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  • richardmitnick 3:52 pm on April 9, 2018 Permalink | Reply
    Tags: , , , , SLAC LCLS-II, Superconducting electron gun   

    From SLAC: “SLAC Produces First Electron Beam with Superconducting Electron Gun” 


    SLAC Lab

    1
    Image of the first electron beam (bright colors) produced with a superconducting electron gun at SLAC and analyzed with an energy spectrometer. The beam energy was more than a million electronvolts. (SLAC National Accelerator Laboratory)

    April 9, 2018
    Manuel Gnida

    Making a high-quality beam of high-energy electrons starts with an electron gun: It knocks electrons out of atoms with a laser beam so they can be accelerated to nearly the speed of light for experiments that explore nature’s fastest atomic processes.

    Now accelerator scientists at the Department of Energy’s SLAC National Accelerator Laboratory are testing a new type of electron gun for a future generation of instruments that take snapshots of the atomic world in never-before-seen quality and detail, with applications in chemistry, biology, energy and materials science.

    Unlike other electron sources at SLAC, the new one is superconducting: When chilled to extremely low temperatures, some of its key components conduct electricity with nearly 100 percent efficiency. This allows it to produce superior, almost continuous electron beams that will be needed for future high-energy X-ray lasers and ultrafast electron microscopes. The new superconducting electron gun recently produced its first beam of electrons at SLAC.

    “This is an important milestone,” says Xijie Wang, who leads the project. “The use of superconducting accelerator technology represents the beginning of a new era at the lab that will create unforeseen research opportunities, and will keep us at the forefront of science for decades to come.”

    2
    SLAC’s accelerator scientists are testing a superconducting electron gun (inside the large vessel at center), a new type of electron source that could be used in next-generation X-ray lasers and ultrafast electron microscopes. (Dawn Harmer/SLAC National Accelerator Laboratory)

    A Superior Electron Source

    At SLAC and other labs, beams of high-energy electrons are used as tools to precisely examine the atomic fabric of our world and to look at atomic-scale processes that occur within femtoseconds, or millionths of a billionth of a second. The beams are used directly, in instruments for ultrafast electron diffraction and microscopy (UED/UEM), or indirectly in X-ray lasers like SLAC’s Linac Coherent Light Source (LCLS), where the energy of the electron beam is converted into powerful X-ray light.

    SLAC LCLS

    In both approaches, the electrons are produced with an electron gun. It consists of a photocathode, where electrons are released when a metal is hit by a laser pulse; a hollow metal cavity, which accelerates the electrons with a radiofrequency field; and a magnetic lens that bundles the electrons into a tight beam.

    Conventional electron guns use cavities made of normal-conducting metals like copper. But the new device’s cavity is made of niobium, which becomes superconducting at temperatures close to absolute zero. Several groups around the world are actively pursuing the superconducting technology for next-generation particle accelerators and X-ray lasers.

    “Superconducting electron guns have the potential to outperform current guns,” says accelerator physicist Theodore Vecchione, coordinator of the SLAC project. “For instance, while the electron gun that’s being installed as part of the future LCLS-II will generate electron pulses at an extremely high repetition rate, the superconducting gun should be able to produce similar pulses at four times higher beam energy.

    SLAC/LCLS II projected view

    It should also be able to achieve twice the beam acceleration over a given distance, producing a tighter beam of electrons with extraordinary average brightness.”

    3
    SLAC schematic of superconducting electron gun

    LCLS-II will already use superconducting cryomodules to bring electrons up to speed, which will allow the X-ray laser to fire 8,000 times faster after the upgrade. A superconducting electron gun could be ready for a future high-energy upgrade that would further enhance its scientific potential.

    “In addition to advancing X-ray science, the superconducting technology could also turn into an electron source for the UED/UEM techniques we’re developing,” says SLAC accelerator physicist Renkai Li. “It would further improve the quality of atomic-level images and movies we’re able to capture now.”

    A Top R&D Priority

    The SLAC team is testing a superconducting gun that was originally built for a project at the University of Wisconsin, Madison. About two years ago, the DOE relocated the gun to SLAC, asking the lab to recommission it for R&D work in the field of future electron sources.

    “There is a lot of excitement at the lab and the DOE about the opportunity to develop the superconducting technology into something that will drive future applications that require powerful electron beams,” says Bruce Dunham, associate lab director for SLAC’s Accelerator Directorate. “It’s very exciting to see the new gun produce its first electron beam, as it represents the very first step toward that future.”

    Over the past few months, the team installed the gun at SLAC’s Next Linear Collider Test Accelerator (NLCTA) facility and built an experimental setup with diagnostics needed to analyze the generated electron beam. “This successful effort involved many different groups around the lab, including people working on lasers, metrology, vacuum and controls,” says Keith Jobe, the NLCTA facility manager. “We’re also grateful to Bob Legg and other members of the original Wisconsin team, who were very helpful in getting this effort underway here.”

    Now that the team has demonstrated the superconducting gun is working and capable of producing electron beams with energies above a million electronvolts, they are planning their next steps. They first want to make a number of upgrades to improve the gun’s performance, including an overhaul of its refrigeration system. Then, they will be ready to push the technology to higher beam energies that could pave the way for future applications.

    The project is funded by the DOE Office of Science. LCLS is a DOE Office of Science user facility.

    See the full article here .

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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  • richardmitnick 4:14 pm on April 4, 2018 Permalink | Reply
    Tags: , , , SLAC LCLS-II, Tick Tock on the ‘Attoclock:’ Tracking X-Ray Laser Pulses at Record Speeds,   

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


    SLAC Lab

    April 4, 2018
    Amanda Solliday
    Angela Anderson

    1
    In this illustration, ultrashort X-ray pulses (pink) at the Linac Coherent Light Source ionize neon gas at the center of a ring of detectors.

    SLAC/LCLS

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

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

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

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

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

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

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

    Timekeeping in Attoseconds

    2
    An illustration of the ring-shaped array of 16 individual detectors arranged in a circle like numbers on the face of a clock. An X-ray laser pulse hits a target at the center and sets free electrons that are swept around the detectors. The location, where the electrons reach the “clock,” reveals details such as the variation of the X-ray energy and intensity as a function of time within the ultrashort pulse itself. (Frank Scholz & Jens Buck / DESY)

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

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

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

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

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

    Finding the True Colors

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

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

    SLAC/LCLS II projected view

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

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

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

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

    Progress in Motion

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

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

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

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

    LCLS is a DOE Office of Science user facility.

    See the full article here .

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 9:06 am on January 23, 2018 Permalink | Reply
    Tags: , , , , SLAC LCLS-II,   

    From LBNL- “It All Starts With a ‘Spark’: Berkeley Lab Delivers Injector That Will Drive X-Ray Laser Upgrade” 

    Berkeley Logo

    Berkeley Lab

    January 22, 2018
    Glenn Roberts, Jr.
    geroberts@lbl.gov
    (510) 486-5582

    Unique device will create bunches of electrons to stimulate million-per-second X-ray pulses.

    1
    Joe Wallig, left, a mechanical engineering associate, and Brian Reynolds, a mechanical technician, work on the final assembly of the LCLS-II injector gun in a specially designed clean room at Berkeley Lab in August. (Credit: Marilyn Chung/Berkeley Lab)

    Every powerful X-ray pulse produced for experiments at a next-generation laser project, now under construction, will start with a “spark” – a burst of electrons emitted when a pulse of ultraviolet light strikes a 1-millimeter-wide spot on a specially coated surface.

