Shell structure at N=28 near the dripline: spectroscopy of ${}^{42}$Si, ${}^{43}$P and ${}^{44}$S

Abstract

Measurements of the N=28 isotones 42Si, 43P and 44S using one- and two-proton knockout reactions from the radioactive beam nuclei 44S and 46Ar are reported. The knockout reaction cross sections for populating 42Si and 43P and a 184 keV gamma-ray observed in 43P establish that the d_{3/2} and s_{1/2} proton orbits are nearly degenerate in these nuclei and that there is a substantial Z=14 subshell closure separating these two orbits from the d_{5/2} orbit. The increase in the inclusive two-proton knockout cross section from 42Si to 44S demonstrates the importance of the availability of valence protons for determining the cross section. New calculations of the two-proton knockout reactions that include diffractive effects are presented. In addition, it is proposed that a search for the d_{5/2} proton strength in 43P via a higher statistics one-proton knockout experiment could help determine the size of the Z=14 closure.

Phys. Rev. C, in press

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Cited by in corpus (13)

• Collapse of the N=28 shell closure in ${}^{42}$Si
• A new effective interaction for $0\hslash \omega$ shell model calculations in the sdpf valence space
• The merging of the islands of inversion at N=20 and N=28
• Well-developed deformation in 42Si
• The Neutron-Rich Edge of the Nuclear Landscape. Experiment and Theory
• State-of-the-art of beyond mean field theories with nuclear density functionals
• In-beam gamma-ray spectroscopy of very neutron-rich nuclei: Excited states in 46S and 48Ar
• Is the structure of 42Si understood?
• Evolution of single-particle structure of silicon isotopes
• Low-lying 2${}^{+}$ states generated by $pn$-quadrupole correlation and $N=28$ shell quenching
• Correlations in intermediate-energy two-proton removal reactions
• Isoscalar g Factors of Even-Even and Odd-Odd Nuclei
• Determination of proton and neutron contributions to the $0_{g.s.}^{+}\to 2_1^{+}$ excitations in ${}^{42}$Si and ${}^{44}$S using inelastic proton scattering in inverse kinematics and intermediate energy Coulomb excitation