Berkeley Lab

ATAP News, February 2016

LCLS-II Readiness Reviewed; Progress on Undulators, Electron Gun
APEX Capabilities Enable New UED Tool for Materials Science
IBT Expertise Helps Spin Doctors Increase Their Sensitivity
ATAP Helps Measure Antihydrogen’s (Lack of) Charge With Unprecedented Precision
Moore Foundation Backs LPA FEL Work with $2.4M Grant
BELLA Center Demonstrates LPA Staging, Key to Future Goals
Diversity Ideas Wanted; Save the Date for Outreach and Education Activities
Personal Drones, Riding and Charging of Hoverboards Banned at Lab

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FEL_LPA_concept_800x232y Staging_sim_cookie_150x149y LNdemo_200x124y NoDroneZone_100x93y

WPLeemans_150px   Director’s Corner: Exploring New Opportunities in the New Year

ATAP scientists and engineers begin 2016 as they ended 2015, with impressive progress on many fronts, and can celebrate the new year as corresponding- or co-authors of three articles published in Nature journals.

Technical progress continues on our contributions toward LCLS-II as that SLAC-based project moves toward construction approval. Meanwhile, a testbed for one of its enabling technologies, APEX, is about to become a tool for user science in its own right through ultrafast electron diffraction.

The ATAP-led Berkeley Center for Magnet Technology (BCMT) was designated as DOE’s lead laboratory for HEP R&D in high-field magnet technology. This is a testament to their years of hard work and progress in superconducting magnets. BCMT’s contributions to those and many other types of magnets are central to the needs of ATAP, LBNL, and numerous other research communities, including LCLS-II and the Advanced Light Source Upgrade. We’ll detail their recent accomplishments and plans in an upcoming issue of this newsletter.

ATAP faculty scientists co-authored a Nature article about their latest discovery, as part of a CERN collaboration, in the properties of antihydrogen — a discovery made possible by advanced accelerator science.

The expertise of our Ion Beam Technology Program was key to a multi-laboratory effort that realized a tremendous increase in the sensitivity of electron spin detection; this was described in another Nature article.

Meanwhile, prospects for laser-plasma accelerator facilities were explored by colleagues from around the world in two ATAP-organized workshops in January.

The necessary technologies are still in their early days, but hold the long-term promise of colliders that have a much smaller physical and financial footprint compared to present-day, RF-based approaches. The Plasma-Based Accelerator Facilities for Colliders Workshop (January 7-9) had two goals: identifying the key physics and technology research and development needed to realize a plasma-based collider, and formulating a nationally and internationally coordinated roadmap for carrying out this research over the next two decades. Fifty-five participants came from across the US, with a substantial international contingent as well. Eight universities, five DOE national laboratories, nine other research institutions, and two funding agencies that support our work — the DOE and the Gordon and Betty Moore Foundation — were represented.

BELLA is also expected to have many shorter-term spinoffs. One of them is ion acceleration, a capability whose uses include high-energy-density physics. To explore these prospects, we organized the Workshop on High-Energy-Density Physics with BELLA-i. Nearly 60 colleagues from thirteen universities, three DOE laboratories and nine other institutes in the US and abroad, and two private-sector firms participated in this January 20-22 event.

This productive month culminated with the publication of a Nature article about BELLA Center’s successful demonstration of “staging,” or coupling of successive accelerator modules in series, which is a key enabling technology en route to high energy and beam quality.

We invite you to read on and learn more…

LCLS-II_undulator_reversed_99x92y   LCLS-II Readiness Reviewed; Technical Progress Continues

In early December, the Department of Energy reviewed the Linac Coherent Light Source-II project’s readiness for two approval milestones: Critical Decision 2 (approval of performance baseline) and, concurrently, CD-3 (approval for start of construction). The LBNL team made several presentations to subcommittees at the review.

These presentations ran the gamut of LBNL’s contributions to the multi-institutional, SLAC-based LCLS-II project. Topics included accelerator physics and beam dynamics; injector source design and production planning; APEX R&D; undulator design and production planning; cryogenic systems requirements and design verification; undulator cost estimate details; and project management.

The review committee generally approved readiness of the Project for CD-2 and CD-3, with some recommendations that must be addressed in early 2016 before formal approval by DOE, which is expected in the first quarter of this year.