    A team at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) designed and built a unique version of a device, called an injector gun, that can produce a steady stream of these electron bunches that will ultimately be used to produce brilliant X-ray laser pulses at a rapid-fire rate of up to 1 million per second.

    The injector arrived Jan. 22 at SLAC National Accelerator Laboratory (SLAC) in Menlo Park, California, the site of the Linac Coherent Light Source II (LCLS-II), an X-ray free-electron laser project.


    Stanford/SLAC Campus


    SLAC/LCLS II projected view

    2
    An electron beam travels through a niobium cavity, a key component of a future LCLS-II X-ray laser, in this illustration. Kept at minus 456 degrees Fahrenheit, these cavities will power a highly energetic electron beam that will create up to 1 million X-ray flashes per second. (Credit: SLAC National Accelerator Laboratory)

    Getting up to speed

    The injector will be one of the first operating pieces of the new X-ray laser. Initial testing of the injector will begin shortly after its installation.

    The injector will feed electron bunches into a superconducting particle accelerator that must be supercooled to extremely low temperatures to conduct electricity with nearly zero loss. The accelerated electron bunches will then be used to produce X-ray laser pulses.

    Scientists will employ the X-ray pulses to explore the interaction of light and matter in new ways, producing sequences of snapshots that can create atomic- and molecular-scale “movies,” for example, to illuminate chemical changes, magnetic effects, and other phenomena that occur in just quadrillionths (million-billionths) of a second.

    This new laser will complement experiments at SLAC’s existing X-ray laser, which launched in 2009 and fires up to 120 X-ray pulses per second. That laser will also be upgraded as a part of the LCLS-II project.

    SLAC/LCLS

    3
    A rendering of the completed injector gun and related beam line equipment. (Credit: Greg Stewart/SLAC National Accelerator Laboratory)

    The injector gun project teamed scientists from Berkeley Lab’s Accelerator Technology and Applied Physics Division with engineers and technologists from the Engineering Division in what Engineering Division Director Henrik von der Lippe described as “yet another success story from our longstanding partnership – (this was) a very challenging device to design and build.”

    “The completion of the LCLS-II injector project is the culmination of more than three years of effort,” added Steve Virostek, a Berkeley Lab senior engineer who led the gun construction. The Berkeley Lab team included mechanical engineers, physicists, radio-frequency engineers, mechanical designers, fabrication shop personnel, and assembly technicians.

    “Virtually everyone in the Lab’s main fabrication shop made vital contributions,” he added, in the areas of machining, welding, brazing, ultrahigh-vacuum cleaning, and precision measurements.

    The injector source is one of Berkeley Lab’s major contributions to the LCLS-II project, and builds upon its expertise in similar electron gun designs, including the completion of a prototype gun. Almost a decade ago, Berkeley Lab researchers began building a prototype for the injector system in a beam-testing area at the Lab’s Advanced Light Source.

    LBNL/ALS

    That successful effort, dubbed APEX (Advanced Photoinjector Experiment), produced a working injector that has since been repurposed for experiments that use its electron beam to study ultrafast processes at the atomic scale.

    7
    The APEX electron gun and test beamline at the ALS Beam Test Facility. APEX team members include (from left) Daniele Filippetto, Fernando Sannibale, and John Staples of the Accelerator and Fusion Research Division and Russell Wells of the Engineering Division. (Photo by Roy Kaltschmidt, Lawrence Berkeley National Laboratory)

    4
    Daniele Filippetto, a Berkeley Lab scientist, works on the High-Repetition-rate Electron Scattering apparatus (HiRES), which will function like an ultrafast electron camera. HiRES is a new capability that builds on the Advanced Photo-injector Experiment (APEX), a prototype electron source for advanced X-ray lasers. (Roy Kaltschmidt/Berkeley Lab)

    Fernando Sannibale, Head of Accelerator Physics at the ALS, led the development of the prototype injector gun.

    5
    Krista Williams, a mechanical technician, works on the final assembly of LCLS-II injector components on Jan. 11. (Credit: Marilyn Chung/Berkeley Lab)

    “This is a ringing affirmation of the importance of basic technology R&D,” said Wim Leemans, director of Berkeley Lab’s Accelerator Technology and Applied Physics Division. “We knew that the users at next-generation light sources would need photon beams with exquisite characteristics, which led to highly demanding electron-beam requirements. As LCLS-II was being defined, we had an excellent team already working on a source that could meet those requirements.”

    The lessons learned with APEX inspired several design changes that are incorporated in the LCLS-II injector, such as an improved cooling system to prevent overheating and metal deformations, as well as innovative cleaning processes.

    “We’re looking forward to continued collaboration with Berkeley Lab during commissioning of the gun,” said SLAC’s John Galayda, LCLS-II project director. “Though I am sure we will learn a lot during its first operation at SLAC, Berkeley Lab’s operating experience with APEX has put LCLS-II miles ahead on its way to achieving its performance and reliability objectives.”

    Mike Dunne, LCLS director at SLAC, added, “The performance of the injector gun is a critical component that drives the overall operation of our X-ray laser facility, so we greatly look forward to seeing this system in operation at SLAC. The leap from 120 pulses per second to 1 million per second will be truly transformational for our science program.”

    How it works

    Like a battery, the injector has components called an anode and cathode. These components form a vacuum-sealed central copper chamber known as a radio-frequency accelerating cavity that sends out the electron bunches in a carefully controlled way.

    The cavity is precisely tuned to operate at very high frequencies and is ringed with an array of channels that allow it to be water-cooled, preventing overheating from the radio-frequency currents interacting with copper in the injector’s central cavity.

    7
    A copper cone structure inside the injector gun’s central cavity. (Credit: Marilyn Chung/Berkeley Lab)

    A copper cone structure within its central cavity is tipped with a specially coated and polished slug of molybdenum known as a photocathode. Light from an infrared laser is converted to an ultraviolet (UV) frequency laser, and this UV light is steered by mirrors onto a small spot on the cathode that is coated with cesium telluride (Cs2Te), exciting the electrons.

    These electrons are are formed into bunches and accelerated by the cavity, which will, in turn, connect to the superconducting accelerator. After this electron beam is accelerated to nearly the speed of light, it will be wiggled within a series of powerful magnetic structures called undulator segments, stimulating the electrons to emit X-ray light that is delivered to experiments.

    Precision engineering and spotless cleaning

    Besides the precision engineering that was essential for the injector, Berkeley Lab researchers also developed processes for eliminating contaminants from components through a painstaking polishing process and by blasting them with dry ice pellets.

    The final cleaning and assembly of the injector’s most critical components was performed in filtered-air clean rooms by employees wearing full-body protective clothing to further reduce contaminants – the highest-purity clean room used in the final assembly is actually housed within a larger clean room at Berkeley Lab.

    “The superconducting linear accelerator is extremely sensitive to particulates,” such as dust and other types of tiny particles, Virostek said. “Its accelerating cells can become non-usable, so we had to go through quite a few iterations of planning to clean and assemble our system with as few particulates as possible.”

    8
    Joe Wallig, a mechanical engineering associate, prepares a metal ring component of the injector gun for installation using a jet of high-purity dry ice in a clean room. (Credit: Marilyn Chung/Berkeley Lab)

    The dry ice-based cleaning processes function like sandblasting, creating tiny explosions that cleanse the surface of components by ejecting contaminants. In one form of this cleaning process, Berkeley Lab technicians enlisted a specialized nozzle to jet a very thin stream of high-purity dry ice.

