Having read a number of books on cosmology and particle physics, I found my-self raking through 5 or 6 books or looking on the web as I tried to remember some tangible fact that had interested me. In the end, I decided to gather this info and post it under various headings as blogs on MySpace. With the introduction of LaTeX at Physics Forums, I decided to move a couple of them over here. Some are a year old, some are more recent. MySpace blogs
Nucleosynthesis- element-building processes
Parts of the following are condensed from one of the best popular science books I've read regarding stars and atoms, 'The Magic Furnace' by Marcus Chown which I recommend.
Element-building Processes (B2FH)
Atoms are the fundamental building blocks of all matter. They compose of protons, neutrons and electrons (except the hydrogen atom which composes of just 1 proton and 1 electron). The proton is positively charged (+1), the electron negatively charged (-1) and the neutron has no charge. The proton and neutron are hadrons, particles that mediate the nuclear force (the nuclear force is sometimes called the residual strong force as it is a result of the strong force interactions between the quarks that make up the proton and neutron). Atoms naturally range in size from the simple hydrogen atom to uranium-238, which composes of 92 protons, 146 neutrons and 92 electrons (electrons weigh approx. 1/2000th of a proton and are considered to contribute little or nothing to the atoms weight). In the atoms ground state, the number of electrons equals the number of protons. Neutrons are required due to the fact that as the number of protons grow, more mediators of the strong force are required to overcome the same-sign electrostatic repulsion of the protons (such as in the uranium atom, 238 mediators of the nuclear force overcomes (just) the electrostatic repulsion of 92 protons). The hydrogen nucleus is the basic building block of the atomic nucleus and can be fused to create other elements. The neutron is formed through beta decay. Scale wise, a hydrogen atom is 1.06x10^-10 metres in diameter (0.000000106mm), which means spatial wise, 1 billion, trillion (10^21) hydrogen atoms could fit in 1mm cubed. The proton is 10^-15 metres across making the atom to proton size ratio about 100,000:1. This is like a marble in the centre of a stadium. The electron is even smaller at 10^-18 metres.
x-process
Includes elements produced during the big bang such as deuterium (hydrogen-2) (1 proton, 1 neutron), helium-3 (2 protons, 1 neutron), helium-4 (2 protons, 2 neutrons), traces of lithium-6 (3 protons, 3 neutrons) and lithium-7 (3 protons, 4 neutrons). Tritium (hydrogen-3) (1 proton, 2 neutrons) and beryllium-7 (4 protons, 3 neutrons) also produced but unstable, quickly decaying. The universe expanded before the massive temperatures and pressures could create any larger elements and explains why the universe is 75% hydrogen, 24% helium and 1% everything else. Main source of beryllium-9 and boron-10,11- cosmic ray spallation, where the nuclei in cosmic rays break up when colliding with other cosmic rays, beryllium and boron being described as 'nuclear shrapnel'.
Hydrogen-burning
Conversion of hydrogen into helium at a temperature of 15,000,000°c (temperature at the suns core), the power source of a large amount of stars.
-Proton-proton chain
Important in stars with the mass of the sun or less (reaction can take 1 billion years at the temperature of the suns core, most important, responsible for sunlight and life on earth). 2 protons overcome the electrostatic repulsion and collide (the combination is unstable and one proton turns into a neutron by beta decay, ejecting a positron and a neutrino in the process) this creates a deuterium nucleus. This then collides with another proton, which creates a helium-3 nucleus (2 protons, 1 neutron) and ejects a gamma ray in the process. Two helium-3 nuclei collide ejecting 2 of the protons and leaving a helium-4 nucleus (2 protons, 2 neutrons).
-Carbon-nitrogen-oxygen cycle (CNO)
This happens in much larger stars at least the size of red giants, where elements with larger nuclei have been made. Cycle as follows (p-proton, n-neutron)-
carbon-12 (6p, 6n) + p -> nitrogen-13 (7p, 6n) with gamma ray,
nitrogen-13 beta decays to carbon-13 (6p, 7n) with positron & neutrino,
carbon-13 + p -> nitrogen-14 (7p, 7n) with gamma ray,
nitrogen-14 + p -> oxygen-15 (8p, 7n) with gamma ray,
oxygen-15 beta decays to nitrogen-15 (7p, 8n) with positron & neutrino,
nitrogen-15 + p -> carbon-12 (6p, 6n) and helium-4 (2p, 2n).
