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Topic: Solar neutrino problem

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	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 /sno/neutrino.html (1182 words)

	Solar neutrino problem - Wikipedia, the free encyclopedia (Site not responding. Last check: )
		Neutrino is massless; fixed ratio between the number of neutrinos and the number of photons in the cosmic microwave background
		The solar neutrino problem was a major discrepancy between measurements of the neutrinos flowing through the Earth and theoretical models of the solar interior, lasting from the mid-1960s to about 2002.
		The solar neutrino problem was troubling because it meant that either general relativity was incorrect, models of stellar evolution were incorrect, or the Standard Model was incorrect.
	en.wikipedia.org /wiki/Solar_neutrino_problem (1056 words)

	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.
		Neutrinos are special, since as electrically-neutral particles they may have another source of mass, Majorana mass (which cannot work for electrically-charged particles since it would allow particles to turn into anti-particles which would violate conservation of electric charge).
		The problem with this is that the neutrino masses are implausibly smaller than the rest of the known particles (at least 500,000 times smaller than the mass of an electron), which, while it does not invalidate the theory, is not very satisfactory.
	en.wikipedia.org /wiki/Neutrino_oscillation (1162 words)

	A Solution for the Solar Neutrino Problem
		Experiments using the inverse beta process to detect solar neutrinos have discovered that there is a significant shortfall in the number of neutrinos detected compared to the amount expected from the standard solar model.
		The study of solar neutrinos is therefore the only practicable way we have, at present, to study the processes by which the sun (and other stars) shine.
		Neutrinos may be captured by a process known as the inverse beta process, an example of which is the inverse of the electron capture decay of 37Ar:
	www.btinternet.com /~david.reynolds1/neutrino (1495 words)

	The Solar FAQ: Solar Neutrinos and Other Solar Oddities
		Neutrinos are elusive particles, that are emitted in a variety of nuclear reactions and decays.
		Neutrino travel across astronomical distances is obviously inaccessible to laboratory studies, and has for a long time been regarded as the most promising area to search for anomalies, that can explain the missing solar neutrinos.
		The solar neutrino problem alone was suggestive but not compelling evidence; the atmospheric-neutrino results clinched the case for non-standard neutrino behavior, and SNO confirmed that this solved the solar neutrino problem.
	www.talkorigins.org /faqs/faq-solar.html (15805 words)

	Neutrinos
		The electron neutrino (a lepton) was first postulated in 1930 by Fermi to explain why the electrons in beta decay were not emitted with the full reaction energy of the nuclear transition.
		Modern neutrino detectors at IMB in Ohio and Kamiokande in Japan detected neutrinos from Supernova 1987A.
		New experimental evidence from the Super-Kamiokande neutrino detector in Japan represents the strongest evidence to date that the mass of the neutrino is non-zero.
	hyperphysics.phy-astr.gsu.edu /hbase/particles/neutrino.html (1421 words)

	BNL Celebrates 60 Years of Discovery, 1947-2007
		Solar neutrinos – uncharged, elementary particles produced in the nuclear reactions that power the sun – have long been sought after by Brookhaven chemists.
		Following this discovery, Brookhaven’s Solar Neutrino Group participated in two major solar neutrino experiments that elucidated the nature of the “solar neutrino problem”: from 1986-1998 in GALLEX in Gran Sasso, Italy, and from 1996 to 2006 in the Canadian Solar Neutrino Observatory (SNO).
		SNO eventually “solved” the neutrino problem some 30 years after its discovery by demonstrating that two-thirds of the neutrinos emitted by the Sun "disappear" by morphing, or oscillating, among three varieties of neutrinos as they journey to the Earth.
	www.bnl.gov /60th/chemistry.asp (941 words)

	The Solar Neutrino Problem
		One way to solve the solar neutrino problem is to lower the central temperature of the Sun by a few percent.
		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)

	Solar neutrino problem at opensource encyclopedia (Site not responding. Last check: )
		de:Neutrinooszillationit:Problema dei neutrini solari The solar neutrino problem was a major discrepancy between measurements of the neutrinos flowing through the Earth and theoretical models of the solar's interior, lasting from the mid-1960s to about 2002.
		As neutrino detectors became accurate enough to measure the flow of neutrinos from the sun, it became clear that researchers weren't getting as many of them as the models of solar combustion predicted.
		Thus the "missing" solar neutrinos could be the original electron-neutrinos which changed into other types along the way to Earth and therefore escaped detection.
	www.wiki.tatet.com /Solar_neutrino_problem.html (652 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)

