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  • richardmitnick 8:43 pm on November 3, 2021 Permalink | Reply
    Tags: "Fermilab sees record performance from next-generation accelerator component", , DOE's Thomas Jefferson National Facility (US), , , SLAC LCLS-II, SLAC LCLS-II-HE, Superconducting radio-frequency cryomodules, Undulators for LCLS-II   

    From DOE’s Fermi National Accelerator Laboratory (US) : “Fermilab sees record performance from next-generation accelerator component” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From DOE’s Fermi National Accelerator Laboratory (US) , an enduring source of strength for the US contribution to scientific research worldwide.

    November 3, 2021
    Lauren Biron
    Mary Magnuson

    For several years, three U.S. Department of Energy national labs have worked together to further improve state-of-the-art particle accelerator technology. First tests of a prototype built at Fermi National Accelerator Laboratory show the effort has paid off, with a new component setting records.

    The technology under development is called a superconducting radio-frequency cryomodule, a high-tech piece of equipment that efficiently speeds up particles. It is a key building block of modern particle accelerators and X-ray lasers. All supported by the DOE Office of Science, Fermilab, DOE’s Thomas Jefferson National Facility (US) and DOE’s SLAC National Accelerator Laboratory (US) have pooled their expertise for research and development on cryomodules that will enhance SLAC’s X-ray laser, known as the Linac Coherent Light Source.


    Assembly of vCM cold mass prior to insertion into the cryomodule vacuum vessel. Photo: APS-TD process engineering group.

    LCLS produces very bright X-ray beams used to provide researchers insights into the atomic structures of cells, materials and biochemical pathways. An upgrade of LCLS to LCLS-II is currently underway.


    The cryomodules now in development will be part of a future high-energy update, called LCLS-II-HE, that will enable even more precise atomic X-ray mapping.

    Researchers in biomedical and materials science fields can use LCLS-II and LCLS-II-HE, for example, to study how energy flows in tiny molecules and biochemical systems; how light penetrates and interacts with synthetic materials; and how materials might behave in extreme environments. Importantly, scientists also can use LCLS technology to study the properties of electric fields and how factors such as pressure and magnetism might govern particle interactions.

    vCM in the cantilever fixture for insertion of the coldmass into the vacuum vessel. Photo: APS-TD process engineering group.

    To produce X-rays, LCLS-II accelerates electrons using superconducting radio-frequency technology. After reaching close to the speed of light, the electrons fly through a series of magnets, called an undulator, which forces them to travel a zigzag path and give off energy in the form of X-rays that are then used for research.

    Magnets called undulators stretch roughly 100 meters down a tunnel at SLAC National Accelerator Laboratory, with one side (right) producing hard x-rays and the other soft x-rays.Credit: SLAC National Accelerator Laboratory.

    From prototype to production

    The high-energy upgrade of LCLS-II is the solution to a seemingly impossible task. Researchers wanted to double the energy of the X-ray laser, but the upgrade has to be squeezed into a relatively small area between the existing accelerator and another experiment. Current state-of-the-art technology would have required too much room — so the teams had to invent a way to pack more particle punch into their equipment.

    Accelerator experts improved the cryomodules in several ways. They used a process called “nitrogen doping” to optimize the molecular makeup of the walls of the superconducting accelerator cavities, the components that accelerate the particle beam. They also developed new procedures to assemble and finish the components. Improving the cleanliness reduces unwanted effects from any contamination on the surface, including errant dust particles.

    Fermilab’s prototype is a “verification cryomodule.” It’s proof that the design works as expected, the improved cryomodules will successfully fit in the constrained space, and that final production can begin. It’s a strong start to the upgrade that will take place over the next several years and will require 24 new cryomodules: 13 produced at Fermilab and 11 at Jefferson Lab. Researchers improved the cryomodules far beyond current specifications, and the new equipment should result in a 30 percent improvement to LCLS-II’s performance.

    “Structurally, if you’re looking at the cryomodules from the outside, you won’t be able to tell the difference,” said John Hogan, senior team lead at Jefferson Lab. “But if we’re able to maintain that test performance throughout the whole production, it will give the machine much more energy.”

