The electric quadrupole coupling constant of the 31Al ground state is measured to be νQ = | frac(e Q Vz z, h) | = 2196 (21) kHz using two different β-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. Comparison 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 ep = 1.1 e provides a much better description of the nuclear properties in the sd-shell than the adopted value ep = 1.3 e.
|ジャーナル||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|出版ステータス||出版済み - 7 27 2009|
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