  After decades, the theoretical study of core-collapse supernova explosions is
moving from parameterized, spherically symmetric models to increasingly
realistic multi-dimensional simulations. Obtaining nucleosynthesis yields based
on such multi-dimensional core-collapse supernova (CCSN) simulations, however,
is not straightforward and frequently tracer particles are employed. Tracer
particles may be tracked in situ during the simulation, but often they are
reconstructed in a post-processing step based on the information saved during
the hydrodynamics simulation. Reconstruction can be done in a number of ways
and here we compare the approaches of backward and forward integration of the
equations of motion to the results based on inline particle trajectories. We
find that both methods agree reasonably well with the inline results for
isotopes for which a large number of particles contribute. However, for rarer
isotopes that are produced only by a small number of particle trajectories,
deviations can be large. For our setup, we find that backward integration leads
to a better agreement with the inline particles by more accurately reproducing
the conditions following freeze-out from nuclear statistical equilibrium,
because the establishment of nuclear statistical equilibrium erases the need
for detailed trajectories at earlier times. Based on our results, if inline
tracers are unavailable, we recommend backward reconstruction, to the point
when nuclear statistical equilibrium last applied, with an interval between
simulation snapshots of at most 1 ms for nucleosynthesis post-processing.
