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Topic: Muon neutrino

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In the News (Wed 20 Mar 19)

  What's a Neutrino?
Neutrinos are affected only by a "weak" sub-atomic force of much shorter range than electromagnetism, and are therefore able to pass through great distances in matter without being affected by it.
Hence, the "electron neutrino" is associated with the electron, and two other neutrinos are associated with heavier versions of the electron called the muon and the tau (elementary particles are frequently labelled with Greek letters, to confuse the layman).
It is soon recognized to be a heavier version of the electron and muon, and its decay exhibits the same apparent imbalance of energy and momentum that led Pauli to predict the existence of the neutrino in 1931.
www.ps.uci.edu /~superk/neutrino.html   (946 words)

There are six leptons in the present structure, the electron, muon, and tau particles and their associated neutrinos.
The muon is a lepton which decays to form an electron or positron.
The muon is produced in the upper atmosphere by the decay of pions produced by cosmic rays:
hyperphysics.phy-astr.gsu.edu /hbase/particles/lepton.html   (635 words)

The 11,000 hand-blown photomultiplier tubes are half a meter in diameter and coated inside with a thin layer of alkali metal to detect the Cerenkov radiation from the interactions of either electron neutrinos or muon neutrinos.
Their interpretation of this result is that the deficiency is caused by "neutrino oscillation" in which a number of muon neutrinos are transmuted into tau neutrinos which are undetectable.
When a muon neutrino interacts with a nucleus, it can produce an energetic muon which travels only a short distance, emitting a sharply outlined cone of Cerenkov radiation which can be detected by photomultiplier tubes.
hyperphysics.phy-astr.gsu.edu /hbase/particles/neutrino2.html   (479 words)

 Neutrinos Have Mass | Physical Review Focus
Neutrinos dart through matter and space at a pace indistinguishable from the speed of light, so they were initially thought to be massless.
The probability of detection as a muon neutrino, for example, would depend on the size of the muon neutrino component at the moment of detection.
Muon neutrinos produce muons that generate a telltale signature of Cerenkov light, a pattern distinguishable from that of electrons spawned by electron neutrinos.
focus.aps.org /story/v2/st10   (850 words)

 Mass And Oscillations Discovered For Elusive Neutrino
Neutrinos coming through the earth (20,000 km) travel further and have greater distance in which to change from a muon neutrino to another neutrino and back again, through many cycles at typical energies.
The strange situation for neutrinos, different from all the other elementary particles, is that the state of the particle which we call the muon neutrino may not be the same as the particle mass state.
The muon neutrino may be composed of half each of two states of slightly different mass that oscillate in and out of phase with each other as they travel along, alternately interacting as a muon neutrino and then making a tau neutrino.
www.eurekalert.org /pub_releases/1998-06/UoH-MAOD-050698.php   (2764 words)

 Muon Summary
The muon's mass led physicists to believe it was the particle predicted by the Japanese physicist Yukawa Hideki to explain the strong interaction that binds protons and neutrons together in atomic nuclei.
Muons are one of the main components of cosmic radiation at the earth's surface, produced by the decay of ions high in the atmosphere.
Muons do not exist at the levels of energy available in everyday life, but are created in high-energy environments such as those that exist in cosmic ray showers and in particle accelerator reactions.
www.bookrags.com /Muon   (1622 words)

 Information For the Public
The continuing study of neutrino physics suggests that a neutrino of one family might sometimes change into a neutrino of a different family, by a mechanism known as neutrino oscillation.
Neutrinos must have mass, and the mass cannot be identical for all three neutrino flavors.
To determine whether neutrinos oscillate from one flavor to another, and, hence, have mass, a collaboration of 200 scientists from 26 institutions worldwide are planning the MINOS experiment.
www-numi.fnal.gov /public/oscillations.html   (888 words)

 Neutrino Oscillations
As the neutrino continues to travel, the proportion of each vary with distance, so it is said that neutrinos oscillate from one state to another.
Neutrinos produced from the decay of pions and kaons from cosmic-ray interactions in the upper levels of the atmosphere can be measured in underground experiments.
It is difficult to reconcile this neutrino deficit with the current understanding of the sun (standard solar model) which is extremely successful at determining other parameters (in particular, it is very successful at measuring the vibrational frequencies of solar oscillations, or sun-quakes, that can also be measured).
www.physics.usyd.edu.au /hienergy/oscillations.html   (1829 words)

