Reduced basis emulator for elastic scattering in continuum-discretized coupled-channel calculations

TL;DR

This paper introduces a reduced basis emulator for continuum-discretized coupled-channel calculations, significantly speeding up computations while maintaining high accuracy, thus enabling efficient uncertainty quantification in nuclear reactions.

Contribution

The paper presents a novel POD-based reduced basis emulator for CDCC calculations that achieves two orders of magnitude speedup with sub-percent accuracy.

Findings

Achieves ~100x speedup in CDCC calculations.

Maintains sub-percent accuracy in elastic scattering predictions.

Enables efficient uncertainty quantification and Bayesian analysis.

Abstract

I develop a reduced basis emulator for continuum-discretized coupled-channel (CDCC) calculations that achieves speedups of $\sim 10^2$ while maintaining sub-percent accuracy. The emulator is constructed using the proper orthogonal decomposition (POD) method applied to snapshots of CDCC solutions computed at sampled points in the optical potential parameter space. The prediction is performed via Galerkin projection onto the reduced basis. I demonstrate the method using deuteron scattering on $^{58}$Ni at 21.6 MeV as a test case, emulating 18 optical potential parameters simultaneously. The emulator reproduces elastic scattering cross sections with errors below 0.1\% across a wide parameter range. This development enables efficient uncertainty quantification and Bayesian parameter estimation for nuclear reaction calculations that were previously computationally prohibitive.