	BBC - h2g2 - The Solar Neutrino Problem
		Unfortunately current observations using neutrino telescopes show this not to be the case, in fact the actual number observed turns out to be about a third of that predicted by the current standard solar models (SSMs).
		This type (or flavour) of neutrino is produced in vast quantities in the cores of all stars and in even larger numbers in supernova explosions - a total of 19 neutrinos were detected coming from the direction of SN1987A, a supernova explosion that was observed in the Large Magellanic Cloud in February of 1987.
		Originally it was thought that neutrinos were massless particles that travelled at the speed of light, but massless particles do not decay into other members of the same family, so proof that they do indeed alter their flavour confirms that they have mass and, therefore, must travel significantly slower.
	www.bbc.co.uk /dna/h2g2/A2524466 (1926 words)

	The Solar Neutrino Problem
		Neutrinos are produced in the cores of stars by processes such as the PP chain.
		Thus, if neutrinos can be detected from a star, they provide a glimpse directly into the processes going on now in the core of the star, while the visible light emitted at the surface may correspond to energies produced hundreds of thousands of years ago.
		Neutrino experiments are difficult because the neutrinos interact so weakly with matter, but now several independent experiments have confirmed what was already indicated by the earliest such experiments: the Sun is producing approximately a factor of 2 fewer neutrinos than we expect that it should be.
	csep10.phys.utk.edu /astr162/lect/energy/snu.html (357 words)

	Astronomy Online
		This detector is filled with 400 liters of water and cadmium chloride, and measures the interaction between neutrinos emanating from the nuclear reactor and a proton within the nucleus of the cadmium atom.
		Since neutrinos are weak interactive particles, there is little to affect their trajectory, so something happening to the neutrinos between the Sun and Earth is highly unlikely based on the Standard Model.
		This observatory is different from the other neutrino detectors as this one uses heavy water, and is actually capable of detecting all three “flavors” of neutrinos [R9].
	astronomyonline.org /SolarSystem/SolarNeutrinoProblem.asp (2870 words)

	The Solar Neutrino Problem
		However, the community of solar seismologists, who observe small oscillations in spectral line strengths due to pressure waves traversing through the Sun, argue that such a change is not permitted by their results.
		To use explanation (1) with the Sun in thermal equilibrium generally requires stretching several independent observations to the limits of their errors, and in particular the earlier chloride results must be explained away as unreliable (there was significant scatter in the earliest ones, casting doubt in some minds on the reliability of the others).
		The problem is not as severe as the earliest experiments indicated, and further data with better statistics are needed to settle the matter.
	math.ucr.edu /home/baez/physics/ParticleAndNuclear/solarNeutrino.html (1236 words)

	Physics News 586, April 24, 2002
		THE SOLAR NEUTRINO PROBLEM HAS BEEN CLOSED and the ability of neutrinos to change from one type, or "flavor," to another established directly for the first time by the efforts of the Sudbury Neutrino Observatory (SNO) collaboration.
		Solar neutrinos, setting out from the same place, flee unhindered, thus providing the most unadulterated proxy of activity at the core.
		If on their journey to Earth some of the neutrinos (basically solar reactions produce electron-neutrinos exclusively) had changed into muon- or tau-neutrinos, then terrestrial detectors designed only to spot electron neutrinos (e- nu's) would be cheated of their rightful numbers.
	newton.ex.ac.uk /aip/physnews.586.html (887 words)

	Solar Fusion & Neutrinos
		The second neutrino problem is illustrated by the center set in figure 1, compared with the chlorine detector results already mentioned, on the left.
		There was already quite a bit of convincing evidence that neutrino oscillations were the key to solving the solar neutrino problem, when in June 2001, news from the Sudbury Neutrino Observatory added the coup de grace.
		Haxton, W.C. Neutrino Oscillations and the Solar Neutrino Problem
	www.tim-thompson.com /fusion.html (6550 words)

	Solar neutrinos
		In these reactions electron neutrinos are created as well, which leave the Sun unimpeded and which are detected and counted in terrestrial experiments.
		Since the neutrinos are created with different energies in the various nuclear reaction rates and the experiments have different energy sensitivities, the mixture of neutrinos from the various reaction sources (colour-coded in Fig.1) varies from experiment to experiment as seen in the theoretical prediction.
		Figure 1) agree with the measured neutrino energy spectrum shown as symbols with error bars (actually, the energy spectrum of electrons is measured in Super-Kamiokande, which interact with the incoming neutrinos, on whose energies their own spectrum therefore depends).
	www.mpa-garching.mpg.de /HIGHLIGHT/1999/highlight9906_e.html (657 words)

	Physics News Update Number 3 - THE SOLAR NEUTRINO PROBLEM PERSISTS (Site not responding. Last check: )
		The "solar neutrino problem" has in recent years been tackled by two other groups, and they too record puzzling results.
		Unlike Kamiokande and Homestake, which are sensitive only to the relatively high-energy neutrinos released in the beta decay of boron in the sun, the Soviet-American Gallium Experiment (SAGE) in the Caucasus (USSR) is designed to observe the lower-energy neutrinos coming from the more plentiful proton-proton fusion reactions in the sun.
		Some theorists believe that one explanation may be that solar neutrinos may be "oscillating" from one neutrino type (electron, muon, tau) to another on their way to the earth and thus evading detection.
	www.aip.org /enews/physnews/1990/split/pnu003-1.htm (247 words)

