The following CERN press release celebrates the groundbreaking of a major upgrade to the Large Hadron Collider, called the High-Luminosity LHC. The HL-LHC will produce five to seven times more collisions than the current LHC, greatly increasing the chances of new discoveries.
Fermilab is leading the U.S. contribution to the HL-LHC, in addition to building new components for the upgraded detector for the CMS experiment. The main innovation contributed by the United States for the HL-LHC is a novel new type of accelerator cavity that uses a breakthrough superconducting technology. Fermilab is also contributing to the design and construction of superconducting magnets that will focus the particle beam much more tightly than the magnets currently in use in the LHC. Fermilab scientists and engineers have also partnered with other CMS collaborators on new designs for tracking modules in the CMS detector, enabling it to respond more quickly to the increased number of collisions in the HL-LHC.
Major work starts to boost the luminosity of the LHC
The Large Hadron Collider (LHC) is officially entering a new stage. Today, a groundbreaking ceremony at CERN celebrates the start of the civil-engineering work for the High-Luminosity LHC (HL-LHC), a new milestone in CERN’s history. By 2026 this major upgrade will have considerably improved the performance of the LHC by increasing the number of collisions in the large experiments and thus boosting the probability of the discovery of new physics phenomena.
CERN members work on crab cavities for the HL-LHC. Photo: CERN
The LHC started colliding particles in 2010. Inside the 27-kilometer LHC ring, bunches of protons travel at almost the speed of light and collide at four interaction points. These collisions generate new particles, which are measured by detectors surrounding the interaction points. By analyzing these collisions, physicists from all over the world are deepening our understanding of the laws of nature.
While the LHC is able to produce up to 1 billion proton-proton collisions per second, the HL-LHC will increase this number, referred to by physicists as luminosity, by a factor of between five and seven, allowing about 10 times more data to be accumulated between 2026 and 2036. This means that physicists will be able to investigate rare phenomena and make more accurate measurements. For example, the LHC allowed physicists to unearth the Higgs boson in 2012, thereby making great progress in understanding how particles acquire their mass. The HL-LHC upgrade will allow the Higgs boson’s properties to be defined more accurately and to measure with increased precision how it is produced, how it decays and how it interacts with other particles. In addition, scenarios beyond the Standard Model will be investigated, including supersymmetry, theories about extra dimensions and quark substructure (compositeness).
“The High-Luminosity LHC will extend the LHC’s reach beyond its initial mission, bringing new opportunities for discovery, measuring the properties of particles such as the Higgs boson with greater precision, and exploring the fundamental constituents of the universe ever more profoundly,” said CERN Director-General Fabiola Gianotti.
The HL-LHC project started as an international endeavor involving 29 institutes from 13 countries. It began in November 2011, and two years later was identified as one of the main priorities of the European Strategy for Particle Physics, before the project was formally approved by the CERN Council in June 2016. After successful prototyping, many new hardware elements will be constructed and installed in the years to come. Overall, more than 1.2 kilometers of the current machine will need to be replaced with many new high-technology components such as magnets, collimators and radio-frequency cavities.
“Audacity underpins the history of CERN, and the High-Luminosity LHC writes a new chapter, building a bridge to the future,” said CERN Director for Accelerators and Technology Frédérick Bordry. “It will allow new research, and with its new innovative technologies, it is also a window to the accelerators of the future and to new applications for society.”
To allow all these improvements to be carried out, major civil-engineering work at two main sites is needed, in Switzerland and in France. This includes the construction of new buildings, shafts, caverns and underground galleries. Tunnels and underground halls will house new cryogenic equipment, the electrical power supply systems, and various plants for electricity, cooling and ventilation.
During the civil-engineering work, the LHC will continue to operate, with two long technical stop periods that will allow preparations and installations to be made for high luminosity alongside yearly regular maintenance activities. After completion of this major upgrade, the LHC is expected to produce data in high-luminosity mode from 2026 onward. By pushing the frontiers of accelerator and detector technology, it will also pave the way for future higher-energy accelerators.
A groundbreaking ceremony will be held tomorrow to celebrate the start of civil engineering work for a major upgrade to the Large Hadron Collider at CERN in Geneva, Switzerland. When complete, the High-Luminosity LHC (HL-LHC) will produce five to seven times more proton-proton collisions than the currently operating LHC, powering new discoveries about our universe.
For the last decade, scientists, engineers and technicians from the U.S. Department of Energy’s Fermi National Accelerator Laboratory have been working with partners around the world to conduct R&D on new accelerator components that would make operations at the HL-LHC possible. The U.S. research was conducted via the LHC Accelerator Research Program, or LARP. Now the research turns into reality, as construction of the new components begins.
The primary components contributed by the United States for the HL-LHC construction are powerful superconducting magnets and superconducting deflecting cavities, called crab cavities of a novel compact design never before used in an accelerator.
“This is a truly major milestone for the whole U.S. accelerator community,” said Fermilab scientist Giorgio Apollinari, who leads the DOE Office of Science-funded U.S. HL-LHC Accelerator Upgrade Project (AUP). “More than 10 years of research work funded by DOE under LARP have gone into developing these cutting-edge magnets and crab cavities and in demonstrating their technical feasibility for the intended application at HL-LHC. We now look forward with much anticipation to shipping the first components to CERN and seeing them operate as part of the world’s foremost particle collider.”
