Today, the Department of Energy’s Fermilab shipped its final superconducting component for the new particle accelerator for the Linac Coherent Light Source II, or LCLS-II, at DOE’s SLAC National Accelerator Laboratory.
The cryomodule — the major component of the linear accelerator — is the final one required for the LCLS-II project, which will be the world’s brightest X-ray laser when complete.
“This is what we’ve been working toward for six years. Since 2014, our team has been designing, building, testing and delivering the high-performance superconducting cryomodules that will make up this forefront discovery machine,” said Rich Stanek, LCLS-II Fermilab senior team lead. “Sending it off today is the tying of the bow on our contribution effort. We are honored to be a part of LCLS-II, leveraging our expertise in superconducting acceleration technology to power the particle beam for a world-class X-ray laser. Everyone connected to the LCLS-II project should be very proud of their accomplishments.”
An upgrade of SLAC’s LCLS, which was the world’s first hard X-ray free-electron laser, LCLS-II will provide a giant leap in capability. It will fire a staggering 1 million X-ray pulses per second, up from LCLS’s 120 pulses per second. Armed with these rapid-fire rays of light, scientists using LCLS-II will be able to examine microscopic biological and chemical processes in real time and extreme detail.
The particle accelerator that provides the high-energy electrons for the LCLS-II laser will be made of 37 cryomodules, the longest of which is 12 meters (40 feet) in length. Lined up end to end like cars in a train, they form a kind of runway for the electron beam as it ramps up in energy. Eighteen of the cryomodules come from Fermilab, and 19 come from the Department of Energy’s Jefferson Lab. Both labs provided additional spares.
The cryomodule from Fermilab is 12 meters (39 feet) long and will start the transport to SLAC on March 19, 2021. Photo: Ryan Postel, Fermilab
Once the electron beam exits the cryomodules, it is made to move rapidly from side to side through a series of undulators, emitting X-rays as it zigzags. The new undulators were designed and built by DOE’s Lawrence Berkeley National Laboratory and Argonne National Laboratory. Cornell University is also contributing components for LCLS-II.
The LCLS-II cryomodule installation is expected to be complete this spring, and LCLS-II will begin commissioning in 2022 as soon as the LCLS-II cryoplant is commissioned. LCLS-II is supported by the Department of Energy Office of Science.
“The design and construction of the LCLS-II cryomodules has been an example of true cross-institutional collaboration, bringing together three national laboratories’ expertise and capabilities in particle acceleration, superconductivity science and photon science,” said SLAC Deputy Director and LCLS-II Project Director Norbert Holtkamp. “We look forward to welcoming the final cryomodule to SLAC.”
Each cryomodule contains eight superconducting accelerator cavities, hollow structures that look like giant metallic strands of pearls. As the particle beam shoots through one cavity after the other, it picks up energy. The cryomodules, about a meter in diameter, house the cavities and allow them to be cooled to about 2 kelvins, maintaining the necessary temperatures that enable the cavities’ superconductivity.
For the last two decades, Fermilab has developed its superconducting radio-frequency, or SRF, program, which has allowed Fermilab to participate in the design, construction and testing of LCLS-II’s cutting-edge accelerator components.
“We are proud to be a key partner in the construction of this groundbreaking new light source,” said Fermilab Chief Technology Officer Alex Romanenko. “For the last two decades, DOE investment in high-energy physics has allowed Fermilab to dramatically advance R&D and develop its SRF program, leading to important breakthroughs in SRF cavities’ efficiency, thanks to discoveries such as nitrogen doping and fast cooling methods for reducing trapped magnetic fields. These improvements contributed to LCLS-II’s world-leading cryomodules.”
The LCLS-II SRF cryomodule design is a modification of a type developed at the DESY laboratory in Germany. Fermilab’s further R&D in the area of the preparation of superconducting surfaces drew record-setting performance from the accelerator cavities, making them highly energy-efficient while accelerating beam. Work is already underway on the next generation of cryomodules for a future high-energy upgrade to LCLS-II.
Fermilab technicians prepare the cryomodule for transport by performing final checks on instrumentation. Photo: Ryan Postel, Fermilab
“Fermilab and Jefferson Lab’s leadership in SRF made them the perfect partners to engage in the design and construction of the LCLS-II accelerator,” said the DOE Bay Area Site Office Deputy Manager Hanley Lee, the Federal Project Director for the effort. “SLAC’s new X-ray laser would not be the advanced machine we expect it to be without these cutting-edge cryomodules. LCLS-II will be an unprecedented tool for discovery, shining a bright light on hidden processes in nature that could hold keys for improving our health, environment and security. We could not build it without the diverse expertise of researchers from the broad range of fields that came together as part of this extraordinary project.”
Fermilab Director Nigel Lockyer agrees that, in the success of LCLS-II cryomodules, collaboration was key.
“The LCLS-II project is a wonderful partnership of the DOE labs’ strengths,” Lockyer said. “Capitalizing on the accelerator science and technology developed at Fermilab for investigating the basic building blocks of matter, we now apply it to LCLS-II so we can explore new scientific territory. LCLS-II is a testament to the cooperative scientific endeavor.”
Learn more about the LCLS-II cryomodules and project.
Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC, a joint partnership between the University of Chicago and the Universities Research Association, Inc. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @Fermilab.
Fermilab is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.
The Integrable Optics Test Accelerator ring at the Fermilab Accelerator Science and Technology facility, also known as FAST. Photo: Giulio Stancari
The detected intensity from two coherent point-like light sources depends on their relative positions. It is a well-known phenomenon called optical interference. In general, the intensity can range from zero (destructive interference) to some maximum value (constructive interference).
