Precision measurement of the electric quadrupole moment of 31Al and determination of the effective proton charge in the sd-shell

M. De Rydt, G. Neyens, K. Asahi, D.L. Balabanski, J.M. Daugas, M. Depuydt, L. Gaudefroy, S. Grévy, Y. Hasama, Y. Ichikawa, P. Morel, T. Nagatomo (+11 others)
2009 Physics Letters B  
he electric quadrupole coupling constant of the 31Al ground state is measured to be nu_Q = |eQV_zz/h| = 2196(21)kHz using two different beta-NMR (Nuclear Magnetic Resonance) techniques. For the first time, a direct comparison is made between the continuous rf technique and the adiabatic fast passage method. The obtained coupling constants of both methods are in excellent agreement with each other and a precise value for the quadrupole moment of 31Al has been deduced: |Q(31Al)| = 134.0(16) mb.
more » ... mparison of this value with large-scale shell-model calculations in the sd and sdpf valence spaces suggests that the 31Al ground state is dominated by normal sd-shell configurations with a possible small contribution of intruder states. The obtained value for |Q(31Al)| and a compilation of measured quadrupole moments of odd-Z even-N isotopes in comparison with shell-model calculations shows that the proton effective charge e_p=1.1 e provides a much better description of the nuclear properties in the sd-shell than the adopted value e_p=1.3 e.
doi:10.1016/j.physletb.2009.06.043 fatcat:gsdhncnuejcfvm7zr4rggyjzbq