Direct Nuclear Reactions: Theory and Uncertainties

Michigan State University, East Lansing MI

Investigators

Abstract

Direct nuclear reactions provide some of the most versatile probes in nuclear physics and provide access to a large variety of nuclear properties, most of which are relevant for astrophysics and societal applications. Reliable reaction theory with known uncertainties is key for the interpretation of nuclear reaction experiments. This project aims to advance our understanding of the information contained in a number of different reaction data. By quantifying uncertainties and evaluating the level of confidence of the reaction theory used to interpret a given experiment, this project will enable a better use of current and future rare isotope facilities in the U.S. and worldwide. Specifically, the PI and her student will work with experimentalists in planning and interpreting on-going nuclear reaction experiments at the National Superconducting Cyclotron Laboratory and at the future Facility for Rare Isotope Beams at Michigan State University. This project seeks to advance our understanding of the information content and uncertainties concerning direct nuclear reactions, quantifying uncertainties and evaluating the level of confidence of the quantities extracted from the interpretation of experiments. Tools will be developed to use Bayesian statistics to extract constraints on the optical potential from data, as well as defining confidence bands for reaction observables. Strategies for reducing the uncertainty of the theory will also be explored. The Bayesian tools will be applied to extracting a non-local global optical potential for a wide range of masses and energies, informed by ab-initio many-body theories. The Bayes factor will be used to perform model comparisons and establish the level of sophistication needed in a reaction model to describe available data. The PI and her student will focus on advancing the theory for direct reactions with a particular focus on uncertainty quantification. A second goal of this project is to pave the way for a direct connection between many-body and few-body approaches and enable a better understanding of the role of excitation in direct reaction processes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.