 Neutrino Mass
From the impact of cosmic ray on a nucleus in the atmosphere it is expected that the ratio of muon-neutrinos to electron-neutrinos is 2 to 1.
The neutrino states on the left of the equation are the flavor states produced in weak interaction, while the states on the right (with the numerical subscripts) are called the mass states corresponding to free neutrino with different mass.
Neutrino mixing is then considered as a correction within SM providing a window to the new discovery before formulating in detail the deeper theory.
universe-review.ca /R15-13-neutrino.htm   (1881 words)

 The Nobel Prize in Physics 1988
All particles, except the neutrinos, had to be prevented from reaching the detector, as they could give rise to a large number of particle reactions and completely swamp the incredibly few neutrino reactions.
As neutrino interactions are very rare, the background from other processes was disturbing, particularly the background caused by the penetrating muons from the cosmic radiation.
A total of 51 neutrino interactions were registered with a muon observed in the spark chamber.
www.nobelprize.org /nobel_prizes/physics/laureates/1988/illpres/hunt.html   (576 words)

 Standard Model Upended With Discovery Of Neutrino Oscillation, Mass
Atmospheric neutrinos are produced by high-energy collisions of cosmic rays with Earth's upper atmosphere.
According to the neutrino mixing theory of the Standard Model, the probability that a neutrino of one flavor changes to another can be determined by dividing the distance a neutrino travels (L) by its energy (E).
Thus, the 1998 discovery of neutrino oscillation was also the first evidence that neutrinos have mass.
www.spacedaily.com /news/cosmology-04u.html   (701 words)

 Making muon rings round neutrino factories - CERN Courier
Following indications from solar neutrinos as early as 1975, experiments studying neutrinos produced by the decay of cosmic-ray pions and muons in the atmosphere finally confirmed in 1998 that neutrinos undergo transmutations.
As neutrinos are one of the most common particles in the universe, their total mass could provide a significant fraction of the whole mass of creation.
Depending on whether the transmutation into muon neutrinos of electron neutrinos and antineutrinos are enhanced or suppressed by matter, one would be able to distinguish between the two mass scenarios shown in the figure.
www.cerncourier.com /main/article/40/3/14   (0 words)

 Neutrino mass discovered (July 1998) - Physics World - PhysicsWeb
Neutrinos were first detected in 1956 by Fred Reines of the University of California at Irvine and the late George Cowan.
The muon neutrino was first detected by Leon Lederman, Jack Steinberger and Mel Schwartz at the Brookhaven National Laboratory in 1962, a discovery for which they shared the Nobel prize in 1988.
Neutrinos would therefore represent a significant amount of "dark matter", mass that we cannot see but is predicted to exist by cosmological models.
physicsweb.org /article/world/11/7/3   (1362 words)

 Atmospheric Neutrinos at SuperK
Atmospheric neutrinos were first studied in the context of being background to nucleon decay searches.
It was tempting to entertain the notion that the muon neutrinos were oscilating either into an electron neutrino or some other flavor which the detectors were not sensitive to, such as a tau or sterile neutrino.
Muons tend to create sharp ring edges, but electrons induce an electromagnetic shower through brehmstrahlung and pair production and so have a fuzzy edged ring due to the many small overlapping rings from all the electron-positron pairs in the shower.
superk.physics.sunysb.edu /superk/physics/atmospheric-neutrinos   (575 words)

 Atmospheric Neutrinos
The pions decay to a muon and a muon neutrino.
Fully contained muons and electrons are identified by a pattern recognition algorithm that uses the maximum likelihood method to compare the measured distribution of hits and with the expected shape due to a muon (sharp, collapsed angle if beta < 1) and an electron (fuzzy due to the electromagnetic shower).
We studied these so-called upward-going muons and found that the rate of low and high energy events, and their angular distribution, were in poor agreement with the standard prediction, but in good agreement with a hypothesis of neutrino oscillations.
hep.bu.edu /~superk/atmnu   (1258 words)

 Neutrino - Wikipedia, the free encyclopedia
A practical method for investigating neutrino masses (that is, flavour oscillation) was first suggested by Bruno Pontecorvo in 1957 using an analogy with the neutral kaon system; over the subsequent 10 years he developed the mathematical formalism and the modern formulation of vacuum oscillations.
The strongest upper limit on the masses of neutrinos comes from cosmology: the Big Bang model predicts that there is a fixed ratio between the number of neutrinos and the number of photons in the cosmic microwave background.
Atmospheric neutrinos result from the interaction of cosmic rays with atomic nuclei in the Earth's atmosphere, creating showers of particles, many of which are unstable and produce neutrinos when they decay.
en.wikipedia.org /wiki/Muon_neutrino   (4378 words)