LBNL’s participation in LCLS-II prominently includes design and development of the undulators at the heart of the facility’s free-electron lasers. The LBNL LCLS-II undulators team had already gone through final design review for the soft- and hard-x-ray undulators (SXR and HXR) in November, receiving an excellent report from that external review committee. With this milestone behind us, we are now in the process of ordering long-lead-time procurements for the SXR undulators, and have begun finalizing production plans with vendors, a process expected to continue through February. Production will begin after formal approval for start of project construction (CD-3).

The undulator team has made great progress in developing the horizontal-gap vertically polarized undulator (HGVPU), and presented prototyping and staged production plans at the DOE CD-2/3 review of the LCLS-II Project. This novel design, prototyped at Argonne National Laboratory (ANL), is to be included in the LCLS-II Project Baseline in early 2016. LBNL’s role was twofold: collaborating closely with ANL engineers in developing the mechanical design for production, and developing the proven high-performance LBNL magnetic modules for application in the HGVPU.

shipping test showing undulator on a platform Moving a heavy, high-precision apparatus from one laboratory to another requires engineering and testing in its own right. Here HXU32, a prototype LCLS-II undulator, is readied in its shipping frame for a test. Having been tuned and measured, it will make a round trip to SLAC, then undergo precision measurements again to determine whether shipping affected performance.

ATAP and others at LBNL also play a key role in the technically demanding injector for LCLS-II; they are responsible for its design, construction and commissioning. The LCLS-II injector source design has been modified to include a 90° elbow in the coaxial RF power waveguide feeding the VHF gun. This allows the ceramic vacuum window to be placed out of line of sight of radiation produced by field emission in the cavity, addressing a lesson learned in our Advanced Photoinjector Experiment (APEX).

Prototype couplers will be fabricated at LBNL and installed and tested at APEX. Presently APEX is operating at reduced duty cycle to perform beam dynamics measurements. We expect to finish those measurements, providing initial demonstrations of LCLS-II requirements, in March. Then the prototype 90° elbow couplers will be installed and testing will begin.

injectorwindow_600x721y In the Advanced Photoinjector Experiment’s VHF gun and in the LCLS-II injector being derived from it, a ceramic vacuum window separates the “air side” of the radiofrequency power system from the VHF gun cavity. The new 90-degree coupler will keep the ceramic vacuum window out of harm’s way with regard to field emission that occurs in the VHF gun cavity.

DF_HiRES_hutch_100x94y   APEX-Enabled Scattering Experiment Expected to Become New Research Tool for Materials Science

Intended as an R&D testbed for the injectors of the next generation of light sources, APEX, the Advanced Photo-injector Experiment, is also en route to becoming a user-science instrument in its own right through HiRES, the High Repetition-rate Electron Scattering apparatus for ultrafast electron diffraction.

Taking advantage of the unique properties of the APEX electron beam, this innovative instrument will open up new opportunities for ultrafast structural dynamics studies. Initial experiments, expected to begin this spring, will focus on the ultrafast structural response of two-dimensional materials and stacks, with a wide variety of hoped-for applications to be explored. The benefits will help address one of the grand challenges in the understanding of materials: following the dynamics of atoms and molecules.

HiRES is based on a pump-probe scheme and the joint use of finely synchronized electron and photon beams. A sample is excited by a laser pulse with a selected wavelength; then, after a specific delay time, a femtosecond-long electron bunch (typically 105 – 106 particles) interacts with a sample. The electrons have a short wavelength that senses the perturbed potential of the sample and draws an instantaneous picture (in the reciprocal space) on a downstream detector.

Schematic layout of the pump-probe scheme for ultrafast electron diffraction at APEX.
This capability is made possible by APEX, built to produce high-charge, picosecond-long electron pulses with MHz-scale repetition rates to drive the next generation of light sources. This innovative electron source uses blends of selected semiconductor materials as the photocathode, driven by a femtosecond laser, together with high electric fields (tens of megavolts per meter) from continuously stored radio-frequency power.

In experiments intended for its main application, a high-density electron bunch (107 to 109 electrons with sub-millimeter transverse size and picosecond duration) is accelerated to MeV energies each microsecond, providing high (milliampere-class) average flux in addition to high (multi-ampere) peak current. The electron beam can be further accelerated to multi-MeV energies via two standing-wave accelerating cavities operating at 10 Hz, or can be directed to a side beamline for high-flux experiments.

