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Topic: Cosmic neutrino background

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	ScienceDaily: Neutrino
		The neutrino was first postulated in 1931 by Wolfgang Pauli to explain the energy spectrum of beta decays, the decay of a neutron into a proton and an electron.
		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.
		Atmospheric neutrinos result from the interaction of cosmic rays with atoms in the Earth's atmosphere, creating showers of particles, many of which are unstable and produce neutrinos when they decay.
	www.sciencedaily.com /encyclopedia/neutrino (4067 words)

	Neutrino - LearnThis.Info Enclyclopedia (Site not responding. Last check: 2007-10-17)
		The basic standard model of particle physics assumes that the neutrino is massless, although adding massive neutrinos to the basic framework is not difficult, and recent experiments suggest that the neutrino has a small although non-zero mass.
		This phenonemnon known as neutrino oscillation explains why there are many fewer electron neutrinos observed from the sun and the upper atmosphere than expected, and has also been directly observed.
		Neutrinos are produced as a result of the natural background radiation from radioactive atomic nuclei within the Earth.
	encyclopedia.learnthis.info /n/ne/neutrino.html (1348 words)

	Read about Neutrino at WorldVillage Encyclopedia. Research Neutrino and learn about Neutrino here! (Site not responding. Last check: 2007-10-17)
		Detection of neutrinos is therefore very challenging as it has to rely either on large detection volumes or artificially produced neutrino beams of high intensity and energy, since the interaction probability is roughly proportional to the energy of the neutrino.
		Neutrinos are the only known particles that are not significantly attenuated by their travel through the interstellar medium.
		The most important use of the neutrino is in the observation of supernovae, the explosions that end the lives of highly massive stars.
	encyclopedia.worldvillage.com /s/b/Neutrino (2347 words)

	Physics News Update Number 425 - Story THE COSMIC NEUTRINO BACKGROUND (Site not responding. Last check: 2007-10-17)
		There are almost as many neutrinos loose in the universe as photons, and almost as much energy vested in neutrinos as in photons.
		Yet, owing to the extreme reticence of neutrinos to interact with other particles, detecting the neutrino background is not easy as detecting the cosmic photon (microwave) background.
		The pattern of lumps in the microwave background, which will be measured by the upcoming MAP and PLANCK orbiting detectors, encodes information about the neutrino background.
	www.aip.org /pnu/1999/split/pnu425-1.htm (118 words)

	Blackbody Radiation
		A uniform background radiation in the microwave region of the spectrum is observed in all directions in the sky.
		The discovery of the 3K microwave background radiation was one of the crucial steps leading to the calculation of the standard "Big Bang" model of cosmology, its role being that of providing estimates of relative populations of particles and photons.
		The scale of the fluctuations is larger than the horizon at the time the background radiation was emitted, indicating that the fluctuations are primordial, dating from a time before the separation of radiation and matter, the transparency point.
	hyperphysics.phy-astr.gsu.edu /hbase/bkg3k.html (913 words)

	Ripples in Cosmic Neutrino Background Measured for the First Time (Site not responding. Last check: 2007-10-17)
		Neutrinos are elementary particles with no charge and very little mass, which are extremely difficult to study due to their very weak interaction with matter.
		Although it is impossible to measure this "Cosmic Neutrino Background" directly with present-day technology, physicists predict that ripples or waves in it have an impact on the growth of structures in the Universe.
		The research has important implications for the study of neutrinos, showing that theories of the infinitely large (cosmology) and the infinitely small (particle physics) are in agreement.
	universe.nasa.gov /press/2005/050615a.html (317 words)

	Re: Cosmic Antineutrinos - Evidence?
		We expect there to be a sea of neutrinos and antineutrinos, with total number density much larger than the electron density but with approximately equal numbers of particles and antiparticles so that the total lepton number contributed by neutrinos is small.
		It's not a problem of number density: the number density of background neutrinos is comparable to the number density of solar neutrinos at the Earth, and we detect them.
		Neutrino degeneracy alters both the expansion rate and the weak-interaction reaction rates, and it can improve the agreement between the nucleosynthesis and microwave background data.
	www.lns.cornell.edu /spr/2001-02/msg0031267.html (913 words)

