Fermi National Accelerator Laboratory (FNAL; branded as Fermilab) is a national laboratory for high-energy particle physics, located in Batavia, Illinois, United States, near Chicago. It is sponsored by the United States Department of Energy and operated by the University of Chicago through the subordinate Fermi Forward Discovery Group LLC.
Fermilab's Main Injector, two miles (3.3 km) in circumference, is the laboratory's most powerful particle accelerator. The accelerator complex that feeds the Main Injector is under upgrade, and construction of the first building for the new PIP-II linear accelerator began in 2020. Until 2011, Fermilab was the home of the 6.28 km (3.90 mi) circumference Tevatron accelerator. The ring-shaped tunnels of the Tevatron and the Main Injector are visible from the air and by satellite.
Fermilab aims to become a world center in neutrino physics. It is the host of the multi-billion dollar Deep Underground Neutrino Experiment (DUNE) now under construction. The project has suffered delays and, in 2022, the journals Science and Scientific American each published articles describing the project as "troubled".
Ongoing neutrino experiments are ICARUS (Imaging Cosmic and Rare Underground Signals) and NOνA (NuMI Off-Axis νe Appearance). Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment) and MicroBooNE (Micro Booster Neutrino Experiment).
On-site experiments outside of the neutrino program include the SeaQuest fixed-target experiment and Muon g-2. 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. Fermilab also pursues research in quantum information science. It founded the Fermilab Quantum Institute in 2019. Since 2020, it also is home to the SQMS (Superconducting Quantum Materials and Systems) Center.
Due to serious performance issues over the period of a decade, the Department of Energy established new management for Fermilab on January 1, 2025. Fermilab is currently managed by the Fermi Forward Discovery Group, LLC (FFDG). This consortium is led by the 2007-2024 management group, the Fermi Research Alliance (FRA), with Amentum Environment & Energy, Inc., and Longenecker & Associates as new additions. Due to the management crisis, the Director of the Laboratory, Lia Merminga, resigned on January 13, 2025 and is temporarily replaced by Acting Director Young-Kee Kim, from the University of Chicago.
Fermilab is a part of the Illinois Technology and Research Corridor. Argonne National Laboratory, which is another US DOE national laboratory, is located approximately 20 miles (30 kilometers) away.
History
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 and remained director emeritus until his death. The science education center at the site was named in his honor.
Laboratory directors
Since its founding in 1967, Fermilab has been led by 8 directors.
Accelerators
Tevatron
Prior to the startup in 2008 of the Large Hadron Collider (LHC) near Geneva, Switzerland, the Tevatron was the most powerful particle accelerator in the world, accelerating protons and antiprotons to energies of 980 GeV, and producing proton-antiproton collisions with energies of up to 1.96 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.
Fermilab Accelerator Complex
Since 2013, the first stage in the acceleration process (pre-accelerator injector) in the Fermilab chain of accelerators takes place in two ion sources which ionize hydrogen gas. The gas is introduced into a container lined with molybdenum electrodes, each a matchbox-sized, oval-shaped cathode and a surrounding anode, separated by 1 mm and held in place by glass ceramic insulators. A cavity magnetron generates a plasma to form the ions near the metal surface. The ions are accelerated by the source to 35 keV and matched by low energy beam transport (LEBT) into the radio-frequency quadrupole (RFQ) which applies a 750 keV electrostatic field giving the ions their second acceleration. At the exit of RFQ, the beam is matched by medium energy beam transport (MEBT) into the entrance of the linear accelerator (linac).
The next stage of acceleration is a linear particle accelerator (linac). This stage consists of two segments. The first segment has five drift tube cavities, operating at 201 MHz. The second stage has seven side-coupled cavities, operating at 805 MHz. At the end of linac, the particles are accelerated to 400 MeV, or about 70% of the speed of light. Immediately before entering the next accelerator, the H− ions pass through a carbon foil, becoming H+ ions (protons).
