FIAS Scientific Report 2011 - Frankfurt Institute for Advanced Studies ...

Extreme isospin in heavy nuclei
Collaborators: S. Schramm 1 , D. Gridnev 1 , W. Greiner 1 , D. V. Tarasov 2 , V. N. Tarasov 2
1 Frankfurt Institute for Advanced Studies, 2 NSC, Kharkov Institute of Physics and Technology, Ukraine
The focus of many experimental and theoretical efforts in nuclear physics are focused on exploring extreme
states of strongly interacting matter. One aspect of these efforts is the study of very neutron rich nuclei, as they
will be measured extensively in the upcoming FAIR facility at GSI, the FRIB facility in Michigan, and a number
of other laboratories around the world. In addition to the fundamental issues of nuclear stability involved in this
research, the properties of neutron-rich nuclei are crucial input for the nucleosynthesis in supernovae, and the
isospin dependence of the nuclear interactions has direct impact on the properties and stability of neutron stars.
In order to study this region of large isospin we investigated the stability of heavy nuclei around Uranium and
studied the maximum amount of neutrons the different elements can contain. We calculated nuclear properties
for a variety of non-relativistic Skyrme forces as well as relativistic and chiral effective nuclear models. We
could observe a huge difference of this maximum neutron number depending on the model adopted (as can ben
seen in Fig. 1), where differences in the maximum neutron number exceed 70 neutrons (!) in specific cases.
Following the isotope chain, a change of nuclear deformation from spherical to prolate, then oblate, and back
to spherical shape could be observed (Fig. 2).
The results show that there are still huge theoretical uncertainties in the properties of nuclei with large neutron
excess. In the future, performing combined calculations of the neutron drip line, phase structure of strong
interactions, as well as neutron star phenomenology will help to correlate model predictions over a larger range
of observables, helping to constrain models to a much bigger extent.
Binding Energy -B [MeV]
-1900
-1920
-1940
-1960
-1980
-2000
-2020
SLy6
-2040
170 180 190 200 210 220 230 240 250 260
Neutron Number
SkI4
SkM*
NL-Z2
Figure 1: Total binding energy of Uranium isotopes
for different parameterizations. The curves show
the result for a relativistic mean-field (NL-Z2) and
Skyrme models (SkM*, SkI4, SLy6). The chiral
model χM (not shown) has its minimum at N = 184.
Figure 2: Deformation β2 for different Californium isotopes
for the Skyrme parameter set SkM*.
Related publications in 2011:
S. Schramm, D. Gridnev, D. V. Tarasov, V. N. Tarasov and W. Greiner, The quest for the heaviest uranium
isotope, arXiv:1107.1055 [nucl-th].
V. N. Tarasov, K. A. Gridnev, D. K. Gridnev, D. V. Tarasov, S. Schramm, X. Vinas and W. Greiner, Stability
peninsulas on the neutron drip line, arXiv:1106.5910 [nucl-th].
51