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Topic: Neutrino

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In the News (Mon 18 Mar 19)

  Neutrino oscillation - Wikipedia, the free encyclopedia
Neutrino oscillation is a quantum mechanical phenomenon whereby a neutrino created with a specific lepton flavor (electron, muon or tau) can later be measured to have a different flavor.
Neutrino oscillation is of theoretical and experimental interest as observation of the phenomenon implies that the neutrino has a non-zero mass, which is not part of the original Standard Model of particle physics.
It is generally accepted that neutrino oscillations are due to a mismatch between the flavor and mass eigenstates of neutrinos.
en.wikipedia.org /wiki/Neutrino_oscillation   (2336 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/Neutrino   (3985 words)

 neutrino - HighBeam Encyclopedia
NEUTRINO [neutrino] [Ital.,=little neutral (particle)], elementary particle with no electric charge and a very small mass emitted during the decay of certain other particles.
Neutrinos are also emitted when a pion decays into a muon and in the decays of a number of other elementary particles.
Neutrinos are stable and can be absorbed only by the same weak interactions through which they are created; an energetic neutrino can induce the reverse of the decay that produced it.
www.encyclopedia.com /html/n1/neutrino.asp   (568 words)

 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.
If neutrinos have mass, they also interact gravitationally with other massive particles, but gravity is by far the weakest of the four known forces.
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).
www.ps.uci.edu /~superk/neutrino.html   (946 words)

 SPACE.com -- Physicists Solve 30-Year-Old Neutrino Case
Neutrinos seems to account for a small but significant fraction -- possibly up to 18 percent -- of the mysterious "dark matter'' in the universe that cannot be observed by telescopes or other ordinary means.
The neutrino shortage meant either that theories describing the nuclear furnace at the Sun's core were wrong, or that something was happening to the particles on their way to Earth.
Neutrino experiments have to be performed deep underground because at the Earth's surface a heavy rain of cosmic rays and other high-energy particles drowns out the meek particles.
www.space.com /scienceastronomy/generalscience/neutrino_wg_010618.html   (691 words)

 The Neutrino and the SNP
Other sources of neutrinos include exploding stars (supernovae), relic neutrinos (from the birth of the universe) and nuclear power plants (in fact a lot of the fuel's energy is taken away by neutrinos).
This is important because neutrinos are by far the most numerous particle in the universe (other than photons of light) and so even a tiny mass for the neutrinos can enable them to have an effect on the evolution of the Universe through their gravitational effects.
The neutrinos produced in the core of the sun escape unhindered and a very small number may be detected with suitable apparatus on earth.
www.sno.phy.queensu.ca /public/neutrino.html   (1182 words)

 Michael Hornish Neutrino Page
Neutrino physics is quite unique in that it spans from nuclear and particle physics (which study the smallest objects in the universe) to astrophysics and cosmology (which study the largest objects in the universe).
Detecting a neutrino from the sun is to detect one from a reaction that occurred about eight minutes prior, whereas light that reaches the earth from the surface of the sun in eight minutes took a million years to move from the center of the sun to the surface!
Furthermore, while neutrino oscillations (the phenomenon of one flavor of neutrino "oscillating" into a second flavor) has been well established in recent experiments, therefore identifying a difference in the masses of the various flavors of neutrinos, determining the absolute neutrino mass values continues to be unresolved.
www.tunl.duke.edu /~hornish/neutrino.shtml   (1644 words)

 neutrino concept from the Astronomy knowledge base   (Site not responding. Last check: 2007-10-22)
The neutrino has a very low cross-section for interaction with matter and is almost impossible to detect, hence the uncertainty over its rest mass.
The Sun produces neutrinos from thermonuclear reactions in its core, and a large flux of neutrinos carries away most of the energy, of a supernova.
Experiments to detect cosmic neutrinos involve large masses of "stopping" material and indirect detection of the effects of neutrino absorption.
www.site.uottawa.ca:4321 /astronomy/neutrino.html   (388 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)

 The neutrino
Neutrinos are very difficult to detect because of their very low probability of interacting with matter, or more technically speaking, because of their "weak interaction".
Yet neutrinos are not at all rare particles artificially produced for the use of scientists.
Neutrinos also carry with them the weak and still ill-detected signals of far astrophysics phenomena such as star collapses, because they are not absorbed in outer space.
choruswww.cern.ch /Public/textes/english/node1.html   (1169 words)

