Berkeley Lab

ATAP News, April 2017


As accelerator physicists and engineers, we depend on instrumentation and controls as our eyes and hands by proxy: measuring things that we could not see even if it were safe to look; guiding and shaping things that we cannot touch. It all has to work rapidly and precisely without disturbing the exquisite beam properties that the users require.

To further this essential aspect of today’s accelerator facilities and tomorrow’s, we have organized the Berkeley Accelerator Controls and Instrumentation Center (BACI). Our goal is broadly applicable technology development that will benefit many types of machines throughout the DOE complex.

Another important aspect of many current and future projects is also in the news: advanced undulators. Just this week, SLAC received the first industrially produced soft-X-ray undulator modules for LCLS-II. A total of 21 of these LBNL-designed modules will be installed, followed by 32 of their hard-X-ray counterparts, which we are developing in collaboration with Argonne. Looking toward light sources of the future, we recently set a magnetic-field record for superconducting undulators. Read on for more details about these exciting areas of progress…


INTRODUCING BACI, THE BERKELEY ACCELERATOR CONTROLS AND INSTRUMENTATION CENTER


An incubator for concepts and technologies with wide-ranging benefits that serve LBNL, DOE, and beyond

As particle accelerators grow ever more powerful, and the needs of their scientific users become more subtle and precise, their instrumentation and control systems must become ever more sophisticated. Instrumentation is the “eyes and ears” of the control system that uses this input to manipulate the particle beam; the two go together and are often referred to as AC&I. ATAP’s new BACI Center serves as a central resource for expertise in these areas throughout the accelerator community.

BACI focuses on three areas of the accelerator controls and instrumentation field where Berkeley Lab has traditional strengths: advanced RF design and engineering; ultrahigh-precision controls; and high-dynamic-range beam instrumentation.

Many of the solutions to these problems are applicable to various kinds of accelerators of interest to different user communities — rings or linacs, protons/ions or electrons — so agency investments will yield wide-ranging benefits.

“At Berkeley Lab, we have a long tradition of integrating accelerator theory, modeling, experiment and technology development to advance new accelerators,” says Dr. John Byrd, who headed the former Center for Beam Physics and now will lead BACI. “Our goal here is focusing on new AC&I that will benefit the whole accelerator community, rather than being tied to specific projects.”

Projects and facilities have typically been developing their own instrumentation and controls, he explains, and in that world of schedules and deliverables, there are strong drivers to be technically conservative. BACI has more freedom to take risks in the name of advancing the state of the art, hoping to establish a basis of true next-generation AC&I concepts that individual projects can then build upon to meet their needs.

“This is an especially opportune juncture of maturing and emerging enabling technologies for AC&I, present and future projects that require improvements in this area, and the capabilities of Berkeley Lab,” says Fernando Sannibale, head of ATAP’s accelerator physics program for the Advanced Light Source and principal investigator of APEX, the Advanced Photoinjector Experiment, two key BACI efforts.

State-of-the-art AC&I built on deep foundations

BACI emerges from the Center for Beam Physics, which in turn grew from the Exploratory Studies Group under Swapan Chattopadhyay, and whose deepest roots go back to the 1970s and the beam cooling efforts under Glen Lambertson. Over the course of the years it has developed deep expertise in electron and ion acceleration, “RF gymnastics,” and timing, synchronization, and controls distribution, guided by the integration of theoretical, simulation and experimental tools. (The simulation and modeling aspects of the former Center for Beam Physics were organized late last year as the Accelerator Modeling Program.)

“We have established ourselves a partner of choice for many of the most demanding accelerator projects over the past two decades,” says ATAP Director Wim Leemans. The scientists and engineers who are now part of BACI have a record of success that includes the PEP-II B-factory at SLAC; the Spallation Neutron Source at Oak Ridge National Laboratory; LCLS and now LCLS-II at SLAC; and the PIP-II radiofrequency quadrupole linac at Fermilab. This engagement in a wide variety of projects, with partners throughout the DOE research complex and internationally, has developed a broad range of skills in RF, controls, and instrumentation at a wide variety of accelerators. “Now,” adds Leemans, “we’re combining these skills into a unique and cohesive program aligned with the needs of the Office of Science.”

