CERN Neutrinos to Gran Sasso
Encyclopedia
The CERN Neutrinos to Gran Sasso (CNGS) project is a physics project of the European Organization for Nuclear Research
(CERN). The aim of the project is to analyse the hypothesis of neutrino oscillation
by directing a beam of neutrino
s from CERN's facilities to the detector of the OPERA experiment
at the Gran Sasso National Laboratory
(LNGS), located in the Gran Sasso mountain in Italy
. The CNGS facility is housed at the Meyrin
site of CERN, at the Franco
–Swiss
border near Geneva
, Switzerland. It uses the Super Proton Synchrotron
(SPS) accelerator as a source of high-energy proton
s.
was sent to the target on 11 July 2006, with the CNGS facility being approved for physics operations on 18 August 2006.
beam is taken from the SPS at and is made to collide with a graphite
target within the CNGS tunnel. The resulting particles, most importantly kaons and pions among many other particles, are then focused by magnetic lens
ing and travel 1 kilometre (0.621372736649807 mi) down the CNGS tunnel in a vacuum tube. These particles are naturally unstable and as they travel along the tunnel they decay into muon
s and muon neutrino
s. This beam of particles then collides into an iron graphite target. The final target stops the remaining protons, pion
s and kaon
s, but the neutrinos continue their flight unaffected, as they rarely interact with matter. The number of muons is measured at this point, which gives an indication of the beam's profile and intensity. This beam then passes 732 kilometres (454.8 mi) through the crust
of the Earth
and it is expected that during flight some of the muon neutrinos convert into other neutrino types such as tau neutrinos. Once the beam arrives at Gran Sasso, the OPERA
and ICARUS experiments are used to detect the neutrinos.
On 22 September 2011, the OPERA collaboration garnered international attention when they released a preprint
reporting the OPERA neutrino anomaly
, wherein neutrinos were measured to be travelling, on average, at faster-than-light
speed.
CERN
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
(CERN). The aim of the project is to analyse the hypothesis of neutrino oscillation
Neutrino oscillation
Neutrino oscillation is a quantum mechanical phenomenon predicted by Bruno Pontecorvowhereby a neutrino created with a specific lepton flavor can later be measured to have a different flavor. The probability of measuring a particular flavor for a neutrino varies periodically as it propagates...
by directing a beam of neutrino
Neutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
s from CERN's facilities to the detector of the OPERA experiment
OPERA Experiment
The Oscillation Project with Emulsion-tRacking Apparatus is a scientific experiment for detecting tau neutrinos from muon neutrino oscillations. It is a collaboration between CERN in Geneva, Switzerland, and the Laboratori Nazionali del Gran Sasso in Gran Sasso, Italy and uses the CERN Neutrinos...
at the Gran Sasso National Laboratory
Laboratori Nazionali del Gran Sasso
Laboratori Nazionali del Gran Sasso is a particle physics laboratory of the INFN, situated near the Gran Sasso mountain in Italy, between the towns of L'Aquila and Teramo, about 120 km from Rome. In addition to a surface portion of the laboratory, there are extensive underground facilities...
(LNGS), located in the Gran Sasso mountain in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
. The CNGS facility is housed at the Meyrin
Meyrin
Meyrin is a municipality of the Canton of Geneva, Switzerland. It is the city located nearest to the CERN particle physics laboratory.Meyrin was originally a small agricultural village until the 1950s, when construction of CERN began just to the north...
site of CERN, at the Franco
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
–Swiss
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
border near Geneva
Geneva
Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
, Switzerland. It uses the Super Proton Synchrotron
Super Proton Synchrotron
The Super Proton Synchrotron is a particle accelerator of the synchrotron type at CERN. It is housed in a circular tunnel, in circumference, straddling the border of France and Switzerland near Geneva, Switzerland. The SPS was designed by a team led by John Adams, director-general of what was...
(SPS) accelerator as a source of high-energy proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s.
History
Approval for the CNGS project was signed by the CERN Council in December 1999, with civil engineering on the project starting the following September. Construction of the tunnels and service caverns was completed in mid 2004, with equipment installation completed in summer 2005 and commissioning being carried out throughout spring 2006. The first proton beamProton beam
Proton beams, a type of ion beams, are the result of proton particle acceleration by means of a cyclotron or a synchrotron and can be used e.g. in Proton Beam Therapy for cancer treatment or for proton beam writing in lithography....
was sent to the target on 11 July 2006, with the CNGS facility being approved for physics operations on 18 August 2006.
Function
A protonProton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
beam is taken from the SPS at and is made to collide with a graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
target within the CNGS tunnel. The resulting particles, most importantly kaons and pions among many other particles, are then focused by magnetic lens
Magnetic lens
A magnetic lens is a device for the focusing or deflection of charged particles, such as electrons or ions. Charged particles are deflected based upon the strength of the magnetic field, which can be varied by controlling the current flowing through several electromagnets...
ing and travel 1 kilometre (0.621372736649807 mi) down the CNGS tunnel in a vacuum tube. These particles are naturally unstable and as they travel along the tunnel they decay into muon
Muon
The muon |mu]] used to represent it) is an elementary particle similar to the electron, with a unitary negative electric charge and a spin of ½. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton...
s and muon neutrino
Muon neutrino
The muon neutrino is a subatomic lepton elementary particle which has the symbol and no net electric charge. Together with the muon it forms the second generation of leptons, hence its name muon neutrino. It was first hypothesized in the early 1940s by several people, and was discovered in 1962 by...
s. This beam of particles then collides into an iron graphite target. The final target stops the remaining protons, pion
Pion
In particle physics, a pion is any of three subatomic particles: , , and . Pions are the lightest mesons and they play an important role in explaining the low-energy properties of the strong nuclear force....
s and kaon
Kaon
In particle physics, a kaon is any one of a group of four mesons distinguished by the fact that they carry a quantum number called strangeness...
s, but the neutrinos continue their flight unaffected, as they rarely interact with matter. The number of muons is measured at this point, which gives an indication of the beam's profile and intensity. This beam then passes 732 kilometres (454.8 mi) through the crust
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
and it is expected that during flight some of the muon neutrinos convert into other neutrino types such as tau neutrinos. Once the beam arrives at Gran Sasso, the OPERA
OPERA Experiment
The Oscillation Project with Emulsion-tRacking Apparatus is a scientific experiment for detecting tau neutrinos from muon neutrino oscillations. It is a collaboration between CERN in Geneva, Switzerland, and the Laboratori Nazionali del Gran Sasso in Gran Sasso, Italy and uses the CERN Neutrinos...
and ICARUS experiments are used to detect the neutrinos.
Results
The first candidates for neutrino oscillation were announced in May 2010 by the OPERA experiment.On 22 September 2011, the OPERA collaboration garnered international attention when they released a preprint
Preprint
A preprint is a draft of a scientific paper that has not yet been published in a peer-reviewed scientific journal.-Role:Publication of manuscripts in a peer-reviewed journal often takes weeks, months or even years from the time of initial submission, because manuscripts must undergo extensive...
reporting the OPERA neutrino anomaly
OPERA neutrino anomaly
The OPERA neutrino anomaly is the detection of apparently faster-than-light neutrinos by the OPERA experiment as publicly announced in September 2011. The detection is anomalous because speeds exceeding that of light in a vacuum are generally thought to violate special relativity, a prevailing...
, wherein neutrinos were measured to be travelling, on average, at faster-than-light
Faster-than-light
Faster-than-light communications and travel refer to the propagation of information or matter faster than the speed of light....
speed.