    Experts pay attention to quality factor, called Q0, which measures a cryomodule’s efficiency — basically, how much excess heat it generates. Superconducting cavities generate about 10,000 times less heat than normal conducting cavities made out of copper. But they have to be kept at cryogenic temperatures (usually around 2 Kelvin, or negative 456 degrees Fahrenheit), requiring a cryogenic plant. To keep the cryogenic requirements reasonable, many accelerators are operated in a “pulsed mode,” with pauses between pulses to reduce the cryogenic load. The nitrogen doping process increases the Q0 so much that it allows the cryomodules in LCLS-II to operate at full tilt without stopping, a feature called “continuous wave mode.”

    The verification cryomodule achieved a record in this continuous mode; electrons passing through the module will have their energy increased by an incredible 200 million electronvolts. The rapid acceleration within a single cryomodule is what will enable the high-energy LCLS-II to reach higher energies in a shorter distance while using fewer cryomodules. The team was also able to maintain the high-quality factor, meaning faster acceleration with minimal excess heat.

    Fermilab senior team lead Tug Arkan said the prime focus of the high-energy upgrade is quality and performance, building on the labs’ experience working together. “For LCLS-II, we designed; we procured parts; we assembled the parts into the cryomodules; we tested the cryomodules; and then we successfully delivered them to SLAC,” said Arkan. “We are starting LCLS-II-HE with the proven success from LCLS-II experience. We will leverage from our successes and also from our unwanted outcomes and adapt the lessons learned to LCLS-II-HE.”

    Jefferson Lab and Fermilab are now assembling the needed cryomodules, which should be complete in 2024. The equipment will be shipped to SLAC and stored until scientists are ready to move them into their positions at the end of the LCLS-II accelerator chain.

    The vCM at the Fermilab Cryomodule Test Facility. Photo: APS-TD process engineering group.

    Once the team at SLAC installs and commissions the LCLS-II-HE, researchers in everything from biomedical science and molecular physics to renewable energy will find the facility useful.

    “LCLS-II-HE will enable higher X-ray energies and better tools and capabilities for the science community,” said Greg Hays, the LCLS-II-HE project director at SLAC. “Increased gradient with reduced heat loads will cut the number of required liquid helium refrigeration plants in half and reduced the length of the overall accelerator, allowing it more than double the energy of LCLS-II by making it only 50 percent longer.”

    The advances in cryomodule fabrication, installation and operation will also be useful for future particle accelerators both big and small. Many particle accelerators use the same superconducting radio-frequency technology as LCLS-II to accelerate particles, so applying the engineering principles from the LCLS-II-HE upgrade will allow other research teams to create high-performing accelerator cryomodules that create little excess heat and can operate efficiently.

    “Higher-gradient performance with lower heat generation will dramatically improve future particle accelerators,” Hays said. “It translates to lower construction and operation costs.”

    See the full article here.


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    Fermi National Accelerator Laboratory (US), located just outside Batavia, Illinois, near Chicago, is a Department of Energy (US) national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

    Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

    In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE (Micro Booster Neutrino Experiment), NOνA (NuMI Off-Axis νe Appearance) and SeaQuest.

    Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment).

    The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year. SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector. In 2017, the ICARUS neutrino experiment was moved from CERN to Fermilab.

    In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.
    Asteroid 11998 Fermilab is named in honor of the laboratory. Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

    The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.

    After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.
    The later directors include:

    John Peoples, 1989 to 1996
    Michael S. Witherell, July 1999 to June 2005
    Piermaria Oddone, July 2005 to July 2013
    Nigel Lockyer, September 2013 to the present

    Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid.

    DOE’s Fermi National Accelerator Laboratory(US) campus .

    DOE’s Fermi National Accelerator Laboratory(US)/MINERvA Reidar Hahn.

    DOE’s Fermi National Accelerator Laboratory(US) DAMIC | Fermilab Cosmic Physics Center.

    DOE’s Fermi National Accelerator Laboratory(US) Muon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles..

    DOE’s Fermi National Accelerator Laboratory(US) Short-Baseline Near Detector under construction.

    DOE’s Fermi National Accelerator Laboratory(US) Mu2e solenoid

    Dark Energy Camera [DECam] built at DOE’s Fermi National Accelerator Laboratory(US).

