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MINOS experiment
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Cosmic rays detected deep underground reveal secrets of the upper atmosphere
Cosmic-rays detected half a mile underground in a disused U.S. iron-mine can be used to detect major weather events occurring 20 miles up in the Earth's upper atmosphere, a new study has revealed. Published in the journal Geophysical Research Letters and led by scientists from the UK's National Centre for Atmospheric Science (NCAS) and the Science and Technology Facilities Council (STFC), this remarkable study shows how the number of high-energy cosmic-rays reaching a detector deep underground, closely matches temperature measurements in the upper atmosphere (known as the stratosphere).
For the first time, scientists have shown how this relationship can be used to identify weather events that occur very suddenly in the stratosphere during the Northern Hemisphere winter. These events can have a significant effect on the severity of winters we experience, and also on the amount of ozone over the poles - being able to identify them and understand their frequency is crucial for informing our current climate and weather-forecasting models to improve predictions.

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Posts: 131433
Date:
MiniBooNE experiment
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Physics Bridges Long Distances to Study Tiny Particles

A remote monitoring station allows McMicken physicists to actively participate in Fermilab's MiniBooNE experiment.

These extremely tiny particles - many times smaller than the electrons that orbit individual atoms - are thought to play a role in everything from solar energy to radioactive decay to the "dark matter" that makes up most of the universe.
Neutrinos' small size and the difficulty in isolating them for study has made it hard for physicists to fully understand how they relate to the other subatomic particles that form the building blocks of atoms and molecules. But an experiment being conducted by researchers from the University of Cincinnati and 17 other universities could unlock critical secrets about the nature of neutrinos.

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Posts: 131433
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RE: Neutrinos
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Title: Three-flavour neutrino oscillation update
Authors: Thomas Schwetz, Mariam Tortola, Jose W.F. Valle
(Version v2)

We review the present status of three-flavour neutrino oscillations, taking into account the latest available neutrino oscillation data presented at the Neutrino 2008 Conference. This includes the data released this summer by the MINOS collaboration, the data of the neutral current counter phase of the SNO solar neutrino experiment, as well as the latest KamLAND and Borexino data. We give the updated determinations of the leading 'solar' and 'atmospheric' oscillation parameters. We find from global data that the mixing angle \theta_{13} is consistent with zero within 0.9\sigma and we derive an upper bound of \sin^2\theta_{13} < 0.035 (0.056) at 90% CL (3 \sigma).

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The detection of extra dimensions beyond the familiar four--the three dimensions of space and one of time--would be among the most earth-shattering discoveries in the history of physics. Now scientists at the Fermi National Accelerator Laboratory in Batavia, Ill., are designing a new experiment that would investigate tantalizing hints that extra dimensions may indeed exist.
While observing a beam of muon neutrinos generated by one of Fermilabs particle accelerators, the MiniBooNE researchers found that an unexpectedly high number of the particles in the low-energy range (below 475 million electron volts) had transformed into electron neutrinos. After a year of analysis, the investigators have failed to come up with a conventional explanation for this so-called low-energy excess. The mystery has focused attention on an intriguing and very unconventional hypothesis: a fourth kind of neutrino may be bouncing in and out of extra dimensions.

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L

Posts: 131433
Date:
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Title: Three-flavour neutrino oscillation update
Authors: Thomas Schwetz, Mariam Tortola, Jose W.F. Valle

We review the present status of three-flavour neutrino oscillations, taking into account the latest available neutrino oscillation data presented at the Neutrino 2008 Conference. This includes the data released this summer by the MINOS collaboration, the data of the neutral current counter phase of the SNO solar neutrino experiment, as well as the latest KamLAND and Borexino data. We give the updated determinations of the leading 'solar' and 'atmospheric' oscillation parameters. We find from global data that the mixing angle \theta_{13} is consistent with zero within 0.9\sigma and we derive an upper bound of \sin^2\theta_{13} < 0.035 (0.056) at 90% CL (3\sigma).