	Neutrino Physics and Cosmology: Scientific Motivation (Site not responding. Last check: 2007-10-17)
		The research interests of this project will include theoretical schemes for neutrino mixing and oscillations and study of their effects in the earthbound laboratories, in astrophysical objects and in the early universe as well as a study of the origin of extremely high energy neutrinos and their interactions with the cosmic neutrino background.
		Indeed neutrinos are the prime examples of the "inner space-outer space" connection which defines the modern field of astroparticle physcis.
		We are studying the flavour evolution of neutrinos in the early universe in the context of sterile-neutrino hypothesis by solving the appropriate quantum-kinetic equations.
	www.nordita.dk /~kainulai/motivation.html (1746 words)

	Hot Dark Matter (Site not responding. Last check: 2007-10-17)
		The foremost HDM candidate is a particle known as the "neutrino." This elusive particle was predicted to exist as early as 1931 by physicist Wolfgang Pauli in order to account for the conservation of momentum and energy in beta decay.
		Pauli's assertion that the neutrino would be exceptionally elusive proved correct, as it would be another 25 years from the time of its prediction that two experimentalists would finally detect a neutrino.
		Given their great speeds, neutrinos would tend to free stream out of any overdense regions--that is, regions with densities greater than the average density in the Universe.
	astron.berkeley.edu /~mwhite/darkmatter/hdm.html (776 words)

	Preprints in Neutrinophysics (Site not responding. Last check: 2007-10-17)
		Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources.
		High-energy neutrino detection from individual GRBs would mean that they are hadronically dominated, that is, that the amount of energy deposited in the form of nonthermal hadrons in GRB blast waves greatly exceeds the radiated energy inferred from their photon emission spectra.
		It is shown that the generic 1-loop contributions to neutrino masses are too small to account for the solar and atmospheric neutrino oscillations and thus some fine cancellation in tree-level contribution is required to severely constrain the viable parameter space.
	kmheeger.lbl.gov /nupreprints/nupreprints012004.html (10643 words)

	Neutrino Transparency Temperature
		In evaluating the energy density in the background radiation in the universe, it is necessary to include both the photon 3K background and the neutrino background.
		The amount of energy in this neutrino background can be estimated with the use of the Stefan- Boltzmann law, treating the neutrinos as massless particles at 1.9K.
		We used the fact that the neutrinos are more numerous by the factor (7/2)/2 =7/4, there being a factor of 2 for the effective number of photons because of two polarization states.
	hyperphysics.phy-astr.gsu.edu /hbase/astro/neutemp.html (453 words)

	Munch (Site not responding. Last check: 2007-10-17)
		We study the expected diffuse cosmic neutrino flux produced by Population III (PopIII) stars during their nuclear burning phases as well as from their final stages of evolution (core collapse).
		Due to the large cosmic redshift, however, the typical energies are in the MeV and sub-MeV range where the solar and geophysical neutrino fluxes are much larger.
		In this model neutrinos annihilate as soon as they become non-relativistic in the early universe, and a non-zero neutrino mass has a marginal effect on the matter power spectrum.
	home.fnal.gov /~bertone/DM/JC112204.html (1531 words)

	Cosmic ray / Gamma ray / Neutrino experiments
		GNO [Gallium Neutrino Observatory] is the successor project of GALLEX.
		The 28th ICRC (International Cosmic Ray Conference) was in Tsukuba, Japan, in August 2003.
		The Commission on Cosmic Rays of the IUPAP publishes the Cosmic Ray News Bulletin.
	www.mpi-hd.mpg.de /hfm/CosmicRay/CosmicRaySites.html (2637 words)