    After assembly, the injector was vacuum-sealed and filled with nitrogen gas to stabilize it for shipment. The injector’s cathodes degrade over time, and the injector is equipped with a “suitcase” of cathodes, also under vacuum, that allows cathodes to be swapped out without the need to open up the device.

    “Every time you open it up you risk contamination,” Virostek explained. Once all of the cathodes in a suitcase are used up, the suitcase must be replaced with a fresh set of cathodes.

    The overall operation and tuning of the injector gun will be remotely controlled, and there is a variety of diagnostic equipment built into the injector to help ensure smooth running.

    Even before the new injector is installed, Berkeley Lab has proposed to undertake a design study for a new injector that could generate electron bunches with more than double the output energy. This would enable higher-resolution X-ray-based images for certain types of experiments.

    Berkeley Lab Contributions to LCLS-II

    John Corlett, Berkeley Lab’s senior team leader, worked closely with the LCLS-II project managers at SLAC and with Berkeley Lab managers to bring the injector project to fruition.

    9
    Steve Virostek, a senior engineer who led the injector gun’s construction, inspects the mounted injector prior to shipment. (Credit: Marilyn Chung/Berkeley Lab)

    “In addition to the injector source, Berkeley Lab is also responsible for the undulator segments for both of the LCLS-II X-ray free-electron laser beamlines, for the accelerator physics modeling that will optimize their performance, and for technical leadership in the low-level radio-frequency controls systems that stabilize the superconducting linear accelerator fields,” Corlett noted.

    James Symons, Berkeley Lab’s associate director for physical sciences, said, “The LCLS-II project has provided a tremendous example of how multiple laboratories can bring together their complementary strengths to benefit the broader scientific community. The capabilities of LCLS-II will lead to transformational understanding of chemical reactions, and I’m proud of our ability to contribute to this important national project.”

    LCLS-II is being built at SLAC with major technical contributions from Argonne National Laboratory, Fermilab, Jefferson Lab, Berkeley Lab, and Cornell University. Construction of LCLS-II is supported by DOE’s Office of Science.

    10
    Members of the LCLS-II injector gun team at Berkeley Lab. (Credit: Marilyn Chung/Berkeley Lab)

    View more photos of the injector gun and related equipment: here and here.

    See the full article here .

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  • richardmitnick 3:06 pm on January 19, 2018 Permalink | Reply
    Tags: , , Fermilab delivers first cryomodule for ultrapowerful X-ray laser at SLAC, , SLAC LCLS-II,   

    From FNAL: “Fermilab delivers first cryomodule for ultrapowerful X-ray laser at SLAC” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    January 19, 2018

    Science contact
    Rich Stanek
    rstanek@fnal.gov
    630-840-3519

    Media contact
    Andre Salles, Fermilab Office of Communication,
    asalles@fnal.gov
    630-840-6733

    A Fermilab team built and tested the first new superconducting accelerator cryomodule for the LCLS-II project, which will be the nation’s only X-ray free-electron laser facility.

    1
    The first cryomodule for SLAC’s LCLS-II X-ray laser departed Fermilab on Jan. 16. Photo: Reidar Hahn

    Earlier this week, scientists and engineers at the U.S. Department of Energy’s Fermilab in Illinois loaded one of the most advanced superconducting radio-frequency cryomodules ever created onto a truck and sent it heading west.

    Today, that cryomodule arrived at the U.S. DOE’s SLAC National Accelerator Laboratory in California, where it will become the first of 37 powering a three-mile-long machine that will revolutionize atomic X-ray imaging. The modules are the product of many years of innovation in accelerator technology, and the first cryomodule Fermilab developed for this project set a world record in energy efficiency.

    These modules, when lined up end to end, will make up the bulk of the accelerator that will power a massive upgrade to the capabilities of the Linac Coherent Light Source at SLAC, a unique X-ray microscope that will use the brightest X-ray pulses ever made to provide unprecedented details of the atomic world. Fermilab will provide 22 of the cryomodules, with the rest built and tested at the U.S. DOE’s Thomas Jefferson National Accelerator Facility in Virginia.

    The quality factor achieved in these components is unprecedented for superconducting radio-frequency cryomodules. The higher the quality factor, the lower the cryogenic load, and the more efficiently the cavity imparts energy to the particle beam. Fermilab’s record-setting cryomodule doubled the quality factor compared to the previous state-of-the-art.

    “LCLS-II represents an important technological step which demonstrates that we can build more efficient and more powerful accelerators,” said Fermilab Director Nigel Lockyer. “This is a major milestone for our accelerator program, for our productive collaboration with SLAC and Jefferson Lab and for the worldwide accelerator community.”

    Today’s arrival is merely the first. From now into 2019, the teams at Fermilab and Jefferson Lab will build the remaining cryomodules, including spares, and scrutinize them from top to bottom, sending them to SLAC only after they pass the rigorous review.

    “It’s safe to say that this is the most advanced machine of its type,” said Elvin Harms, a Fermilab accelerator physicist working on the project. “This upgrade will boost the power of LCLS, allowing it to deliver X-ray laser beams that are 10,000 times brighter than it can give us right now.”

    With short, ultrabright pulses that will arrive up to a million times per second, LCLS-II will further sharpen our view of how nature works at the smallest scales and help advance transformative technologies of the future, including novel electronics, life-saving drugs and innovative energy solutions. Hundreds of scientists use LCLS each year to catch a glimpse of nature’s fundamental processes.

    To meet the machine’s standards, each Fermilab-built cryomodule must be tested in nearly identical conditions as in the actual accelerator. Each large metal cylinder — up to 40 feet in length and 4 feet in diameter — contains accelerating cavities through which electrons zip at nearly the speed of light. But the cavities, made of superconducting metal, must be kept at a temperature of 2 Kelvin (minus 456 degrees Fahrenheit).

    2
    Thirty-seven cryomodules lined end to end — half from Fermilab and half from Jefferson Lab — will make up the bulk of the LCLS-II accelerator. Photo: Reidar Hahn

    To achieve this, ultracold liquid helium flows through pipes in the cryomodule, and keeping that temperature steady is part of the testing process.

    “The difference between room temperature and a few Kelvin creates a problem, one that manifests as vibrations in the cryomodule,” said Genfa Wu, a Fermilab scientist working on LCLS-II. “And vibrations are bad for linear accelerator operation.”

    In initial tests of the prototype cryomodule, scientists found vibration levels that were higher than specification. To diagnose the problem, they used geophones — the same kind of equipment that can detect earthquakes — to rule out external vibration sources. They determined that the cause was inside the cryomodule and made a number of changes, including adjusting the path of the flow of liquid helium. The changes worked, substantially reducing vibration levels — to a 10th of what they were originally — and have been successfully applied to subsequent cryomodules.

    Fermilab scientists and engineers are also ensuring that unwanted magnetic fields in the cryomodule are kept to a minimum, since excessive magnetic fields reduce the operating efficiency.

    “At Fermilab, we are building this machine from head to toe,” Lockyer said. “From nanoengineering the cavity surface to the integration of thousands of complex components, we have come a long way to the successful delivery of LCLS-II’s first cryomodule.”

    Fermilab has tested seven cryomodules, plus one built and previously tested at Jefferson Lab, with great success. Each of those, along with the modules yet to be built and tested, will get its own cross-country trip in the months and years to come.