Fermilab is developing magnets such as this one, which is mounted on a test stand at Fermilab, for the High-Luminosity LHC. Photo: Reidar Hahn
In the LHC, superconducting quadrupole magnets focus the beams into collision at four points around the 27-kilometer ring. In the HL-LHC, these focusing magnets must be more powerful to focus the stream of particles much tighter than in the LHC. Fermilab, in collaboration with DOE’s Brookhaven and Lawrence Berkeley national laboratories, developed the basic technology for these new magnets through LARP. The final design was completed in collaboration with CERN for application in the HL-LHC upgrade.
These new magnets are made of a niobium-tin alloy that allows the magnets to reach the desired high magnetic field of 12 tesla. This powerful field is created by running a very high electric current through coils of superconducting wire, which conduct electricity without resistance when cooled to almost absolute zero. Fermilab is the lead U.S. laboratory for this project and is fabricating half of the coils and conducting the final assembly and testing of 11 full cryoassembly magnet structures before shipping them to CERN. The U.S. in total is delivering half of the quadrupole magnets for the upgrade, while CERN is completing the other half.
“These are the next generation of superconducting magnets for accelerators,” said Fermilab’s Ruben Carcagno, the deputy project manager for the HL-LHC AUP. “This is the first time that this new technology will be deployed in a working machine. So it’s a big step.”
Fermilab is developing and constructing cavities like this one for the future HL-LHC. The cavity proper is the structure situated between the four rods. Photo: Leonardo Ristori
In addition to the magnets, the United States will deliver half of the crab cavities to CERN for the HL-LHC, while CERN completes the remaining cavities. The cavities to be produced in the United States are of a radio-frequency dipole (RFD) design and are the product of more than 10 years of research through LARP by Old Dominion University and SLAC National Accelerator Laboratory, with contributions from Thomas Jefferson National Accelerator Facility and U.S. industry. Fermilab will be responsible for fabricating and testing the RFD cavities before delivering them to CERN. These novel cavities will kick or tilt the beams just before they pass through each other to maximize the beam overlap and therefore the possibility of proton collisions.
Once it’s up and running, the HL-LHC will produce up to 15 million Higgs bosons per year, compared to the 4 million produced during the LHC’s 2015-2017 run. The higher luminosity will mean big changes for the LHC experiments as well, and the ATLAS and CMS detectors are undergoing major upgrades of their own. Learn more about Fermilab’s contributions to the HL-LHC upgrades to the CMS detector.
This image shows a three-track neutrino event in the MicroBooNE data with a muon, charged pion and proton candidate in the final state. Image: MicroBooNE collaboration
Physicists on the MicroBooNE collaboration at the Department of Energy’s Fermilab have produced their first collection of science results. Roxanne Guenette of Harvard University presented the results on behalf of the collaboration at the international Neutrino 2018 conference in Germany. The measurements are of three independent quantities that describe neutrino interactions with argon atoms, which make up the 170 tons of total target material used for neutrino collisions inside the MicroBooNE detector.
MicroBooNE started operations in the fall of 2015. The detector, about the size of a school bus, has recorded hundreds of thousands of neutrino-argon collisions since then. It features a time projection chamber with three wire planes that record the particle tracks created by those collisions, similar to a digital camera recording images of fireworks. The Booster particle accelerator at Fermilab is used to create the muon neutrino beam for the experiment.
It is the first low-energy neutrino experiment to make detailed observations of the subatomic processes that happen when a muon neutrino hits and interacts with an argon atom, leading to showers of secondary particles including protons, pions, muons and more. Using noise-reducing analysis techniques, MicroBooNE scientists can interpret the precise images of the particle tracks.
One of the new results reported at the Neutrino 2018 conference was the first measurement of the multiplicity – or number of particles – that these neutrino-argon collisions generate. A new paper describing these results was submitted to the journal Physical Review D last week. Other measurements determined the likelihood, or more precisely the cross section, of a neutrino-argon collision occurring and producing a neutral pion or a more inclusive final state.
The new results are of great importance for the groundbreaking measurements to be performed by neutrino experiments with liquid-argon TPCs. This includes the search for a fourth type of neutrino with the Short-Baseline Neutrino program at Fermilab, which comprises three neutrino detectors: the ICARUS detector, built by Italy’s INFN, refurbished at CERN, and then shipped to Fermilab in 2017; the new Short Baseline Near Detector; and MicroBooNE. The measurements are also important for the international Deep Underground Neutrino Experiment hosted by Fermilab, which will use both neutrino and antineutrino collisions with argon to search for differences between neutrino and antineutrino interactions, with the goal of understanding what role neutrinos played in the evolution of the universe.
“We are building on the success of neutrino interaction measurements in ICARUS and ArgoNeuT now with much larger statistics in MicroBooNE, to enable precise cross section measurements on argon,” said MicroBooNE co-spokesperson Bonnie Fleming, who holds a joint appointment with Fermilab and Yale University. “These are the first high-statistics, precision measurements on argon. They will be critical for the DUNE program.”
Nearly 200 scientists from 31 institutions in Israel, Switzerland, Turkey, the United Kingdom and the United States are members of the MicroBooNE collaboration. The experiment is funded by the U.S. Department of Energy Office of Science.