BACI’s three areas of focus were selected because they are built upon existing LBNL expertise — world-leading in many cases — and stand to be of widespread benefit. Watch for more about them, and articles on their achievements, in future issues of this newsletter.

  • Advanced RF Design and Engineering
    • CW normal-conducting cavities and RF structures
    • RF measurement and characterization
    • Beam impedance modeling and measurement
  • Ultrahigh-Precision Controls
    • RF controls
    • Femtosecond synchronization
    • Controls for complex systems
  • High-Dynamic-Range Beam Instrumentation
    • Beam orbit feedback systems
    • Halo measurement and control

Advanced RF Design and Engineering

Radiofrequency (RF) design for accelerating, manipulating, and controlling beams is a longtime area of strength for BACI that integrates accelerator physics and engineering. Over the past three decades we have developed a number of demanding ion-accelerator “front ends,” including units for the Spallation Neutron Source and a recent radiofrequency-quadrupole linac for Fermilab’s PIP-II project.

Montage of BACI hardware
Click for larger version
A selection of RF structures built at Berkeley Lab over the past two decades illustrates capabilities in advanced RF for both electron and proton accelerators. Clockwise from upper left: A schematic of the APEX photocathode RF gun, which was selected as the LCLS-II injector; the PEP-II B-Factory main higher-order-mode-damped RF cavities; the Muon Ionization and Cooling Experiment (MICE) cavity with beryllium window; the Spallation Neutron Source (SNS) RFQ; the Relativistic Heavy Ion Collider (RHIC) Schottky cavity pickups; and the Advanced Light Source (ALS) harmonic cavity.

Studying and mitigating the deleterious effects of beam impedance — interaction of the fields of an intense beam with the vacuum chamber and accelerator components — is another of our longtime strengths.

In recent years Berkeley Lab has developed a unique capability in developing normal-conducting structures for continuous (CW) acceleration, hitherto the province of more-expensive superconducting cavities. Berkeley Lab has also become a leader in the design of broadband RF structures such as kickers for fast beam manipulation (key to upcoming projects such as ALS-U, the Advanced Light Source Upgrade), as well as in ultrafast sources of high-quality electron beams, vital to LCLS-II and already providing a spinoff application in the form of the HiRES tool for ultrafast electron diffraction.

Ultrahigh-Precision Controls

The stability of accelerators is in large part determined by the stability of the electromagnetic fields that accelerate and guide the beam. Berkeley Lab has become a center of excellence in low-level RF controls; building upon success with RF controls on behalf of the Spallation Neutron Source linac at Oak Ridge and then the FERMI@Elettra free-electron laser, we are now leading a multilab effort on this aspect of the LCLS-II project and looking forward to contributing to PIP-II, with its superconducting linac.

Another challenge is the synchronization of accelerators with lasers, which are used in many applications throughout modern accelerator complexes. We have applied our RF control approach to stabilizing mode-locked laser oscillators, a critical technique for a wide variety of accelerator applications, such as photocathode RF guns, laser-based beam diagnostics, and staged laser-plasma acceleration.

An area of special expertise is high-precision fiber-optic distributed timing and synchronization systems that can operate across wide areas. Though the idea had been invented elsewhere, LBNL brought unique innovations and a high degree of development to this system. Its femtoseconds-across-kilometers capability has proved especially useful to LCLS and now LCLS-II.

A spinoff of our expertise is being explored: the use of field-programmable gate arrays to read the outputs of microwave-sensed outputs in quantum computing.

