driven plasma wake acceleration experiment.

Marlene won a student-poster prize at the 2016 North American Particle Accelerator Conference, and was also chosen to represent her US Particle Accelerator School class with a talk about their class project — a concept for a light source based on a compact storage ring with a laser-plasma accelerator injector.

In 2019 she was selected for the Laser-Plasma Accelerator Workshop’s John Dawson Thesis Prize, which honors the best doctoral dissertations in their field, as well as the Viktor-Hess Thesis Prize of the Austrian Physical Society.

“The key ingredients are passion and the motivation to do something. I believe that if you have that, there’s nothing that can stop you.”

How did you get interested in accelerator physics?
I started out at CERN doing data analysis for one of the detector collaborations, but I was always more oriented toward the technical side and became more interested in the accelerator itself. I used to work in conventional accelerators, designing and building beamlines. but for a PhD you want something that’s research oriented and new, so I was attracted toward their plasma wakefield concepts.

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After I finished my PhD, a second segment of our experimental work began, and I really enjoyed the work and was well integrated into the team, so I stayed on for a bit more than a year after graduation because I didn’t want to leave the experiment while it was running.

At CERN, instead of big laser systems, we used proton bunches to excite the plasma wakefields. I thought it would be good to have a postdoc that was similar but not the same, so I could make use of the experience but broaden my horizons. So I decided to come to BELLA, where we do similar physics but in a different way.

My interests include both particle physics and accelerator technology, and working on the BELLA petawatt laser and the staging experiments, I feel that I’m really in the mainstream of the long-term goals of BELLA. It’s no secret why I wanted to come here, and for me it’s really the perfect match, staying true to what I wanted to have a career in, and also pushing myself to learn about lasers as well as particle accelerators.

How do you do team science when it’s so hard to get the team together during the pandemic?

Of course, we went virtual, like everybody. Since June, with the Lab’s phased re-opening I’ve had the possibility to go back to the Lab, but it’s a lot different when you can have the whole team together rather than being almost alone. We’ve had to learn how to work effectively together without physically being together. That involves a lot of Zoom, headphones, and cameras to make the people who can’t be at the Lab feel they’re there.

It isn’t what I would have ever chosen, but I must say I am learning a lot because I have the opportunity to do everything, under the guidance of the experts who otherwise would have done it themselves.

It’s a challenge to overcome, but as scientists, all our work is overcoming challenges, isn’t it? A career path in science involves building things that we don’t know how to build, and being flexible when we encounter obstacles. Our challenges with COVID and with accelerator physics really draw on the same qualities.

A lot of the things we’re trying to do in advanced accelerators, nobody knows if they can be done, but that’s our job, right? — to try, and to seek. Once we show that it can be done, making it work every time is another important job, but to me, pushing forward to that first demonstration is the beauty of what we do.

What inspired you to go into science, and what advice would you give?

I grew up in a very technical family, where we always fixed things ourselves, always built things. My dad bought broken cars and we used to repair them together. One of my favorite things that we did together was building “killer robots.” It may not be necessary, but it’s a background that inspired me to do technical work, and gave me the confidence that I can do it. I even wanted to be a car mechanic, but I was also very good at school, and my father insisted that I go to university.

I didn’t really have anybody who pushed me into accelerator physics, but accelerators are just a big toy to play with! We build them, we use them, we improve them… I saw accelerator people, how they work, how exciting it is when things finally work, and I said, “Yeah, I want to do the same.”

I really like seeing more women getting into the field. It’s important to have more diversity, to be more open, to be more inclusive. All my career, I haven’t exactly been surrounded by a lot of women, let’s say it like that. There’s still work to do, and I’d like to see more of it, to really see it become normal, but I’m happy to see that at least the acknowledgment that it needs to be done is there now.

I think it’s very good that here at the Lab, these things are acknowledged and discussed. Being here, I feel like I fit in, and it’s a very good opportunity to make things better.

I definitely had people in my life who supported me in the choices that I made, and when you feel you can’t do something, that’s what you go back to. The key ingredients are passion and the motivation to do something. I believe that if you have that, there’s nothing that can stop you.