    Fermi National Accelerator Laboratory DUNE/LBNF experiment (US) Argon tank at Sanford Underground Research Facility(US)

    DOE’s Fermi National Accelerator Laboratory (US) MicrobooNE

    FNAL MicroBooNE’s time projection chamber

    FNAL Don Lincoln.

    DOE’s Fermi National Accelerator Laboratory(US)/MINOS.

    DOE’s Fermi National Accelerator Laboratory(US) Cryomodule Testing Facility.

    DOE’s Fermi National Accelerator Laboratory(US) MINOS Far Detector.

    FNAL DUNE LBNF (US) from FNAL to SURF Lead, South Dakota, USA .

    European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] (CH) ProtoDune.

    DOE’s Fermi National Accelerator Laboratory(US)/NOvA experiment map .

    DOE’s Fermi National Accelerator Laboratory(US) NOvA Near Detector at Batavia IL, USA .

    DOE’s Fermi National Accelerator Laboratory(US) ICARUS.

    DOE’s Fermi National Accelerator Laboratory(US) Holometer.

    DOE’s Fermi National Accelerator Laboratory(US) LArIAT.

    DOE’s Fermi National Accelerator Laboratory(US) ICEBERG particle detector.

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  • richardmitnick 4:12 pm on July 25, 2021 Permalink | Reply
    Tags: "This is the first mini particle accelerator to power a laser", , , , Physicists in China used a small “plasma wakefield accelerator” to power a type of laser called a free-electron laser (FEL)., , Shanghai Institute of Optics and Fine Mechanics-[http://english.siom.cas.cn/] (SIOM) (CN), SLAC LCLS-II,   

    From Shanghai Institute of Optics and Fine Mechanics via Science Magazine: “This is the first mini particle accelerator to power a laser” 


    From Shanghai Institute of Optics and Fine Mechanics


    Science Magazine

    Jul. 25, 2021
    Adrian Cho


    From the laser and gas target (left) to the undulators (blue) and electromagnetic spectrometer (right), the novel free-electron laser measures just 12 meters in length. Credit: Shanghai Institute of Optics and Fine Mechanics (CN).

    For 2 decades, physicists have strived to miniaturize particle accelerators—the huge machines that serve as atom smashers and x-ray sources. That effort just took a big step, as physicists in China used a small “plasma wakefield accelerator” to power a type of laser called a free-electron laser (FEL). The 12-meter-long FEL isn’t nearly as good as its kilometers-long predecessors. Still, other researchers say the experiment marks a major advance in mini accelerators.

    “A lot of [scientists] will be looking at this like, ‘Yeah, that’s very impressive!’” says Jeroen van Tilborg, a laser-plasma physicist at the DOE’s Lawrence Berkeley National Laboratory (US) who was not involved in the work. Ke Feng, a physicist at the Shanghai Institute of Optics and Fine Mechanics (SIOM) who worked on the new FEL, isn’t claiming it’s ready for applications. “Making such devices useful and miniature is always our goal,” Feng says, “but there is still a lot of work to do.”

    Particle accelerators are workhorses in myriad fields of science, blasting out fundamental particles and generating intense beams of x-rays for studies of biomolecules and materials. Such accelerators stretch kilometers in length and cost $1 billion or more. That’s because within a conventional accelerator, charged particles such as electrons can gain energy only so quickly. Grouped in compact bunches, the particles zip through a vacuum pipe and pass through cavities that resonate with microwaves. Much as an ocean wave propels a surfer, these microwaves push the electrons and increase their energy. However, if the oscillating electric field in the microwaves grows too strong, it will set off damaging sparks. So, the particles can gain a maximum of about 100 megaelectron volts (MeV) of energy per meter of cavity.

    To accelerate particles in shorter distances, physicists need stronger electric fields. Firing a pulse of laser light into a gas such as helium is one way to generate them. The light rips electrons from the atoms, creating a tsunami of ionization that moves through the gas, followed by a wake of rippling electrons that produces an extremely strong electric field. That wakefield can scoop up electrons and accelerate them to 1000 MeV in just a few centimeters.