Laser Design and Control

Besides the numerous uses of lasers throughout accelerators, the future is likely to include new paradigms (such as the one being explored by ATAP’s BELLA Center) in which lasers actually power accelerators, setting up the potential gradient that accelerates the beams. These accelerators hold great promise for being much more compact and perhaps ultimately relevant to high-energy-physics colliders. Moving this type of accelerator forward requires great improvement in high-average-power, high-repetition-rate, ultrafast lasers.

BACI and collaborators, including the University of Michigan (where a key coherent beam-combining technique was invented) and Lawrence Livermore National Laboratory, are working on a highly promising set of approaches to these problems by combining pulses and combining the output of many fiber apertures. We intend to integrate this with the temporal combination scheme described above, together with other methods of amplifying ultrashort pulses, to produce useful high-power systems.

pulse stacking layout
Block diagram of laser architecture shows the interrelationships of the concepts we are working to combine in order to achieve stepping-stone and, ultimately, HEP LPA driver levels of performance. (Click for larger version.)

High-Dynamic-Range Beam Instrumentation

Instrumentation serves as the “eyes and ears” of all accelerators and covers a wide variety of technologies, techniques and required resolution and bandwidth. Facilities and laboratories have generally developed custom solutions to their specific instrumentation needs. However, there are several commonalities among facilities that would share benefit from R&D, including real-time beam orbit control and the measurement and control of beam loss.

At Berkeley Lab we have developed world-leading expertise in beam orbit measurement and feedback control in storage rings, particularly low-emittance electron rings, that enables transverse stability of the beam at the level of microns over time periods of days. Two important steps are needed to reach this level of performance: high-fidelity measurement of the beam position using RF beam signals, and a real-time feedback network to distribute the information and apply corrections at a rate of tens of kHz. We operate this system on the Advanced Light Source and maintain an instrumentation laboratory for development and testing of hardware improvements.

High-power proton and ion accelerators of the future — not only the LHC and its coming upgrades, but also neutrino sources, spallation neutron sources, and accelerator-driven waste transmutation systems — will have to pay more attention than ever to “halo” and other losses of their multi-megawatt beams. One particular focus of Berkeley Lab work will be a new ring paradigm, the “integrable nonlinear focusing lattice,” that offers the promise of beam current and intensity substantially beyond what is possible with traditional ring layouts and their highly linear focusing elements. Berkeley Lab’s contributions include particle detector instrumentation, with several groups already performing relevant R&D.

Steps Forward

BACI is off to a running start with existing efforts that include laser pulse combining, AC&I for ALS-U, LLRF and timing distribution for LCLS-II, as well as spinoff applications in quantum-computing readouts and a nascent user facility for ultrafast electron diffraction. Challenging future prospects include the PIP-II project at Fermilab, an electron-ion collider, and a next generation of our own Advanced Photoelectron Experiment. We look forward to serving the needs of the accelerators of tomorrow.

A SPECIAL DELIVERY FOR LCLS-II

After a story by Glenn Roberts of the Berkeley Lab Public Affairs Office. Photos courtesy SLAC.

SXR modules arrive at SLAC
April 26, 2017: the first two LBNL-designed, commercially produced soft-X-ray undulator segments for LCLS-II arrive.
In the early afternoon of April 26, the first shipment of powerful magnetic devices for a next-generation laser project arrived at National Accelerator Laboratory in California after a nearly 3,000 mile journey from a factory in New York.

Berkeley Lab is overseeing the development and delivery of these devices, known as soft X-ray undulators. They are a key part of LCLS-II, a free-electron laser being built for SLAC by a partnership of SLAC and Berkeley Lab, Fermilab, Jefferson Lab, and Argonne.

The two devices are the first of what will ultimately be a chain of 21 segments making up the complete soft X-ray undulator. They are at the heart of the free-electron laser, as they will cause the high-energy electron beam from a linear accelerator to emit laserlike beams of X-rays.