    Read more about the LCLS-II project in SLAC’s press release.

    This project is supported by DOE’s Office of Science. LCLS is a DOE Office of Science user facility.

    See the full article here .

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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 4:30 pm on December 19, 2017 Permalink | Reply
    Tags: , , CERN Large Hadron Collider, , , , , Large Electron-Positron Collider, , , , , SLAC LCLS-II,   

    From Symmetry: “Machine evolution” 

    Symmetry Mag
    Symmetry

    12/19/17
    Amanda Solliday

    1
    Courtesy of SLAC

    Planning the next big science machine requires consideration of both the current landscape and the distant future.

    Around the world, there’s an ecosystem of large particle accelerators where physicists gather to study the most intricate details of matter.

    These accelerators are engineering marvels. From planning to construction to operation to retirement, their lifespans stretch across decades.

    But to get the most out of their investments of talent and funding, laboratories planning such huge projects have to think even longer-term: What could these projects become in their next lives?

    The following examples show how some of the world’s big physics machines have evolved to stay at the forefront of science and technology.

    Same tunnel, new collisions

    Before CERN research center in Geneva, Switzerland, had its Large Hadron Collider, it had the Large Electron-Positron Collider. LEP was the largest electron-positron collider ever built, occupying a nearly 17-mile circular tunnel dug beneath the border of Switzerland and France. The tunnel took three years to completely excavate and build.

    The first particle beam traveled around the LEP circular collider in 1989. Long before then, the international group of CERN physicists and engineers were already thinking about what CERN’s next machine could be.

    “People were saying, ‘Well, if we do build LEP, then we should make it compatible with the [then-proposed] Large Hadron Collider,’” says James Gillies, a senior communications advisor and member of the strategic planning and evaluation unit at CERN. “If you want to have a future facility, you often have to engage the people who just finished designing one machine to start thinking about the next one.”

    LEP’s designers chose an energy for the collider that would mass-produce Z bosons, fundamental particles discovered by earlier experiments at CERN. The LHC would be a step up from LEP, reaching higher energies that scientists hoped could produce the Higgs boson. In the 1960s, theorists proposed the Higgs as a way to explain the origin of the mass of elementary particles. And the new machine to look for it could be built in the same 17-mile tunnel excavated for LEP.

    Engineers began working on the LHC while LEP was still running. The new machine required enlargements to underground areas—it needed bigger detectors and new experimental halls.

    “That was challenging because these caverns are huge. As they were being excavated, the pressure on the LEP tunnel was reduced and the LEP beamline needed realignment,” Gillies says. “So you constantly had to realign the collider for experiments as you were digging.”

    After LEP reached its highest energy in 2000, it was switched off. The tunnel remained the same, says Gillies, but there were many other changes. Only one of the LEP detectors, DELPHI, remains underground at CERN as a visitors’ point.

    In 2012, LHC scientists announced the discovery of the long-sought Higgs boson. The LHC is planned to continue running until at least 2035, gradually increasing the intensity of its particle collisions. The research and development into the accelerator’s successor is already happening. The possibilities include a higher energy LHC, a compact linear collider or an even larger circular collider.

    2

    Large Electron-Positron Collider
    Location: CERN—Geneva, Switzerland
    First beam: 1989
    Link to LEP Timeline: Timeline
    Courtesy of CERN

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    Large Hadron Collider
    Location: CERN—Geneva, Switzerland
    First beam: 2008
    Link to LHC Timeline: Timeline
    Courtesy of CERN

    High-powered science
    Decades before the LHC came into existence, a suburb of Chicago was home to the most powerful collider in the world: the Tevatron. A series of accelerators at Fermi National Accelerator Laboratory boosted protons and antiprotons to nearly the speed of light. In the final, 4-mile Tevatron ring, the particles reached record energy levels, and more than 1000 superconducting magnets steered them into collisions. Physicists used the Tevatron to make the first direct measurement of the tau neutrino and to discover the top quark, the last observed lepton and quark, respectively, in the Standard Model.

    The Tevatron shut down in 2011 after the LHC came up to speed, but the rest of Fermilab’s accelerator infrastructure was still hard at work powering research in particle physics—particularly on the abundant, mysterious and difficult-to-detect neutrino.

    Starting in 1999, a brand-new, 2-mile circular accelerator called the Main Injector was added to the Fermilab complex to increase the number of Tevatron particle collisions tenfold. It was joined in its tunnel by the Recycler, a permanent magnet ring that stored and cooled antiprotons.

    But before the Main Injector was even completed, scientists had identified a second purpose: producing powerful beams of neutrinos for experiments in Illinois and 500 miles away in Minnesota.

    FNAL/NOvA experiment map

    By 2005, the proton beam circulating in the Main Injector was doing double duty: sending ever-more-intense beams to the Tevatron collider and smashing into a target to produce neutrinos. Following the shutdown of the Tevatron, the Recycler itself was recycled to increase the proton beam power for neutrino research.

    “I’m still amazed at how we are able to use the Recycler. It can be difficult to transition if a machine wasn’t originally built for that purpose,” says Ioanis Kourbanis, the head of the Main Injector department at Fermilab.

    Fermilab’s high-energy neutrino beam is already the most intense in the world, but the laboratory plans to enhance it with future improvements to the Main Injector and the Recycler, and to build a brand-new neutrino beamline.

    Neutrinos almost never interact with matter, so they can pass straight through the Earth on their way to detectors onsite and others several hundred miles away. Scientists hope to learn more about neutrinos and their possible role in shaping our early universe.

    The new beamline will be part of the Long-Baseline Neutrino Facility, which will send neutrinos 800 miles underground to the massive, mile-deep detectors of the Deep Underground Neutrino Experiment.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    Scientists from around the world will use the DUNE data to answer questions about neutrinos, thanks to the repurposed pieces of the Fermilab accelerator complex.

    5

    FNAL Tevatron

    FNAL/Tevatron map


    FNAL/Tevatron DZero detector


    FNAL/Tevatron CDF detector

    Tevatron
    Location: Fermilab—Batavia, Illinois
    First beam: 1983
    Link to Tevatron Timeline: Timeline
    Courtesy of Fermilab

    6

    Neutrinos at the Main Injector (NuMI) beam
    Location: Fermilab—Batavia, Illinois
    First beam: 2004
    Link to Fermilab Timeline: Timeline
    Courtesy of Fermilab

    A monster accelerator

    When physicists first came up with the idea to build a two-mile linear accelerator at what is now called SLAC National Accelerator Laboratory, managed by Stanford University, they called it “Project M” for “Monster.” Engineers began building it from hand-drawn designs. Once completed, the machine was able to accelerate electrons to near the speed of light, producing its first particle beam in May 1966.

    SLAC Campus

    The accelerator’s scientific purpose has gone through several iterations of particle physics experiments over the decades, from fixed-target experiments to the Stanford Linear Collider (the only electron-positron linear collider ever built) to an injector for a circular collider, the Positron-Electron Project.

    These experiments led to the discovery that protons are made of quarks, the first evidence that the charm quark existed (through observations of the J/psi particle, co-discovered with researchers at MIT) and the discovery of the tau lepton.

    In 2009, the lab used the accelerator as the backbone for a different type of science machine—an X-ray free-electron laser, the Linac Coherent Light Source.