Inspiration for an Application

The APEX team saw that this high repetition rate also enabled average electron beam parameters more appropriate for electron imaging and diffraction, while still maintaining a reasonable electron dose at the sample. Here, sub-nanometer beam emittance is achieved by lowering the average current from mA to nA and shrinking the source size from millimeters down to microns. At the same time, the electron pulse length can be shortened from picoseconds down to femtoseconds. The result: micron-sized ultrafast probes with atomic resolution. Both stroboscopic (repeated) and single-shot experiments will benefit.

PI Daniele Filippetto in the HiRES hutch at the Advanced Light Source.
The HiRES beamline is currently being installed inside the APEX hutch at the Advanced Light Source (ALS). The fiirst experimental collaborations with the Lab’s Material Science Division will start this spring, after a commissioning period, and will focus on the ultrafast structural response of two-dimensional materials and stacks, such as graphene, hBN, and transition-metal dichalcogenides (TMDs).

In particular, by merging the high spatial resolution of static microscopes (like those at LBNL’s National Center for Electron Microscopy) with the structural dynamics studies at HiRES, we will be able to directly correlate the static atomic structure, such as number of layers and their relative orientations, or the presence of stacking faults and local defects, with the response of the material to ultrafast excitation, both on and off resonance. In two-dimensional material stacks, the electronic properties are directly correlated to the atomic structure, so these experiments will directly impact the design of novel electronic devices based on TMDs.

The strong interaction of electrons with matter can also be used for studying weakly scattering samples, such as gases, liquids or biological specimens. It is our plan to broaden the range of possible experiments through collaborative efforts with ALS users and the Chemical Science Division.

To learn more…

These Powerpoint slides from a technical presentation by HiRES principal investigator Daniele Filippetto at the 2013 Femtosecond Imaging and Spectroscopy Workshop describe the APEX gun and the ultrafast electron diffraction concept that became HiRES.

Sannibale et al., “Advanced photoinjector experiment photogun commissioning results,” Physical Review Special Topics: Accelerators and Beams 15, 103501 (October 2012), gives a detailed description of APEX.

The HiRES team of Daniele Filippetto, Houjun Qian, Haider Rasool, and Fernando Sannibale gratefully acknowledges support of the HiRES beamline by the DOE Office of Science, Office of Basic Energy Sciences, through the Early Career Research Program.

Bi_doped-Si_400x222y   Implantation Expertise Helps Enable Ultrasensitive Spin Resonance Demonstration

Spins of atoms and molecules are routinely probed by a suite of spin resonance techniques, which can reveal structural information, enable tracking of chemical reactions, and give insights into the fundamental dynamics of spin systems. Single spins have been observed in special settings and for selected spin systems, such as color centers in diamond. Typically, though, the sensitivity of electron spin resonance techniques is limited, and over a billion spins need to be probed at once to provide a useful signal.

In a paper recently published in Nature Nanotechnology, Bienfait et al. describe a demonstration of ultra-sensitive spin detection in which the sensitivity was increased by nearly four orders of magnitude. This exciting advance was made possible through an international collaboration of “spin resonance buffs,” experts in superconducting electronics, and experts in materials physics. Thomas Schenkel, head of ATAP’s Ion Beam Technology Program, led the LBNL team that tailored the spin properties of the material used in the study.

Tossing bowling balls into just the right places in a boxful of tennis balls…


The key contribution by ATAP’s Ion Beam Technology Group was tailoring the spin properties of the sample: a wafer of silicon-28, the isotope with no nuclear spin of its own, implanted or “doped” with bismuth atoms by IBT. The investigators at Saclay added the superconducting microwave resonator, consisting of an inductor and capacitor made of aluminum, that picks up microwave energy at a precisely chosen frequency and couples it into the sample. The bismuth atoms, whose spins are being detected, are in the layer shown in green of the 150 nanometer thick sample (which is not drawn to scale). From A. Bienfait et al., Nature Nanotechnology, 14 December 2015.

Bismuth was particularly desired as a dopant for the silicon substrate. It is paramagnetic, and exhibits zero-field splitting in its spin level structure at 7.38 GHz. These are crucial attributes because the experiments are done in a superconducting cavity, which can tolerate only a relatively low applied magnetic field. (To further improve the sensitivity of the technique, the collaboration used a material rich in silicon-28, the silicon isotope with zero nuclear spin, which gave exquisitely narrow spin resonance lines and long spin coherence times.)

