The existence of nuclei with exotic combinations of protons and neutrons
provides fundamental information on the forces acting between nucleons. The
maximum number of neutrons a given number of protons can bind, neutron drip
line1, is only known for the lightest chemical elements, up to oxygen. For
heavier elements, the larger its atomic number, the farther from this limit is
the most neutron-rich known isotope. The properties of heavy neutron-rich
nuclei also have a direct impact on understanding the observed abundances of
chemical elements heavier than iron in our Universe. Above half of the
abundances of these elements are thought to be produced in rapid-neutron
capture reactions, r-process, taking place in violent stellar scenarios2 where
heavy neutron-rich nuclei, far beyond the ones known up today, are produced.
Here we present a major step forward in the production of heavy neutron-rich
nuclei: the discovery of 73 new neutron-rich isotopes of chemical elements
between tantalum (Z=72) and actinium (Z=89). This result proves that
cold-fragmentation reactions3 at relativistic energies are governed by large
fluctuations in isospin and energy dissipation making possible the massive
production of heavy neutron-rich nuclei, paving then the way for the full
understanding of the origin of the heavier elements in our Universe. It is
expected that further studies providing ground and structural properties of the
nuclei presented here will reveal further details on the nuclear shell
evolution along Z=82 and N=126, but also on the understanding of the stellar
nucleosyntheis r-process around the waiting point at A~190 defining the speed
of the matter flow towards heavier fissioning nuclei