The soft X-ray undulator units present an impressive combination of brute strength and fine precision. Each weighs about 6.5 tons and is about 11 feet long, with sturdy steel frames that are designed to withstand nearly 7 tons of force to keep the two rows of magnets precisely positioned as they try to repel each other. The distance between the rows can be adjusted within millionths of an inch to tune the properties of the X-ray laser light.

LCLS-II is a major new facility and upgrade to the existing Linac Coherent Light Source, a DOE Office of Science User Facility enabling higher performance, new capabilities, and higher capacity for new experiments. In particular, LCLS-II will provide a continual stream of X-ray pulses that will enable studies at the atomic, molecular, and nano scales, with femtosecond (quadrillionths-of-a-second) time resolution. This knowledge is eagerly sought in fields ranging from biology to materials science.

“The delivery is ahead of schedule and below the baseline budget,” said John Corlett, a physicist who is Berkeley Lab’s senior team leader in the LCLS-II project collaboration.

Corlett added, “This is a major achievement—the culmination of years of work in designing the undulator, qualifying the design, and working with vendors.”

Additionally, Berkeley Lab is overseeing the final design and mass production of a set of 32 hard X-ray undulator segments. The Lab collaborated with Argonne National Laboratory in the design and development of these segments. (“Hard” refers to higher-energy X-rays, and “soft” refers to lower-energy X-rays.) Undulators using permanent magnets were first used for storage ring light sources and are now in use for free-electron lasers. The late Klaus Halbach of Berkeley Lab was a pioneer in developing the permanent-magnet array used in these devices.

Berkeley Lab is also fabricating a unique electron “gun” that kick-starts the rapid-fire electron bunches needed to produce intense electron beams for LCLS-II. The new gun is derived from the Advanced Photoinjector Experiment (APEX) gun, which was successfully developed at Berkeley Lab and is now being used for ultrafast electron experiments.


“We are glad to contribute our expertise to this realization of a unique new tool for science.”
— ATAP Director Wim Leemans

As the electron beams go through the undulators, the alternating magnetic fields inside will cause electrons to wiggle, giving off some of their energy in the form of light. As the beam goes through the long chain of undulator segments, each precisely spaced field adds to its intensity.

The soft X-ray undulator will be capable of producing up to 1 million soft X-ray pulses per second, and the hard X-ray chain can produce X-ray laser pulses that are up to 10,000 times brighter, on average, than those of the existing LCLS.

“Tremendous effort has gone into the design and development of these undulators at Berkeley Lab and across the project collaboration,” said James Symons, associate laboratory director of Physical Sciences at Berkeley Lab. He oversees both the Engineering and the Accelerator Technology and Applied Physics divisions, which worked together to design and prototype the undulators. “We, and the X-ray user community, are looking forward to their installation and to ‘first light’ at LCLS-II.”


Six and a half tons of precision called for special handling from start to end of the 3000-mile trip.
Wim Leemans, Director of Berkeley Lab’s Accelerator Technology and Applied Physics Division, added, “It’s exciting to see the undulators move from the drawing board to the delivery truck after all those years of work. We are glad to contribute our expertise to this realization of a unique new tool for science.”

Berkeley Lab engineer Matthaeus Leitner has key technical and budgetary responsibility for the undulators, while his colleague Steve Virostek plays the same role for the injector system. Other Berkeley Lab contributions to LCLS-II include accelerator physics and technology studies in beam dynamics, free-electron laser design, the low-level radiofrequency system, and the management and integration of cryogenics systems.

John Galayda of SLAC, Director of the LCLS-II project team, said, “The LBNL team’s performance has been crucial to the LCLS-II project’s good progress to date.”

The soft X-ray undulator shipments will continue every six weeks to SLAC from their assembly at a vendor in Buffalo, N.Y. The shipments will wrap up in spring 2018. To prevent damage and misalignment during their coast-to-coast journey, the undulator segments are shipped in a climate-controlled truck that includes a special shock-absorbing frame.

