Pawel Danielewicz

Professor of Physics


Education and training

  • MS, Physics, Warsaw University, 1977
  • PhD, Physics, Warsaw University, 1981


My research is in nuclear reaction theory. Primarily I am
interested in the central energetic reactions of heavy nuclei.
These reactions test bulk nuclear properties such as the
Equation of State (EoS) of nuclear matter. Particular focus
is now on determining the dependence of nuclear pressure
on temperature and the symmetry energy that describes
changes in the matter with changes in neutron-proton
imbalance. Insights into the symmetry energy would allow
to extrapolate from large nuclei explored in the laboratory,
with low neutron-over-proton excess, to neutron stars, with
large excess. I am interested in the many-body theory tied
to the central reactions, such as the semiclassical transport
theory and the quantum nonequilibrium Green’s function
theory. I use the theory to understand what happens in the
reactions and to learn about the bulk nuclear properties,
by analyzing reaction measurements. When more
information can be gained from data in an adjacent field or
any methods are not there for my use, I often dive into the
adjacent fields and tackle challenges there, to move the
overall efforts forward.

Current research projects I am engaged in include the
use of the so-called charge-exchange reactions to learn
about the symmetry energy at the densities characteristic
for nuclei, the use of the charged pion yields from central
reactions to learn about the symmetry energy at higher
densities than in the nuclei, and the use of central reactions
to create transient rings out of nuclear matter. Moreover,
I am engaged in the development of quantum transport
theory suitable for studying collisions of heavy nuclei
and of other systems. Charge exchange reactions, where
proton incident on a nucleus turns into a neutron, probe
the relative distributions of neutrons vs protons in a
nucleus. The latter distribution is largely governed by the
symmetry energy. The rings out of nuclear matter form in
the transport theory simulations of collisions at modest
incident energy, in effect of a low-density instability in
the nuclear EoS, while the matter expands, mimicking the
formation of smoke rings. Experimental observation of
such rings would validate the current understanding of the
low-density EoS and give insight into phenomena in the
crusts of neutron stars.

Possible incoming student projects, of different difficulty,

  • Exploring impacts of a medium-modification of pion
    production and absorption rates on pion yields from
    central collisions of heavy nuclei
  • Generalizing error analysis to produce faithful errors
    on the conclusions drawn from charge-exchange and
    elastic scttering reactions. The traditional analysis
    falters due to a serious difference in the accuracy of
    measuring charged protons and neutral neutrons
  • Constructing and implementing modern energy
    functional for exploring EoS in central reactions
  • Advancing quantum transport theory for central
    reactions, based on nonequilibrium Green’s functions

Scientific publications