Recently, the injector for the Linear Coherent Light Source (LCLS-II) at SLAC completed the formal transition to operations. The source had been developed in collaboration between Berkeley Lab and SLAC

Honors for our employees in 2019 included the election of Ji Qiang as the 29th Fellow of the American Physical Society in our Division’s history; the US Particle Accelerator School Prize for Cameron Geddes; and Berkeley Lab Director’s Awards for Eric Esarey (Scientific Achievement), Ian Pong (Scientific Achievement, Early Career), and Martha Condon (Service).

We communicated our results as lead or co-authors in 26 articles in the refereed literature and another 25 in conference proceedings and other unrefereed publications during fiscal 2019, including 9 articles in Physical Review journals, 4 Physical Review Letters, one in Nature, and a Nature Scientific Reports article. ATAP personnel were on the teaching teams for two US Particle Accelerator School courses and gave three CERN Accelerator School lectures.

Autumn brought us extremes of hot, dry winds and a pair of Public Safety Power Shutdowns by our electric utility. Among the literally hundreds of people who kept us safe and well-informed during these shutdowns of our main site and the methodical re-energization afterward were our Deputy Division Director for Operations, Asmita Patel, and EH&S Coordinator, Pat Thomas. All in all we handled the outages with the cooperation, selflessness, and team spirit that make Berkeley Lab the leader that it is.

I feel honored and humbled to look back on what we accomplished this year, and look forward to moving ahead strongly with new projects and initiatives in 2020.

Here, for the first time, researchers have demonstrated that a neural network (a computerized pattern-recognition algorithm) can learn to predict the beam size during regular operation, given sufficient data about how ID configurations affect the beam. The predictions can then be used to neutralize beam perturbations before they occur (“feed-forward” vs. feedback correction), achieving an order-of-magnitude improvement in stability that fulfills the requirements for future light sources. Their work is described in S.C. Leemann, S. Liu, A. Hexemer, M.A. Marcus, C.N. Melton, H. Nishimura, and C. Sun, “Demonstration of machine learning-based model-independent stabilization of source properties in synchrotron light sources,” Physical Review Letters 123, 194801 (2019).

How to train your synchrotron

Vertical beam size (red) greatly improves when stabilization is on (yellow area). Blue trace is the parameter that is tuned to cancel out fluctuations.

Machine learning fundamentally requires two things: a reproducible problem and huge amounts of data. In this study, researchers fed electron-beam data from the ALS, including the positions of the IDs and the blips in electron-beam performance caused by ID adjustments, into a neural network. The algorithm was then able to learn the complex nonlinear relationships between the ID settings and vertical beam size and make corrections to negate the blips. The vertical beam size was stabilized to within 0.2 µm, or 0.4% of the beam size, compared to 2–3% without correction. The system is also fast: it can make corrections up to 10 times per second, although three times per second appears to be adequate for improving performance at this stage.

One key advantage of this approach is that data acquisition for retraining the neural network can be carried out continuously, even while the feed-forward system is active during a regular user run. Continuous retraining allows the neural network to constantly adapt to a drifting machine and changes in ID configurations during run periods, independent of static physics models.

Future-ready, steady light beams

Because the size of the electron beam mirrors the resulting light beam, this correction scheme also optimizes the light reaching beamline endstations. To demonstrate this, the researchers observed the effects of the algorithm on scanning transmission x-ray microscopy (STXM) images taken at Beamline 5.3.2.2. Highly sensitive to low-frequency variations in light intensity, STXM scans will exhibit banding in response to ID motion elsewhere in the ring. With the neural-network correction on, the bands disappeared.

Banding that appears in STXM images during ID motion (left) disappears after neural-network (NN) stabilization is turned on (right).

Changchun Sun (from left), Hiroshi Nishimura, Simon C. Leemann, C. Nathan Melton, Alex Hexemer, and Y. Lu in the ALS control room. The team successfully demonstrated how machine-learning tools can improve the stability of photon-beam size via adjustments that largely cancel out problematic fluctuations — from a level of a few percent to 0.4 percent, with sub-micron precision.

This enhanced performance is also well suited for advanced x-ray techniques such as ptychography, which can resolve the structure of samples down to the level of nanometers, and x-ray photon correlation spectroscopy (XPCS), which is useful for studying rapid changes in highly concentrated materials that don’t have a uniform structure.

The technique could generally be applied to other light sources and will be especially beneficial for specialized studies enabled by the ALS Upgrade (ALS-U) Project, which will have an even higher demand for consistent, reliable light-beam properties.