Simon Leemann

Back home and onward to the future

After working on several advanced electron accelerators around the world, Bay Area native Simon Leemann came back home in 2017. He now serves as Deputy for Accelerator Operations and Development at Berkeley Lab’s Advanced Light Source, where ATAP provides the accelerator-physics team.

Most recently his interests have turned to applying machine learning to stabilizing beams at the ALS, then to incorporating these techniques in to the design process for future accelerators.

Join us for three questions drawn from a wide-ranging discussion of how a colleague with enthusiasm for a new idea can send you in a promising direction, how artificial intelligence will transform work, and the value of cultural and intellectual diversity…

“It’s always enriching to have someone come into the group from outside and make you realize, ‘There’s a very different way of looking at this problem.’”

Machine learning is one of the hot new tools in accelerators and many other areas. How did you get involved?
It’s funny how I pretty much stumbled into it. In our group, Hiroshi Nishimura had been telling us about it, and showed us examples of how it could be used to predict things. After a while, we realized how this could be used to anticipate problems and correct them before they occur.

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Hiroshi and I had been working on the same topic for many years (unbeknownst to him). He was the original author of the Tracy tracking code, which I had been using since the early 2000s to do tracking studies. We also had a mutual friend in Etienne Forest, who had also been in AFRD [ATAP’s predecessor, the Accelerator and Fusion Research Division] and is now with KEK in Japan.

So while we had never actually met or talked, our work had been closely related all along. When I came to Berkeley, we had a lot of catching up to do! It was natural for us to hit it off here and start collaborating on something new and different. He was so enthusiastic about the idea that I figured, “why not give it a try?”

To be perfectly honest with you, I was a bit skeptical at first, but it turns out that machine learning isn’t really some kind of magical black box — you can learn how the box works, and understand why in some cases it works and in other cases it doesn’t. It’s not the way we’re used to attacking a problem — by taking a physics model, putting data in and getting a prediction. Now, all of a sudden, the model is the output! Automation development kind of pushes us into a different corner. Instead of doing the tasks, we’re going to be designing the machine that does the tasks. But it still takes a lot of human ingenuity to do these kinds of experiments.

So where do you go with it from here?
The first thing that we did with machine learning at the ALS, and which turned out to quite successful, was heavily based in operations and was rather specific to the ALS — not necessarily something that you could just use anywhere. But we also wanted to follow a more theoretical idea and see if we could use these kinds of tools to assist us in design, so something we’ve been looking at ever since is how we might incorporate machine learning into the design workflow behind a machine like ALS-U.

ALS-U by then had already gone through the design process, so now we’re trying to replicate those results, using a modified tool set that hopefully runs a lot faster and makes it easier for people to find new solutions and makes the whole process more robust. Going forward, another thing I like a lot about this is that the predictive capability allows you to react to something before it actually happens. Hopefully a lot of the things we currently do in accelerators using feedback can be replaced with feedforward. This is very attractive because feedbacks are tricky. They have to be tuned and are geared toward specific modes of operation. Feedforward gets rid of all that and fixes something before it becomes a problem.

You’re a California native. What brought you back to Berkeley?
I was born in Oakland and grew up in Walnut Creek, but then was gone for a long time, so this was like coming back to a lot of childhood memories.

My parents immigrated to the United States from Europe and ended up going back there. I finished high school over there. I missed California a lot (especially the weather!) but the prospect of going to a really great college for what amounts to $1500 a year tuition was kind of a no-brainer. I went to ETH in Zurich and graduated just as the Swiss Light Source was coming up, so that got me hooked on accelerator science at a really exciting time.

Family tradition

Simon is a second-generation ATAP accelerator physicist. His father, Beat T. Leemann, was an accelerator physicist with AFRD, working primarily with the Bevalac and later contributing to the design of the Superconducting Super Collider.

Simon’s uncle, Christoph Leemann, was deputy leader of AFRD’s Advanced Accelerator Studies Group. He left in 1985 to join the Continuous Electron Beam Accelerator Facility, as Jefferson Lab was originally known, and was appointed Laboratory Director there in 2006.

