N = 14 shell closure in 22O viewed through a neutron sensitive probe.

Area of Science:

• Nuclear Physics
• Nuclear Structure
• Exotic Nuclei

Background:

• Investigating nuclear shell closures far from stability is crucial for understanding nuclear forces.
• The N = 14 shell closure in neutron-rich isotopes is a key area of interest.
• Previous studies on oxygen isotopes provide context for the behavior of 22O.

Purpose of the Study:

• To probe the N = 14 neutron gap in the neutron-rich nucleus 22O using a neutron-sensitive method.
• To determine the contribution of neutrons to the 2(1)+ excited state in 22O.
• To examine the stability of the N = 14 shell closure near the neutron drip line.

Main Methods:

• Proton elastic and inelastic scattering angular distributions for 22O were measured.
• Experiments utilized the MUr à STrip detector array at the Grand Accélérateur National d'Ions Lourds (GANIL) facility.
• Microscopic analysis involved continuum Skyrme-Hartree-Fock-Bogoliubov and quasiparticle random phase approximation calculations.

Main Results:

• A deformation parameter beta(p,p') = 0.26 +/- 0.04 was obtained for the 2(1)+ state in 22O.
• This value indicates a weaker neutron contribution to the 2(1)+ state compared to 20O.
• The ratio of neutron to proton contributions to the 2(1)+ state is close to the N/Z ratio.

Conclusions:

• The results demonstrate a strong N = 14 shell closure in 22O, even near the neutron drip line.
• The observed weak neutron contribution to the 2(1)+ state supports the robustness of this shell closure.
• This finding has implications for nuclear structure models and the understanding of exotic nuclei.