Although ion implantation is a standard technique for the control of electronic properties of materials like silicon, achieving the required doping profiles with bismuth is tricky. Bismuth is a considerably larger and much heavier atom compared to the silicon host material or the usual pentavalent dopants like phosphorus and arsenic; imagine tossing bowling balls into just the right places in a boxful of tennis balls. Coaxing the right number of bismuth atoms into lattice positions and removing residual damage from the implant process was accomplished by then-ATAP postdoctoral fellow Christoph Weis, with support from Cheuk Chi Lo, in Schenkel’s group.

In their next steps, researchers will be expanding on this theme of the tailoring of various properties of materials (e.g., spin properties for sensing and quantum information processing) by experimenting with extreme processing conditions, such as rapid volumetric heating and intense electronic excitation. These conditions will be created by intense ion pulses from the heavy-ion linac NDCX-II, an ATAP accelerator facility for high-energy-density physics.

To learn more…

A. Bienfait, J. J. Pla, Y. Kubo, M. Stern, X. Zhou, C. C. Lo, C. D. Weis, T. Schenkel, M. Thewalt, D. Vion, D. Esteve, B. Julsgaard, K. Mølmer, J. Morton, and P. Bertet, “Reaching the quantum limit of sensitivity in electron spin resonance”, Nature Nanotechnology, online Dec. 14 (2015), doi:10.1038/nnano.2015.282.
“A New Spin on Quantum Computing,” a popular article by Glenn Roberts of LBNL Public Affairs, puts the demonstration and its potential applications, including quantum computing, into a user perspective.

ALPHA ion trap   Antihydrogen: Zero Charge is a Big Deal

Ion trap photo courtesy ALPHA

Antihydrogen — an antiproton with a positron — has been the subject of considerable interest in recent years because this simple antimatter atom, which can be made and studied with accelerator technology, is relevant to deep fundamental questions in physics. The latest in a series of experiments by the CERN-based ALPHA collaboration, with key contributions from ATAP and UC-Berkeley scientists, shows with much greater precision than ever before that the net charge of an antihydrogen atom is zero.

This would seem to be an intuitive conclusion — one positively charged ordinary proton and one negatively charged electron cancel each other’s charges, so why wouldn’t an antiproton and a positron? Physicists, however, cannot simply assume such a conclusion. One of the grand challenges of the field is figuring out why the observable universe appears to consist almost entirely of normal matter, not antimatter, so any potential differences between the two are targets for careful investigation. A difference in charge between an antiproton or positron and their normal-matter counterparts might have been an important clue (and would have led to rework of the Standard Model of Particles and Interactions).

After this work, we know that the charge of a positron is the same in magnitude as that of an antiproton (though opposite in sign, of course) to within 0.7 parts per billion, and that the charge of a positron is the same as that of an electron to within 1 part per billion: respectively 25 and 20 times the previous accuracy of such measurements.

This precision was made possible in part by ATAP faculty scientists Joel Fajans and Jonathan Wurtele, who along with graduate student Lenny Evans are co-authors of the Nature paper describing these results. They applied “stochastic acceleration” — a more subtle technique than had been used in previous work, hence the order of magnitude improvement in the measurement — to attempt to move the antihydrogen items out of the ion trap that contained them. A net charge would have kicked them out of the ion trap; they stayed put.

The quest for differences between hydrogen and antihydrogen continues, with a focus on another topic of ongoing interest to the collaboration (and a challenging one to study): does antimatter fall up instead of down?

To Learn More…

After repeated pounding, antihydrogen reveals its charge: zero,” a popular article by Robert Sanders of UC-Berkeley Media Relations.

Ahmadi et al., “An improved limit on the charge of antihydrogen from stochastic acceleration,” Nature 529 (21 January 2016), pp. 373-376, the technical paper describing the experiment and its results.

The websites of the Fajans Group at UC-Berkeley, particularly its Antihydrogen Trapping page; the Wurteley Group website at UC-Berkeley; and the ALPHA experiment at CERN.

LPA_FEL_100x67y   Moore Foundation Backs BELLA FEL with $2.4M Grant

Based on a story by Jon Wiener of LBNL Public Affairs

Lawrence Berkeley National Laboratory (Berkeley Lab) researchers will receive $2.4 million from the Gordon and Betty Moore Foundation to develop compact free-electron lasers that will serve as powerful, affordable x-ray sources for scientific discovery. This new technology could lead to portable and high-contrast imaging with x-ray accelerators to observe chemical reactions, visualize the flow of electrons, or watch biological processes unfold.