The Berkeley Lab workshop was organized into four Working Groups that focused on these topics:
(WG1) Single-particle dynamics, including nonlinearities, and spin dynamics. Conveners: S. Nagaitsev, L. Spentzouris, Y. Cai.
(WG2) High-brightness beam generation (including polarized beams), transport, manipulation and cooling. Conveners: J. Rosenzweig, P. Piot, A. Valishev
(WG3) Mitigation and control of collective phenomena: instabilities, space charge, beam-beam, beam-ion effects, wakefields, and coherent synchrotron radiation. Conveners: J. Power, Z. Huang, S. Cousineau
(WG4) Connections to other GARD roadmaps (cross-cutting WG1-3) [Conveners: J.-L. Vay, M. Conde, M. Hogan]

The upcoming Chicago-area workshop will emphasize four different topics:
(WG1) Advanced accelerator instrumentation and controls.
(WG2) Modeling and simulation tools (including energy deposition); fundamental theory and applied math.
(WG3) Early conceptual integration and optimization, maturity evaluation
(WG4) Connections to other GARD roadmaps; synergies with non-HEP

Jean-Luc Vay, head of ATAP’s Accelerator Modeling Program, organized the Workshop with the help of the ATAP operations team.

Senior Staff Scientist Eric Esarey, director of ATAP’s Berkeley Lab Laser Accelerator Center (BELLA), was honored in the Scientific category.

His focus is on understanding the fundamental principles of intense laser interactions with beams and plasmas, and on developing practical accelerators and radiation sources that rely on these principles. The laser-plasma accelerator (LPA) work at BELLA is among the most exciting frontiers of accelerator science; with the ability to generate gigavolts-in-centimeters accelerating gradients, LPAs offer the potential to reduce the size of future colliders for high-energy physics by orders of magnitude.

Nearer-term applications for these compact machines are already being explored, including compact accelerators for basic science, medicine, and defense, as well as drivers for future light sources, such as x-ray free-electron lasers.

Eric was one of the principal founders of this world-leading center. One of BELLA’s strengths is its integration of theory and computer modeling with experiment, and Eric has led the understanding of LPA physics and adjacent phenomena.

“We have had a big impact on each other’s careers,” writes Gérard Mourou, 2018 Nobel laureate in physics as co-developer of a revolutionary laser technique called chirped-pulse amplification or CPA. Mourou describes Eric as “a true pioneer in the field of laser-plasma accelerators” and goes on to call him “the world’s leading theorist on intense laser interactions with underdense plasmas {…} responsible for many of the key concepts and developments for laser-plasma accelerators and their applications.”

This expertise has been expressed in more than 220 refereed papers, including some considered landmarks in their field, and more than 100 invited and plenary talks at major international conferences. Eric is serving as general chair of the upcoming LBNL-hosted 2020 Advanced Accelerator Concepts Workshop.

Eric is also known as a mentor of colleagues at all levels from graduate students and postdocs through senior scientific staff. Virtually every member of the BELLA Center since 1998 has benefitted from his guidance, including over two dozen students, several who went on to full-time staff positions here.

Ian Pong, Scientific (Early Career)
“For technical and managerial excellence in pushing Nb₃Sn superconductors and cables toward their performance limits in support of high-energy physics colliders and fusion-energy facilities through the U.S. Magnet Development Program and U.S. High-Luminosity LHC Accelerator Upgrade Project.”

Research scientist Ian Pong was recognized in the Scientific (Early Career) category.

The entire history of particle accelerators has been interwoven with the history of stronger, better, and more cost-effective magnets. Both as a technical expert in designing and applying an advanced superconductor called niobium-three-tin (Nb₃Sn) and as a team and collaboration leader, Ian has helped achieve Berkeley Lab and DOE priorities at the frontier of magnet technology.

Among these priorities is the ongoing luminosity upgrade of CERN’s Large Hadron Collider, the first significant use of Nb₃Sn in an accelerator. Another is the International Thermonuclear Experimental Reactor (ITER), the fusion-energy community’s flagship project, which will include the largest single Nb₃Sn procurement in history.

In addition to his work as the Control Account Manager for Cable Winding and Magnet Testing in the High-Luminosity LHC Accelerator Upgrade Project, Ian represented the Physical Sciences Area — the LBNL associate laboratory directorate that includes the ATAP Division — on the LBNL Project Management Advisory Board.

Not only technical excellence but also interpersonal and leadership skills are crucial for today’s interdisciplinary, multi-institutional, and international team science. In a Critical Decision 2/3b review of the HL-LHC AUP, Ian was singled out for the exemplary quality of his management and delivery of his scope of work, and a reviewer described him as the best example for other subsystem managers.

Ian’s expertise is regularly sought by other institutions, helping maintain LBNL’s leadership as a center for superconducting magnet technology. He has a wide network of collaborators, having co-authored peer-reviewed papers with over 110 colleagues from more than 40 institutes.

Ian has also attracted high quality young researchers to join his team. Serving as both a leader and a role model for younger scientists, he has mentored an entry-level scientist, a postdoctoral fellow, two mechanical technicians, 1 QA/QC technician and 16 students.

