Neutron Skin Thickness of ^{48}Ca from a Nonlocal Dispersive Optical-Model Analysis.

Area of Science:

• Nuclear Physics
• Quantum Mechanics
• Particle Physics

Background:

• Understanding the distribution of neutrons and protons in atomic nuclei is fundamental to nuclear physics.
• The neutron skin, a region where neutron density exceeds proton density, influences nuclear stability and reactions.
• Previous models have provided estimates, but precise determination remains a challenge.

Purpose of the Study:

• To perform a nonlocal dispersive optical-model analysis for neutrons and protons in Calcium-48.
• To extract neutron and proton self-energies above and below the Fermi energy.
• To determine the charge and neutron matter distributions and precisely measure the neutron skin thickness.

Main Methods:

• Nonlocal dispersive optical-model analysis.
• Fitting elastic-scattering angular distributions, total and reaction cross sections.
• Analysis of single-particle energies, neutron and proton numbers, and charge distribution.

Main Results:

• Extracted neutron and proton self-energies.
• Determined charge and neutron matter distributions in Calcium-48.
• Deduced a best-fit neutron skin of 0.249±0.023 fm, with values up to 0.33 fm consistent.

Conclusions:

• The nonlocal dispersive optical-model provides a robust framework for nuclear structure analysis.
• The energy dependence of total neutron cross sections is highly sensitive to neutron skin thickness.
• Accurate neutron skin measurements are vital for refining nuclear models and understanding nuclear forces.