Currently, x-ray light sources hold great scientific promise but there are only a handful of them worldwide: each is miles long and costs hundreds of millions of dollars to develop. What’s more, access to these facilities is limited enough to constitute a bottleneck in the pipeline of scientific experiments that could take advantage of these capabilities.

“We want to develop these accelerators in such a way that accessing the light produced by these beams is much less expensive and can be performed in much smaller settings.”
— ATAP Division and BELLA Center Director Wim Leemans

Unlike conventional accelerators, which use high-power radio waves, laser-plasma accelerators use high-power optical lasers to energize electrons across short distances, typically centimeters. These electrons “surf” on waves generated by the interaction between the laser and the plasma. An x-ray FEL based on a laser-plasma accelerator might achieve power comparable to that of an FEL based on a conventional accelerator, but with far less size and expense.

Until now, the laser-plasma technology has been hampered by the quality of the x-ray beams, which need to be high-power and easily steered. Berkeley Lab researcher Wim Leemans and his colleagues have been refining this technology for more than a decade.

“We are now in the position that we know enough that we want to push for this next big challenge: can we build small accelerators and produce radiation that is typically produced by larger accelerators,” said Leemans, director of the Accelerator Technology and Applied Physics Division (ATAP) at Berkeley Lab. “We want to develop these accelerators in such a way that accessing the light produced by these beams is much less expensive and can be performed in much smaller settings.”

Leemans also directs the Berkeley Lab Laser Accelerator (BELLA) Center, which houses one of the most powerful lasers in the world. For this new project, he has put together a team consisting of Berkeley Lab senior scientist Carl Schroeder (lead for theory) and scientist Jeroen van Tilborg (lead for experiment), along with postdoctoral researchers and graduate students, and technical staff.

Conceptual diagram of a free-electron laser based on a laser-plasma accelerator. The Moore Foundation grant will enhance existing BELLA Center R&D toward an x-ray FEL.

During the course of his career, Leemans says he has seen “tremendous progress” toward generating high-quality electron beams from laser plasma accelerators. “Ultimately, if it turns out that we have the beam quality under control, there’s nothing stopping us from going toward x-rays,” he said. “If we can push down the wavelength of the light into the x-ray spectrum, potentially even into hard x-rays, then we have radiation sources with a footprint that is probably one-tenth or less than the big machines.”

The $2.4 million grant will be for a three-year period, and is part of the Moore Foundation’s Emergent Phenomena in Quantum Systems (EPiQS) Initiative, which supports discovery-driven research on quantum materials and aims to stimulate breakthroughs in the field that fundamentally change our understanding of the organizing principles of complex matter.

“This project aligns with our common long-term goal of dramatically increasing access to x-ray sources with unprecedented intensity, coherence and time resolution,” said Ernie Glover, a former staff scientist at LBNL’s Advanced Light Source and DOE Distinguished Postdoctoral Research Fellow and now a science program officer in the Emergent Phenomenon in Quantum Systems (EPiQS) Initiative at the Moore Foundation. “If successful, this project will demonstrate a path to significantly reduce the size and cost of these sources and greatly expanding their scientific impact.”

“With support from the Moore Foundation, we hope we can show that this technology is real and that it will revolutionize the way accelerators can be built in the future for universities, companies, small institutes and beyond—that’s our goal,” said Leemans.

To Learn More…

The BELLA Center’s website includes a description of their work on compact future light sources based on laser-plasma accelerators.

This research is funded by the Gordon and Betty Moore Foundation EPiQS initiative through Grant 4898. The Gordon and Betty Moore Foundation fosters path-breaking scientific discovery, environmental conservation, patient care improvements and preservation of the special character of the Bay Area. Visit or follow @MooreFound.

Staging_sim_cookie_150x149y  BELLA Center Demonstrates Staging; Major Proof of Concept On Road to Future Laser-Plasma Accelerators

Berkeley Lab Laser Accelerator Center researchers have recently demonstrated coupling of an accelerated beam from one laser-plasma accelerator (LPA) stage into another. Their work is described in an article published February 1 in Nature.

