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Topic: Primordial nucleosynthesis

	PRIMORDIAL NUCLEOSYNTHESIS (Site not responding. Last check: 2007-10-31)
		Primordial Nucleosynthesis and the abundances of the light elements
		The current abundances of the light elements reflect what occurred during the epoch of primordial nucleosynthesis and therefore place strong constraints on the state of the universe and the baryon density during that time.
		Therefore the abundance of deuterium today places a lower limit on the amount of deuterium produced in the epoch of primordial nucleosynthesis, and thus on the density of baryons.
	www.astro.cornell.edu /academics/courses/astro201/primordnuc.htm (336 words)

	Big Bang nucleosynthesis - Wikipedia, the free encyclopedia
		In physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang.
		At the time at which nucleosynthesis occurs, the temperature is high enough for the mean energy per particle to be greater than the binding energy of deuterium; therefore any deuterium that is formed is immediately destroyed (a situation known as the deuterium bottleneck).
		Steigman, Gary, Primordial Nucleosynthesis: Successes And Challenges arXiv:astro-ph/0511534; Forensic Cosmology: Probing Baryons and Neutrinos With BBN and the CBR arXiv:hep-ph/0309347; and Big Bang Nucleosynthesis: Probing the First 20 Minutes arXiv:astro-ph/0307244.
	en.wikipedia.org /wiki/Big_bang_nucleosynthesis (2144 words)

	Primordial Nucleosynthesis
		Translated literally, primordial refers to the early universe, while nucleosynthesis is the synthesizing, or forming, of nuclei.
		Primordial nucleosynthesis is a period in the early universe.
		On the later side of nucleosynthesis, the temperature was too low, so that there was simply not enough energy to form the nucleons.
	www.geocities.com /biggerleif/Nucleosynthesis.html (629 words)

	Chapter 27, Section 3 (Site not responding. Last check: 2007-10-31)
		The theory of stellar nucleosynthesis accounts very well for the observed abundances of heavy elements in the universe, but there are discrepancies between theory and observations when it comes to the abundances of the light elements, especially helium.
		However, it is difficult to disentangle the contributions to the present-day helium abundance from primordial nucleosynthesis and later hydrogen burning in stars.
		Our best hope of determining the amount of primordial helium is to study the oldest stars known, since they formed early on, before stellar nucleosynthesis had had time to change significantly the helium content of the universe.
	astronomy.nju.edu.cn /astron/at3/AT32703.HTM (1934 words)

	ASP: The Biggest Bang of Them All
		It was the theory of primordial nucleosynthesis that first put the Big Bang theory on solid footing.
		Primordial nucleosynthesis is a merger of Big Bang theory and high-energy particle physics.
		In addition, primordial nucleosynthesis produced a fourth atomic nucleus: deuterium, a form of hydrogen which contains a neutron in addition to the proton.
	www.astrosociety.org /education/publications/tnl/37/universe2.html (1207 words)

	Elements and the Cosmos - Cambridge University Press
		Baryon inhomogeneous cosmologies and primordial nucleosynthesis of Li-Be-B; 5.
		Nucleosynthesis in SNe II and a function of progenitor mass; 12.
		Primordial lithium abundance from observations of SN 1987A; 14.
	www.cambridge.org /catalogue/catalogue.asp?isbn=052141475X (446 words)

	Quantum Origins of Cosmic Structure: SYNOPSIS
		Primordial nucleosynthesis after embryonic inflation, the subject of Chapter 6, yields spatially varying abundances of elements, including heavy elements in all the densest cosmic regions.
		Photon-to-baryon ratios at the start of primordial nucleosynthesis are shown (in Chapter 5) to have ranged from negligible to infinite, in patterns closely coupled to the primeval nebula-mass-ratio distribution.
		Confirmation of the parts of the theory pertaining to the primordial origin of heavy elements and their spatial patterns of abundances (i.e., the diversity, early on, of elements and isotopes), by comparing predicted and observed abundances, would be tantamount to tracing the contents of nebulae back to the era of primordial nucleosynthesis, shortly after inflation.
	www.princeton.edu /evm/qocsSYNOPSIS.html (4197 words)

