Creation of heavy elements in neutron-star mergers

Research Project, 2021 – 2026

For decades it has been a mystery where in the Universe the
heaviest elements in Nature where created, until a
spectacular event on August 17, 2017 gave us a first answer.
On that day, gravitational waves as well as astronomical
observations, covering the entire electromagnetic spectrum
from gamma radiation to radio waves, provided, for the firsttime,
data on the merging of two neutron stars into a black
hole. This astrophysical phenomenon is very much
connected to the creation of heavy elements, as data indicate
that the collision of two neutron stars results in a high flux of neutrons, which gives rise to a complex chained network of
nuclear reactions and decays, called the r-process (for rapid
neutron capture process). As early as in 1957, it was realized
that such a process must exist to explain the origin of the
heaviest elements in Nature, but it was not known where in
the Universe the necessary high flux of neutrons occurs. In
order to interpret the data on the observed neutron-star
merger and similar future observations, it is important to
understand the underlying nuclear physics processes, which
are far from being well-understood. Nuclear fission has a key
role in the r-process, which this project will investigate.
Fission limits the mass of nuclei, which can be formed during
the r-process. Moreover, if a nucleus splits into two lighter
nuclei, it influences the reaction network. Within this project,
we will use the unique capabilities of the HIE-ISOLDE
radioactive beam facility at CERN together with a novel
superconducting solenoid spectrometer, to obtain highprecision
data on the fission probabilities of previously
inaccessible, heavy neutron-rich isotopes. These data will
allow us to understand how fission influences the origin of
heavy elements in the Universe in our quest to understand
the origin and stability of matter.