    “Looking around, SLAC was the only place in the world with a linear accelerator capable of driving a free-electron laser,” says Claudio Pellegrini, a distinguished professor emeritus of physics at the University of California, Los Angeles and a visiting scientist and consulting professor at SLAC. Pellegrini first proposed the idea to transform SLAC’s linear accelerator.

    The new machine, a DOE Office of Science user facility, would be the world’s first laser of its kind that could produce extremely bright hard X-rays, the high-energy X-rays that let scientists take snapshots of atoms and molecules.

    “Much of the physics and many of the tools learned and developed during the operation of the Stanford Linear Collider were directly applicable to the free electron laser,” says Lia Merminga, head of the accelerator directorate at SLAC. “This was a big factor in the LCLS being commissioned in record time. Without the Stanford Linear Collider experience, this significant body of work would have to be reinvented and reproduced almost from scratch.”

    Little about the accelerator itself needed to change. But to create a free-electron laser, scientists needed to design a new part: an electron gun, a device that generates electrons to be injected into the accelerator. A collaboration of several national labs and UCLA created a new type of electron gun for LCLS, while other national labs helped build undulators, a series of magnets that would wiggle the electrons to create X-rays.

    LCLS used only the last third of SLAC’s original linear accelerator. In part of the remaining section, scientists are developing plasma wakefield and other new particle acceleration techniques.

    For the X-ray laser’s next iteration, LCLS-II, scientists are aiming for an even brighter laser that will fire 1 million pulses per second, allowing them to observe rare and exceptionally transient events.

    SLAC/LCLS II

    To do this, they will need to replace the original copper structures with superconducting technology. The technology is derived from designs for a large International Linear Collider [ILC] proposed to be built in Japan.

    ILC schematic

    “I’m in awe of the foresight of the original builders of SLAC’s linear accelerator,” Merminga adds. “We’ve been able to do so much with this machine, and the end is not yet in sight.”

    7

    Fixed target and collider experiments

    Location: SLAC—Menlo Park, California
    First beam: 1966
    Link to SLAC Timeline: Timeline
    Courtesy of SLAC

    8

    Linac Coherent Light Source
    Location: SLAC—Menlo Park, California
    First beam: 2009
    Link to SLAC Timeline: Timeline
    Courtesy of SLAC

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 6:56 am on November 8, 2017 Permalink | Reply
    Tags: Great Flickr photos, , SLAC LCLS-II,   

    From SLAC: “Photos: Move-in Begins at the LCLS-II Cryoplant” 


    SLAC Lab

    Great images from SLAC for LCLS-II on Flickr, which I cannot copy.

    Flickr Photos: Move-in Begins at the LCLS-II Cryoplant

    Flickr Photos: LCLS-II Feed Caps and End Caps

    SLAC LCLS-II

    See the full article here .

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 5:46 pm on June 20, 2017 Permalink | Reply
    Tags: , , , SLAC LCLS-II, Superconducting undulators, ,   

    From LBNL: “R&D Effort Produces Magnetic Devices to Enable More Powerful X-ray Lasers” 

    Berkeley Logo

    Berkeley Lab

    June 20, 2017
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    Berkeley Lab demonstrates a record-setting magnetic field for a prototype superconducting undulator.

    1
    This Berkeley Lab-developed device, a niobium tin superconducting undulator prototype, set a record in magnetic field strength for a device of its kind. This type of undulator could be used to wiggle electron beams to emit light for a next generation of X-ray lasers.
    (Credit: Marilyn Chung/Berkeley Lab)

    Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Argonne National Laboratory have collaborated to design, build, and test two devices, called superconducting undulators, which could make X-ray free-electron lasers (FELs) more powerful, versatile, compact, and durable.

    X-ray FELs are powerful tools for studying the microscopic structure and other properties of samples, such as proteins that are key to drug design, exotic materials relevant to electronics and energy applications, and chemistry that is central to industrial processes like fuel production.

    The recent development effort was motivated by SLAC National Accelerator Laboratory’s upgrade of its Linac Coherent Light Source (LCLS), the nation’s only X-ray FEL.

    SLAC LCLS-II

    This upgrade, now underway, is known as LCLS-II. All existing X-ray FELS, including both LCLS and LCLS-II, use permanent magnet undulators to generate intense pulses of X-rays. These devices produce X-ray light by passing high-energy bunches of electrons through alternating magnetic fields produced by a series of permanent magnets.

    Superconducting undulators (SCUs) offer another technical solution and are considered among the most promising technologies to improve the performance of the next generation FELs, and of other types of light sources, such as Berkeley Lab’s Advanced Light Source (ALS) and Argonne’s Advanced Photon Source (APS).

    LBNL/ALS

    ANL APS

    SCUs replace the permanent magnets in the undulator with superconducting coils. The prototype SCUs have successfully produced stronger magnetic fields than conventional undulators of the same size. Higher fields, in turn, can produce higher-energy free-electron laser light to open up a broader range of experiments.

    Berkeley Lab’s 1.5-meter-long prototype undulator, which uses a superconducting material known as niobium-tin (Nb3Sn), set a record in magnetic field strength for a device of its design during testing at the Lab in September 2016.

    “This is a much-anticipated innovation,” agreed Wim Leemans, Director, Accelerator Technology and Applied Physics (ATAP) . “Higher performance in a smaller footprint is something that benefits everyone – the laboratories that host the facilities, the funding agencies, and above all, the user community.”

    Argonne’s test of another superconducting material, niobium-titanium, successfully reached its performance goal, and additionally passed a bevy of quality tests. Niobium-titanium has a lower maximum magnetic field strength than niobium-tin, but is further along in its development.

    3
    The superconducting undulator R&D project at Berkeley Lab was a team effort. Among the contributors: (from left) Heng Pan, Jordan Taylor, Soren Prestemon, Ross Schlueter, Diego Arbelaez, Jim Swanson, Ahmet Pekedis, Scott Myers, Tom Lipton, and Xiaorong Wang. (Credit: Marilyn Chung/Berkeley Lab)

    Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Argonne National Laboratory have collaborated to design, build, and test two devices, called superconducting undulators, which could make X-ray free-electron lasers (FELs) more powerful, versatile, compact, and durable.

    X-ray FELs are powerful tools for studying the microscopic structure and other properties of samples, such as proteins that are key to drug design, exotic materials relevant to electronics and energy applications, and chemistry that is central to industrial processes like fuel production.

    The recent development effort was motivated by SLAC National Accelerator Laboratory’s upgrade of its Linac Coherent Light Source (LCLS), the nation’s only X-ray FEL. This upgrade, now underway, is known as LCLS-II. All existing X-ray FELS, including both LCLS and LCLS-II, use permanent magnet undulators to generate intense pulses of X-rays. These devices produce X-ray light by passing high-energy bunches of electrons through alternating magnetic fields produced by a series of permanent magnets.

    Superconducting undulators (SCUs) offer another technical solution and are considered among the most promising technologies to improve the performance of the next generation FELs, and of other types of light sources, such as Berkeley Lab’s Advanced Light Source (ALS) and Argonne’s Advanced Photon Source (APS).

    SCUs replace the permanent magnets in the undulator with superconducting coils. The prototype SCUs have successfully produced stronger magnetic fields than conventional undulators of the same size. Higher fields, in turn, can produce higher-energy free-electron laser light to open up a broader range of experiments.