    Physicists hoping to harness wakefields have shown they can generate very short, intense bursts of electrons. But within a burst, the energies of those electrons typically vary by a few percent, too much for most practical applications. Now, SIOM physicist Wentao Wang, Feng, and colleagues have improved the output of their plasma wakefield accelerator enough to do something potentially useful with it: power an FEL.

    In an FEL, physicists fire electrons down a vacuum pipe and through a line devices called undulators. Within an undulator, small magnets above and below the beam pipe lined up like teeth, with the north poles of neighboring magnets alternating up and down. As electrons pass through the undulators, the rippled magnetic field shakes them back and forth, causing them to emit light. As the light builds up and travels along with the bunch of electrons, it pushes back on the electrons and separates them into sub-bunches that then radiate in concert to amplify the light into a laser beam.

    The world’s first x-ray laser, at SLAC National Accelerator Laboratory, is an FEL powered by the lab’s famous 3-kilometer long linear accelerator.

    Researchers in Europe and Japan have also built large x-ray FELs. But by shooting the electron beam from their plasma wakefield accelerator through a chain of three 1.5-meter-long undulators, the SIOM team has made an FEL small enough to fit into a long room.

    To make that possible, SIOM physicists had to shrink the spread in the electrons’ energy to 0.5%. They succeeded by optimizing the laser and the gas target to better control the electrons’ acceleration send them more smoothly down the vacuum pipe, Wang says. Teams in the United States and Europe have explored more complex schemes for filtering out electrons of a specific energy, but the SIOM team took a simpler approach, van Tilborg says. “Everything is just a little better optimized,” he says.

    Others had used plasma wakefield accelerators to coax light out of undulators before. But Wang and colleagues demonstrated amplification, showing the light’s intensity increases 100-fold in the third undulator, they report this week in Nature. “This a huge step forward,” says Agostino Marinelli, an accelerator physicist at DOE’s SLAC National Accelerator Laboratory (US).

    The tiny FEL is a far cry from its bigger brethren, which generate beams billions of times brighter than other x-ray sources, with an energy spread as low as 0.1%. The new FEL produces much fainter pulses of longer wavelength ultraviolet light with an energy spread of 2%. SLAC researchers are also upgrading the LCLS to produce millions of pulses per second; the novel FEL can produce 5 per second.

    Reaching x-ray wavelengths with the device will be difficult, Marinelli predicts. “These are very impressive results, but I would be very careful of extrapolating this to x-ray energies,” Still, the SIOM team says that’s their goal. “It is hard to say how long it will take to reach the hard x-ray wavelengths, maybe a decade or longer,” says Ruxin Li, an SIOM physicist and team member. “We look forward to that day.”

    See the full article here.


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  • richardmitnick 4:38 pm on September 15, 2020 Permalink | Reply
    Tags: "Upgraded X-ray laser shows its soft side", , , SLAC LCLS-II, ,   

    From SLAC National Accelerator Lab: “Upgraded X-ray laser shows its soft side” 

    From SLAC National Accelerator Lab


    From phys.org

    September 15, 2020
    Ali Sundermier

    The second phase of a major upgrade project is now online at the Linac Coherent Light Source (LCLS), the pioneering X-ray free-electron laser at Department of Energy’s SLAC National Accelerator Laboratory. On September 12, scientists ushered an electron beam through a new undulator to produce “soft” X-rays. This follows the upgraded facility’s first light in July, produced with another undulator that generates “hard” X-rays.

    Undulators, integral to X-ray free electron lasers like LCLS, use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. Hard X-rays, which are more energetic, allow researchers to image materials and biological systems at the atomic level. Soft X-rays can capture how energy flows between atoms and molecules, tracking chemistry in acton and offering insights into new energy technologies.

    The new soft X-ray undulator, the second major piece of the LCLS-II upgrade project to fall into place, was designed and built by DOE’s Lawrence Berkeley National Laboratory and installed at SLAC over the past 18 months. While LCLS isn’t the first facility to house more than one undulator, it will be the only one capable of shining both beams on the same sample simultaneously, expanding the scientific reach of the X-ray laser.

