I am a member of Filomena Nunes's research group at the Facility for Rare Isotope Beams at Michigan State University. We are currently working on the development of theoretical tools to study direct nuclear reactions. 

My graduate school work was on the calculation of microscopic nucleon-nucleus optical potentials based on two- and three-nucleon interactions from chiral effective field theory.  A python script for using the Whitehead-Lim-Holt global optical potential can be downloaded here.

A full list of my publications may be found here: https://inspirehep.net/authors/1621981

Recent Papers

Microscopic nucleus-nucleus optical potentials from nuclear matter with uncertainty analysis from chiral forces

T.R. Whitehead


Nucleus-nucleus optical potentials are constructed from an energy density functional approach first outlined by Brueckner et al. The interaction term of the energy density functional comes from the complex nucleon self-energy computed in nuclear matter with two- and three-body chiral nuclear forces. Nuclear density distributions are calculated from Skyrme functionals constrained to the equations of state calculated from the same chiral forces used for the self-energy. Predictions for elastic scattering cross sections and fusion cross sections are compared to experimental data. Very good agreement is found with experiment for elastic scattering of heavier nucleus-nucleus systems at energies in the range of 20<E<90 MeV/N, while accurate descriptions of lighter and lower-energy systems may require the inclusion of collective excitations.

Prediction of (p,n) Charge-Exchange Reactions with Uncertainty Quantification

T.R. WhiteheadT. Poxon-PearsonF.M. NunesG. Potel

Phys.Rev.C 105 (2022) 5, 054611

Background: Charge-exchange reactions are a powerful tool for exploring nuclear structure and nuclear astrophysics, however, a robust charge-exchange reaction theory with quantified uncertainties is essential to extracting reliable physics. Purpose: The goal of this work is to determine the uncertainties due to optical potentials used in the theory for charge-exchange reactions to isobaric analogue states. Method: We implement a two-body reaction model to study (p,n) charge-exchange transitions and perform a Bayesian analysis. We study the (p,n) reaction to the isobaric analog states of 14C, 48Ca, and 90Zr targets over a range of beam energies. We compare predictions using standard phenomenological optical potentials with those obtained microscopically. Results: Charge-exchange cross sections are reasonably reproduced by modern optical potentials. However, when uncertainties in the optical potentials are accounted for, the resulting predictions of charge-exchange cross sections have very large uncertainties. Conclusions: The charge-exchange reaction cross section is strongly sensitive to the input interactions, making it a good candidate to further constrain nuclear forces and aspects of bulk nuclear matter. However, further constraints on the optical potentials are necessary for a robust connection between this tool and the underlying isovector properties of nuclei.

Global Microscopic Description of Nucleon-Nucleus Scattering with Quantified Uncertainties

T.R. WhiteheadY. Lim, and J.W. Holt

Phys. Rev. Lett. 127, 182502

We develop for the first time a microscopic global nucleon-nucleus optical potential with quantified uncertainties suitable for analyzing nuclear reaction experiments at next-generation rare-isotope beam facilities. Within the improved local density approximation and without any adjustable parameters, we begin by computing proton-nucleus and neutron-nucleus optical potentials from a set of five nuclear forces from chiral effective field theory for 1800 target nuclei in the mass range 12≤A≤242 for energies between 0  MeV<E≲150  MeV. We then parameterize a global optical potential for each chiral force that depends smoothly on the projectile energy as well as the target nucleus mass number and isospin asymmetry. Uncertainty bands for elastic scattering observables are generated from a full covariance analysis of the parameters entering in the description of our global optical potential and benchmarked against existing experimental data for stable target nuclei. Since our approach is purely microscopic, we anticipate a similar quality of the model for nucleon scattering on unstable isotopes.

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