After I did a postdoc in the free-electron laser world, I went to work at MAX-Lab in Sweden, where they were building a brand-new fourth-generation storage ring. Once again, that was a really great time — it was the first machine being designed using this new multibend achromat paradigm (which is also a key enabling technology for ALS-U). Being around for that design and commissioning, it was a really great time, and I consider myself tremendously lucky to have hit that window in time.

Several aspects of the Swiss Light Source drew upon experience gained with the ALS, and benefitted from contacts with several of its key people, so quite often, when you wanted to understand how or why something at SLS had been done in a certain way, you’d end up learning about the ALS.

I also met both Dave Robin and John Byrd that way. Dave, of course, is still here at Berkeley Lab as Project Director of ALS-U, and John moved to Argonne to be Accelerator Division director at the Advanced Photon Source, which like the ALS is planning a major upgrade. Anyway, after chatting with John for a while about harmonic cavities, he asked me where I was and what I was doing. After I answered, I remember how he then just blurted out, “Why don’t you come work for us?”. Still makes me laugh to this day. It took me a couple of years to take him up on that.

There aren’t that many large accelerators, so people in the field usually end up traveling around quite a bit. This turns out to be a really great thing. It’s always enriching to have someone come into the group from outside and make you realize, “There’s a very different way of looking at this problem.”

How are you doing all these team things under pandemic restrictions?
I have to say, it’s really difficult. I haven’t been to the Lab myself since March 16. A year ago I would have said, “We can’t work like that,” but I’m just constantly in contact with people, having all these discussions.

I love sitting in the control room or down at the equipment racks with actual people and looking at things and having face-to-face discussions. That said, it’s surprising how well remote operations have worked, and part of it is because people are trying really hard. I think a lot of us realize that it’s a difficult time, take that into account, and make a real effort to act accordingly — give everybody the benefit of the doubt and realize that they’re all trying to do their best.

It’s mind-boggling how mundane these tools have become to us. It’s become completely normal, but had we faced this pandemic just 20 years ago, it would have been a different story. That’s something to be grateful for.


Injection Source: An Accelerator Physicist on the Front Lines of the Pandemic

Ina Reichel administers vaccine to first responder

First dose for a first responder: Reichel at an MRC vaccination clinic

Berkeley Lab employees have found a number of ways of combatting COVID-19, including research. ATAP Outreach and Education Coordinator Ina Reichel, a licensed Emergency Medical Technician (EMT), takes a more direct approach.

Ina volunteers with the Contra Costa County Medical Reserve Corps (MRC), which has been running COVID vaccine clinics for specific high-priority groups in the county. Reichel assisted with these clinics through Contra Costa Fire by serving as one of the EMTs observing people after they have received the vaccine in case of adverse reactions, a very small but existent possibility.

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Ina has recently begun volunteering in MRC’s vaccination program for residents and staff at elder care facilities.

“Many people are complaining about the slow roll-out of the vaccine, but seeing the number of people it takes has really been an eye-opener,” says Reichel. “It’s more labor-intensive than a flu shot. The pre-screening involves about a dozen health questions, and we have to keep paperwork for the clinic and issue a vaccine card that includes the name of the vaccine, the lot number, the date, and the name of the clinic or health-care provider.” At Reichel’s first clinic, a team of 17 volunteers plus the person in charge of the MRC vaccinated some 350 people, at a 75 dose-per-hour pace during the busiest period. From late December through the end of January, the MRC provided around 1000 volunteer hours, administering 6000 doses.

The MRC in normal years provides between 1500 and 2000 volunteer hours, mostly by providing medical staff for emergency evacuation shelters during fire season, flu shot clinics in the fall, and some community outreach like teaching “Stop the Bleed” classes at high schools. As the pandemic unfolded in 2020, they began additional and expanded activities (approximately doubling their volunteer hours), both to get more people than usual vaccinated for the flu and to get more of their staff trained in running efficient, high throughput vaccine clinics.

Recently Ina has gone from monitoring vaccine recipients to administering the dose. In order to break through the personnel bottleneck involved in mass vaccination, Contra Costa County expanded their local operational scope of practice (LOSOP) so that EMTs, paramedics and dentists (with proper training and supervision) could administer the vaccine.