    The soft X-ray undulator will produce X-ray pulses that last for less than a millionth of a billionth of a second, allowing scientists to investigate quantum and chemical systems more directly than ever before. These ultrashort pulses will soon be put to work at the new Time-resolved atomic, Molecular and Optical Science (TMO) instrument, the first of the LCLS-II era. There, it will allow scientists to investigate—at the quantum level—fundamental phenomena central to complex processes such as photosynthesis, quantum computing, and the forming and breaking of bonds that govern all chemical reactions.

    When LCLS-II is completed in the next two years, it will increase the X-ray laser’s average power by thousands of times, producing up to a million pulses per second compared to 120 per second today. The final step is currently being installed: a brand new accelerator that uses cryogenic superconducting technology to ramp up to these never-before-achieved repetition rates.

    A screenshot showcasing the X-ray beam produced with LCLS using the new soft X-ray undulator. Credit: SLAC National Accelerator Laboratory.

    See the full article here .

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    SLAC National Accelerator Lab.


    SLAC/LCLS II projected view.

    SLAC LCLS-II Undulators The Linac Coherent Light Source’s new undulators each use an intricately tuned series of magnets to convert electron energy into intense bursts of X-rays. The “soft” X-ray undulator stretches for 100 meters on the left side of this hall, with the “hard” x-ray undulator on the right. Credit: Alberto Gamazo/SLAC National Accelerator Laboratory.

    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.

    SSRL and LCLS are DOE Office of Science user facilities.

  • richardmitnick 10:18 am on August 12, 2019 Permalink | Reply
    Tags: , , , Cryomodules and Cavities, Fermilab modified a cryomodule design from DESY in Germany, , , , LCLS-II will provide a staggering million pulses per second., Lined up end to end 37 cryomodules will power the LCLS-II XFEL., , , , SLAC LCLS-II, SLAC’s linear particle accelerator, ,   

    From Fermi National Accelerator Lab: “A million pulses per second: How particle accelerators are powering X-ray lasers” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    August 12, 2019
    Caitlyn Buongiorno

    About 10 years ago, the world’s most powerful X-ray laser — the Linac Coherent Light Source — made its debut at SLAC National Accelerator Laboratory. Now the next revolutionary X-ray laser in a class of its own, LCLS-II, is under construction at SLAC, with support from four other DOE national laboratories.


    Researchers in biology, chemistry and physics will use LCLS-II to probe fundamental pieces of matter, creating 3-D movies of complex molecules in action, making LCLS-II a powerful, versatile instrument at the forefront of discovery.

    The project is coming together thanks largely to a crucial advance in the fields of particle and nuclear physics: superconducting accelerator technology. DOE’s Fermilab and Thomas Jefferson National Accelerator Facility are building the superconducting modules necessary for the accelerator upgrade for LCLS-II.

    SLAC National Accelerator Laboratory is upgrading its Linac Coherent Light Source, an X-ray laser, to be a more powerful tool for science. Both Fermilab and Thomas Jefferson National Accelerator Facility are contributing to the machine’s superconducting accelerator, seen here in the left part of the diagram. Image: SLAC

    A powerful tool for discovery

    Inside SLAC’s linear particle accelerator today, bursts of electrons are accelerated to energies that allow LCLS to fire off 120 X-ray pulses per second. These pulses last for quadrillionths of a second – a time scale known as a femtosecond – providing scientists with a flipbook-like look at molecular processes.

    “Over time, you can build up a molecular movie of how different systems evolve,” said SLAC scientist Mike Dunne, director of LCLS. “That’s proven to be quite remarkable, but it also has a number of limitations. That’s where LCLS-II comes in.”

    Using state-of-the-art particle accelerator technology, LCLS-II will provide a staggering million pulses per second. The advance will provide a more detailed look into how chemical, material and biological systems evolve on a time scale in which chemical bonds are made and broken.

    To really understand the difference, imagine you’re an alien visiting Earth. If you take one image a day of a city, you would notice roads and the cars that drive on them, but you couldn’t tell the speed of the cars or where the cars go. But taking a snapshot every few seconds would give you a highly detailed picture of how cars flow through the roads and would reveal phenomena like traffic jams. LCLS-II will provide this type of step-change information applied to chemical, biological and material processes.