The resulting protons then enter the booster ring, a 468 m (1,535 ft) circumference circular accelerator whose magnets bend beams of protons around a circular path. The protons travel around the Booster about 20,000 times in 33 milliseconds, adding energy with each revolution until they leave the Booster accelerated to 8 GeV. In 2021, the lab announced that its latest superconducting YBCO magnet could increase field strength at a rate of 290 tesla per second, reaching a peak magnetic field strength of around 0.5 tesla.
The final acceleration is applied by the Main Injector [circumference 3,319.4 m (10,890 ft)], which is the smaller of the two rings in the last picture below (foreground). Completed in 1999, it has become Fermilab's "particle switchyard" in that it can route protons to any of the experiments installed along the beam lines after accelerating them to 120 GeV. Until 2011, the Main Injector provided protons to the antiproton ring [circumference 6,283.2 m (20,614 ft)] and the Tevatron for further acceleration but now provides the last push before the particles reach the beam line experiments.
Proton improvement plan
Recognizing higher demands of proton beams to support new experiments, Fermilab began to improve their accelerators in 2011. Expected to continue for many years, the project has two phases: Proton Improvement Plan (PIP) and Proton Improvement Plan-II (PIP-II).
PIP (2011–2018)
The overall goals of PIP are to increase the repetition rate of the Booster beam from 7 Hz to 15 Hz and replace old hardware to increase reliability of the operation. Before the start of the PIP project, a replacement of the pre-accelerator injector was underway. The replacement of almost 40 year-old Cockcroft–Walton generators to RFQ started in 2009 and completed in 2012. At the Linac stage, the analog beam position monitor (BPM) modules were replaced with digital boards in 2013. A replacement of Linac vacuum pumps and related hardware is expected to be completed in 2015. A study on the replacement of 201 MHz drift tubes is still ongoing. At the boosting stage, a major component of the PIP is to upgrade the Booster ring to 15 Hz operation. The Booster has 19 radio frequency stations. Originally, the Booster stations were operating without solid-state drive system which was acceptable for 7 Hz but not 15 Hz operation. A demonstration project in 2004 converted one of the stations to solid state drive before the PIP project. As part of the project, the remaining stations were converted to solid state in 2013. Another major part of the PIP project is to refurbish and replace 40 year-old Booster cavities. Many cavities have been refurbished and tested to operate at 15 Hz. The completion of cavity refurbishment is expected in 2015, after which the repetition rate can be gradually increased to 15 Hz operation. A longer term upgrade is to replace the Booster cavities with a new design. The research and development of the new cavities is underway, with replacement expected in 2018.
PIP-II
The goals of PIP-II include a plan to delivery 1.2 MW of proton beam power from the Main Injector to the Deep Underground Neutrino Experiment target at 120 GeV and the power near 1 MW at 60 GeV with a possibility to extend the power to 2 MW in the future. The plan should also support the current 8 GeV experiments including Mu2e, Muon g−2, and other short-baseline neutrino experiments. These require an upgrade to the Linac to inject to the Booster with 800 MeV. The first option considered was to add 400 MeV "afterburner" superconducting Linac at the tail end of the existing 400 MeV. This would have required moving the existing Linac up 50 metres (160 ft). However, there were many technical issues with this approach. Instead, Fermilab is building a new 800 MeV superconducting Linac to inject to the Booster ring.
Construction of the first building for the PIP-II accelerator began in 2020. The new Linac site will be located on top of a small portion of Tevatron near the Booster ring in order to take advantage of existing electrical and water, and cryogenic infrastructure. The PIP-II Linac will have low energy beam transport line (LEBT), radio frequency quadrupole (RFQ), and medium energy beam transport line (MEBT) operated at the room temperature at with a 162.5 MHz and energy increasing from 0.03 MeV. The first segment of Linac will be operated at 162.5 MHz and energy increased up to 11 MeV. The second segment of Linac will be operated at 325 MHz and energy increased up to 177 MeV. The last segment of linac will be operated at 650 MHz and will have the final energy level of 800 MeV.