	PHY320 Initial Conditions and Primordial Nucleosynthesis
		The terms "initial conditions" and "primordial nucleosynthesis" imply a beginning to the universe.
		In this primordial universe the elementary particles could be created out of thermal energy - such was the temperature that matter and antimatter was in a state of equilibrium with the thermal radiation.
		The standard model of primordial nucleosynthesis which we are sketching here predicts abundances for these elements which cover several orders of magnitude and are usually displayed as a function of the present density of nucleons or the nucleon/photon ratio.
	www.shef.ac.uk /physics/teaching/phy320/topic4.html (1506 words)

	Origin of the Light Elements
		Approximately 25 percent by mass of the matter in the universe is now in the form of helium nuclei: the rest consists of protons.
		A Helium abundance of about 1/4 by mass turns out to be a robust prediction of the Big Bang theory, and depends only on the fact that the very early universe passed through a high temperature, high density phase, much like the center of a star.
		A considerable fraction of any primordial deuterium at the beginning of the galaxy would have been destroyed by the present time.
	astron.berkeley.edu /~mwhite/darkmatter/bbndetails.html (884 words)

	ORIGIN OF THE LIGHT ELEMENTS
		The deuterium soon gains another neutron to form tritium, which in turn rapidly absorbs a proton to form a helium nucleus of mass 4, consisting of two protons and two neutrons.
		There is no stable element of mass 5, nor of mass 8, so additional nucleosynthesis via He + p or He + He is generally not possible although trace amounts of one or two heavier elements, most notably lithium (of mass 7) do form.
		A Helium abundance of about 25% turns out to be a robust prediction of the Big Bang theory, and depends only on the fact that the very early universe passed through a high temperature, high density phase, much like the center of a star.
	www.astro.ubc.ca /people/dscott/bbndetails.html (870 words)

	Open Questions: The Big Bang
		From calculations of the amount of deuterium that should be produced by nucleosynthesis, there must have been about one baryon per 1.8 billion photons in order to account for the amount of deuterium that is actually observed.
		General nucleosynthesis doesn't really get going until more like 300 seconds, when there are no longer enough energetic photons to destroy deuterium, and enough deuterium nuclei have formed to combine with additional neutrons to make helium-3, helium-4, and lithium-7.
		Although nuclei of a few lightweight elements were formed in the nucleosynthesis process, they were not yet atoms as we know them, since they were fully ionized – electrons still moved about freely instead of being bound to a nucleus.
	www.openquestions.com /oq-co008.htm (20607 words)

	Interstellar Medium Encyclopedia Articles @ LaunchBase.org (Launch Base) (Site not responding. Last check: 2007-10-31)
		This mixture is usually extremely tenuous, with typical gas densities ranging from a few hundred to a few hundred million particles per cubic meter.
		As a result of primordial nucleosynthesis, the gas is roughly 90% hydrogen and 10% helium by number, with additional elements ("metals" in astronomical parlance) present in trace amounts.
		The medium is also responsible for extinction and reddening, the decreasing light intensity and dominant observable wavelengths of a star as the light travels through the medium.
	www.launchbase.org /encyclopedia/Interstellar_medium (893 words)

	Nucleosynthesis, Trento 1997, Topics (Site not responding. Last check: 2007-10-31)
		For example the observations of primordial Deuterium abundance as deduced from the lyman alpha forests of Quasar spectra.
		The applicablility of inferred presolar deuterium and helium 3 abundances as the taggers of the primordial abundances.
		Impact of the low energy nuclear reaction rates and their uncertainties on the nucleosynthesis prediction of the primordial abundances; in particular for Lithium and heavier elements.
	www.helsinki.fi /~hkurkisu/prog.html (199 words)

	Galaxies and the Universe - The Pregalactic Universe
		We deal here with the first generarion of stars, primordial nucleosynthesis, the epoch of recombination, and the thermal history of various cosmic backgrounds.
		Primordial nucleosynthesis led to to chemical properties of the first generation of stars, perhaps also affecting the cooling rate at early times.
		Primordial nucleosynthesis also depends on the number of flavors of neutrino; the more there are, the more neutrons will be produced in the early universe and the more helium will remain.
	www.astr.ua.edu /keel/galaxies/primal.html (2116 words)