Once delivered to SLAC, the undulator segments must be fine-tuned. “The undulators have been specially designed to allow for very rapid tuning,” said Henrik von der Lippe, Berkeley Lab’s Engineering Division director. “The process will require as little as two days, compared to the two weeks or more needed by earlier undulators.”

Now that the soft-X-ray undulator segments are in production, engineers are conducting magnetic tests on a pre-production version of a hard X-ray undulator segment. These segments will be assembled by vendors in Buffalo, N.Y., and in Los Angeles, and then shipped to Berkeley Lab for tuning before final delivery to SLAC.

DIVERSITY & OUTREACH

ATAP’s Kelly Swanson Steps Up to the Plate for a Grad Slam

 Wim Leemans and Kelly Swanson
ATAP Director Wim Leemans congratulates BELLA student Kelly Swanson after watching her take top honors in the “Grad Slam” semifinals at UC Berkeley
Doctoral research in physics requires a rigorous work ethic and formidable analytical powers — and summarizing it at a scale of less than a minute per year takes presentation skills every bit as strong. ATAP’s Kelly Swanson just proved that she has all these qualities.

Swanson, a doctoral student in the University of California-Berkeley Physics Department and ATAP’s BELLA Center, is the 2017 winner of UCB’s Grad Slam. The event challenges graduate students from each UC campus to explain their research in three minutes, live and onstage along the lines of a poetry or storytelling “slam.” In addition to first prize from the distinguished panel of judges, she won the “People’s Choice” award in an audience vote.

Swanson will go on to compete against peers from the other eight UC campuses in the final round on May 4. Click here to see the full story on the UCB Physics Department website.

The UCB Graduate Division has put the entire Slam online (this link takes you directly to Swanson’s talk, about half an hour into the event).

“I’m proud of what she has accomplished,” said ATAP Director Wim Leemans, who is Swanson’s research advisor. (Prof. Marjorie Shapiro, of the UCB Physics Department and LBNL’s Physics Division, is her faculty advisor.) Dr. Leemans added, “She presented a complicated aspect of what particle physics is all about, why there is a need for innovation, and how the laser plasma accelerator technology we are developing at BELLA Center has the potential to change the way future accelerators will be built — and all that in just three minutes! She did it with lots of energy and charm as well.”

Another LBNL/UCB Physics student, Stephanie Mack, who works at the Lab’s Molecular Foundry, took third place in the field of eight semifinalists representing a variety of graduate disciplines throughout the campus.

The competition helps build skills that will pay off throughout a scientific life. Dr. Fiona Doyle, Dean of the Graduate Division, quoted in an article on the Graduate Division website, praised the “true passion for the research that our students are doing” that came through in their talks, “and also the significant work they put in to distill it to a concise format that could be grasped by everyone in the audience.”

Our congratulations to all the competitors, and best wishes to Kelly in the final round!

ATAP Postdoc Serena Persichelli Wins “Accelerating Diversity Prize” from International Collaboration

Editor’s Note: Dr. Persichelli was recently awarded the “Accelerating Diversity Prize” by the CERN-based Future Circular Collider (FCC) collaboration, which looks toward machines beyond the Large Hadron Collider, and has been invited to participate in the 2017 FCC Week conference. Here she shares her thoughts on being a young woman building a career in a traditionally male-dominated science, technology, engineering, and mathematics [STEM] field. The article reproduced below was published by CERN as “Diversity matters for the FCC collaboration,” 23 February 2017.

Serena Persichelli The Future Circular Collider study, with the generous support of IEEE-CSC, launched a call for applications for the “FCC Accelerating Diversity prize” to encourage scientists representing different areas of diversity to attend the FCC Week 2017 and exploit one of the many research opportunities offered by the FCC study. In this article meet Serena Persichelli, one of the winners of the FCC Diversity prize, who presently works in Lawrence Berkeley National Laboratory (LBL):

I have decided to join the Particle Accelerators field inspired by the idea to be part of world leading science projects designed to be unsurpassed by any currently envisioned technology, such as LHC and FCC. To pursue this interest, I studied Electronics Engineering in the University of Rome La Sapienza. My PhD research project, based on the study of the beam-wall interaction in proton machines, was entirely carried out at CERN, when in 2012 I joined the Hadron Synchrotron Collective effects section (HSC).