And on the receiving end…
Volunteering as an EMT with direct patient contact put Ina in Phase 1a for the COVID-19 vaccine, so she has already received both doses. Her personal experience corroborates the emerging understanding that the side effects (mostly flu-like symptoms and pain at the injection site) are worse after the second dose. She suggests assuming that you may need to take a sick day following your second dose.

IDEA In Action: Upgrading from Bystander to Upstander

Graphic of people talking

Resources online

The Lab has a wide variety of resources on how to become an “Upstander:” someone who not only recognizes when something is wrong, but knows what to do about it. Learning how to intervene positively and respectfully is a great step in fostering the A in IDEA (Inclusiveness, Diversity, Equity, and Accountability).

As the IDEAs In Action website puts it, through active listening and standing up for ourselves and others when needed, colleagues can learn the skills to help create a happier, healthier laboratory — not just the right thing to do, but a positive step toward stronger teams at the home of team science.

Some Readings for Black History Month

As February comes to an end, you can carry the learning experience forward with these curated recommendations offered by ATAP staff:

•  Citizen — An American Lyric by Claudia Rankine. “Rankin’s book is a stunning compilation of poems, prose poems/essays and imagery that reflect on the American experience, on race, hurt and beauty.”

•  The Warmth of Other Suns: The Epic Story of America’s Great Migration by Isabelle Wilkerson.

•  The Street. “A novel by Ann Petry, written in 1946, it describes social issues that are still very relevant.”

•  Born a Crime: Stories from a South African Childhood by Trevor Noah. “Entertaining and educational.”

•  Sign My Name to Freedom: A Memoir of a Pioneering Life by Betty Reid Soskin. “Among the many other achievements of her 99 remarkable years and still counting, Soskin is America’s oldest National Park Service Ranger. She works at the Rosie the Riveter WWII Home Front National Historic Park in Richmond, California, which she had been instrumental in helping to establish.”

Bay Area places to read about now, and visit when they re-open:

•  Port Chicago Naval Magazine.

•  Exhibits about the Buffalo Soldiers at Fort Point National Historical Site.

AAERG, the Berkeley Lab African American Employee Resource Group, has many other resources, as does the Berkeley Lab IDEA site.



Happy 90th Birthday to Berkeley Lab, With Many More to Come!

Berkeley Lab 90th logo

It was 90 years ago when Ernest Orlando Lawrence, who had recently invented the cyclotron, founded his “Radiation Laboratory” on the University of California, Berkeley campus. These were the seminal events in what would become Berkeley Lab — a pioneer in both the US national laboratory system and the transformative concept of team science.

Join us throughout the year as the Laboratory celebrates those past 90 years and looks forward to The Next 90. An interactive website, social-media feeds, a podcast series, and monthly talks are among the ways you can learn more about where we came from and where we hope to go.

Nuclear Science Day for Scouts Goes Virtual; Volunteers Wanted

Warren Byrne at Nuclear Science Day for Scouts

At a previous Nuclear Science Day for Scouts, ATAP’s Warren Byrne, top left, explains the ALS Upgrade project. At right is a portrait of Laboratory founder Ernest Orlando Lawrence holding one of the first working cyclotrons. (Accelerators are considered nuclear facilities for merit-badge purposes.)

The Lab’s 10th annual Nuclear Science Day for Scouts takes place Saturday, Feb. 27. This virtual event is designed for Girl Scouts and Boy Scouts to learn about nuclear science. Volunteers are needed to help with hosting of activities, grading worksheets, and supporting Zoom logistics.

Nuclear Science Day for Scouts is a perennially popular outreach and education tradition at the Lab. At the last pre-pandemic event in 2019, some 180 Scouts from across California visited the Lab to learn about nuclear science, including related career possibilities, which fulfilled one of the requirements for a merit badge.

The event is sponsored by the Nuclear Science Division, ATAP, the Advanced Light Source, and the Government and Community Relations Office. The signup sheet has more information on this year’s virtual volunteer opportunities.