	Top 20 Encyclopedia
		In cosmology, Big Bang nucleosynthesis (alternately: Primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang.
		It is believed to be responsible for the formation of hydrogen (H-1 or H), its isotope deuterium (H-2 or D), the helium isotopes He-3 and He-4, and the lithium isotope Li-7.
		Big Bang nucleosynthesis predicts about 25% helium-4, and this number is extremely insensitive to the conditions of the universe.
	encyc.connectonline.com /index.php/Big_Bang_nucleosynthesis (1830 words)

	Cosmology
		Soon afterwards, even primordial nucleosynthesis would reach high enough precision as to admit direct comparison with accurate predictions of the standard and alternative models.
		Concerning other cosmological implications, we applied primordial nucleosynthesis considerations to test scalar-tensor theories with power law couplings (a kind of couplings which are not constrained by weak field tests in the solar system).
		With respect to astrophysical problems, we studied relativistic stellar models known as boson stars, and collaborated to introduce the concept of gravitational memory and evolution for these stellar structures, showing that, because of an evolving gravitational coupling, appreciable changes in the configurations are expectable.
	www.iar.unlp.edu.ar /garra/garra-cosm.html (1217 words)

	Cosmology: A Research Briefing (Site not responding. Last check: 2007-10-31)
		Thus, many interactions that were close to thermal equilibrium in the early universe later froze out at a predictable epoch, and left relics, some of which survive to the present day (see Table 1).
		Along with the Hubble expansion and the cosmic microwave background radiation, one of the pillars of the Big Bang theory is its successful prediction of the abundances of the light elements deuterium, helium, and lithium.
		The nucleosynthesis calculations thus imply either that (1) the total density of the universe is much less than the critical density and it will never stop expanding, or (2) the dominant component of the universe is not ordinary (baryonic) matter.
	www.nap.edu /readingroom/books/cosmology/5.html (4008 words)

	[No title] (Site not responding. Last check: 2007-10-31)
		It is well known that primordial nucleosynthesis (Big Bang Nucleosynthesis, BBN) and cosmic microwave background radiation (CMBR) provide a unique window on the early Universe.
		In the framework of the general relativity it describe an expansion of self-gravitating medium under the assumption that physical laws at the nucleosynthesis epoch were the same as now.
		Certainly, the basic physics of the processes is the same as in the standard code but we have completely revised the integration routine, added new and updated nuclear reactions and specially designed it for the problem discussed.
	www.ioffe.ru /astro/QC/early_00.htm (442 words)

	nucleosynthesis concept from the Astronomy knowledge base (Site not responding. Last check: 2007-10-31)
		primordial nucleosynthesis (6 facts) (big-bang nucleosynthesis) - The production of heavy nuclei from the fusion of lighter ones during the Big Bang.
		All other elements would have to be formed later, in nucleosynthesis processes.
		It is believed that most of the helium, the next lightest element after hydrogen, was formed when the universe was a few minutes old, The creation of elements that occurred just minutes after the Big Bang.
	www.csi.uottawa.ca:4321 /astronomy/nucleosynthesis.html (180 words)

	[No title]
		The primordial nucleosynthesis bounds demand that the mirror sector should have a smaller temperature T' than the ordinary one T, and by this reason its evolution can be substantially deviated from the standard cosmology.
		A consequence of the evaporation of primordial fl holes in the early universe may be the generation of mirror matter.
		A simple way to reconcile the constraints of big bang nucleosynthesis in such a theory is to postulate that the reheating temperature after inflation in the mirror universe is lower than that in the visible one.
	people.zeelandnet.nl /smitra/mirror.htm (8552 words)

	stellar nucleosynthesis concept from the Astronomy knowledge base (Site not responding. Last check: 2007-10-31)
		explosive nucleosynthesis (3 facts) - The nucleosynthetic processes which are thought to occur in supernovae.
		These explosive processes are thought to produce the nuclei from neon up to and including the e-process nuclei and possibly the r-process nuclei.
		K and produces the iron peak nuclei., The nucleosynthesis processes that are believed to occur in supernovae.
	www.site.uottawa.ca:4321 /astronomy/stellarnucleosynthesis.html (202 words)

