2021FRIB/NSCL Graduate Brochure

Filomena Nunes
Professor of Physics
Managing Director of FRIB Theory Alliance
Theoretical Nuclear Physics
Selected Publications
Direct comparison between Bayesian and
frequentist uncertainty quantification for nuclear
reactions, G.B. King, A. Lovell, L. Neufcourt, F.M.
Nunes Phys. Rev. Letts. 122, 232502 (2019).
Constraining Transfer Cross Sections Using Bayes’
Theorem, A. E. Lovell, F. M. Nunes. Phys. Rev. C 97,
064612 (2018).
Optical potential from first principles, J. Rotureau,
P. Danielewicz, G. Hagen, F.M. Nunes, and T.
Papenbrock, Phys. Rev. C 95, 024315 (2017).
Establishing a theory for deuteron-induced
surrogate reactions, G. Potel, F.M. Nunes, and I.J.
Thompson, Phys. Rev. C 92, 034611 (2015)
Engenharia Fisica
Technologica,
Instituto Superior
Tecnico Lisboa,
1992
PhD, Theoretical
Physics,
University of Surrey,
England,
1995
Nuclear Theory and Science of the Facility for Rare
Isotope Beams, A.B. Balantekin, J. Carlson, D.J.
Dean, G.M. Fuller, R.J. Furnstahl, M. Hjorth- Jensen,
R.V.F. Janssens, Bao-An Li, W. Nazarewicz,
F.M. Nunes, W.E. Ormand, S. Reddy, B.M. Sherrill, M.
Phys. Lett. A 29, 1430010 (2014).
Joined NSCL in
February 2003
nunes@nscl.msu.edu
I study direct nuclear reactions and structure models that
are useful in the description of reactions. Unstable nuclei are
mostly studied through reactions, because they decay back
to stability, often lasting less than a few seconds. My group
focuses on developing models for reactions with exotic
unstable nuclei, and quantifying the uncertainties in those
predictions. Reaction theory makes the critical connection
between experiments such as the ones performed at
NSCL and the nuclear structure (or nuclear astrophysics)
information we want to extract. Within the realm of direct
reactions, we have studied inelastic excitation, breakup and
transfer reactions.
The motivation to study these reactions are three-fold.
Breakup and transfer reactions can be used as indirect
methods to obtain capture rates of astrophysical relevance.
These capture rates enter in the simulations of stars, and
explosive sites such as novae, supernovae and neutron
star mergers. In addition, reliable models for some specific
direct reactions are crucial for nuclear waste management
and reactors. Finally, and most importantly, we also need
reactions to unveil the hidden secrets of the effective nuclear
force that binds some exotic systems and not others.
Nuclei are many body systems of large complexity.
Describing a reaction while retaining all the complexity
of the projectile and target nuclei would be a daunting
task. Fortunately, to describe many direct reactions, only
a few structure degrees of freedom are necessary. Thus,
we develop simplified few-body models that retain the
important features.
Another important line of research in my group is the use
of Bayesian statistical tools to quantify the uncertainty on
our predictions and help in experimental design. The fewbody
methods we use rely on effective potentials between
constituents that are not well known. The uncertainties
coming from these effective potentials need to be quantified.
An example of such studies is shown in the figures.
KEYWORDS
Reaction Theory | Breakup Reactions | Transfer
Reactions | Few-Body Methods | Uncertainty
Quantification | High-Performance Computing
Indirect Methods in Astrophysics
We consider neutron elastic scattering on Ca48 at 12 MeV. The
parameters in the effective n-Ca48 potential have been constrained
recently with elastic scattering data (PRL 122, 232502). We compare
the traditional Chi2 fiting procedure to the Bayesian approach, and
show that the uncertainty bands for reactions observables obtained
in the Bayesian approach as more realistic than the standard chi2
fitting. In Fig 1 we show the uncertainty bands obtained in the two
approaches for the angular distribution and in Fig 2 we show the
corresponding correlations between the potential parameters.
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