I am currently employed at Lawrence Berkeley National Laboratory (LBL), where I am involved in the conceptual design studies for the Advanced Light Source upgrade (ALS-U). I am still collaborating with my home university and CERN in the framework of the FCC studies: in this context I work on the beam-wall interaction in new devices designed for the FCC-ee machine.

I have decided to join the Particle Accelerators field inspired by the idea to be part of world leading science projects designed to be unsurpassed by any currently envisioned technology, such as LHC and FCC. To pursue this interest, I studied Electronics Engineering in the University of Rome La Sapienza. My PhD research project, based on the study of the beam-wall interaction in proton machines, was entirely carried out at CERN, when in 2012 I joined the Hadron Synchrotron Collective effects section (HSC). I am currently employed at Lawrence Berkeley National Laboratory (LBL), where I am involved in the conceptual design studies for the Advanced Light Source upgrade (ALS-U). I am still collaborating with my home university and CERN in the framework of the FCC studies: in this context I work on the beam-wall interaction in new devices designed for the FCC-ee machine.

During the course of my studies, I encountered a number of preconceptions and biases about women in STEM. I realized that biases and negative stereotypes, whether intentional or otherwise, contribute in pushing women out of scientific careers.

I strongly believe that is fundamental to promote diversity and women participation in STEM and engineering programs. Even if the number of young female scientists joining big centres like CERN is increasing every year, there is still not enough diversity inside smaller groups, specially in US Labs.

To positively impact junior female scientists, misconceptions about women in STEM must be eradicated. I think is very important to give women more visibility in their field of expertise, endorsing them to engage in leading and managing roles, promoting their active participation at science conferences and workshops, encouraging them to act as a resource for younger scientists.
    Enhancing women’s authority and influence, putting the accent on their commitment and competence, instead of maintaining outdated patterns of gender roles, is going to inspire the next generations of scientists and, eventually, reduce women’s isolation and help to demolish the barriers between genders.”


SAFETY: THE BOTTOM LINE

On March 29, ATAP and Engineering Division personnel matrixed to ATAP held our first joint Safety Day. Our all-hands, all-hazards, all-day effort made very substantive improvements throughout our area. Workspaces are organized and efficient, desks have earthquake refuge space underneath, and thanks to some intrepid volunteers, even the microwave ovens in the breakrooms are clean!

The qualitative benefits are easy to understand, but as scientists and engineers we yearn for the quantitative. Just a few highlights of the tangible results:

  • 33 obsolete or malfunctioning computers, now being processed out through the property accounting system
  • 13 rolling bins and 3/4 of a dumpster of paper and cardboard
  • 22 hoppers, rolling bins, barrels, and pallets of excess equipment and miscellaneous scrap and salvage
  • 6 hoppers, machine carts, and boxes of e-waste
  • 1 cargo container filled with still-needed items that were not in active use
  • 0 accidents and injuries — the best statistic of all, a testimonial to a good job of using appropriate personal protective equipment and staying within our training and physical capabilities

Here is a detailed statistical summary of our accomplishments (LBNL login required).

After an intense morning of clean-up came an afternoon of safety assurance. Fifteen QUEST teams assessed our workplaces; then 20 senior people performed walkthroughs with the help of 11 locally knowledgeable escorts.

The QUEST teams identified some 200 action items that are being tracked to completion. Further walkthroughs are already in progress to assign and prioritize actions and verify completion.

We look forward to another year of doing great science and engineering with the safety, efficiency, and sense of pride that comes from a tidy and well organized workplace.