Fermilab Accelerator Complex

Fermilab’s accelerator complex accelerates protons to high energies before sending them out to various experiments.

Fermilab Accelerator Complex consists of four accelerators that work together to provide world-class particle beams for experiments at the Intensity Frontier.
Batavia, Illinois Location
2012 Start of Operations
2,610 (FY 2019) Number of Users


The Fermilab Accelerator Complex, at Fermi National Accelerator Laboratory, is composed of four accelerators that work in tandem: the linear accelerator (linac), booster, recycler, and main injector. These accelerators produce two primary proton beams, a low energy (8 GeV) proton beam from the Booster and a high energy (120 GeV) beam from the Main Injector. These proton beams produce secondary beams of pion, kaons, muons and neutrinos that serve a variety of experiments.

Booster Neutrino Beam: The Booster accelerator is a ring 1,500 feet in circumference that receives 400 MeV protons from the linac and accelerates them to 8 GeV. These protons are used to generate secondary particle beams to serve the experimental program. The Booster Neutrino Beam is produced to serve several operating and planned Short-Baseline Neutrino (SBN) oscillation experiments. In addition, a muon beam from the Booster will serve the Fermilab Muon g-2 experiment, which begins operations in 2016, and the Muon-to-electron Conversion (Mu2e) experiment, which begins operations in 2019.

  • MiniBooNE: The MiniBooNE experiment seeks to confirm or rule out the existence of a fourth type of neutrino that is “sterile,” or doesn’t interact through the weak force like the known neutrinos. The MiniBooNE detector consists of a 12 meter diameter tank filled with 800 tons of mineral oil with 1,520 photomultiplier tubes lining the inside. The MiniBooNE detector is used to identify the oscillations of muon neutrinos into electron neutrinos by capturing the Cherenkov light made by the fast-moving charged particles neutrinos can produce when they interact with the mineral oil. The MiniBooNE detector also detects neutrinos from the NuMI beam line (see below).
  • MicroBooNE: The MicroBooNE short-baseline neutrino experiment will be the largest Liquid Argon Time Projection Chamber (LArTPC) neutrino detector built in the U.S. The 170 ton experiment begins operations in 2015 and will measure low energy neutrino cross sections and investigate the unexpected excess events observed by the MiniBooNE experiment. The detector serves as the necessary next step in a phased program towards the construction of massive, kiloton scale LArTPC detectors, the preferred technology for the future Long Baseline Neutrino Experiment (LBNE).

Neutrinos at the Main Injector (NuMI): The Main Injector takes the 8 GeV energy protons from the Booster and accelerates them to 120 GeV. These highly energetic protons strike a carbon target to generate muons that subsequently decay to muon neutrinos, resulting in the most intense neutrino beam in the world. The muon neutrino beam is used for studies of both the disappearance of muon neutrinos and the appearance of electron and tau neutrinos. Two experiments currently gather data from the NuMI beam line, a third is starting operations, and a fourth is planned:

  • Main Injector Neutrino Oscillation Search (MINOS): The MINOS Experiment is a long-baseline neutrino experiment designed to observe the phenomena of neutrino oscillations, an effect which is related to neutrino mass. MINOS uses two detectors, one located at Fermilab, at the source of the neutrinos, and the other located 450 miles away, in northern Minnesota, at the Soudan Underground Mine.
  • MINERvA: This is a neutrino scattering experiment that seeks to measure low energy neutrino interactions both in support of neutrino oscillation experiments and also to study the strong dynamics of the nucleon and nucleus that affect these interactions.
  • NOvA: The NOvA far detector, which was completed at Ash River, Minnesota during October, 2014, will use the NuMI beam to directly observe and measure the transformation of muon neutrinos into electron neutrinos with great precision. NOvA will also make important indirect measurements of the mass ordering of the three known neutrino types, which will be a key piece of information in determining the currently unknown masses of neutrinos.