r-process: Is it correct to talk about "primary" and "secondary" r-processes? This website, written in 1994, makes a differentiation between the "primary" and "secondary" r-processes in the context of astrophysics.  As far as I can tell the main difference between the primary and secondary r-processes as explained in that website is the equilibrium of the neutron capture $(n,\gamma)$ and photodissociation $(\gamma,n)$ reactions, with the primary r-process achieving equilibrium and the secondary r-process not.
However, nowhere else have I encountered a differentiation between primary and second r-processes.  For instance, Wikipedia makes no such differentiation, and neither does this textbook.  Obviously this is not an exhaustive list but I've been doing some research for a paper I am writing on the r-process and haven't found anywhere except that website from 1994 making a differentiation.
Is the differentiation between primary and secondary r-processes important?  Has it been shown since 1994 that they are not important in an astrophysical context?  Basically I am asking, why does no one differentiate primary and secondary r-processes anymore (or did they ever?  Is that website just an exception?)?
 A: It seems to me that the main distinction that this article makes is that the primary r-process occurs without the need for pre-existing "seed" nuclei, whilst the secondary r-process does require pre-existing seed nuclei.
The argument appears to be that the r-process elements we see in the solar system are consistent with a scenario in which the seed nuclei were assembled in a system that was in nuclear statistical equilibrium (e.g. the core of a massive star) and which manufactured its own seed nuclei - i.e. a primary r-process - if you start with a (population III) star consisting only of hydrogen and helium, you will still end up with r-process elements being produced in the supernova.
The secondary r-process would occur in a system which was unable to reach nuclear statistical equilibrium and had not for instance manufactured iron-peak seed nuclei. Instead the r-process can only occur using seed nuclei that were already present in the system. This is not thought to be a common route for the r-process, but it is the most common route for the s-process. This occurs inside AGB stars, but the AGB stars did not make the iron-peak seed nuclei. This is why it would be called a secondary process - if you start with an intermediate mass population III star, you would not get s-process elements produced during its evolution.
Its probably not a commonly used term for the r-process because as far as I am aware secondary r-processes are not thought to be effective - the main wikipedia page on nucleosynthesis does say "The primary r-process has been confirmed by astronomers who have observed old stars born when galactic metallicity was still small, that nonetheless contain their complement of r-process nuclei;"
It is however commonly used in other types of nucleosynthesis. For example take nitrogen. Nitrogen is produced in a primary process by intermediate mass stars. In this case the reactants (H and C) are produced inside the star. On the other hand secondary nitrogen production occurs when H burns with C that was already present in the star and can occur in a wider range of masses.
Try a search on "primary and secondary nucleosynthesis".