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Title: The Highest Energy Neutrinos
Authors: Francis Halzen

Measurements of the arrival directions of cosmic rays have not revealed their sources. High energy neutrino telescopes attempt to resolve the problem by detecting neutrinos whose directions are not scrambled by magnetic fields. The key issue is whether the neutrino flux produced in cosmic ray accelerators is detectable. It is believed that the answer is affirmative, both for the galactic and extragalactic sources, provided the detector has kilometre-scale dimensions. We revisit the case for kilometre-scale neutrino detectors in a model-independent way by focussing on the energetics of the sources. The real breakthrough though has not been on the theory but on the technology front: the considerable technical hurdles to build such detectors have been overcome.
Where extragalactic cosmic rays are concerned an alternative method to probe the accelerators consists in studying the arrival directions of neutrinos produced in interactions with the microwave background near the source, i.e. within a GZK radius. Their flux is calculable within large ambiguities but, in any case, low. It is therefore likely that detectors that are larger yet by several orders of magnitudes are required. These exploit novel techniques, such as detecting the secondary radiation at radio wavelengths emitted by neutrino induced showers.

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Title: Why Tau First?
Authors: D. Fargion, D. D'Armiento, P. G. Lucentini De Sanctis
(Version v2)

Electron neutrino has been the first neutral lepton to be foreseen and discovered last century. The un-ordered muon and its neutrino arose later by cosmic rays. The tau discover, the heaviest, the most unstable charged lepton, was found surprisingly on 1975. Its neutrino was hardly revealed just on 2000. So why High Energy Neutrino Astronomy should rise first via tau neutrino, the last, the most rare one? The reasons are based on a chain of three favourable coincidences found last decade: the neutrino masses and their flavour mixing, the UHECR opacity on Cosmic Black Body (GZK cut off on BBR), the amplified tau air-shower decaying in flight. Indeed guaranteed UHE GZK tau neutrinos, feed by muon mixing, while skimming the Earth might lead to boosted UHE tau, mostly horizontal ones. These UHE lepton decay in flight are spread, amplified, noise free Air-Shower: a huge event for an unique particle. To be observed soon: within Auger sky, in present decade. Its discover may sign of the first tau appearance.

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Low-energy neutrinos from the Sun have been spotted by researchers for the first time. Detecting these solar particles confirms theories about how nuclear fusion occurs within the Sun, and how neutrinos oscillate between different types.

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Princeton scientists confirm long-held theory about source of sunshine
Scientists are a step closer to understanding sunshine. A monumental experiment buried deep beneath the mountains of Italy has provided Princeton physicists with a clearer understanding of the sun's heart -- and of a mysterious class of subatomic particles born there.
The researchers, working as part of an international collaboration at the underground Gran Sasso National Laboratory near L'Aquila, Italy, have made the first real-time observation of low-energy solar neutrinos, which are fundamental particles created by nuclear reactions that stream in vast numbers from the sun's core.

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Posts: 131433
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Supernova Neutrino Bursts
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Title: Search for Supernova Neutrino Bursts at Super-Kamiokande
Authors: M.Ikeda, A.Takeda, Y.Fukuda, M.R.Vagins, M.Sakuda

The result of a search for neutrino bursts from supernova explosions using the Super-Kamiokande detector is reported. Super-Kamiokande is sensitive to core-collapse supernova explosions via observation of their neutrino emissions. The expected number of events comprising such a burst is ~10^4 and the average energy of the neutrinos is in few tens of MeV range in the case of a core-collapse supernova explosion at the typical distance in our galaxy (10 kiloparsecs); this large signal means that the detection efficiency anywhere within our galaxy and well past the Magellanic Clouds is 100%. We examined a data set which was taken from May, 1996 to July, 2001 and from December, 2002 to October, 2005 corresponding to 2589.2 live days. However, there is no evidence of such a supernova explosion during the data-taking period. The 90% C.L. upper limit on the rate of core-collapse supernova explosions out to distances of 100 kiloparsecs is found to be 0.32 SN/year.

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