Proton proton chain reaction

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	proton-proton chain
		It involves a chain of fusion reactions in which four protons combine to form a nucleus of helium; the process was first described in 1938 by Hans Bethe and the American physicist Charles Critchfield (1910-).
		The gamma rays produced in the proton-proton reaction take one to 10 million years to work their way out from the star's core, being scattered numerous times and losing energy as they go, until they emerge from the surface as rays of light and heat.
		The proton-proton chain begins with two protons colliding to form a nucleus of deuterium.
	www.daviddarling.info /encyclopedia/P/proton-proton_chain.html (352 words)

	Visualization of an Atomic Chain Reaction
		This chain reaction is caused by the collision of a loose neutron and an Uranium 235 atom.
		The equation showing this is (sinA + 1)b where A equals the angle of collision and b equals the previous position of the proton or neutron in the nuclei.
		The purpose of this project was to show the chain reaction that occurs in an atomic bomb.
	www.asms.net /rtc/19971998/AustinJames.html (160 words)

	PROTON AND NEUTRON CLUSTER FORMATION
		It is stable except in the high-energy environments, such as star cores, where it takes part in the proton – proton chain reaction fusing deuterium and hydrogen, thus producing helium 3 and gamma rays.
		Protons are very stable and scientists have not been able to dislodge a quark from the proton (as yet).
		The interference waves from surrounding protons move the quons of each quark in the proton closer together and speed up the rotational velocity of random quarks as they are compressed.
	www.gravityassociation.org /cmd_html/cmd_19a.htm (212 words)

	Proton-proton chain reaction - Wikipedia, the free encyclopedia
		The proton-proton chain reaction is one of two fusion reactions by which stars convert hydrogen to helium, the other being the CNO cycle.
		The theory that proton-proton reactions were the basic principle by which the Sun and other stars burn was advocated by Arthur Eddington in the 1920s.
		The pp III chain is not a major source of energy in the Sun (as the Sun's core temperature is not high enough), but was very important in the solar neutrino problem because it generates the highest energy neutrinos (≤14.06 MeV).
	en.wikipedia.org /wiki/Proton-proton_chain (669 words)

	The Proton-Proton Chain
		The Proton-Proton or PP Chain, which is important in stars the mass of the Sun and less.
		The primary reactions in the main branch of the PP chain are illustrated in the following figure.
		There are two sequences of reactions that can convert hydrogen to helium and thereby release energy that are important in stars.
	csep10.phys.utk.edu /astr162/lect/energy/ppchain.html (308 words)

	vik dhillon: phy213 - the physics of stellar interiors - hydrogen and helium burning
		The reaction rate of the PP chain is set by the rate of the slowest step, which is the fusion of two protons to produce deuterium.
		The PP chain reactions are summarized pictorially in figure 17.
		The reactions of the CNO cycle are shown pictorially in figure 18.
	www.shef.ac.uk /~phys/people/vdhillon/teaching/phy213/phy213_fusion3.html (811 words)

	The Life-Giving Sun
		photons In the proton-proton chain reaction, hydrogen nuclei are converted to helium nuclei through a number of intermediates.
		Sunspot activity is closely in phase with ejection of solar plasma (protons mainly) and the ensuing atmospheric fireworks in the polar regions of Earth called "aurora".
		This is the principle fusion reaction in the Sun.
	calspace.ucsd.edu /virtualmuseum/ita/07_2.shtml (1029 words)

	Proton-proton fusion
		The latter of these reactions is part of what is usually called the proton-proton cycle, which yields about 25 MeV and can be combined to the form
		The fusing of two protons which is the first step of the proton-proton cycle created great problems for early theorists because they recognized that the interior temperature of the sun (some 14 million Kelvins) would not provide nearly enough energy to overcome the coulomb barrier of electric repulsion between two protons.
		With the development of quantum mechanics, it was realized that on this scale the protons must be considered to have wave properties and that there was the possibility of tunneling through the coulomb barrier.
	hyperphysics.phy-astr.gsu.edu /hbase/astro/procyc.html (403 words)

	[3.0] Stellar Mechanics & Evolution (1)
		The simplest is the "proton-proton (PP) chain" reaction:
		The term "H2" means a deuterium nucleus, with a neutron and a proton, while "He3" means a helium isotope with two protons and a neutron, and "He4" means a normal helium nucleus with two protons and two neutrons.
		Four protons fuse into a helium nucleus, which consists of two protons and two neutrons, and incidentally emit two positive electrons or "positrons", two insubstantial neutrinos, and energy.
	www.vectorsite.net /tastga3.html (3579 words)

	Layers of the sun
		Protons and electrons evaporate off the sun, and reach the earth at velocities of 500 km/s.
		For example, perchloroethane contains some isotopes of chlorine with 37 particles in the nucleus (17 protons, 20 neutrons).
		In the core, fusion reactions produce energy in the form of gamma rays and neutrinos.
	fusedweb.pppl.gov /CPEP/Chart_Pages/5.Plasmas/SunLayers.html (1359 words)

