  Heavy elements are formed in nucleosynthesis processes. Abundances of these
elements can be classified as elemental abundance, isotopic abundance, and
abundance of nuclei. In this work we propose to change nucleon identification
from the usual (Z,A) to (Z,N), which allows reading out new information from
the measured abundances. We are interested in the neutron density required to
reproduce the measured abundance of nuclei assuming equilibrium processes. This
is only possible when two stable nuclei are separated by an unstable nucleus.
At these places we investigated the neutron density required for equilibrium
nucleosynthesis both isotopically and isotonically at temperatures of AGB
interpulse and thermal pulse phases. We obtained an estimate for equilibrium
nucleosynthesis neutron density in most of the cases. Next we investigated the
possibility of partial formation of nuclei. We analyzed the meaning of the
branching factor. We found a mathematical definition for the unified
interpretation of a branching point closed at isotonic case and open at
isotopic case. We introduce a more expressive variant of branching ratio called
partial formation rate. With these we are capable of determining the
characteristic neutron density values.