Triple Alpha Process
Three helium-4 nuclei fuse to create a carbon-12 atom. Very slow process. 100 million°c required, deep inside red giant. This phase would take place in stars later stages in life when the hydrogen fuel had been used up in the core. Beryllium-8 (4 protons, 4 neutrons) was crucial in creating carbon-12 but potentially proved to be a stumbling block in the evolution of the elements as it was unstable and decayed in a micro-fraction of a second. Scientists finally realised, that in large stars where helium was abundant, for a split second, as two alpha particles (helium-4 nuclei) temporarily fused, they would be struck by a third alpha particle, creating carbon-12. This fine-tuning means that life had a chance to develop on local planets. If the helium to carbon process had been any quicker, the stars would have rattled through their fuel and died very quickly.
Alpha Process
The Triple Alpha Process opened the way to forging the heavier elements. Taking carbon-12 and adding a succession of helium-4 nuclei (2 protons, 2 neutrons- alpha particles). This required more extreme conditions than the Triple Alpha Process, 100 million to 1 billion degrees (the core of a red supergiant).
-Carbon burning
Carbon-12, oxygen-16, neon-20, and magnesium-24 created. Lasts about 1000 years (at the end of this phase, stars between 4-8 solar masses eject the envelope into a planetary nebula, leaving an O-Ne-Mg white dwarf).
-Oxygen burning
Oxygen-16, neon-20, magnesium-24, silicon-28 and sulfur-32 created. lasts about 6 months to 1 year. Stars need to be bigger than 8 solar masses.
-Silicon burning
Silicon-28, sulfur-32, argon-36, calcium-40, titanium-44, chromium-48, iron-52, nickel-56 (nickel-56 beta decays into iron-56). lasts about 1 day.
The alpha process is selective, skipping over many nuclei, constrained by the ever-growing electrical charge on nuclei that it is making. When the charge becomes large, alpha particles are repelled so violently, not even the hottest stars can make them stick.
Heavy nuclei (and nuclei missed from the Alpha Process) are created by adding particles unaffected by the electrical charge- neutrons. The next element building processes are neutron build-up schemes. The process starts with a 'seed' (either an 'iron-group' element or a light element), which is then pelted with free neutrons within the star.
S-process
A slow neutron build-up phase, one neutron every 100,000 years. The unstable nuclei beta decay, turning the neutrons into protons (producing an electron and an anti-neutrino in the process). This process produces heavy elements which are neutron-poor (such as barium and zirconium) but cannot make elements heavier than Bismuth-209 (83 protons, 126 neutrons). The s-process occurs in large red supergiants. Another process was required in order to create neutron-rich elements.
R-process
A rapid neutron build-up phase, one neutron every second. Most probably occurs in the fury of supernova explosions. Forms some of the heaviest elements, thorium, uranium, californium.
Although the s & r process make most heavy nuclei, they cannot make them all-
P-process
A proton capture phase, the seed nuclei is bombarded with protons in a hydrogen rich medium with the temperature in excess of 1 billion°c. Forms elements such as platinum-190 and Ytterbium-168. Occurs in supernova.
Equilibrium process
Abundances of various elements magically 'freeze out' in the mid of the frenzy of the supernova (some iron-group elements retaining their medium nuclei count)
The above processes explain why hydrogen and helium are the greatest quanities in the universe (75% and 24% respectively) due to being formed in the furnace of the initial moments of the universe; why the next most abundant elements in the universe are oxygen, carbon, neon, nitrogen, magnesium, silicon and iron, the seven elements assembled in the greatest quantities by stellar nuclear reactions; and how gold, uranium and iodine were forged in the thermonuclear fury of a supernova, whereas barium and zirconium was cooked over 1000's of millennia in red supergiants and why any metal with an atomic number above iron is considered rare due to the nucleosynthesis process involved i.e. supernova (apart from lead, which is fairly common due to the fact that any metal with an atomic number above 82 (such as uranium-92, thorium-90, radium-88, radon-86 and polonium-84) eventually decay into the ground state of lead by ejecting alpha particles (2 protons, 2 neutrons), over millions of years, making lead fairly abundent).
