Emulation of coupled-channels scattering for strongly deformed nuclei
Abstract
Nucleon scattering off strongly deformed nuclei such as the actinides requires coupled-channels (CC) calculations in which several members of the ground-state rotational band are coupled explicitly, which makes Bayesian uncertainty quantification of deformed global optical potentials costly. We reformulate the direct boundary matching method (DBMM) by imposing its outgoing-wave boundary condition through a generalized Bloch operator; the resulting Bloch-DBMM solver converges as fast as the modern R-matrix method and extends to charged projectiles on targets with deformed charge distributions. On top of it we build a reduced-basis emulator, CCB-ROM, whose basis vectors span all channels of a Jπ block simultaneously, and generalize the coupled-channels empirical interpolation method to arbitrary non-affine deformed interactions. For n,p+232Th inelastic scattering with the ground-state band coupled through the 8+ state, at 4 and 35 MeV, the Bloch-DBMM solver is benchmarked against Frescox, and the emulator replaces a 2700-dimensional system by one of dimension Nb≤200, with a cost of 𝒪(Nb3) independent of the number of channels, reproducing the exact solver calculations for all five band members with speed-ups of over two orders of magnitude. CCB-ROM thus delivers differential cross sections, transmission coefficients and reaction cross sections from one calculation, at a cost compatible with Bayesian calibration of deformed optical potentials for neutrons and protons alike, and extends naturally to closed channels and to compound-nucleus reaction codes.
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BibTeX
@misc{catacorarios2026emulation,
title = {{Emulation of coupled-channels scattering for strongly deformed nuclei}},
author = {M. Catacora-Rios and Kyle Beyer and Jin Lei and Filomena Nunes},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03910},
eprint = {2610.03910},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03910},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Emulation of coupled-channels scattering for strongly deformed nuclei
AU - M. Catacora-Rios
AU - Kyle Beyer
AU - Jin Lei
AU - Filomena Nunes
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.03910
UR - https://arxiv.org/abs/2610.03910
AB - Nucleon scattering off strongly deformed nuclei such as the actinides requires coupled-channels (CC) calculations in which several members of the ground-state rotational band are coupled explicitly, which makes Bayesian uncertainty quantification of deformed global optical potentials costly. We reformulate the direct boundary matching method (DBMM) by imposing its outgoing-wave boundary condition through a generalized Bloch operator; the resulting Bloch-DBMM solver converges as fast as the modern R-matrix method and extends to charged projectiles on targets with deformed charge distributions. On top of it we build a reduced-basis emulator, CCB-ROM, whose basis vectors span all channels of a J^π block simultaneously, and generalize the coupled-channels empirical interpolation method to arbitrary non-affine deformed interactions. For n,p+^232Th inelastic scattering with the ground-state band coupled through the 8^+ state, at 4 and 35 MeV, the Bloch-DBMM solver is benchmarked against Frescox, and the emulator replaces a 2700-dimensional system by one of dimension N_b≤200, with a cost of 𝒪(N_b^3) independent of the number of channels, reproducing the exact solver calculations for all five band members with speed-ups of over two orders of magnitude. CCB-ROM thus delivers differential cross sections, transmission coefficients and reaction cross sections from one calculation, at a cost compatible with Bayesian calibration of deformed optical potentials for neutrons and protons alike, and extends naturally to closed channels and to compound-nucleus reaction codes.
ER -