arXiv subjects

S. L. Tabor

Publications and source records attributed to S. L. Tabor.

20 records · Page 2Linked to original sources

arXiv2004

$p$-$sd$ shell gap reduction in neutron-rich systems and cross-shell excitations in $^{20}$O

Excited states in $^{20}$O were populated in the reaction $^{10}$Be($^{14}$C,$α$) at Florida State University. Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and $γ$ radiation was detected with the FSU $γ$ detector array. Five new states were observed below 6 MeV from the $α$-$γ$ and $α$-$γ$-$γ$ coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the $N = Z = 8$ shell gap. Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the $p$-$sd$ shell gap as neutrons are added.

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arXiv2004

29Na: Defining the edge of the Island of Inversion for Z=11

The low-energy level structure of the exotic Na isotopes 28,29Na has been investigated through beta-delayed gamma spectroscopy. The N=20 isotones for Z=10-12 are considered to belong to the ``island of inversion'' where intruder configurations dominate the ground state wave function. However, it is an open question as to where and how the transition from normal to intruder-dominated configurations happens in an isotopic chain. The present work, which presents the first detailed spectroscopy of 28,29Na, clearly demonstrates that such a transition in the Na isotopes occurs between 28Na (N=17) and 29Na (N=18), supporting the smaller N=20 shell gap in neutron rich sd shell nuclei. The evidence for inverted shell structure is found in intruder dominated spectroscopy of low-lying states, beta-decay branching ratios and shell model analysis.

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