Shell evolution approaching the N= 20 island of inversion: Structure of 26Na

Wilson, G. L.; Catford, W. N.; Orr, N. A.; Diget, C. Aa.; Matta, A.; Hackman, G.; Williams, Spencer J.; Celik, I. C.; Achouri, N. L.; Falou, H. Al; Ashley, Robert; Austin, R. A. E.; Ball, G. C.; Blackmon, J. C.; Boston, A. J.; Boston, H. C.; Brown, Susannah; Cross, D. S.; Djongolov, M.; Drake, T.E.; Hager, U.; Fox, S. P.; Fulton, B. R.; Galinski, N.; Garnsworthy, A. B.; Jamieson, Drew; Kanungo, R.; Leach, K. G.; Orce, J. N.; Pearson, C. J.; Porter-Peden, M.; Sarazin, F.; Simpson, E. C.; Sjue, Sky; Smalley, D.; Sumithrarachchi, C.; Triambak, S.; Unsworth, C.; Wadsworth, R.

doi:10.1016/j.physletb.2016.05.093

Cited by 17 publications

(69 citation statements)

References 58 publications

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“…A secondary beam of 28 Mg was obtained from the ISAC2 facility at TRIUMF using a primary beam of 100 μA of 520 MeV protons bombarding a SiC production target. The extraction of the 28 Mg 1+ ions was compromised by the failure to hold a sufficiently high voltage on the source and it was necessary to employ a charge state breeder (CSB [25]) to produce 28 Mg 5+ ions for injection into the radio frequency quadrupole at the start of the ISAC acceleration system [26]. The efficiency of the CSB was 10 −3 and it inevitably introduced contaminants.…”

Section: Methodsmentioning

confidence: 99%

“…The efficiency of the CSB was 10 −3 and it inevitably introduced contaminants. These included radioactive nuclei, which had mass to charge ratios close to that of 28 Mg 5+ and moreover there were stable contaminants derived from the CSB itself. The beam transmitted to the secondary target station comprised ≈99% of the stable isobar 28 Si at a rate of 300 000 pps.…”

Section: Methodsmentioning

confidence: 99%

“…These included radioactive nuclei, which had mass to charge ratios close to that of 28 Mg 5+ and moreover there were stable contaminants derived from the CSB itself. The beam transmitted to the secondary target station comprised ≈99% of the stable isobar 28 Si at a rate of 300 000 pps. Approximately 1% of the beam, or 3000 pps was found to be the intended isotope 28 Mg (t 1/2 = 20.9 h), as discussed below.…”

Section: Methodsmentioning

confidence: 99%

“…Before reviewing all of the experimental levels, some general comments can be made. A key feature is the pair of 3/2 − and 7/2 − states just above 1 MeV, which represent intruder configurations from the f p shell in which a neutron in the 0 f 7/2 or 1p 3/2 orbital is coupled to a 28 Mg core. In this picture, the core can be in its 0 + ground state or excited to a higher-energy configuration such as 2 + but the neutron-transfer reaction can populate these states only via the component with the 0 + core, leaving aside any two-step contributions to the reaction mechanism.…”

Section: Levels and Structure Of 29 Mgmentioning

confidence: 99%

“…1). The object of the present work is, therefore, to investigate the 28 Mg(d, p) 29 Mg reaction, which permits the transfer of a neutron into the 0d 3/2 , 0 f 7/2 , 1p 3/2 and higherlying orbitals. As such, the energies of the observed strongly populated (or single-particle) states may be related to the spacing between the neutron sd and f p orbitals.…”

Section: Introductionmentioning

confidence: 99%

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Shell evolution approaching the N=20 island of inversion: Structure of Mg29

Matta¹,

Catford²,

Orr³

et al. 2019

Phys. Rev. C

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The island of inversion for neutron-rich nuclei in the vicinity of N = 20 has become the testing ground par excellence for our understanding and modeling of shell evolution with isospin. In this context, the structure of the transitional nucleus 29 Mg is critical. The first quantitative measurements of the single-particle structure of 29 Mg are reported, using data from the d (28 Mg, p γ) 29 Mg reaction. Two key states carrying significant = 3 (f-wave) strength were identified at 2.40 ± 0.10 (J π = 5/2 −) and 4.28 ± 0.04 MeV (7/2 −). New state-of-the-art shell-model calculations have been performed and the predictions are compared in detail with the experimental results. While the two lowest 7/2 − levels are well described, the sharing of single-particle strength disagrees with experiment for both the 3/2 − and 5/2 − levels and there appear to be general problems with configurations involving the p 3/2 neutron orbital and core-excited components. These conclusions are supported by an analysis of the neutron occupancies in the shell-model calculations.

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