    To reach this level of detail, SLAC needs to implement technology developed for particle physics – superconducting acceleration cavities – to power the LCLS-II free-electron laser, or XFEL.

    This is an illustration of the electron accelerator of SLAC’s LCLS-II X-ray laser. The first third of the copper accelerator will be replaced with a superconducting one. The red tubes represent cryomodules, which are provided by Fermilab and Jefferson Lab. Image: SLAC

    Accelerating science

    Cavities are structures that impart energy to particle beams, accelerating the particles within them. LCLS-II, like modern particle accelerators, will take advantage of superconducting radio-frequency cavity technology, also called SRF technology. When cooled to 2 Kelvin, superconducting cavities allow electricity to flow freely, without any resistance. Like reducing the friction between a heavy object and the ground, less electrical resistance saves energy, allowing accelerators to reach higher power for less cost.

    “The SRF technology is the enabling step for LCLS-II’s million pulses per second,” Dunne said. “Jefferson Lab and Fermilab have been developing this technology for years. The core expertise to make LCLS-II possible lives at these labs.”

    Fermilab modified a cryomodule design from DESY, in Germany, and specially prepared the cavities to draw the record-setting performance from the cavities and cryomodules that will be used for LCLS-II.

    The cylinder-shaped cryomodules, about a meter in diameter, act as specialized containers for housing the cavities. Inside, ultracold liquid helium continuously flows around the cavities to ensure they maintain the unwavering 2 Kelvin essential for superconductivity. Lined up end to end, 37 cryomodules will power the LCLS-II XFEL.

    See the full here.


    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

    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 1:05 pm on May 31, 2019 Permalink | Reply
    Tags: "SLAC fires up electron gun for LCLS-II X-ray laser upgrade", , , , SLAC LCLS-II   

    From SLAC National Accelerator Lab: “SLAC fires up electron gun for LCLS-II X-ray laser upgrade” 

    From SLAC National Accelerator Lab

    May 30, 2019
    Manuel Gnida

    Image of the first beam of photoelectrons for SLAC’s next-generation LCLS-II X-ray laser. (SLAC National Accelerator Laboratory)

    Crews at the Department of Energy’s SLAC National Accelerator Laboratory have powered up a new electron gun, a key component of the lab’s upgrade of its Linac Coherent Light Source (LCLS) X-ray laser, and last night it fired its first electrons.

    Located at the front end of the next-generation machine known as LCLS-II, the gun is part of what is called an injector, which will generate a nearly continuous stream of electrons to drive the production of powerful X-ray beams at a rate that is 8,000 times faster than LCLS to date.

    A crane lowers the LCLS-II electron gun into the X-ray laser’s accelerator tunnel at SLAC. (Dawn Harmer/SLAC National Accelerator Laboratory)

    The successful production of electrons was the culmination of the past 15 months, during which teams have installed and tested parts of the injector at SLAC, building on design and testing work over the past few years at DOE’s Lawrence Berkeley National Laboratory.

    “It’s a milestone that shows the complex injector system is working and that allows us to begin the crucial task of optimizing its performance,” said SLAC accelerator physicist Feng Zhou, who is in charge of LCLS-II injector commissioning. “The injector is a very critical system because the quality of the electron beam it creates has a huge effect on the quality of X-rays that will ultimately come out of LCLS-II.”

    Making X-rays with electrons

    X-ray lasers use pulsed beams of electrons to generate their X-ray light. These beams gain tremendous energy in massive linear particle accelerators and then give some of that energy off in the form of extremely bright X-ray flashes when they fly through special magnets known as undulators.

    The injector’s role is to produce an electron beam with high intensity, a small cross-section and minimal divergence, the right pulse rate and other properties required to achieve the best possible X-ray laser performance.

    The electrons fired by the injector come from an electron gun. It consists of a hollow metal cavity where flashes of laser light hit a photocathode that responds by releasing electrons. The cavity is filled with a radiofrequency (RF) field that boosts the energy of the freed electrons and accelerates them in bunches toward the gun’s exit.

    Magnets and another RF cavity inside the injector squeeze the electrons into smaller, shorter bunches, and an accelerator section, to be installed over the next few months, will increase the energy of the bunches to allow them to enter the main stretch of the X-ray laser’s linear accelerator. Spanning almost a kilometer in length, this superconducting accelerator will increase the speed of the electron bunches to almost the speed of light.

