Momentum Distributions and Spatial Signatures of Proton Halos in the sd Shell
Abstract
We perform a theoretical study of intermediate-energy quasifree one-proton knockout reactions on proton targets. Single-particle wave functions constrained by the experimental proton separation energies are employed to calculate longitudinal momentum distributions, one-proton removal cross sections, and full momentum-space profiles for 26P, 27S and 31Ar nuclei. To establish robust criteria to identify proton halos, the analysis is extended beyond the traditional momentum-width approach by investigating the spatial extension of the valence proton through root-mean-square radii and the probability that the proton resides outside the core nucleus, P(r>Rcore). We also examine Coulomb-barrier systematics, mirror-nucleus comparisons, realistic spectroscopic mixtures, finite experimental momentum resolution, and uncertainties associated with the proton separation energy. Our calculations indicate that proton-halo structure cannot be identified reliably from a single observable. A consistent interpretation emerges only when momentum distributions, spatial observables, Coulomb effects, and many-body structure are considered simultaneously. Within the present model, 26P exhibits the strongest proton-halo signatures, while 27S retains pronounced halo-like features despite its larger Coulomb barrier. The more strongly confined 31Ar provides a useful comparison and illustrates the progressive suppression of halo observables with increasing binding and core charge.
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BibTeX
@misc{diba2026momentum,
title = {{Momentum Distributions and Spatial Signatures of Proton Halos in the sd Shell}},
author = {Taslima S. C. Diba and Carlos A. Bertulani and Ronaldo V. Lobato},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.06524},
eprint = {2608.06524},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.06524},
}
RIS
TY - UNPB
TI - Momentum Distributions and Spatial Signatures of Proton Halos in the sd Shell
AU - Taslima S. C. Diba
AU - Carlos A. Bertulani
AU - Ronaldo V. Lobato
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2608.06524
UR - https://arxiv.org/abs/2608.06524
AB - We perform a theoretical study of intermediate-energy quasifree one-proton knockout reactions on proton targets. Single-particle wave functions constrained by the experimental proton separation energies are employed to calculate longitudinal momentum distributions, one-proton removal cross sections, and full momentum-space profiles for ^26P, ^27S and ^31Ar nuclei. To establish robust criteria to identify proton halos, the analysis is extended beyond the traditional momentum-width approach by investigating the spatial extension of the valence proton through root-mean-square radii and the probability that the proton resides outside the core nucleus, P(r>R_core). We also examine Coulomb-barrier systematics, mirror-nucleus comparisons, realistic spectroscopic mixtures, finite experimental momentum resolution, and uncertainties associated with the proton separation energy. Our calculations indicate that proton-halo structure cannot be identified reliably from a single observable. A consistent interpretation emerges only when momentum distributions, spatial observables, Coulomb effects, and many-body structure are considered simultaneously. Within the present model, ^26P exhibits the strongest proton-halo signatures, while ^27S retains pronounced halo-like features despite its larger Coulomb barrier. The more strongly confined ^31Ar provides a useful comparison and illustrates the progressive suppression of halo observables with increasing binding and core charge.
ER -