    Berkeley Lab’s 1.5-meter-long prototype undulator, which uses a superconducting material known as niobium-tin (Nb3Sn), set a record in magnetic field strength for a device of its design during testing at the Lab in September 2016.

    “This is a much-anticipated innovation,” agreed Wim Leemans, Director, Accelerator Technology and Applied Physics (ATAP) . “Higher performance in a smaller footprint is something that benefits everyone – the laboratories that host the facilities, the funding agencies, and above all, the user community.”

    Argonne’s test of another superconducting material, niobium-titanium, successfully reached its performance goal, and additionally passed a bevy of quality tests. Niobium-titanium has a lower maximum magnetic field strength than niobium-tin, but is further along in its development.
    Photo – The superconducting undulator R&D project at Berkeley Lab was a team effort. Among the contributors: (from left) Heng Pan, Jordan Taylor, Soren Prestemon, Ross Schlueter, Diego Arbelaez, Jim Swanson, Ahmet Pekedis, Scott Myers, Tom Lipton, and Xiaorong Wang. (Credit: Marilyn Chung/Berkeley Lab)

    The superconducting undulator R&D project at Berkeley Lab was a team effort. Among the contributors: (from left) Heng Pan, Jordan Taylor, Soren Prestemon, Ross Schlueter, Diego Arbelaez, Jim Swanson, Ahmet Pekedis, Scott Myers, Tom Lipton, and Xiaorong Wang. (Credit: Marilyn Chung/Berkeley Lab)

    “The superconducting technology in general, and especially with the niobium tin, lived up to its promise of being the highest performer,” said Ross Schlueter, Head of the Magnetics Department in Berkeley Lab’s Engineering Division. “We’re very excited about this world record. This device allows you to get a much higher photon energy” from a given electron beam energy.

    “We have expertise here both in free-electron laser undulators, as demonstrated in our role in leading the construction of LCLS-II’s undulators, and in synchrotron undulator development at the ALS,” noted Soren Prestemon, Director of the Berkeley Center for Magnet Technology (BCMT), which brings together the Accelerator Technology and Applied Physics Division (ATAP) and Engineering Division, to design and build a range of magnetic devices for scientific, medical, and other applications.

    “The Engineering Division has a long history of forefront research on undulators, and this work continues that tradition,” states Henrik von der Lippe, Director, Engineering Division.

    Diego Arbelaez, the lead engineer in the development of Berkeley Lab’s device, said earlier work at the Lab in building superconducting undulator prototypes for a different project were useful in informing the latest design, though there were still plenty of challenges.

    Niobium-tin is a brittle material that cannot be drawn into a wire. For practical use, a pliable wire, which contains the components that will form niobium-tin when heat-treated, is used for winding the undulator coils. The full undulator coil is then heat-treated in a furnace at 1,200 degrees Fahrenheit.

    The niobium-tin wire is wound around a steel frame to form tightly wrapped coils in an alternating arrangement. The precision of the winding is critical for the performance of the device. Arbelaez said, “One of the questions was whether you can maintain precision in its winding even though you are going through these large temperature variations.”

    After the heat treatment, the coils are placed in a mold and impregnated with epoxy to hold the superconducting coils in place. To achieve a superconducting state and demonstrate its record-setting performance, the device was immersed in a bath of liquid helium to cool it down to about minus 450 degrees Fahrenheit.

    4
    Ahmet Pekedis, left, and Diego Arbelaez inspect the completed niobium tin undulator prototype. (Credit: Marilyn Chung/Berkeley Lab)

    Another challenge was in developing a fast shutoff to prevent catastrophic failure during an event known as “quenching.” During a quench, there is a sudden loss of superconductivity that can be caused by a small amount of heat generation. Uncontrolled quenching could lead to rapid heating that might damage the niobium-tin and surrounding copper and ruin the device.

    This is a critical issue for the niobium-tin undulators due to the extraordinary current densities they can support. Berkeley Lab’s Marcos Turqueti led the effort to engineer a quench-protection system that can detect the occurrence of quenching within a couple thousandths of a second and shut down its effects within 10 thousandths of a second.

    Arbelaez also helped devise a system to correct for magnetic-field errors while the undulator is in its superconducting state.

    SLAC’s Paul Emma, the accelerator physics lead for LCLS-II, coordinated the superconducting undulator development effort.

    Emma said that the niobium-tin superconducting undulator developed at Berkeley Lab shows potential but may require more extensive continuing R&D than Argonne’s niobium-titanium prototype. Argonne earlier developed superconducting undulators that are in use at its APS, and Berkeley Lab also hopes to add superconducting undulators at its ALS.

    “With superconducting undulators,” Emma said, “you don’t necessarily lower the cost but you get better performance for the same stretch of undulator.”

    5
    A close-up view of the superconducting undulator prototype developed at Berkeley Lab. To construct the undulator, researchers wound a pliable wire in alternating coils around a steel frame. The pliable wire was baked to form a niobium-tin compound that is very brittle but can achieve high magnetic fields when chilled to superconducting temperatures. (Credit: Marilyn Chung/Berkeley Lab)

    A superconducting undulator of an equivalent length to a permanent magnetic undulator could produce light that is at least two to three times – perhaps up to 10 times – more powerful, and could also access a wider range in X-ray wavelengths, Emma said, producing a more efficient FEL.

    Superconducting undulators also have no macroscopic moving parts, so they could conceivably be tuned more quickly with high precision. Superconductors also are far less prone to damage by high-intensity radiation than permanent-magnet materials, a significant issue in high-power accelerators such as those that will be installed for LCLS-II.

    There appears to be a clear path forward to developing superconducting undulators for upgrades of existing and new X-ray free-electron lasers, Emma said, and for other types of light sources.

    “Superconducting undulators will be the technology we go to eventually, whether it’s in the next 10 or 20 years,” he said. “They are powerful enough to produce the light we are going to need – I think it’s going to happen. People know it’s a big enough step, and we’ve got to get there.”

    James Symons, Berkeley Lab’s Associate Director for Physical Sciences, said, “We look forward to building on this effort by furthering our R&D on superconducting undulator systems.

    The Advanced Light Source, Advanced Photon Source, and Linac Coherent Light Source are DOE Office of Science User Facilities. The development of the superconducting undulator prototypes was supported by the DOE’s Office of Science.”

    See the full article here .

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  • richardmitnick 2:11 pm on April 27, 2017 Permalink | Reply
    Tags: Also involved in LCLS II are FNAL JLab and ANL, , LBNL contribution, , SLAC LCLS-II,   

    From LBNL: “Special Delivery: First Shipment of Magnetic Devices for Next-Gen X-Ray Laser” 

    Berkeley Logo

    Berkeley Lab

    April 27, 2017
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    Berkeley Lab is overseeing development of specialized undulators that will produce X-ray light at LCLS-II by wiggling electrons

    1

    2
    The first two undulator segments—devices that will be used to produce X-ray laser beams for a project known as LCLS-II—arrived at SLAC National Accelerator Laboratory in Menlo Park, Calif., on Wednesday. (Credit: SLAC National Accelerator Laboratory)

    The first shipment of powerful magnetic devices for a next-generation laser project arrived at SLAC National Accelerator Laboratory on Wednesday after a nearly 3,000-mile journey from a factory in New York to California in a customized delivery truck.

    The Department of Energy’s Lawrence Berkeley National Laboratory (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 four other DOE national laboratories: Berkeley Lab, Fermilab, Jefferson Lab, and Argonne.

    The two devices that arrived this week to LCLS-II 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.

