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The N = 28 shell closure has been investigated via the 46Ar(d,p)47Ar transfer reaction in inverse kinematics. Energies and spectroscopic factors of the neutron p(3/2), p(1/2), and f(5/2) states in 47Ar were determined and compared to those of the 49Ca isotone. We deduced a reduction of the N = 28 gap by 330(90) keV and spin-orbit weakenings of approximately 10(2) and 45(10)% for the f and p states, respectively. Such large variations for the f and p spin-orbit splittings could be accounted for by the proton-neutron tensor force and by the density dependence of the spin-orbit interaction, respectively. This contrasts with the picture of the spin-orbit interaction as a surface term only.

The Nϭ21 nucleus 34 Al, located at the boundary of the island of inversion, was studied via intermediateenergy Coulomb excitation. A ␥ ray with an energy of 657Ϯ9 keV has been observed in 34 Al and its production cross section has been measured. This ␥ ray may connect states which are members of the lowlying neutron d 5/2 -f 7/2 multiplet.

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