Element-building Processes (B2FH)
Atoms are the fundamental building blocks of all matter. They compose of protons, neutrons and electrons (except the hydrogen atom which composes of just 1 proton and 1 electron). The proton is positively charged (+1), the electron negatively charged (-1) and the neutron has no charge. The proton and neutron are hadrons, particles that mediate the nuclear force (the nuclear force is sometimes called the residual strong force as it is a result of the strong force interactions between the quarks that make up the proton and neutron). Atoms naturally range in size from the simple hydrogen atom to uranium-238, which composes of 92 protons, 146 neutrons and 92 electrons (electrons weigh approx. 1/2000th of a proton and are considered to contribute little or nothing to the atoms weight). In the atoms ground state, the number of electrons equals the number of protons. Neutrons are required due to the fact that as the number of protons grow, more mediators of the strong force are required to overcome the same-sign electrostatic repulsion of the protons (such as in the uranium atom, 238 mediators of the nuclear force overcomes (just) the electrostatic repulsion of 92 protons). The hydrogen nucleus is the basic building block of the atomic nucleus and can be fused to create other elements. The neutron is formed through beta decay. Scale wise, a hydrogen atom is 1.06x10^-10 metres in diameter (0.000000106mm), which means spatial wise, 1 billion, trillion (10^21) hydrogen atoms could fit in 1mm cubed. The proton is 10^-15 metres across making the atom to proton size ratio about 100,000:1. This is like a marble in the centre of a stadium. The electron is even smaller at 10^-18 metres.
x-process
Includes elements produced during the big bang such as deuterium (hydrogen-2) (1 proton, 1 neutron), helium-3 (2 protons, 1 neutron), helium-4 (2 protons, 2 neutrons), traces of lithium-6 (3 protons, 3 neutrons) and lithium-7 (3 protons, 4 neutrons). Tritium (hydrogen-3) (1 proton, 2 neutrons) and beryllium-7 (4 protons, 3 neutrons) also produced but unstable, quickly decaying. The universe expanded before the massive temperatures and pressures could create any larger elements and explains why the universe is 75% hydrogen, 24% helium and 1% everything else. Main source of beryllium-9 and boron-10,11- cosmic ray spallation, where the nuclei in cosmic rays break up when colliding with other cosmic rays, beryllium and boron being described as 'nuclear shrapnel'.
Hydrogen-burning
Conversion of hydrogen into helium at a temperature of 15,000,000°c (temperature at the suns core), the power source of a large amount of stars.
-Proton-proton chain
Important in stars with the mass of the sun or less (reaction can take 1 billion years at the temperature of the suns core, most important, responsible for sunlight and life on earth). 2 protons overcome the electrostatic repulsion and collide (the combination is unstable and one proton turns into a neutron by beta decay, ejecting a positron and a neutrino in the process) this creates a deuterium nucleus. This then collides with another proton, which creates a helium-3 nucleus (2 protons, 1 neutron) and ejects a gamma ray in the process. Two helium-3 nuclei collide ejecting 2 of the protons and leaving a helium-4 nucleus (2 protons, 2 neutrons).
-Carbon-nitrogen-oxygen cycle (CNO)
This happens in much larger stars at least the size of red giants, where elements with larger nuclei have been made. Cycle as follows (p-proton, n-neutron)-
carbon-12 (6p, 6n) + p -> nitrogen-13 (7p, 6n) with gamma ray,
nitrogen-13 beta decays to carbon-13 (6p, 7n) with positron & neutrino,
carbon-13 + p -> nitrogen-14 (7p, 7n) with gamma ray,
nitrogen-14 + p -> oxygen-15 (8p, 7n) with gamma ray,
oxygen-15 beta decays to nitrogen-15 (7p, 8n) with positron & neutrino,
nitrogen-15 + p -> carbon-12 (6p, 6n) and helium-4 (2p, 2n).
Triple Alpha Process
Three helium-4 nuclei fuse to create a carbon-12 atom. Very slow process. 100 million°c required, deep inside red giant. This phase would take place in stars later stages in life when the hydrogen fuel had been used up in the core. Beryllium-8 (4 protons, 4 neutrons) was crucial in creating carbon-12 but potentially proved to be a stumbling block in the evolution of the elements as it was unstable and decayed in a micro-fraction of a second. Scientists finally realised, that in large stars where helium was abundant, for a split second, as two alpha particles (helium-4 nuclei) temporarily fused, they would be struck by a third alpha particle, creating carbon-12. This fine-tuning means that life had a chance to develop on local planets. If the helium to carbon process had been any quicker, the stars would have rattled through their fuel and died very quickly.
