Probing the N= 14 subshell closure: g factor of the Mg26(21+

B. P. McCormick

¹

,

A.E. Stuchbery

²

,

T. Kibédi

³

et al.

Abstract

The first-excited state g factor of 26 Mg has been measured relative to the g factor of the 24 Mg(2 + 1 ) state using the high-velocity transient-field technique, giving g = +0.86 ± 0.10. This new measurement is in strong disagreement with the currently adopted value, but in agreement with the sd-shell model using the USDB interaction. The newly measured g factor, along with E(2 + 1 ) and B(E2) systematics, signal the closure of the νd 5/2 subshell at N = 14. The possibility that precise g-factor measurements may indicate the onset of neutron pf admixtures in first-excited state even-even magnesium isotopes below 32 Mg is discussed and the importance of precise excited-state g-factor measurements on sd shell nuclei with N = Z to test shell-model wavefunctions is noted.

Collapse of N$=$28 magicity in exotic $^{40}$Mg -- Probe of deformed halo and 2n-radioactivity at Mg neutron drip-line

“…On the other hand, zero neutron pairing energy at N=14 points towards the magicity of N=14 as seen in Refs. [58][59][60] and our work [61] which indicated towards the weakening of magicity in conventional magic numbers and the emergence of new magic numbers N=14 [62] and 40 [63] at the neutron drip-line. However, non-zero pairing interaction in 40 Mg and 42,44 Mg indicates the possibility of halo formation.…”

First-excited state g factors in the stable, even Ge and Se isotopes

“…The technique has been reviewed in Refs. [12,24], and previous measurements by this method using the Australian National University (ANU) Hyperfine Spectrometer [34] have been described in detail elsewhere [25,28,35,36]. Data were collected over five separate runs, the details of which are listed in Table I.…”

Pushing the limits of excited-state g-factor measurements

“…The TF method gives the sign of the g factor and is best suited for relative g-factor measurements on excited states with lifetimes in the picosecond range. The following subsection describes a contemporary measurement of g( 26 Mg; 2 + )/g( 24 Mg; 2 + ) by the high-velocity TF method [7]. * e-mail: andrew.stuchbery@anu.edu.au…”