@article{3072590, title = "High-precision quadrupole moment reveals significant intruder component in Al20 1333 ground state", author = "Heylen, H. and De Rydt, M. and Neyens, G. and Bissell, M.L. and Caceres, L. and Chevrier, R. and Daugas, J.M. and Ichikawa, Y. and Ishibashi, Y. and Kamalou, O. and Mertzimekis, T.J. and Morel, P. and Papuga, J. and Poves, A. and Rajabali, M.M. and Stödel, C. and Thomas, J.C. and Ueno, H. and Utsuno, Y. and Yoshida, N. and Yoshimi, A.", journal = "Physical Review C", year = "2016", volume = "94", number = "3", publisher = "American Physical Society", issn = "2469-9985, 2469-9993", doi = "10.1103/PhysRevC.94.034312", abstract = "The electric quadrupole moment of the Al201333 ground state, located at the border of the island of inversion, was obtained using continuous-beam β-detected nuclear quadrupole resonance (β-NQR). From the measured quadrupole coupling constant νQ=2.31(4) MHz in an α-Al2O3 crystal, a precise value for the electric quadrupole moment is extracted: QsAl33=141(3) mb. A comparison with large-scale shell model calculations shows that Al33 has at least 50% intruder configurations in the ground state wave function, favoring the excitation of two neutrons across the N=20 shell gap. Al33 therefore clearly marks the gradual transition north of the deformed Na and Mg nuclei towards the normal Z≥14 isotopes. © 2016 American Physical Society." }