Alpha Process
The Triple Alpha Process opened the way to forging the heavier elements. Taking carbon-12 and adding a succession of helium-4 nuclei (2 protons, 2 neutrons- alpha particles). This required more extreme conditions than the Triple Alpha Process, 100 million to 1 billion degrees (the core of a red supergiant).
-Carbon burning
Carbon-12, oxygen-16, neon-20, and magnesium-24 created. Lasts about 1000 years (at the end of this phase, stars between 4-8 solar masses eject the envelope into a planetary nebula, leaving an O-Ne-Mg white dwarf).
-Oxygen burning
Oxygen-16, neon-20, magnesium-24, silicon-28 and sulfur-32 created. lasts about 6 months to 1 year. Stars need to be bigger than 8 solar masses.
-Silicon burning
Silicon-28, sulfur-32, argon-36, calcium-40, titanium-44, chromium-48, iron-52, nickel-56 (nickel-56 beta decays into iron-56). lasts about 1 day.
The alpha process is selective, skipping over many nuclei, constrained by the ever-growing electrical charge on nuclei that it is making. When the charge becomes large, alpha particles are repelled so violently, not even the hottest stars can make them stick.
Heavy nuclei (and nuclei missed from the Alpha Process) are created by adding particles unaffected by the electrical charge- neutrons. The next element building processes are neutron build-up schemes. The process starts with a 'seed' (either an 'iron-group' element or a light element), which is then pelted with free neutrons within the star.
S-process
A slow neutron build-up phase, one neutron every 100,000 years. The unstable nuclei beta decay, turning the neutrons into protons (producing an electron and an anti-neutrino in the process). This process produces heavy elements which are neutron-poor (such as barium and zirconium) but cannot make elements heavier than Bismuth-209 (83 protons, 126 neutrons). The s-process occurs in large red supergiants. Another process was required in order to create neutron-rich elements.
R-process
A rapid neutron build-up phase, one neutron every second. Most probably occurs in the fury of supernova explosions. Forms some of the heaviest elements, thorium, uranium, californium.
Although the s & r process make most heavy nuclei, they cannot make them all-
P-process
A proton capture phase, the seed nuclei is bombarded with protons in a hydrogen rich medium with the temperature in excess of 1 billion°c. Forms elements such as platinum-190 and Ytterbium-168. Occurs in supernova.
Equilibrium process
Abundances of various elements magically 'freeze out' in the mid of the frenzy of the supernova (some iron-group elements retaining their medium nuclei count)
The above processes explain why hydrogen and helium are the greatest quanities in the universe (75% and 24% respectively) due to being formed in the furnace of the initial moments of the universe; why the next most abundant elements in the universe are oxygen, carbon, neon, nitrogen, magnesium, silicon and iron, the seven elements assembled in the greatest quantities by stellar nuclear reactions; and how gold, uranium and iodine were forged in the thermonuclear fury of a supernova, whereas barium and zirconium was cooked over 1000's of millennia in red supergiants and why any metal with an atomic number above iron is considered rare due to the nucleosynthesis process involved i.e. supernova (apart from lead, which is fairly common due to the fact that any metal with an atomic number above 82 (such as uranium-92, thorium-90, radium-88, radon-86 and polonium-84) eventually decay into the ground state of lead by ejecting alpha particles (2 protons, 2 neutrons), over millions of years, making lead fairly abundent).
Total Comments 3
Comments
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That was really informative. It blows my mind to even try to comprehend how all of this got to be known.
I'll put "The Magic Furnace" on my reading list - it's a subject I know little about.Posted Aug22-08 at 10:02 PM by WCOLtd 
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traces of beryllium (3 protons, 3 neutrons) and boron (4 protons, 4 neutrons)
I think the parenthesis are incorrect, it's my understanding that Lithium has 3 protons, and generally 4 neutrons Beryllium has 4 protons, and usually 5 neutrons, and Boron contains 5 protons and usually 6 neutrons.
The atomic number of the elements indicate the number of protons and the atomic weight minus the atomic number should indicate the number of neutrons (unless it's an isotope).Posted Aug29-08 at 11:31 AM by WCOLtd
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in sun there are lots of protons ejected by CME and by solar wind they are fired into space by magnetics fields ; there should be an equal lot of neutron where are they ??
Posted Feb10-12 at 08:27 AM by al2207