    The LCLS-II electron gun in a Berkeley Lab clean room where it was assembled. (Marilyn Chung/Lawrence Berkeley National Laboratory)

    The million-pulse challenge

    The most delicate injector component is the electron gun, and for LCLS-II the technical demands are bigger than ever, said John Schmerge, deputy director of SLAC’s Accelerator Directorate.

    “The first generation of LCLS produced 120 X-ray flashes per second, which means the injector laser and RF power only had to operate at that rate,” he said. “LCLS-II, on the other hand, will also have the capability of firing up to a million times per second, so the RF power needs to be switched on all the time and the laser has to work at the much higher rate.”

    This creates major challenges.

    First, the continuous RF field produces a lot of heat inside the cavity. With a power equivalent to about 80 microwave ovens operating at full power at all times, it could damage the electron gun and degrade its performance.

    To handle the large amount of power, the LCLS-II gun, which was built at Berkeley Lab, is equipped with a water cooling system. It is also much larger than its predecessor – several feet rather than inches in diameter – so heat is distributed over a larger surface area.

    “The LCLS-II project got a flying start, profiting from Berkeley Lab’s experience designing and running this unique electron source,” said SLAC’s John Galayda, who until recently led the LCLS-II project. “It continues to be a great collaboration that is crucial in building the next-generation X-ray laser.”

    Another challenge is the laser system, said Sasha Gilevich, SLAC engineer in charge of the LCLS-II injector laser.

    “To produce electrons efficiently, we want to shine ultraviolet light onto the photocathode, but there is no commercial laser system capable of providing UV pulses with the unique properties required by LCLS-II at the rate of a million pulses per second,” she said. “Instead, we send the light of an infrared laser through an optical system containing non-linear crystals that convert it into ultraviolet light. But because of the heat generated in the crystals, doing this conversion at such a high pulse rate is very demanding, and we’re still in the process of optimizing our system for the best performance.”

    The LCLS-II electron gun being installed at SLAC. (Dawn Harmer/SLAC National Accelerator Laboratory)

    New electron source, new challenges

    LCLS-II’s unique capabilities will also rely on a high-efficiency photocathode to produce the initial electron burst. It consists of a flat disc – merely tens of nanometers thick and a centimeter in diameter – of a semiconductor mounted on a metal support. This allows the electrons to be produced about 1,000 times more efficiently than with the copper cathode used previously.

    But the advance comes with a trade-off, said SLAC accelerator physicist Theodore Vecchione: “While the copper cathode lasted for years, the new one is not nearly as robust and may last only a few weeks.”

    That’s why Vecchione has been tasked with setting up a facility at the lab to fabricate a stockpile of cathodes, which cannot be simply purchased off the shelf, and to make sure the LCLS-II cathode can be replaced whenever needed.

    Now that the injector has generated its first electrons, the commissioning team will spend the next few months optimizing the properties of the electron beam and automating the injector controls. However, it won’t be until next year, when LCLS-II’s superconducting linear accelerator has been installed, that they will be able to test the full injector, including the short accelerator section that will boost the electron energy to 100 million electronvolts, and get it ready to do its job of generating some of the most powerful X-rays the world has ever seen.

    See the full article here .

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    SLAC/LCLS II projected view

    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 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

    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.”

    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.


    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.”

    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 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 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

    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.


    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

    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.
    (510) 486-5582

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

    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

    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.


    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.


    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.

    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)

    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.

    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.

    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.”

    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.

    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.

    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

    Media contact
    Andre Salles, Fermilab Office of Communication,

    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.

    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).

    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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    FNAL Icon

    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: , , , , , , , Large Electron-Positron Collider, , , , , SLAC LCLS-II,   

    From Symmetry: “Machine evolution” 

    Symmetry Mag

    Amanda Solliday

    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.


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


    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.


    FNAL Tevatron

    FNAL/Tevatron map

    FNAL/Tevatron DZero detector

    FNAL/Tevatron CDF detector

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


    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.


    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.”


    Fixed target and collider experiments

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


    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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

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