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RE: Neutrinos
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Cosmologists at UCL are a step closer to determining the mass of the elusive neutrino particle, not by using a giant particle detector, but by gazing up into space.
Although it has been shown that a neutrino has a mass, it is vanishingly small and extremely hard to measure - a neutrino is capable of passing through a light year (about six trillion miles) of lead without hitting a single atom.
New results using the largest ever survey of galaxies in the universe puts total neutrino mass at no larger than 0.28 electron volts - less than a billionth of the mass of a single hydrogen atom. This is one of the most accurate measurements of the mass of a neutrino to date.

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Neutrino 'ghost particle' sized up by astronomers

Scientists have made their most accurate measurement yet of the mass of a mysterious neutrino particle.
Neutrinos are sometimes known as "ghost particles" because they interact so weakly with other forms of matter.
Previous experiments had shown that neutrinos have a mass, but it was so tiny that it was very hard to measure.
Using data from the largest ever survey of galaxies, researchers put the mass of a neutrino at no greater than 0.28 electron volts.

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Geo-neutrinos
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Discovery of subatomic particles could answer deep questions in geology

An international team including scientists from Princeton University has detected subatomic particles deep within the Earth's interior. The discovery could help geologists understand how reactions taking place in the planet's interior affect events on the surface such as earthquakes and volcanoes. Someday, scientists may know enough about the sources and flow of heat in the Earth to predict events like the recent volcanic eruption in Iceland.
The finding, made by the Borexino Collaboration at the Gran Sasso National Laboratory of the Italian Institute of Nuclear Physics, was reported in a paper published in the April issue of Physics Letters B. The work builds on earlier evidence of so-called "geoneutrinos" obtained during a Japanese experiment in 2005.

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Unexpected difference between neutrinos and antineutrinos suggested at MINOS

An international team of scientists from the MINOS experiment at the Fermi National Accelerator laboratory (Fermilab) today, 14 June, announced the world's most precise measurement to date of the parameters that govern antineutrino oscillations, the back-and-forth transformations of antineutrinos from one type to another. This result provides information about the difference in mass between different antineutrino types. The measurement showed an unexpected variance in the values for neutrinos and antineutrinos. This mass difference parameter, called delta m▓ ("delta m squared"), is smaller by approximately 40 percent for neutrinos than for antineutrinos.
However, there is a still a five percent probability thatá delta m▓ is actually the same for neutrinos and antineutrinos. With such a level of uncertainty, MINOS physicists need more data and analysis to know for certain if the variance is real.
Neutrinos and antineutrinos behave differently in many respects, but the MINOS results, presented today at the Neutrino 2010 conference in Athens, Greece and in a colloquium at Fermilab, are the first observation of a potential fundamental difference that established physical theory could not explain.

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Neutrino oscillation
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On Monday, May 31, the OPERA Collaboration based at the Gran Sasso underground laboratory in Italy announced a rare breakthrough in particle physics: the first direct observation of a muon neutrino turning into a tau neutrino. The observation confirms that indeed neutrinos do oscillate among "flavours."
Since the mid-1960s neutrino oscillation has provided the best explanation for the so-called missing solar neutrino problem. Physicist Ray Davis, working deep in the Homestake Mine in South Dakota, found just a third of the neutrinos that theorists predicted should be created in the sun. His experiment was sensitive to electron neutrinos, the only kind the sun makes; the idea was that the other two-thirds had transformed themselves into muon and tau neutrinos on their way to Earth.
Experiments like SNO, Canada's Sudbury Neutrino Observatory that recorded all three flavours of neutrinos arriving from the sun, and Japan's KamLAND, the Kamioka Liquid scintillator Anti-Neutrino Detector that records neutrinos produced by nuclear reactors, have long studied oscillation indirectly, by measuring the ratio of the neutrinos they do see to the ones they don't.

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First 'chameleon particle' spotted after changing type

Physicists at OPERA say they are 98 per cent confident that they have detected a tau neutrino in the beam. This confirms serious cracks in the standard model of particle physics, which says neutrinos are massless. Neutrinos can only oscillate if they have mass.
Previous evidence for oscillation was indirect. In 1998, physicists found that some muon and electron neutrinos, which had been produced in the atmosphere and sun, had disappeared en route to the Super-Kamiokande detector in Japan, which cannot detect tau neutrinos.
But other less likely explanations, such as neutrino decay, could not be entirely ruled out.

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Geo-neutrino
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UMass Amherst Physicists Use Underground Lab to Detect Rare Particles, Peek into Earth's Centre

Using a delicate instrument located under a mountain in central Italy, two University of Massachusetts Amherst physicists are measuring some of the faintest and rarest particles ever detected, geo-neutrinos, with the greatest precision yet achieved. The data reveal, for the first time, a well defined signal, above background noise, of the extremely rare geo-neutrino particle from deep within Earth.
Funded by the National Science Foundation, UMass Amherst researchers Laura Cadonati and Andrea Pocar are part of the Borexino international team whose results are available in the current online edition of the journal Physics Letters B.

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Neutrino
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Could a neutrino -- an electrically neutral and nearly mass-free sibling to the electroná -- have triggered dark energy, the anti-gravity force discovered just over a decade ago?
That's the latest idea from a team of theoretical physicists who suggest that dark energy was created from neutrino condensate in the split second after the universe's birth 13.7 billion years ago.
The idea sprang from calculations showing that the density of dark energy is comparable to the value of neutrino mass, said lead researcher Jitesh Bhatt, with the Physical Research Laboratory in Ahmedabad, India.

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Queen Mary scientists shed light on a mysterious particle
Physicists at Queen Mary, University of London have begun looking deep into the Earth to study some of nature's weirdest particles -- neutrinos
Starting from the end of November, Queen Mary's Particle Physics Research Centre is the sole recipient of the T2K experiment data. The T2K Collaboration is a 500-strong alliance of scientists in 12 countries, who have come together to investigate the ghostly neutrino.

"Trillions of neutrinos pass through our bodies every second, but you don't notice; they pass through space and the Earth with almost no effect. This makes neutrinos very difficult to study and yet they are thought to play a fundamental role in the formation of the Universe and understanding where we came from" - Physicist Dr Francesca Di Lodovico.

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Title: Using Cold Atoms to Measure Neutrino Mass
Authors: M. Jerkins, J. R. Klein, J. H. Majors, and M. G. Raizen

We propose a -decay experiment based on a sample of ultracold atomic tritium. These initial conditions allow us to explore boundstate -decay, as well as ordinary -decay in which we can detect the helium ion in coincidence with the . We construct a two-dimensional fit incorporating both the shape of the -spectrum and the direct reconstruction of the neutrino mass peak. We present simulation results of the feasible limits on the neutrino mass achievable in these three-body and two-body tritium -decay experiments.

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