 Neutrino history
The neutrino quest begins, but people had to be quite reckless and persevering in those years because, as soon as 1934, Hans Bethe and Rudolf Peierls showed that the cross section (probability of interaction) between neutrinos and matter should be extremely small: billions of time smaller than the one of an electron.
During the sixties and seventies, electrons and neutrinos of high energy are used to probe the composition of nucleons (that is neutrons and protons).
The more is the number of neutrino families, the larger is the width of the Z mass distribution.
wwwlapp.in2p3.fr /neutrinos/anhistory.html   (2664 words)

 Neutrino Unbound
The physics of neutrinos entered a new millennium of precision measurements that will hopefully shed more light on the mysterious and fascinating properties of these elusive particles.
Neutrino Unbound provides information on experimental and theoretical work on the physics and astrophysics of neutrinos, with special attention to neutrino oscillations, direct detection of neutrino masses and neutrinoless double-beta decay.
Observation of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam
www.nu.to.infn.it   (245 words)

 The Solar Neutrino Problem
Other theories state that left-handed neutrinos may precess into right-handed neutrinos, or that neutrinos of one flavor and orientation may transform into neutrinos of another flavor and orientation.
It has been claimed that the neutrino flux is correlated to solar radius and solar wind mass flux; and anti-correlated to line-of-sight magnetic flux, p-mode frequencies, and (you guessed it) sunspots.
Another possibility, rarely discussed, is that the solar neutrino flux is actually constant and it is the cosmic ray background that is varying.
www.maths.qmw.ac.uk /~lms/research/neutrino.html   (879 words)

 Neutrino Masses
Neutrinos are fundamental, subatomic particles that are similar to electrons but are neutral meaning that they possess no electric charge.
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.
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)

 Neutrino Mine Hits Pay Dirt
Solar neutrinos are produced when two protons fuse together to form a deuterium nucleus, a positron, and a neutrino.
Therefore, neutrinos should flow from the sun like photons from a light bulb—radiating evenly in all directions, as if the surface of a sphere were being illuminated from its center.
One explanation is that the neutrino “flavor”; oscillates between the detectable “electron”; neutrino type, and the much heavier “muon”; neutrino and maybe even the “tau”; neutrino, neither of which can be detected.
pr.caltech.edu /periodicals/EandS/articles/LXV4/neutrino.html   (569 words)

 Highbeam Encyclopedia - Search Results for neutrino   (Site not responding. Last check: 2007-10-22)
neutrino astronomy NEUTRINO ASTRONOMY [neutrino astronomy] study of stars by means of their emission of neutrinos, fundamental particles that result from nuclear reactions and are emitted by stars along with light.
neutrino NEUTRINO [neutrino] [Itallittle neutral (particle elementary particle with no electric charge and a very small mass emitted during the decay of certain other particles.
The neutrino was first postulated in 1930 by Wolfgang Pauli in order to maintain the law of conservation of energy during beta
www.encyclopedia.com /articles/09132.html   (588 words)

 Solar Neutrino Viewgraphs
We show that solar plus reactor neutrino experiments set an upper limit of 7.3% to the fraction of energy that the Sun produces via the CNO fusion cycle, which is an order of magnitude improvement upon the previous limit.
New experiments are required to detect CNO neutrinos corresponding to the 1.5% of the solar luminosity that the standard solar model predicts is generated by the CNO cycle.
My summary of the current situation in solar neutrino research is that there is no viable explanation of all the experiments that is based upon changing the solar model, but that a number of proposed particle-physics explanations do fit all the available data.
www.sns.ias.edu /~jnb/SNviewgraphs/snviewgraphs.html   (2096 words)

 Glossary Item - Neutrino
Neutrinos are neutral particles that rarely interact with matter.
Neutrinos were detected experimentally by Clyde Cowan and Fred Reines at the Savannah River reactor in South Carolina in 1956.
The other two types of neutrinos, the muon-neutrino and the tau-neutrino, are associated with particles known as muons and taus.
education.jlab.org /glossary/neutrino.html   (277 words)

 Neutrino's?   (Site not responding. Last check: 2007-10-22)
Saundra Answer 1: The existence of neutrinos was postulated to explain what was observed when a nucleus undergoes beta decay via electron emission (a neutron in the nucleus changes into a proton, and the nucleus emits an electron).
Eventually the neutrino was detected, in the early 1950's, through nuclear reactors (which produce huge numbers of neutrinos).
Neutrinos are considered to be the force-carriers associated with the fundamental force called the weak force.
www.newton.dep.anl.gov /askasci/ast99/ast99055.htm   (348 words)

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