Tentative evidence of subshell closures atN = 6, 14, 16, 56 andZ = 6, 14, 16, 38 from binding-energy systematics and atN = 56,Z = 64 from energy levels of doubly even nuclei

In-beam γ-ray spectroscopy of the neutron-rich nitrogen isotopesN19−22

“…Using e p = 1.5 e and e n = 0.5 e effective charges, the shell model gives 29 and 24 e 2 fm 4 for the B(E2; 0 + → 2 + ) transition probability for 20 15 N nucleus, the Z = 8 shell gap gets weaker by 1645 keV. This estimate is in agreement with the previous observation, according to which the Z = 8 shell gap gets weaker by 1.5(3) MeV while going from 16 O to 22 O [5]. In the shell model calculation, the 5/2 + state is at 4.889 keV in 21 N, at a slightly lower energy than observed in 15 N. This suggests that the WBT interaction does not account fully for the weakening of the Z = 8 shell closure.…”

“…The existence of N = 14, 16 subshell closures has already been deduced from the analysis of the 1985 mass systematics [16] and confirmed later for a larger mass region [15]. The effect of these subshell closures is clearly shown in the 24,26 Ne isotopes, too, having relatively higher 2 + energies and lower E2 transition probabilities than their neighbors.…”

Measurement of theB(E2,01+→21+)Gibelin1, Beaumel2, Motobayashi3 et al. 2007Phys. Rev. C282122View full textAdd to dashboardCite

“…They can be recognized among others from the relatively high excitation energy of their first excited state, a low value of the quadrupole electromagnetic transition probability B(E2, 0 + 1 → 2 + 1 ), sudden change in the binding energy or the nuclear radius when crossing a shell closure. The sub-shell closure at N =16 was already revealed from the analysis [1] of the 1985 nuclear mass evaluation [2]. Recently, the change of nuclear radii at N =16 has also been observed [3].…”