	[No title]
		It is suggested that a large deep underocean (or ice) neutrino detector, given the presence of significant numbers of neutrinos in the PeV energy range as predicted by various models of Active Galactic Nuclei, can make unique measurements of the properties of neutrinos.
		It will be possible to observe the existence of the tau neutrino, measure its mixing with other flavors, in fact test themixing pattern for all three flavors based upon the mixing parameters suggested by the atmospheric and solar neutrino data, andmeasure the tau neutrino cross section.
		The key signature is the charged current tau neutrino interaction, which produces a double cascade, one at either end of a lightly radiating track.
	www.physto.se /~lbe/peo.html (1016 words)

	The Big Bang
		The strongest evidence that something like the Big Bang really happened is the Cosmic Background Radiation predicted by Cosmologist George Gamov in 1948 and discovered by Arno Penzias and Robert Wilson of Bell Labs in 1965.
		If neutrinos have mass, the large number of Cosmic Neutrinos may have implications for the dark matter in the Universe.
		The Cosmic Background Spectrum as measured by NASA's COBE Satellite.
	cassfos02.ucsd.edu /public/tutorial/BB.html (1168 words)

	News: Ripples in cosmic neutrino background measured for the first time
		Ripples in cosmic neutrino background measured for the first time
		Astrophysicists from the Universities of Oxford and Rome have for the first time found evidence of ripples in the Universe’s primordial sea of neutrinos, confirming the predictions of both Big Bang theory and the Standard Model of particle physics.
		The high quality of recent cosmological data allows us to investigate neutrinos in the cosmological framework, obtaining measurements which are competitive with, if not superior to, particle accelerator findings.’
	www.admin.ox.ac.uk /po/news/2004-05/jun/15.shtml (319 words)

	Ripples in Cosmic Neutrino Background Measured for the First Time
		The paper "Indication for Primordial Anisotropies in the Neutrino Background from WMAP and SDSS" by Roberto Trotta and Alessandro Melchiorri has been accepted for publication in Physical Review Letters.
		WMAP is a NASA Explorer mission measuring the temperature of the cosmic background radiation over the full sky with unprecedented accuracy.
		We do not guarantee the accuracy or completeness of information on or available through this site, and we are not responsible for inaccuracies or omissions in that information or for actions taken in reliance on that information.
	i-newswire.com /goprint25517.html (598 words)

	How Ultra High-Energy Neutrinos Might Be Made, Seen
		Ultra high-energy neutrinos might be made in a variety of ways (in the warped space near fl holes, say, or in the decay of exotic massive particles)and might be detected on Earth in a variety of ways.
		One reason for the new interest in vigorous neutrinos is that it could help solve the mystery of why there are more than expected cosmic rays at energies above 10^20 eV.
		The way around this cutoff might be to argue that ultrahigh-energy (UHE) neutrinos, which don't interact with photons, might be ferrying huge energies through the universe and that the surplus of highest-energy cosmic rays comes about from chance encounters between the UHE nu's and particles such as protons or other neutrinos.
	unisci.com /stories/20022/0418021.htm (466 words)

	New Scientist SPACE - Breaking News - Big bang neutrinos smoothed out the universe
		About one second after the big bang, the expanding fireball became transparent to the neutrinos, which then streamed freely through space to form a “neutrino background”.
		However, it is impossible to observe this cosmic neutrino background - never mind any ripples inside it - because ghostly neutrinos fly through matter without stopping and are notoriously hard to detect.
		That would have smoothed out the microwave background and altered the distribution of galaxies in a characteristic way, which the scientists simulated on computers.
	www.newscientistspace.com /article.ns?id=dn7533 (614 words)

	Citebase - The Very Low Energy Solar Flux of Electron and Heavy-Flavor Neutrinos and Antineutrinos
		We calculate the thermal flux of low-energy solar neutrinos and antineutrinos of all flavors arising from a variety of neutrino pair processes: Compton production (including plasmon-pole diagrams), neutral current decay of thermally populated nuclear states, plasmon decay, and electron transitions from free to atomic bound states.
		We derive a model independent relation between the neutrino mass and the equation of state parameter of the neutrino dark energy, which is applicable for gener...
		We study some implications on standard matter oscillations of solar neutrinos induced by a background of extremely low energy thermal neutrinos trapped inside the Sun by means of coherent refractive interactions.
	www.citebase.org /cgi-bin/citations?id=oai:arXiv.org:nucl-th/0006055 (1085 words)