Consider two high-energy electrons circulating in a particle storage ring, such as the Integrable Optics Test Accelerator at Fermilab. As it was discovered in 1947, when high-energy electrons are forced to travel in a curved path, they emit light, known as synchrotron radiation. If we record the detected synchrotron light intensity at every revolution in a storage ring, we will observe slight fluctuations of its magnitude from turn to turn because the relative positions of the two electrons change.
The IOTA storage ring, hosted by the Department of Energy’s Fermilab, can store a billion electrons. Just as in the two-electron case, the turn-to-turn fluctuations of the billion electrons’ radiation intensity still exist, and for the same reasons. The fluctuations are very small, below 0.1% (root-mean-square). Still, our research group was able to measure them, and we showed that this information can be used to gain insights into the electron beam’s properties, such as its dimensions and divergence — a measure of spread in directions of motion of the electrons in the beam.
The proof-of-principle measurements in IOTA were performed in the near-infrared synchrotron light spectrum range. The sensitivity of this noninvasive method for determining the electron beam properties improves when synchrotron light of shorter wavelength and higher brightness is used. This means it may particularly benefit existing state-of-the-art and next-generation low-emittance high-brightness ultraviolet and X-ray synchrotron light sources, where noninvasive electron beam characterization is difficult.
For instance, we think this method could measure transverse beam sizes on the order of 10 microns in the Advanced Photon Source Upgrade at Argonne National Laboratory, by using the turn-to-turn fluctuations in the X-ray synchrotron light. This is an important step in making tighter electron beams, which in turn generate brighter X-rays. With brighter X-rays, researchers will be able to accelerate research in chemistry, materials science and medicine, including COVID-19 research.
A paper on this result will be published in Physical Review Letters. An expanded companion paper will be published in Physical Review Accelerators and Beams. Corresponding papers “Transverse beam emittance measurement by undulator radiation power noise” and “Measurements of undulator radiation power noise and comparison with ab initio calculations” were published on arXiv.
Research at IOTA is supported by the DOE Office of Science.
The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.
Ihar Lobach is a physics graduate student at the University of Chicago conducting research at Fermilab’s Integrable Optics Test Accelerator. His academic advisor is Fermilab scientist and University of Chicago Professor Sergei Nagaitsev, and his Fermilab research supervisor is Fermilab scientist Giulio Stancari.
Editor’s note: This is a modified version of an article previously posted by the CERN Courier.
The TOTEM collaboration at the LHC, in collaboration with the DØ collaboration at the Tevatron collider at Fermilab, have announced the discovery of the odderon – an elusive state of three fundamental particles called gluons that was predicted almost 50 years ago. The result was presented on Friday 5 March during a meeting at CERN, and follows the joint publication in December 2020 of a CERN/Fermilab preprint by TOTEM and DØ reporting the observation.
“This result probes the deepest features of the theory of quantum chromodynamics, notably that gluons interact between themselves and that an odd number of gluons are able to be “colourless”, thus shielding the strong interaction,” says TOTEM spokesperson Simone Giani of CERN. “A notable feature of this work is that the results are produced by combining the LHC and Tevatron data at different energies.”
States comprising two, three or more gluons are usually called “glueballs”, and are peculiar objects made only of the carriers of the strong force. The advent of quantum chromodynamics (QCD) led theorists to predict the existence of the odderon in 1973. Proving its existence has been a major experimental challenge, however, requiring detailed measurements of protons as they glance off one another in high-energy collisions.
Part of the TOTEM installation in the LHC tunnel 220 m downstream from the CMS experiment. (Image: M. Brice/CERN)
While most high-energy collisions cause protons to break into their constituent quarks and gluons, roughly 25% are elastic collisions where the protons remain intact but emerge on slightly different paths (deviating by around a millimetre over a distance of 200 m at the LHC). TOTEM measures these small deviations in proton–proton scattering using two detectors located on either side of the CMS experiment 220 m from the interaction point , while DØ employed a similar setup at the Tevatron proton–antiproton collider.
At lower energies, differences in proton–proton vs proton–antiproton scattering are due to the exchange of different virtual mesons – particles made up of a quark and an antiquark. At multi-TeV energies, on the other hand, proton interactions are expected to be mediated purely by gluons. In particular, elastic scattering at low-momentum transfer and high energies has long been explained by the exchange of a pomeron – a “colour-neutral” virtual glueball made up of an even number of gluons.
However, in 2018, TOTEM reported measurements at high energies that could not easily be explained by this traditional idea. Instead, a further QCD object seemed to be at play, supporting models in which a three-gluon compound, or one containing higher odd numbers of gluons, was being exchanged. The results were sufficient to claim evidence for the odderon, although not yet its definitive observation.
The D⌀ experiment at Fermilab’s former Tevatron collider. Credit: Fermilab
The new work is based on a model-independent analysis of data at medium-range momentum transfer. The TOTEM and DØ teams compared LHC proton–proton data (recorded at collision energies of 2.76, 7, 8 and 13 TeV and extrapolated to 1.96 TeV), with Tevatron proton–antiproton data measured at 1.96 TeV, and found evidence again for the odderon. When the teams combined the result with measurements at different scattering angles at 13 TeV by the TOTEM collaboration, the significance of the result was boosted to the discovery level.
“When combined with the measurements at 13 TeV, the significance of the result is in the range of 5.2–5.7 standard deviations and thus constitutes the first experimental observation of the odderon,” said Christophe Royon of the University of Kansas, who presented the results on behalf of DØ and TOTEM last week. “This is a major discovery by CERN and Fermilab.”
In addition to the new TOTEM-DØ model-independent study, several theoretical papers based on data from the Intersecting Storage Rings, the Super Proton Synchrotron, the Tevatron and the LHC, and on model-dependent inputs, provide additional evidence supporting the conclusion that the odderon exists.