    3
    Workers at KTC, a company in Buffalo, N.Y., prepare the first powerful magnetic devices known as soft X-ray undulator segments for the cross-country journey to SLAC National Accelerator Laboratory in Menlo Park, Calif. Berkeley Lab is overseeing the development and delivery of these segments for use in the LCLS-II project, an upgrade to SLAC’s X-ray laser. (Credit: Keller Technology Corp./KTC)

    LCLS-II is a major new facility and upgrade to the existing Linac Coherent Light Source [LCLS], a DOE Office of Science User Facility enabling higher performance, new capabilities, and higher capacity for new experiments.

    SLAC/LCLS

    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.

    SLAC/LCLS II schematic

    “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.

    4
    A prototype LCLS-II soft X-ray undulator, which is designed to wiggle electrons, causing them to emit brilliant X-ray light, undergoes magnetic measurements at Berkeley Lab. (Credit: Roy Kaltschmidt/Berkeley Lab)

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

    Berkeley Lab is also 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.

    6
    The APEX electron gun and test beamline at the Advanced Light Source’s Beam Test Facility.

    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.”

    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.”


    This movie introduces LCLS-II, a future X-ray light source. It will generate over 8,000 times more light pulses per second than today’s most powerful X-ray laser, LCLS, and produce an almost continuous X-ray beam. (Credit: SLAC National Accelerator Laboratory)

    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 being 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 now 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.

    Work on the LCLS-II undulators is supported by the DOE Office of Science.

    See the full article here .

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  • richardmitnick 1:45 pm on April 18, 2017 Permalink | Reply
    Tags: , , , Gabriella Carini, How do you catch femtosecond light?, , , , , SLAC LCLS-II,   

    From SLAC: “How do you catch femtosecond light?” 


    SLAC Lab

    1
    Gabriella Carini
    Staff Scientist
    Joined SLAC: 2011
    Specialty: Developing detectors that capture light from X-ray sources
    Interviewed by: Amanda Solliday

    Gabriella Carini enjoys those little moments—after hours and hours of testing in clean rooms, labs and at X-ray beamlines—when she first sees an instrument work.

    She earned her PhD in electronic engineering at the University of Palermo in Italy and now heads the detectors department at the Linac Coherent Light Source (LCLS), the X-ray free-electron laser at SLAC.

    SLAC/LCLS

    Scientists from around the world use the laser to probe natural processes that occur in tiny slivers of time. To see on this timescale, they need a way to collect the light and convert it into data that can be examined and interpreted.

    It’s Carini’s job to make sure LCLS has the right detector equipment at hand to catch the “precious”, very intense laser pulses, which may last only a few femtoseconds.

    When the research heads in new directions, as it constantly does, this requires her to look for fresh technology and turn these ideas into reality.

    When did you begin working with detectors?

    I moved to the United States as a doctoral student. My professor at the time suggested I join a collaboration at Brookhaven National Laboratory, where I started developing gamma ray detectors to catch radioactive materials.

    Radioactive materials give off gamma rays as they decay, and gamma rays are the most energetic photons, or particles of light. The detectors I worked on were made from cadmium zinc telluride, which has very good stopping power for highly energetic photons. These detectors can identify radioactive isotopes for security—such as the movement of nuclear materials—and contamination control, but also gamma rays for medical and astrophysical observations.

    We had some medical projects going on at the time, too, with detectors that scan for radioactive tracers used to map tissues and organs with positron emission tomography.

    From gamma ray detectors, I then moved to X-rays, and I began working on the earliest detectors for LCLS.

    How do you explain your job to someone outside the X-ray science community?

    I say, “There are three ingredients for an experiment—the source, the sample and the detector.”

    You need a source of light that illuminates your sample, which is the problem you want to solve or investigate. To understand what is happening, you have to be able to see the signal produced by the light as it interacts with the sample. That’s where the detector comes in. For us, the detector is like the “eyes” of the experimental set-up.

    What do you like most about your work?

    2

    There’s always a way we can help researchers optimize their experiments, tweak some settings, do more analysis and correction.

    This is important because scientists are going to encounter a lot of different types of detectors if they work at various X-ray facilities.

    I like to have input from people who are running the experiments. Because I did experiments myself as a graduate student, I’m very sensitive to whether a system is user-friendly. If you don’t make something that researchers can take the best advantage of, then you didn’t do your job fully.

    And detectors are never perfect, no matter which one you buy or build.

    There are a lot of people who have to come together to make a detector system. It’s not one person’s work. It’s many, many people with lots of different expertise. You need to have lots of good interpersonal skills.

    What are some of the challenges of creating detectors for femtosecond science?

    In more traditional X-ray sources the photons arrive distributed over time, one after the other, but when you work with ultrafast laser pulses like the ones from LCLS, all your information about a sample arrives in a few femtoseconds. Your detector has to digest this entire signal at once, process the information and send it out before another pulse comes. This requires deep understanding of the detector physics and needs careful engineering. You need to optimize the whole signal chain from the sensor to the readout electronics to the data transmission.

    We also have mechanical challenges because we have to operate in very unusual conditions: intense optical lasers, injectors with gas and liquids, etc. In many cases we need to use special filters to protect the detectors from these sources of contamination.

    4
    And often, you work in vacuum. With “soft” or low-energy X-rays, they are absorbed very quickly in air. Your entire system has to be vacuum-compatible. With many of our substantial electronics, this requires some care.

    So there are lots of things to take into account. Those are just a few examples. It’s very complicated and can vary quite a bit from experiment to experiment.

    Is there a new project you are really excited about?

    All of LCLS-II—this fills my life! We’re coming up with new ideas and new technologies for SLAC’s next X-ray laser, which will have a higher firing rate—up to a million pulses per second. For me, this is a multidimensional puzzle. Every science case and every instrument has its own needs and we have to find a route through the many options and often-competing parameters to achieve our goals.

    X-ray free-electron lasers are a big driver for detector development. Ten years ago, no one would have talked about X-ray cameras delivering 10,000 pictures per second. The new X-ray lasers are really a game-changer in developing detectors for photon science, because they require detectors that are just not readily available.

    LCLS-II will be challenging, but it’s exciting. For me, it’s thinking about what we can do now for the very first day of operation. And while doing that, we need to keep pushing the limits of what we have to do next to take full advantage of our new machine.

    6

    SLAC LCLS-II

    See the full article here .

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  • richardmitnick 3:55 pm on April 17, 2017 Permalink | Reply
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    From SLAC: “SLAC’s X-ray Laser Glimpses How Electrons Dance with Atomic Nuclei in Materials” 


    SLAC Lab

    September 22, 2016

    Studies Could Help Design and Control Materials with Intriguing Properties, Including Novel Electronics, Solar Cells and Superconductors.

    From hard to malleable, from transparent to opaque, from channeling electricity to blocking it: Materials come in all types. A number of their intriguing properties originate in the way a material’s electrons “dance” with its lattice of atomic nuclei, which is also in constant motion due to vibrations known as phonons.

    This coupling between electrons and phonons determines how efficiently solar cells convert sunlight into electricity. It also plays key roles in superconductors that transfer electricity without losses, topological insulators that conduct electricity only on their surfaces, materials that drastically change their electrical resistance when exposed to a magnetic field, and more.

    At the Department of Energy’s SLAC National Accelerator Laboratory, scientists can study these coupled motions in unprecedented detail with the world’s most powerful X-ray laser, the Linac Coherent Light Source (LCLS). LCLS is a DOE Office of Science User Facility.