	Primordial Nucleosynthesis - H. Reeves
		The succss of big bang nucleosynthesis implies that these radii have not varied by more than a few percent since the first minutes.
		I have described two instances in which the good success of standard Big Bang nucleosynthesis in reproducing the abundance observations of the light elements has been used for the development of high energy physics and of early cosmological models.
		The first case is in relation with the families of elementary particles, the other case is in the formulation of multidimensional cosmologies (as superstring theories) taking into account the observed constancies of the 4-D versions of the coupling constants.
	nedwww.ipac.caltech.edu /level5/Sept01/Reeves/Reeves4.html (1111 words)

	Origin of the chemical elements
		The accepted scenario is that the first major element to condense out of the primordial soup was helium
		The course of further nucleosynthesis and the subsequent fate of the star itself depends on the star’s mass.
		If the mass of the star is no greater than 1.4 times the mass of our sun, the star collapses to a white dwarf, and eventually cools to a dark, dense dead star.
	www.chem1.com /acad/webtext/geochem/02txt.html (1157 words)

	Physics Today July 2001 (Site not responding. Last check: 2007-10-31)
		A lower-than-expected second acoustic peak implied one of two possibilities, both quite unpalatable to inflation theorists: Either the primordial spectrum of density fluctuations just before inflation was far from being scale invariant; or the abundance of baryons (protons and neutrons) just after inflation was significantly greater than the theory of primordial nucleosynthesis predicts.
		At the April meeting of the American Physical Society in Washington, DC, John Carlstrom (University of Chicago), leader of the DASI team, reported that the height of the second peak yielded a cosmic baryon density in excellent agreement with the theory of primordial nucleosynthesis.
		All three groups reported at the Washington meeting that the theoretical fits to their data yielded a primordial spectrum of adiabatic quantum fluctuations that had essentially no dependence on length scale.
	www.aip.org /pt/vol-54/iss-7/p16.html (1673 words)

	Primordial nucleosynthesis -- Schramm 95 (1): 42 -- Proceedings of the National Academy of Sciences
		Primordial nucleosynthesis -- Schramm 95 (1): 42 -- Proceedings of the National Academy of Sciences
		primordial deuterium is converged upon, the nature of the field
		Big Bang nucleosynthesis (BBN) and the light element abundances are in the middle of a major transformation in approach.
	www.pnas.org /cgi/content/full/95/1/42 (3663 words)

	Nucleosynthesis in the Early Universe (Site not responding. Last check: 2007-10-31)
		This lab will help you understand how helium is formed in the early universe, out of a "primordial soup" of neutrons and protons.
		In the very early universe when the temperature was very high, there were equal numbers of protons and neutrons.
		We will use the Particle Soup: Nucleosynthesis exercise from the University of Washington Astronomy Clearing House.
	www.rpi.edu /dept/phys/Courses/Astronomy/indexNucleoSyn.html (263 words)

	Physics, UCSD - Faculty Profile: George M. Fuller
		I am presently working on two broad subject topics: the neutrino and weak interaction physics of stellar evolution, stellar collapse, and supernovae; and the physics of the early and late-early universe.
		The supernova explosion mechanism and heavy element nucleosynthesis are determined by the neutrinos emitted in the collapse of the core of a massive star.
		My graduate students and I have worked to characterize how primordial nucleosynthesis depends on the spatial distribution of baryon-to-photon number.
	physics.ucsd.edu /fac_staff/profiles/fgm.html (293 words)

	[No title]
		Inhomogeneous Primordial Nucleosynthesis and New Abundance Constraints on Omega bh 2
		Nucleosynthesis in the Presence of Primordial Isocurvature Baryon Fluctuations
		Stochastic Isocurvature Baryon Fluctuations, Baryon Diffusion, and Primordial Nucleosynthesis
	www.columbia.edu /~fms5/w483.html (1689 words)

	Big Bang Nucleosynthesis (Site not responding. Last check: 2007-10-31)
		Primordial nucleosynthesis and dark matter (IWDM Heidelberg, 1996)
		Nucleosynthesis bounds on a time-varying cosmological `constant' (1996)
		Primordial nucleosynthesis, additional neutrinos and neutral currents from the superstring (1986)
	www-thphys.physics.ox.ac.uk /users/SubirSarkar/bbn.html (155 words)

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