Posts Tagged ‘neutrino

The Daya Bay reactor neutrino experiment begins taking data

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The two antineutrino detectors in Daya Bay Hall #1, shown here prior to the pool being filled with ultrapure water. The pool is lined with photomultiplier tubes to track any "stiff" (highly energetic) cosmic rays that make it all the way through the overlying rock. Credit: Roy Kaltschmidt, Lawrence Berkeley National Laboratory

The Daya Bay Reactor Neutrino Experiment has begun its quest to answer some of the most puzzling questions about the elusive elementary particles known as neutrinos. The experiment’s first completed set of twin detectors is now recording interactions of antineutrinos (antipartners of neutrinos) as they travel away from the powerful reactors of the China Guangdong Nuclear Power Group in southern China.
Neutrinos are uncharged particles produced in nuclear reactions, such as in the sun, by cosmic rays, and in nuclear power plants. They come in three types or “flavors” — electron, muon, and tau neutrinos — that morph, or oscillate, from one form to another, interacting hardly at all as they travel through space and matter, including people, buildings, and planets like Earth.
The start-up of the Daya Bay experiment marks the first step in the international effort of the Daya Bay Collaboration to measure a crucial quantity related to the third type of oscillation, in which the electron-flavored neutrinos morph into the other two flavored neutrinos. This transformation is due to the least-known neutrino “mixing angle,” denoted by θ13 (theta one-three), and could reveal clues leading to an understanding of why matter predominates over antimatter in the universe…. Read the rest of this entry »

Written by physicsgg

August 16, 2011 at 8:15 am

A new neutrino oscillation

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Starting in the late 1960s, neutrino detectors began to see signs that neutrinos, now known to come in the flavors electron (νe), muon (νμ), and tau (ντ), could transform from one flavor to another. The findings implied that neutrinos must have mass, since massless particles travel at the speed of light and their clocks, so to speak, don’t tick, thus they cannot change…..

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Written by physicsgg

July 19, 2011 at 9:28 am

Posted in High Energy Physics

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The antineutrino vanishes differently

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CPT symmetry, the combination of charge conjugation, parity inversion, and time reversal, is a fundamental symmetry of particle and nuclear physics and is considered sacred. It is conserved in field theories that explain the strong, weak, and electromagnetic interactions. In the lepton sector, CPT symmetry requires that muon neutrino disappearance oscillations be identical to muon antineutrino disappearance oscillations in vacuum. A test of CPT symmetry was recently performed by the MINOS experiment at Fermilab, which, due to its magnetic field, is the first experiment to distinguish μ- and μ+ tracks and separately measure the disappearance of muon neutrinos and muon antineutrinos [1]. (Previous experiments have measured a mixture of neutrino and antineutrino oscillations.) Remarkably, as reported in Physical Review Letters, MINOS appears to observe a difference between muon neutrino and muon antineutrino disappearance…..
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Written by physicsgg

July 6, 2011 at 9:30 am