EBTX,
Uranium breaks down to lead with intermediaries and Helium is a byproduct of the alpha decay. Remember that an Alpha particle is a Helium nuclei. It has an atomic mass of 4, 2 of the mass units derived from protons, the other 2 from neutrons. When the Helium nuclei encounters free electrons, either from metals or more usually the beta particles (electrons) from other decay processes; then a helium atom is formed and the original Uranium loses 4 mass units (since 2 are protons, the uranium transmutes into Thorium. This process continues until stable lead is formed. As a side note, in nature the helium found to fill your birthday balloons is tapped from lead mines where decaying isotopes and uranium are also located.
The natural decay series for U-238 is as follows can be found at
www.ccnr.org/decay_U238.html
Several folks have asserted that we have a poor understanding of fusion. I am not sure where this assertion comes from. We have performed fusion many times in true scientific experiments where the yield of the reaction can be modelled and predicted at least in H-bombs. Perhaps our failures at reactor design and manipulating high pressure/high temp materials is responsible for assuming that the process is a mystery. I feel well supported in saying that science has a good understanding of fusion and fission and that these explanations are not usually at odds with the MM as I understand it. Spectroscopy of the galaxy has shown evidence of star compositions coupled with our satelite exploration and earth observations of our sun.
Fusion processes follow a similar proportional plan very similar to electron configurations. Protons and neutrons stack up in a planned order. Those nuclei that do not comply to this complex arrangement are said to be radioactively decaying until they do reach a stable configuration. This is why many of the large atoms decay to lead then stop. Lead, iron, carbon, oxygen, helium (there are several others) are like stable islands in a decaying flood of radioactivity. Fusion calculations predict that iron is the stopping place for fusion in small stars because the pressure/temp necessary to fuse two iron nuclei together is beyond a small stars forces. I am compelled by the evidence suggesting that elements larger than iron must be formed during supernova and then spread into nebula to be incorporated in new star and solar system development. Element distribution studies support these probabilities as well.
Mark