	News: Ripples in cosmic neutrino background measured for the first time
		According to the standard Big Bang model, neutrinos permeate the Universe at a density of about 150 per cm³.
		The high quality of recent cosmological data allows us to investigate neutrinos in the cosmological framework, obtaining measurements which are competitive with – if not superior to – particle accelerator findings.’
		This map of the remnant heat from the Big Bang provides answers to fundamental questions about the origin and fate of the Universe.
	www.admin.ox.ac.uk /po/050615.shtml (491 words)

	The Extragalactic Neutrino Background Radiations From Blazars and Cosmic Rays (ResearchIndex) (Site not responding. Last check: 2007-10-17)
		The Extragalactic Neutrino Background Radiations From Blazars and Cosmic Rays
		Abstract: Blazar emission of gamma rays and cosmic ray production of gamma rays in gas-rich clusters have been proposed recently as alternative sources of the high energy extragalactic diffuse gamma ray background radiation.
		This neutrino background may be detected by the new generation of large neutrino telescopes under construction and may be used to trace the origin of the...
	citeseer.ist.psu.edu /88393.html (342 words)

	Citebase - How to detect the cosmic neutrino background?
		Authors: Ringwald, A. A measurement of the big bang relic neutrinos would open a new window to the early universe.
		The associated absorption dips in the ultrahigh energy cosmic neutrino spectrum may be searched for at forthcoming neutrino and air shower detectors.
		Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth.
	citebase.eprints.org /cgi-bin/citations?id=oai:arXiv.org:hep-ph/0301157 (964 words)

	Amazon.com: An Introduction to Modern Cosmology: Books: Andrew Liddle (Site not responding. Last check: 2007-10-17)
		Here the subject of Heavy Neutrinos is treated, and the author introduces an "exponential suppression factor" which has the wrong notation,with the temperature term in the numerator of the negative exponent.
		The big bang model is the main part, with concise introduction to dark matter/energy, neuclosynthesis, cosmic microwave background, inflation etc. After reading this book, you will have a general idea about most of the concepts in cosmology and about what is going on in modern cosmology.
		There is a chapter on the successes of this model: explanation of the cosmic background radiation, universal expansion, and the relative abundance of elements in the early universe.
	www.amazon.com /exec/obidos/tg/detail/-/0470848359?v=glance (1896 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		In the standard big bang cosmology the canonical value for the ratio of relic neutrinos to cosmic microwave background (CMB) photons is 9/11.
		Within the framework of the standard model of particle physics there are small corrections, in sum about 1{percent}, due to slight heating of neutrinos by electron-positron annihilations and finite-temperature QED effects.
		We show that this leads to changes in the predicted CMB anisotropies that will bias determination of the other cosmological parameters if not correctly taken into account.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=341405 (177 words)

	Schedule
		Neutrino News from the Lab and the Cosmos
		Neutrino Clustering in CDM Halos and Ultra High Energy Cosmic Rays
		Low reheating temperature and thermalization of neutrino background in the early universe
	www-astro-theory.fnal.gov /Conferences/NuCosmo/schedule.html (102 words)

	Astronomy 182: Lecture 11
		§During BBN, neutrinos moved at almost the speed of light,
		forming a background neutrino `radiation’ in addition to the
		§The cosmic neutrino background has not been detected and there
	astro.uchicago.edu /~frieman/A182/Lectures/Lecture11/slide0081.htm (81 words)

	Joint Particle Seminar (Site not responding. Last check: 2007-10-17)
		Unlike the relic photons, relic neutrinos have not so far been observed.
		The Cosmic Neutrino Background is the oldest relic from the Big Bang, produced a few seconds after the Bang itself.
		Due to their impact in cosmology, relic neutrinos may be revealed indireclty in the near future through cosmological observations.
	www.physics.uci.edu /NEW/050209.html (124 words)

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