HELP on r-PROCESS ABUNDANCES (atoms per 10ùÿ of Hydrogen) (plotted on a logarithmic scale)
This is the r-process contribution to standard abundance distribution, the remaining part being brought about by s-processes (which includes a very small contribution due to the p-process). The standard abundance distribution (SAD) is the elemental abundance of elements within the gas cloud from which the sun and the solar system condensed. The r-process is the rapid neutron capture process whereby isotopes capture neutrons at a very high rate (from a high neutron flux), transmuting them into higher isotopes, on a timescale which allows insufficient time for any radioactive isotopes so produced to decay by beta decay processes before the next neutron capture event occurs. The timescale for the r-process to occur is of the order of hours to minutes in neutron densities greater than 10Ö¢/cmÖ at temperatures in excess of 10ƒKelvin. Such r-processes are thought to occur within supernovae explosions. The r-process results in the production of isotopes far from the line of beta stability. After this r-process has occurred, the isotopes are then allowed to decay by whatever route they chose, producing this observed abundance of elements due to the r-process. It is thus able to produce elements heavier than bismuth, all the way up to thorium and uranium in fact.
See graphs on 's-process abundance' and 'standard abundance distribution'.
This r-process graph is simply the SAD minus the s-process (plus p-process) abundance.
It is interesting to plot a scattergram of s-process abundance against r-process abundance.