	University of Hertfordshire, Astronomy
		The proton-proton chain releases energy because the sum of the final masses is 0.7% less than the total original masses, the difference (the mass defect) being converted into energy.
		It is a particle emitted in one type of radioactive decay in which a proton turns into a neutron and a neutrino is emitted.
		The (atomic) number of protons in a nucleus determines the chemical element.
	www.herts.ac.uk /astro_ub/aP_ub.html (2418 words)

	Proton-Proton Chain
		The proton-proton chain is a three-step series of reactions, the first of which we have seen already:
		The above reaction occurs via another force the weak force, which as its names suggests is feeble.
		The reaction rate is set by the slowest step, in this case the first because usually
	www.astro.soton.ac.uk /~pac/PH112/html/notes/notes/node114.html (135 words)

	Botany online: Membranes and Transport - Active Transport
		As a consequence of the respiratory chain and of photosynthesis are protons channelled out of the mitochondrial matrix and the thylacoids of the chloroplasts, respectively.
		A proton is transported into a compartment and the energy for the transport is supplied by the simultaneous transport of an anion or a substrate molecule in the same direction.
		That way is both a chemical proton gradient and an electric potential generated.
	www.biologie.uni-hamburg.de /b-online/e22/22d.htm (1230 words)

	proton-proton chain concept from the Astronomy knowledge base
		Although the neutrinos from this reaction are detectable, they have not been observed.
		PP II (3 facts) - A thermonuclear reaction in which hydrogen nuclei are transformed into helium nuclei.
		The p-p chain divides into three main branches: PP I, PP II and PP III.
	www.csi.uottawa.ca:4321 /astronomy/proton-protonchain.html (372 words)

	Organic Chemistry at Penn State: Reactions
		E2 mechanism favored by strong bases: the base removes a proton from the carbon adjacent to one bearing the leaving group in a one-step bimolecular reaction that requires periplanar orientation of the hydrogen and the leaving group (anti-periplanar preferred)
		E1 mechanism for tertiary or secondary allylic or benzylic substrates: the leaving group departs in a unimolecular rate-limiting step, generating the carbocation, which in the second step is deprotonated (with base) on the carbon adjacent to the cationc center, yielding the olefin; carbocation rearrangements may compete
		Here is just a list of the reactions that we discussed in detail in class.
	courses.chem.psu.edu /chem38/reactions/reactions.html (982 words)

	P-Pchain
		Known as the proton-proton chain, the reaction process depicted above is the dominant fusion mechanism in light stars, including our sun.
		Stellar fusion reactions gradually convert hydrogen into helium through the p-p chain.
		Because fusion reactions cease to release energy once elements heavier than iron are involved, the larger stars also eventually run out of fuel, but this time they collapse in a supernova.
	www.upei.ca /~physics/p261/projects/fusion1/P-Pchain.htm (270 words)

	The First Nuclear Chain Reaction
		These facts implied the possibility of a chain reaction, similar in certain respects to the reaction which is the source of the sun's energy.
		An atomic chain reaction may be compared to the burning of a rubbish pile from spontaneous combustion.
		This quantity of uranium necessary for a chain reaction under given conditions is known as the critical mass, or more commonly, the "critical size" of the particular pile.
	hep.uchicago.edu /cp1.html (4322 words)

	The Chain Reaction (from nuclear energy) -- Britannica Student Encyclopedia
		The polymerase chain reaction enables investigators to obtain the large quantities of DNA that are required for various experiments and procedures in molecular biology, forensic analysis, evolutionary biology, and medical diagnostics.
		The bombarding particle may be an alpha particle, a gamma-ray photon, a neutron, a proton, or a heavy ion.
		Brief biography of this Italian-born American physicist and winner of Nobel Prize for Physics in 1938, who developed the mechanism for controlled chain reaction in nuclear fission which provided ability to control nuclear energy was in the atom bombs that were used at the end of World War II.
	www.britannica.com /ebi/article-205769?tocId=205769 (1079 words)

	McGraw-Hill AccessScience: Proton-proton chain
		Because hydrogen is the fuel consumed in the process, it is referred to as hydrogen burning by means of the proton-proton chain.
		The chain can be thought of as the conversion of four hydrogen atoms into a helium atom plus energy in the form of photons or neutrinos, or the kinetic energy of particles.
		group of nuclear reactions involving fusion of light nuclei that converts hydrogen into helium.
	www.accessscience.com /Encyclopedia/5/55/Est_551400_frameset.html (246 words)

	Chapter 31 Tutorial
		Charge is conserved so the number of protons must be the same on both sides of the reaction, also, the total number of protons and neutrons should be the same on both sides.
		A Nuclear Reaction occurs when a nuclear particle (usually a neutron, proton or alpha particle) interacts with a Nucleus.
		There is a minimum size necessary for the chain reaction to occur before the neutrons escape the mass.
	www.image-ination.com /hints/hint31.html (1104 words)