	The Solar Neutrino Problem
		The theory stated that neutrinos would interact with chlorine atoms from the cleaning fluid and produce the radioactive element Argon 37, which then could be detected as an electron is emitted during its decay.
		The presence of detected neutrinos was far less than anticipated rate of fusion reaction taking place in the core of the Sun.
		Neutrinos are a sub-atomic particle that is not absorbed readily, so the majority of the few particles detected were created in the cores of distant stars and not the Sun.
	www.grantchronicles.com /astro22.htm (199 words)

	Implications of Solar Neutrino Experiments
		All four solar neutrino experiments observe a deficit of solar neutrinos compared to the predictions of the standard solar model.
		With or without new neutrino properties, the solar neutrinos are and will be an important probe of the core of the sun.
		Future model independent determinations of solar neutrino spectrum without MSW (postscript, 213K) ; with MSW by SNO and BOREXINO data (postscript, 212K) and by SNO, BOREXINO, and Super-K data (postscript, 149K) ; simultaneous constraint on Tc and B flux (postscript, 94K) with MSW.
	dept.physics.upenn.edu /neutrino/solar.html (381 words)

	Raymond Davis Jr., Solar Neutrinos, and the Solar Neutrino Problem - DOE R&D Accomplishments
		Raymond Davis, Jr., who conducted research in the Chemistry Department at Brookhaven National Laboratory (BNL) from 1948 through 1984, was awarded the 2002 Nobel Prize in Physics "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos." Dr. Davis is also a recipient of the 2003 Fermi Award.
		He was the first scientist to detect solar neutrinos, ghostlike particles produced in the nuclear reactions that power the sun.
		His results threw the field of astrophysics into an uproar, and, for nearly three decades, physicists tried to resolve the so-called "solar neutrino puzzle." Experiments in the 1990s using different detectors around the world eventually confirmed the solar neutrino discrepancy.
	www.osti.gov /accomplishments/davis.html (413 words)

	Plasma Physics and Astrophysics Research Papers and Proposals
		With the present airglow enhancement problem, the necessary variation of the electron energy is caused by the non-linearity of the plasma oscillation driven by the radio wave.
		The inconsistency of this approach is for instance apparent from the treatment in the textbook of Rishbeth and Garriott (1969) (Chpt.4.3): the assumption of quasi neutrality (electron density=ion density at all heights) implicates obviously an electric polarization field E=0, in contradiction to the value derived from the suggested force equations for the electrons and ions.
		Also, decades of fruitless attempts in hot fusion research and the 'missing neutrino problem' in connection with the energy output of the sun are not exactly indicators that established nuclear theory is correct.
	www.plasmaphysics.org.uk /research (6598 words)

	Spaceflight Now \| Breaking News \| Solar neutrino problem solved
		When neutrinos interact with heavy water, an electron is ejected from the molecule at a speed greater than the speed of light in the water itself, generating a flash of light known as Cerenkov radiation.
		The SNO data showed that the total number of neutrinos detected was equal to the number of electron neutrinos predicted to come from the Sun.
		Combined with the number of neutrinos expected to exist in the universe, physicists estimate that the combined mass of those neutrinos roughly equals the total mass of all the visible stars in the universe.
	www.spaceflightnow.com /news/n0106/20sno (1067 words)

	The solar neutrino problem
		The solar neutrino problem had origin from the discrepancy between the expectations of the solar
		Be neutrino flux from the four equations of Table
		This is the paradox of the present situation of the Solar neutrino problem.
	www.nupecc.org /nupecc/report97/report97_neutrino/node23.html (167 words)

	Spaceflight Now \| Breaking News \| Solar neutrino problem solved
		When neutrinos interact with heavy water, an electron is ejected from the molecule at a speed greater than the speed of light in the water itself, generating a flash of light known as Cerenkov radiation.
		The SNO data showed that the total number of neutrinos detected was equal to the number of electron neutrinos predicted to come from the Sun.
		Combined with the number of neutrinos expected to exist in the universe, physicists estimate that the combined mass of those neutrinos roughly equals the total mass of all the visible stars in the universe.
	spaceflightnow.com /news/n0106/20sno (1059 words)

	E.03 What is the "Solar Neutrino Problem?"
		The first, and most well-known, "solar neutrino problem" is that every experiment has measured a shortfall of neutrinos.
		The observed number of neutrinos in the gallium experiments can be compared with the number expected from the PP1 process and from the PP3 process, after accounting for the fact that the gallium experiments only see a fraction of the PP3 process neutrinos.
		Reducing the temperature of the standard solar model by 6 per cent would entirely explain GALLEX; indeed, Bahcall has ublished an article arguing that there may be no solar neutrino problem at all.
	www.faqs.org /faqs/astronomy/faq/part5/section-5.html (1268 words)

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