Please see the Publications tab of this website for a complete listing.

S. Diederichs (University of Hamburg and LBNL); C. Benedetti, E. Esarey (LBNL); J. Osterhoff (DESY); C.B. Schroeder (LBNL), “High-Quality Positron Acceleration in Beam-Driven Plasma Accelerators,” Physical Review Accelerators and Beams 23, 121301 (3 December 2020),

Nikola Maksimovic, Ian M. Hayes, Vikram Nagarajan, James G. Analytis (University of California, Berkeley and LBNL); Alexei E. Koshelev (ANL); John Singleton (LANL); Yeonbae Lee and Thomas Schenkel (LBNL), “Magnetoresistance Scaling and the Origin of H-Linear Resistivity in BaFe2(As1−xPx)2,” Physical Review X 10, 041062 (29 December 2020),

J. Park, J.H. Bin, S. Steinke, Q. Ji, S.S. Bulanov, M. Thevenet, J.-L. Vay, T. Schenkel, C.G.R. Geddes, C.B. Schroeder, E. Esarey, “Target normal sheath acceleration with a large laser focal diameter,” Physics of Plasmas 27, 123104 (21 December 2020),

V. Ranjan (CEA Saclay; J. O’Sullivan (University College London); E. Albertinale, B. Albanese (CEA Saclay); T. Chanelière (Université Grenoble Alpes); T. Schenkel (LBNL); D. Vion, D. Esteve, E. Flurin (CEA Saclay); J.J.L. Morton (University College London); and P. Bertet (CEA Saclay), “Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms,” Physical Review Letters 125, 210505 (20 November 2020),

D. Rohrbach, Z. Ollmann, M. Hayati (University of Bern); C.B. Schroeder (LBNL); W.P. Leemans, T. Feurer (DESY), “THz-driven split ring resonator undulator,” Physical Review Accelerators and Beams 24, 010703 (28 January 2021), 10.1103/PhysRevAccelBeams.24.010703

J.-L. Vay, A. Huebl, A. Almgren, L.D. Amorim, J. Bell (LBNL); L. Fedeli (CEA Saclay); L. Ge (SLAC); K. Gott (LBNL); D.P. Grote (LLNL); M. Hogan (SLAC); R. Jambunathan, R. Lehe, A. Myers (LBNL); C. Ng (SLAC); M. Rowan, O. Shapoval (LBNL); M. Thévenet (DESY); H. Vincenti (CEA Saclay); E. Yang (LBNL); N. Zaïm (CEA Saclay); W. Zhang, Y. Zhao, and E. Zoni (LBNL), “Modeling of a chain of three plasma accelerator stages with the WarpX electromagnetic PIC code on GPUs,” Physics of Plasmas 28, 2, 10.1063/5.0028512, Special Collection: Building the Bridge to Exascale Computing: Applications and Opportunities for Plasma Science (9 February 2021),


A look around public spaces shows a lot of people wearing masks, as they should… but not everyone is wearing them properly. It’s especially important now that more-contagious strains of the virus are in circulation. A good fit is key to protecting yourself and others. The essence of a good fit: air passes in and out through the mask, not around the sides or past the nose.

A mask should fit securely over both mouth and nose… and be protected from contamination when not being worn.

Great information on the subject is available on the Berkeley Lab EH&S COVID-19 website, under “Face Coverings and Respirators.”

This is no time to let our guard down, so close to the goal line! Diligence regarding these simple precautions will get us through this and into the era of widespread vaccine deployment.

For more information on how Berkeley Lab is prioritizing health and safety, and tips on what you can do to keep yourself and others safe from COVID-19, visit The State of California and the Centers for Disease Control and Prevention also have great information on how to stop the spread, including mask selection and use.

PPE: It Isn’t Just For COVID

It’s all too easy for familiarity to turn into complacency or neglect with regard to personal protective equipment requirements when working in labs and shops — and under conditions of social distancing and reduced staffing, we might not get the reminders we usually would. Let’s take a moment to remember that PPE and observance of safety rules is all the more important in pandemic times … and spare a glance to make sure our co-workers are taking precautions appropriate to the hazards.

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