As of 2022, the estimated PIP-II accelerator start date for the accelerator is 2028. The project was approved for construction in April 2022 with an expected cost to the Department of Energy of $978M and with an additional $330M in contributions from international partners.
Experiments
Discoveries by Fermilab experiments
The following particles were first directly observed at Fermilab:
The top quark announced in 1995 by the DØ experiment and CDF experiment.
The bottom quark, which was observed as a quark-antiquark pair called the Upsilon meson announced in 1977 by Experiment 228.
The tau neutrino, announced in July 2000 by the DONUT collaboration.
The bottom Omega baryon (Ω−b), announced by the DØ experiment of Fermilab in 2008.
In 1999, physicists at on the KTeV experiment were also the first to observe direct CP violation in kaon decays.
The DØ experiment and CDF experiment each made important contributions to the observation of the Higgs Boson, announced in 2012.
Evolution of the post-Tevatron experimental program
Fermilab dismantled the CDF (Collider Detector at Fermilab) experiment to make the space available for IARC (Illinois Accelerator Research Center).
Fermilab physicists continue to play a key role in the world-wide collider program.
The LHC Physics Center (LPC) at Fermilab is a regional center of the Compact Muon Solenoid Collaboration (the experiment is housed at CERN). The LPC offers a vibrant community of CMS scientists from the US and plays a major role in the CMS detector commissioning, and in the design and development of the detector upgrade. Fermilab is the host laboratory for USCMS, which includes researchers from 50 U.S. universities including 715 students. Fermilab hosts the largest CMS Tier 1 computing center, handling approximately 40% of global CMS Tier 1 computing requests. On February 9, 2022, Fermilab's Patricia McBride (physicist) was elected spokesperson of the CMS collaboration.
During this time-frame, the laboratory also established a new program in research in cutting-edge information science, including the development of quantum teleportation technology for the quantum internet and increasing the lifetime of superconducting resonators for use in quantum computers.
On-site program in the 2020s
The on-site program in the 2020s is largely focused on the Intensity Frontier of particle physics, especially neutrino physics and rare physics searches using muons. A program exploring nucleon structure is also continuing.
List of recent past, ongoing, and planned experiments running on-site
ANNIE: The Accelerator Neutrino Neutron Interaction Experiment (Status, June 2023: completed run, planned future run)
Deep Underground Neutrino Experiment (DUNE), formerly known as Long Baseline Neutrino Experiment (LBNE) (Status, June 2023: planned future run)
ICARUS experiment: Originally located at the Laboratori Nazionali del Gran Sasso (LNGS) and moved to Fermilab. (Status, June 2023: running)
MiniBooNE: Mini Booster Neutrino Experiment (Status, June 2023: completed run)
MicroBooNE: Micro Booster Neutrino Experiment (Status, June 2023: completed run)
MINERνA: Main INjector ExpeRiment with νs on As (Status, June 2023: completed run)
Mu2e: Muon-to-Electron Conversion Experiment (Status, June 2023: planned future run)
Muon g−2: Measurement of the anomalous magnetic dipole moment of the muon (Status, June 2023: completed run)
NOνA: NuMI Off-axis νe Appearance (Status, June 2023: running)
SeaQuest (Status, June 2023: completed run)
SBND: Short-Baseline Neutrino Detector (Status, June 2023: planned future run)
SpinQuest (Status, June 2023: planned future run)
LBNF/DUNE
Fermilab strives to become the world leader in neutrino physics through the Deep Underground Neutrino Experiment at the Long Baseline Neutrino Facility. Other leaders are CERN, which leads in Accelerator physics with the Large Hadron Collider (LHC), and Japan, which has been approved to build and lead the International Linear Collider (ILC). Fermilab will be the site of LBNF's future beamline, and the Sanford Underground Research Facility (SURF), in Lead, SD, is the site selected to house the massive far detector. The term "baseline" refers to the distance between the neutrino source and the detector. The far detector current design is for four modules of instrumented liquid argon with a fiducial volume of 10 kilotons each.