    SLAC/LCLS

    1
    An illustration shows how laser light excites electrons (white spheres) in a solid material, creating vibrations in its lattice of atomic nuclei (black and blue spheres). SLAC’s LCLS X-ray laser reveals the ultrafast “dance” between electrons and vibrations that accounts for many important properties of materials. (SLAC National Accelerator Laboratory)

    “It has been a long-standing goal to understand, initiate and control these unusual behaviors,” says LCLS Director Mike Dunne. “With LCLS we are now able to see what happens in these materials and to model complex electron-phonon interactions. This ability is central to the lab’s mission of developing new materials for next-generation electronics and energy solutions.”

    LCLS works like an extraordinary strobe light: Its ultrabright X-rays take snapshots of materials with atomic resolution and capture motions as fast as a few femtoseconds, or millionths of a billionth of a second. For comparison, one femtosecond is to a second what seven minutes is to the age of the universe.

    Two recent studies made use of these capabilities to study electron-phonon interactions in lead telluride, a material that excels at converting heat into electricity, and chromium, which at low temperatures has peculiar properties similar to those of high-temperature superconductors.

    Turning Heat into Electricity and Vice Versa

    Lead telluride, a compound of the chemical elements lead and tellurium, is of interest because it is a good thermoelectric: It generates an electrical voltage when two opposite sides of the material have different temperatures.

    “This property is used to power NASA space missions like the Mars rover Curiosity and to convert waste heat into electricity in high-end cars,” says Mariano Trigo, a staff scientist at the Stanford PULSE Institute and the Stanford Institute for Materials and Energy Sciences (SIMES), both joint institutes of Stanford University and SLAC. “The effect also works in the opposite direction: An electrical voltage applied across the material creates a temperature difference, which can be exploited in thermoelectric cooling devices.”

    Mason Jiang, a recent graduate student at Stanford, PULSE and SIMES, says, “Lead telluride is exceptionally good at this. It has two important qualities: It’s a bad thermal conductor, so it keeps heat from flowing from one side to the other, and it’s also a good electrical conductor, so it can turn the temperature difference into an electric current. The coupling between lattice vibrations, caused by heat, and electron motions is therefore very important in this system. With our study at LCLS, we wanted to understand what’s naturally going on in this material.”

    In their experiment, the researchers excited electrons in a lead telluride sample with a brief pulse of infrared laser light, and then used LCLS’s X-rays to determine how this burst of energy stimulated lattice vibrations.

    2
    This illustration shows the arrangement of lead and tellurium atoms in lead telluride, an excellent thermoelectric that efficiently converts heat into electricity and vice versa. In its normal state (left), lead telluride’s structure is distorted and has a relatively large degree of lattice vibrations (blurring). When scientists hit the sample with a laser pulse, the structure became more ordered (right). The results elucidate how electrons couple with these distortions – an interaction that is crucial for lead telluride’s thermoelectric properties. (SLAC National Accelerator Laboratory)

    “Lead telluride sits at the precipice of a coupled electronic and structural transformation,” says principal investigator David Reis from PULSE, SIMES and Stanford. “It has a tendency to distort without fully transforming – an instability that is thought to play an important role in its thermoelectric behavior. With our method we can study the forces involved and literally watch them change in response to the infrared laser pulse.”

    The scientists found that the light pulse excites particular electronic states that are responsible for this instability through electron-phonon coupling. The excited electrons stabilize the material by weakening certain long-range forces that were previously associated with the material’s low thermal conductivity.

    “The light pulse actually walks the material back from the brink of instability, making it a worse thermoelectric,” Reis says. “This implies that the reverse is also true – that stronger long-range forces lead to better thermoelectric behavior.”

    The researchers hope their results, published July 22 in Nature Communications, will help them find other thermoelectric materials that are more abundant and less toxic than lead telluride.

    Controlling Materials by Stimulating Charged Waves

    The second study looked at charge density waves – alternating areas of high and low electron density across the nuclear lattice – that occur in materials that abruptly change their behavior at a certain threshold. This includes transitions from insulator to conductor, normal conductor to superconductor, and from one magnetic state to another.

    These waves don’t actually travel through the material; they are stationary, like icy waves near the shoreline of a frozen lake.

    “Charge density waves have been observed in a number of interesting materials, and establishing their connection to material properties is a very hot research topic,” says Andrej Singer, a postdoctoral fellow in Oleg Shpyrko’s lab at the University of California, San Diego. “We’ve now shown that there is a way to enhance charge density waves in crystals of chromium using laser light, and this method could potentially also be used to tweak the properties of other materials.”

    This could mean, for example, that scientists might be able to switch a material from a normal conductor to a superconductor with a single flash of light. Singer and his colleagues reported their results on July 25 in Physical Review Letters.

    The research team used the chemical element chromium as a simple model system to study charge density waves, which form when the crystal is cooled to about minus 280 degrees Fahrenheit. They stimulated the chilled crystal with pulses of optical laser light and then used LCLS X-ray pulses to observe how this stimulation changed the amplitude, or height, of the charge density waves.

    “We found that the amplitude increased by up to 30 percent immediately after the laser pulse,” Singer says. “The amplitude then oscillated, becoming smaller and larger over a period of 450 femtoseconds, and it kept going when we kept hitting the sample with laser pulses. LCLS provides unique opportunities to study such process because it allows us to take ultrafast movies of the related structural changes in the lattice.”

    Based on their results, the researchers suggested a mechanism for the amplitude enhancement: The light pulse interrupts the electron-phonon interactions in the material, causing the lattice to vibrate. Shortly after the pulse, these interactions form again, which boosts the amplitude of the vibrations, like a pendulum that swings farther out when it receives an extra push.

    A Bright Future for Studies of the Electron-Phonon Dance

    Studies like these have a high priority in solid-state physics and materials science because they could pave the way for new materials and provide new ways to control material properties.

    With its 120 ultrabright X-ray pulses per second, LCLS reveals the electron-phonon dance with unprecedented detail. More breakthroughs in the field are on the horizon with LCLS-II – a next-generation X-ray laser under construction at SLAC that will fire up to a million X-ray flashes per second and will be 10,000 times brighter than LCLS.

    “LCLS-II will drastically increase our chances of capturing these processes,” Dunne says. “Since it will also reveal subtle electron-phonon signals with much higher resolution, we’ll be able to study these interactions in much greater detail than we can now.”

    Other research institutions involved in the studies were University College Cork, Ireland; Imperial College London, UK; Duke University; Oak Ridge National Laboratory; RIKEN Spring-8 Center, Japan; University of Tokyo, Japan; University of Michigan; and University of Kiel, Germany. Funding sources included DOE Office of Science; Science Foundation Ireland; Volkswagen Foundation, Germany; and Federal Ministry of Education and Research, Germany. Preliminary X-ray studies on lead telluride were performed at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), a DOE Office of Science User Facility, and at the Spring-8 Angstrom Compact Free-electron Laser (SACLA), Japan.

    SLAC/SSRL

    SACLA Free-Electron Laser Riken Japan


    his movie introduces LCLS-II, a future light source at SLAC. It will generate over 8,000 times more light pulses per second than today’s most powerful X-ray laser, LCLS, and produce an almost continuous X-ray beam that on average will be 10,000 times brighter. (SLAC National Accelerator Laboratory)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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