 IceCube: Neutrino History - 1990
In this theory the probability for a neutrino to change type varies periodically with distance and is referred to as neutrino oscillations.
If the muon or electron neutrinos are changing type before they enter the detector that would cause a discrepancy between the measured and predicted ratios.
Neutrinos can easily pass through the entire earth, so the distances vary from the height of the atmosphere to the diameter of the earth.
icecube.wisc.edu /info/neutrinos/1990.php   (651 words)

 Atmospheric Neutrinos at SuperK
Atmospheric neutrinos were first studied in the context of being background to nucleon decay searches.
It was tempting to entertain the notion that the muon neutrinos were oscilating either into an electron neutrino or some other flavor which the detectors were not sensitive to, such as a tau or sterile neutrino.
Muons tend to create sharp ring edges, but electrons induce an electromagnetic shower through brehmstrahlung and pair production and so have a fuzzy edged ring due to the many small overlapping rings from all the electron-positron pairs in the shower.
ale.physics.sunysb.edu /nngroup/superk/physics/atmospheric-neutrinos   (575 words)

 Scientific American: Ask the Experts: Physics: What is a neutrino?
A neutrino is a subatomic particle that is very similar to an electron, but has no electrical charge and a very small mass, which might even be zero.
Neutrinos are one of the most abundant particles in the universe.
Supernovae too are predominantly a neutrino phenomenon, because neutrinos are the only particles that can penetrate the very dense material produced in a collapsing star; only a small fraction of the available energy is converted to light.
www.sciam.com /askexpert_question.cfm?articleID=000C732C-3B0C-1C71-84A9809EC588EF21   (755 words)

 symmetry - May 2005 - The Elusive Neutrino
Neutrinos are capable of traversing the entire Earth in the blink of an eye.
As neutrinos travel through matter and space, they transform from one type into another, either appearing as electron neutrinos, muon neutrinos, or tau neutrinos.
The idea of neutrino transformation gained significant support in 1998, when the Super-Kamiokande collaboration improved on earlier experiments and announced that some muon neutrinos produced in the Earth's atmosphere also "disappeared" before traversing the Super-Kamiokande detector, 2000 feet underground in an old zinc mine in Japan.
www.symmetrymag.org /cms/?pid=1000112   (2646 words)

 The Ultimate Neutrino Page - Comments on Neutrino 98
Atmospheric neutrinos are secondary particles produced by cosmic rays (protons) hitting the atmosphere of the earth.
Superkamiokande measured the muon neutrino to electron neutrino ratio to be 63 % of the predicted ratio.
Particularly, the conversions to sterile neutrinos may help the nucleosynthesis (Peltoniemi 95), and David Caldwell in his talk stated that "the model with sterile neutrinos is the only robust solution".
cupp.oulu.fi /neutrino/neutrino98.html   (2496 words)

 Neutrino Masses
There are three types, or "flavors," of neutrinos, one of which is associated with the electron, one of which is associated with the muon, and one of which is associated with the tau lepton.
The muon and tau are heavier versions of the electron (The mass of the muon (respectively, tau) is about 200 (respectively, 3500) times the mass of an electron).
When neutrinos are initially produced, they spin in a very specific way: If you take your left hand and point your thumb in the direction that the neutrino is moving and let your fingers curl naturally, the fingers indicate the spinning direction.
www.jupiterscientific.org /sciinfo/numasses.html   (1989 words)

 The Ultimate Neutrino Page
The above decay scenario leads to muon neutrinos with energy spectrum of some tens of MeV, and electron neutrinos and muon antineutrinos with smaller mean energy.
The appearance of high energy electron neutrinos is therefore a signal of neutrino oscillation.
As the neutrino beam does not contain any significant amount of tau neutrinos, an appearance of a charged tau lepton in a nearby detector is a signal of neutrino oscillation.
cupp.oulu.fi /neutrino/nd-osc.html   (544 words)

 Muon Neutrino Mass at NuMass Experiment, University of Minnesota
This proposal to improve the muon neutrino mass limit by a factor of 20 (from 170 keV down to 8 keV) will be the largest factor improvement made in any neutrino species mass within the last 25 years.
Muons that are produced in the forward direction at a point halfway around the ring will therefore have the maximum radial displacement from the parent pion initial impact point when they return to the detector.
If the neutrino has mass, this will reduce the energy of the forward-going muon and shrink the edge of the decay muon distribution by an amount which is sensitive to the neutrino mass, but relatively insensitive to the uncertainty in the pion mass.
www.hep.umn.edu /numass   (458 words)

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