Martha Condon, Service
“In honor of exceptional and versatile service to the Laboratory over her four decade career as the lead administrator at the startup of multiple new and ongoing research programs in support of the DOE mission.”

An exemplar among the “hidden figures” who support our scientific excellence, ATAP Division Administrator Martha Condon has had a distinguished 39-year career in administrative support. Her achievements run the gamut from conference planning to property management, publications management, preparation of Building 71 for the BELLA Laser, facilitating complicated subcontracts with multiple institutions and businesses, assisting with the proposal process, and supervising/mentoring administrative staff.

She has supported the Division during several directorship transitions while also managing ongoing routine administrative functions, ensuring stewardship of resources and people. She has also been the startup administrator for multiple program and project launches.

Arranging and running events of all kinds and sizes, from small meetings to conferences, is another highlight among Martha’s diverse talents. Presently she is helping organize the 2020 Advanced Accelerator Concepts Workshop. She has also been an integral part of the logistical, planning, organization, and execution of our Safety Days, helping make them a success that in recent years has been joined and emulated by other Physical Sciences Divisions.

Deeply respected by scientific and operations staff within the Division and collaborating business partners across the laboratory, Martha’s award nomination elicited comments like “a treasure” with “superpowers”; “we just could not have done it without Martha’s tireless persistence and leadership
{…} everything worked without a hitch”; “I can’t begin to estimate the amount of administrative effort she has saved me and the Division staff by proactively solving a problem”; and “I knew we could rely on her for anything.”

If it was alive in our lifetime, it can probably be composted

Creating a diversion: Food scraps and paper plate, used paper towels (found in Other Recycling and Landfill bins, respectively) should have gone into Compost

One of the most common items we might divert from the landfill stream, according to Sustainable Berkeley Lab’s Brie Fulton, is paper that is food-soiled or otherwise unsuitable for the paper-recycling bins. Our compost ends up in an industrial-scale facility that can handle things your home compost heap couldn’t.

Unfortunately our composting vendor has concluded that they cannot handle plant-oil-based plastics, and of course metal and regular plastics don’t go in the compost, but almost any sort of food scraps or food-related paper goods, including paper cups and plates, are fair game. This will go a long way toward meeting the Lab’s goal of diverting 90% of waste from the landfill.

Clean paper or cardboard should go to their highest and best use via the paper-recycling bin.

Keeping it clean
When it comes to Other Recyclables, Fulton points out the usefulness of making sure our diverted materials can actually be recycled. Rinsing a yogurt cup or other food container before putting it in the recycling bin is an example. Such items don’t need re-use levels of cleanliness, but the less they are contaminated, the more readily they will find a market, and the less processing they will need.

The recyclability of plastics is a complicated issue. Signage at the receptacle, and the Waste Guide, show whether any particular plastic can go in the Other Recyclables bin or must be consigned to the landfill. Plastic films (plastic bags, cling/stretch wrap, candy wrappers, etc.) unfortunately must go into the landfill. (Consider alternatives to using them.) And styrofoam is not practical to recycle in our system (although clean packing peanuts can be re-used, so please put them in the special bin available in most mailrooms).

Meeting sustainability: simple measures with high-multiplier benefits
Meetings, workshops, and other gatherings of people unfamiliar with local customs, or just the locations of recycling bins, are often a low point for our waste-diversion goals. When planning a meeting, please consider talking with the custodians about recycling bins — and just as you might show a safety slide so that people unfamiliar with the area know what to do in an emergency, you might show a recycling slide to encourage attendees to find the right bin. (And please make sure handouts are really needed by your attendees and agenda.)

Is centralizing the key to better recycling?
The individual office trash can is another opportunity to improve our waste-diversion performance. For practical reasons, its contents are generally destined for the waste stream rather sorting, and Fulton has observed that its convenience causes things to end up in the landfill unnecessarily. Consider “kicking the can” and instead taking your items to the appropriate central bins.

Half the contents Fulton finds in under-desk bins are food scraps and soiled paper, both of which can usually be composted. Getting them out of your office and into the central bins also makes your office less attractive to rodents and insect pests (more on this in the article below), so that’s a win-win.

Reduce, re-use, recycle… in that order
The best way to handle waste is to avoid making it in the first place. Can you use the same paper coffee cup all day at a meeting, or perhaps bring a reusable mug? Is a product made of (and packaged in) reusable or easily recyclable materials, rather than single-use material destined for a landfill, competitive in performance and price? Saving the Earth is done with decisions and actions throughout the complete lifecycle of a product.

To learn more…
 • Explore the Sustainable Berkeley Lab website for in-depth information about how each of us can do great research with a lighter ecological footprint, and to learn what our waste-management professionals are doing behind the scenes. The Waste Guide is a great place to start.
 • Sustainability Program Manager Brie Fulton is available to give a talk to your group and to consult on waste prevention and management for both ongoing work and special events.