LPAs have made remarkable progress (BELLA holds the record, accelerating electrons to 4.2 GeV in a 9 cm accelerating structure) and hold tremendous promise for making particle accelerators smaller and more affordable. However, many of their applications, including the long-term goal of colliders for high-energy physics, will require more energy than is practical for a single accelerating stage.

A single stage LPA for high-energy physics would require a high plasma density (some 1015 cm-3), which leads to a low acceleration gradient and therefore great length (a kilometer for an HEP collider) and unacceptably high laser pulse energy (10 kilojoules or more). Worse, collider-grade electron-beam quality could not be obtained in this manner. Coupling one stage of acceleration into another is the way around these problems.

To be ready for that next phase of progress, one of BELLA’s goals has been the coupling of LPA stages in series, each powered by separate, synchronized lasers.

Staginglayout_1500x590y Conceptual diagram of the staging experiment. The inset shows simulation results for various combinations of spot size and beam energy. A plasma mirror couples the LPA stages. In these experiments, intended to demonstrate staging concepts rather than reach maximal energy, a 120 MeV input beam from the first stage was coupled into the second stage and given an additional 100 MeV of acceleration. The laser used for the 100-MeV gain was not the BELLA petawatt laser, but a 20x smaller laser (50 terawatts), and only 30% of that power was employed.

In addition to being a pathway to higher energies, staging can also be used to decelerate an electron beam that has served its purpose, rather than sending it to a beam dump that must be shielded against the radiation that would result. This could further improve the compactness of, say, future light sources (see the Moore Foundation article in this issue) or portable applications in homeland security or medical treatment.

Measurements show that, of the 33 picocoulombs of charge from the 120-MeV output of the first stage, 3.5% of the charge was successfully coupled into the second stage, where it gained another 100 MeV of energy. Simulations of modules that provide multi-GeV energy boosts to high quality electron beams by operating at lower densities (i.e., larger transverse wake size) suggest that 100% trapping can be achieved.

StagingResults_650x655y Spectra of electron beams from staged acceleration.

(a) Maximum electron energy (blue) and total electron beam charge (red) as a function of the delay of the two driving laser pulses. A single data point represents an average of 5 measurements and the error bar shows the standard deviation.

(b) Waterfall plot of electron spectra (5-shot average), each with the reference subtracted, as function of delay.

(c) A 100-shot average unperturbed reference for delays of 100-300 fs before arrival of the second laser pulse.

(d – g) 2D charge maps (5-shot average), with the reference subtracted, for the first two maxima and minima of the energy oscillation shown in (a). Parts (d-g) correspond to delays of -107 fs, -153 fs, -193 fs and -240 fs, respectively.

Simulation and modeling go hand in hand with advanced accelerator R&D today, and BELLA is no exception. Especially significant in the staging experiment were calculations of the laser–plasma interaction including laser and wakefield evolution, and of electrons acceleration and modulation, within the computational framework of INF&RNO (Integrated Fluid and Particle Simulation Code).

INF&RNO, developed by ATAP and part of the Berkeley Lab Accelerator Simulation Toolkit (BLAST), was used for detailed study of how the wakefield in the second accelerating stage affects the electron beam. Shown in (b) above are electron spectra (with an unperturbed reference spectrum subtracted) as a function of the delay between the arrival of the electron bunch and the laser pulse. The simulations show that the observed energy modulations depend on the phasing of the electron bunch within the wake. The periodicity of the modulation is determined by the plasma density and is consistent with the experimental observation.

Running on a Cray supercomputer at DOE’s National Energy Research Scientific Computing Center (NERSC) at Berkeley Lab, the highly efficient INF&RNO code for modeling laser and plasma interactions could turn a day’s experimental data into a simulation almost overnight, like “dailies” on a movie set. Among many other questions, intricacies of laser timing could be explored; focusing the energetic but ragged beam from the gas jet could be simulated even as the serendipitous discovery of how to actually do it was becoming a reality.

“Through matching to the experimental observations, simulation can see everything,” says Carlo Benedetti of the BELLA Center’s simulation team, who led development of INF&RNO. “We can see how the laser beam is behaving and understand which electrons are the ones being accelerated.”

— From an article by Glenn Roberts, Jr., LBNL Public Affairs

Although there is much work still to be done before staging is perfected, this demonstration is a major milestone in the development of laser-driven plasma-based accelerators — an achievement applicable not only to the dream of colliders, but also to any other LPA application that requires electron energies beyond the single-stage limits. A future step will use the much more powerful laser beam from BELLA in the quest to get 5 GeV from the first stage and 10 from the second, with near 100% charge trapping.

