Neutrinos at the Main Injector
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Neutrinos at the Main Injector, or NuMI, is a project at
Fermilab Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been opera ...
which creates an intense beam of
neutrino A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
s aimed towards the Far Detector facility near Ash River, Minnesota for use by several
particle detector In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nu ...
s. , the MINOS, MINERνA and
NOνA A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramat ...
experiments use the NuMI beam. NOνA home page
retrieved 5 October 2007.


Neutrino production

The first step in the production of the NuMI beam is to direct a beam of protons from Fermilab's
Main Injector Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operat ...
onto a carbon target. Interactions of the proton beam in the target produce
meson In particle physics, a meson ( or ) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, ...
s, primarily
pions In particle physics, a pion (or a pi meson, denoted with the Greek letter pi: ) is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the lightest mesons and, more gene ...
and kaons, which are focused toward the beam axis by two magnetic horns. The mesons then decay into muons and neutrinos during their flight through a long decay tunnel. A
hadron In particle physics, a hadron (; grc, ἁδρός, hadrós; "stout, thick") is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules that are held together by the e ...
absorber downstream of the decay tunnel removes the remaining protons and mesons from the beam. The muons are absorbed by the subsequent earth shield, while the neutrinos continue through it to the MINERνA, MINOS, and NOvA near detectors on-site at
Fermilab Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been opera ...
. The neutrinos then travel through the Earth to the MINOS far detector cavern in the Soudan Mine 735 km away and the NOvA far detector 810 km away at Ash River, MN, then onwards into space.


Naming

Because of the close relationship between NuMI and the MINOS experiment, MINOS is sometimes conflated with NuMI. For instance, the MINOS webpage was at www-numi.fnal.gov instead of www-minos.fnal.gov.


References

{{Neutrino detectors Accelerator neutrino experiments Fermilab Fixed-target experiments