	NSW HSC ONLINE - Physics
		Further helium is produced by fusion of hydrogen in main-sequence stars, either by the proton-proton chain reaction in cooler stars, or by the carbon-nitrogen-oxygen cycle in hotter stars.
		Fusion of a proton and a deuterium nucleus to form a helium-3 nucleus, with the release of gamma radiation.
		Fusion of two hydrogen nuclei (protons) to form a heavy hydrogen (deuterium) nucleus.
	hsc.csu.edu.au /physics/options/astrophysics/2979/PHYS976net.html (3442 words)

	Week8_Part2
		It carboxylates the 5-carbon sugar ribulose-1,5-bisphosphate and produces 2 molecules of 3-phosphoglycerate; oxygen is a competitive inhibitor of the reaction, competing with CO for binding.
		Reaction centers similar to PS I of higher plants.
		J. Deisenhofer and H. Michel, "The Photosynthetic reaction center from the purple bacterium Rhodopseudomonas viridis." Science 245: 1463-1473 (Nobel Prize lecture/article).
	www.bmb.psu.edu /courses/micro401/Wk8Pt2.htm (790 words)

	Lecture 26 - Protostars and Stellar Energy (3/22/96)
		The strong nuclear force is the force that holds protons and neutrons together in the nucleus of the atom, overcoming the mutual electrical repulsion of the protons.
		This is because it turns a proton into a neutron (D is deuterium a kind of hydrogen consisting of a proton and a neutron bound together) using the weak force (hence the positron and neutrino).
		Thus, if you take four hydrogen nuclei (protons) and convert them into one helium nucleus (2 proton, 2 neutrons), you find that the sum of the 4 proton masses is 0.7% larger than the mass of 1 helium nucleus.
	www.aoc.nrao.edu /~smyers/courses/astro01/L26.html (1899 words)

	The Big Bang, the Elements & Radiation
		This so-called “proton-proton chain reaction” (often abbreviated as the “pp cycle”) provides 98.5% of our Sun’s energy, which powers most life on earth and all of the forms of life with which we are most familiar.
		If the mass of the star is large enough, it will then collapse and then rebound, resulting in a supernova whose intense particle flux adds neutrons and protons into the atomic nuclei and produces all the higher elements up to uranium.
		The later lines in the diagram indicate the reactions occurring in aging stars that have used up most of their “easy” hydrogen fuel and have accumulated heavier elements.
	calspace.ucsd.edu /virtualmuseum/ita/03_2.shtml (1024 words)

	Inelastic proton scattering
		B decay neutrinos which are produced during the proton-proton fusion chain in the center of the sun.
		The research objective of this collaboration is to measure the medium energy polarized proton induced response from various target nuclei and determine spinobservables (like spin-flip probability functions and spin rotation parameters) by means of a proton spin-polarimeter to be operated in the focal plane of the BBS magnetic spectrometer.
		The GT transition strengths have been measured very accurately with the (p,n) reaction at bombarding energies between 160 and 795 MeV.
	pikp101.uni-muenster.de /ppprime.htm (748 words)

	The Proton-Proton Chain
		This reaction produces an isotope of helium with three particles in its nucleus, two protons and one neutron.
		In the next step of the proton-proton chain, one of these deuterium nuclei collides and fuses with a normal hydrogen atom
		If they can get close enough, one of the protons may change to a neutron, emit a positive electron (a positron or anti-electron), and stick.
	www.physics.louisville.edu /astro/students/107-01/topics/fusion/node4.html (282 words)

	speculative fact, gamma ray bursters
		For instance, if a proton and proton collide (also referred to as positive hydrogen ions) they can start the fusion reaction sequence diagrammed in Figure 2.
		A reaction with sufficient energy close to home could be something relatively small, like a antimatter explosion limited to a few tons of mass, but an event at the edge of the universe would have to be so energetic as to be physically impossible.
		Gamma rays are produced in nuclear reactions, including fission in nuclear power plants or radioactive decay, fusion in nuclear bombs or stellar interiors, reactions in cyclotrons where the particles are speeded and constrained by magnetic fields, and more exotic events such as matter- antimatter annihilation.
	www.sff.net /people/mmolvray/grb/grblog2.htm (4480 words)

	Life of a star
		This is called the proton proton chain reaction.
		This takes more temperature than the proton proton chain because more temperature is needed to overcome the electrostatic repulsion of helium nuclei (each twice the electric charge of a proton).
		This begins when the temperature in the center of the protostar exceeds 10 million K, which is sufficient to begin nuclear fusion of hydrogen nuclei (proton + proton -> deuterium nucleus + positron + light).
	www.csam.montclair.edu /~west/starslife.html (1113 words)

	Zoom Astronomy Glossary: P
		The proton-proton chain is a hypothetical fusion reaction thought to occur deep inside stars.
		The proton was discovered by Rutherford in 1919 (after the discovery of the electron and before the discovery of the neutron).
		In an atom, protons are in the nucleus, surrounded by electrons.
	www.enchantedlearning.com /subjects/astronomy/glossary/indexp.shtml (4061 words)

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