To Learn More…

Coupling Tabletop Accelerators Produces Fundamental Breakthrough,” a story by Glenn Roberts, Jr., of LBNL Public Affairs, further explains the experiment and places it in context.

The experiment and results are described in a technical paper by S. Steinke, J. van Tilborg, C. Benedetti, C.G.R. Geddes, C.B. Schroeder, J. Daniels, K.K. Swanson, A.J. Gonsalves, K. Nakamura, N.H. Matlis, B. H. Shaw, E. Esarey, and W.P. Leemans, “Multistage coupling of independent laser plasma accelerators,” Nature, available online 1 February 2016,

A Nature “News and Views” article by Brigitte Cros puts the work into perspective.

The BELLA website has more information on the staging beamline and many of the near- and long-term applications of laser-plasma accelerators.

LNdemo_200x124y   Workplace Life: Opportunities To Let Your Voice Be Heard

2016 Labwide Employee Survey: Deadline February 5

By now all LBNL employees should have received, by e-mail, a link to the 2016 version of the familiar Employee Survey from MOR Associates. It only takes a few minutes, and more respondents mean better results. This an excellent anonymized opportunity to let Lab management know what works and where we have opportunities for improvement. The survey is open until February 5th.

Help Us Increase ATAP’s Diversity

A Diversity in Hiring Task Force has been looking at how we might improve our hiring process to increase ethnic and gender diversity in the Division. The Task Force is chaired by Qing Ji; other members are Warren Byrne, Tony Gonsalves, Tamara Krake, Chad Mitchell, Ian Pong and Ina Reichel. The Task Force is expected to present a report to ATAP management in mid-March. If you have any suggestions on how to increase diversity through improvements in our recruitment and hiring process (or in any other ways), please contact any member of the Task Force.

Save the Dates for Educational Outreach

Finally, here’s a save-the-date announcement of two fun and rewarding opportunities to reach out to the next generation of potential science and technology leaders. Daughters and Sons To Work Day is Thursday, April 21, followed closely by the Nuclear Science Division’s Scouting Day on Saturday, April 23.

Both events are made possible by many Lab employees volunteering their time — not only to assist with teaching and give tours, but also to help with registration, make sure visitors get to the right places at the right times, etc. Many hands make light work, so please keep your calendar open on those days and consider helping, even if you are not a scientist. Few of the volunteer roles require scientific credentials, and the kids will have a richer experience if they see that the Lab has interesting and rewarding opportunities in support roles as well. More details on how to volunteer for these events (and how to sign up your own children or grandchildren) will be communicated in the coming months.

So save the dates, and help kids see what got you interested in science and technology and what is so great about working at the Lab. Who knows: you might improve our 2025 workforce and perhaps even be fondly remembered as an early influence by one of the Nobel laureates of 2050. The future begins now!


ATAP Safety Day makes a clean sweep

[Editor’s Note: A URL in an e-mailed newsletter pointed to this February page rather than the April page for Safety Day information. Our apologies for the inconvenience; please click here to view the full April content.]

NoDroneZone_100x93y   Safety: The Bottom Line

The Lab’s a No-Fly Zone for Personally Owned Drones…

“Drones” and other unmanned aerial vehicles can be a fun hobby and even professionally useful in science. LBNL, though, prohibits the use of personally owned drones (as well as kites, balloons, or anything else that flies) on Lab-controlled property or the sites of its projects. Procurement and use for official business must be cleared through the Lab’s Aviation Point of Contact (Ross Fisher) to ensure that the special Federal Aviation Administration guidelines applicable to a national lab are followed. Click here for more information on Lab policies that affect the uses of unmanned aerial vehicles.

…And Hoverboards Can’t Hover Here Either

Those sideways, motorized skateboards (that don’t actually hover) rivaled drones as this year’s must-have Christmas present… at least until units with defective or under-engineered batteries made national headlines for catching fire. Hoverboards may not be charged at LBNL, nor may they be ridden here (just as skateboards and Segways are forbidden). This is just common-sense safety. As any number of YouTube videos attest, people tend to fall off hoverboards even on flat ground, never mind on our hills… and setting your lab (or your boss’s) on fire is no way to ring in the New Year. If you (or your kids) use hoverboards at home, please read and understand the instructions for both riding and recharging them.