  We revisit the problem of the production of light atomic nuclei in
ultrarelativistic heavy-ion collisions. While their production systematics is
well produced by hadro-chemical freezeout at temperatures near the QCD
pseudo-critical temperature, their small binding energies of a few MeV per
nucleon suggest that they cannot survive as bound states under these
conditions. Here, we adopt the concept of effective chemical potentials in the
hadronic evolution from chemical to thermal freezeout (at typically $T_{\rm
fo}$$\simeq$100\,MeV), which, despite frequent elastic rescatterings in
hadronic matter, conserves the effective numbers of particles which are stable
under strong interactions, most notably pions, kaons and nucleons. It turns out
that the large chemical potentials that build up for antibaryons result in
thermal abundances of light nuclei and antinuclei, formed at thermal freezeout,
which essentially agree with the ones evaluated at chemical freezeout. Together
with their transverse-momentum spectra, which also indicate a kinetic freezeout
near $T_{\rm fo}$, this provides a natural explanation for their production
systematics without postulating their survival at high temperatures.
