Proton inelastic scattering off a neutron halo nucleus, 11 Li, has been studied in inverse kinematics at the IRIS facility at TRIUMF. The aim was to establish a soft dipole resonance and to obtain its dipole strength. Using a high quality 66 MeV 11 Li beam, a strongly populated excited state in 11 Li was observed at E x =0.80 ± 0.02 MeV with a width of Γ = 1.15 ± 0.06 MeV. A DWBA (distorted-wave Born approximation) analysis of the measured differential cross section with isoscalar macroscopic form factors leads to conclude that this observed state is excited in an electric dipole (E1) transition. Under the assumption of isoscalar E1 transition, the strength is evaluated to be ex- * Corresponding author.

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Background: Neutron-rich nuclei around neutron number N = 60 show a dramatic shape transition from spherical ground states to prolate deformation in 98 Sr and heavier nuclei. Purpose: The purpose of this study is to investigate the single-particle structure approaching the shape transitional region. Method: The level structures of neutron-rich 93,94,95 Sr were studied via the 2 H( 94,95,96 Sr, t ) one-neutron stripping reactions at TRIUMF using a beam energy of 5.5 AMeV. γ -rays emitted from excited states and recoiling charged particles were detected by using the TIGRESS and SHARC arrays, respectively. States were identified by gating on the excitation energy and, if possible, the coincident γ radiation. Results: Triton angular distributions for the reactions populating states in ejectile nuclei 93,94,95 Sr were compared with distorted wave Born approximation calculations to assign and revise spin and parity quantum numbers and extract spectroscopic factors. The results were compared with shell-model calculations and the reverse (d, p) reactions and good agreement was obtained. Conclusions: The results for the 2 H( 94 Sr, t ) 93 Sr and 2 H( 95 Sr, t ) 94 Sr reactions are in good agreement with shellmodel calculations. A two-level mixing analysis for the 0 + states in 94 Sr suggest strong mixing of two shapes. For the 2 H( 96 Sr, t ) 95 Sr reaction the agreement with the shell-model is less good. The configuration of the ground state of 96 Sr is already more complex than predicted, and therefore indications for the shape transition can already be observed before N = 60.

Background: The region around neutron number N = 60 in the neutron-rich Sr and Zr nuclei is one of the most dramatic examples of a ground state shape transition from (near) spherical below N = 60 to strongly deformed shapes in the heavier isotopes.Purpose: The single-particle structure of 95−97 Sr approaching the ground state shape transition at 98 Sr has been investigated via single-neutron transfer reactions using the (d, p) reaction in inverse kinematics. These reactions selectively populate states with a large overlap of the projectile ground state coupled to a neutron in a single-particle orbital.Method: Radioactive 94,95,96 Sr nuclei with energies of 5.5 AMeV were used to bombard a CD2 target. Recoiling light charged particles and γ rays were detected using a quasi-4π silicon strip detector array and a 12 element Ge array. The excitation energy of states populated was reconstructed employing the missing mass method combined with γ-ray tagging and differential cross sections for final states were extracted.Results: A reaction model analysis of the angular distributions allowed for firm spin assignments to be made for the low-lying 352, 556 and 681 keV excited states in 95 Sr and a constraint has been placed on the spin of the higher-lying 1666 keV state. Angular distributions have been extracted for 10 states populated in the d( 95 Sr, p) 96 Sr reaction, and constraints have been provided for the spins and parities of several final states. Additionally, the 0, 167 and 522 keV states in 97 Sr were populated through the d( 96 Sr, p) reaction. Spectroscopic factors for all three reactions were extracted. Conclusions:Results are compared to shell model calculations in several model spaces and the structure of low-lying states in 94 Sr and 95 Sr is well-described. The spectroscopic strength of the 0 + and 2 + states in 96 Sr is significantly more fragmented than predicted. The spectroscopic factors for the d( 96 Sr, p) 97 Sr reaction suggest that the two lowest lying excited states have significant overlap with the weakly deformed ground state of 96 Sr, but the ground state of 97 Sr has a different structure. * Corresponding author: wimmer@phys.s.u-tokyo.ac.jp arranging the nucleons in certain ways across the valence orbitals, which in turn causes a departure from sphericity [1]. The expense of such re-arrangements is dependent on the size of the energy gaps between single-particle orbitals above the Fermi energy. If the energy spacing is small, the valence nucleons can scatter into valence orbitals which are above the Fermi energy and drive the nucleus into a low-energy deformed configuration. On the other hand, if the energy spacing is large, the valence nucleons are unable to scatter into higher orbitals and this favors spherical shapes. The size of these energy gaps is in turn dependent on the number of valence nucleons, due to the monopole component of the residual

The GRIFFIN spectrometer at TRIUMF-ISAC has been used to study excited states and transitions in 50 Sc following the β-decay of 50 Ca. Branching ratios were determined from the measured γ-ray intensities, and angular correlations of γ rays have been used to firmly assign the spins of excited states. The presence of an isomeric state that decays by an M 3 transition with a B(M 3) strength of 13.6(7) W.u. has been confirmed. We compare with the first ab initio calculations of B(M 3) strengths in light and medium-mass nuclei from the valence-space in-medium similarity renormalization group approach, using consistently derived effective Hamiltonians and M 3 operator. The experimental data are well reproduced for isoscalar M 3 transitions when using bare g-factors, but the strength of isovector M 3 transitions are found to be underestimated by an order of magnitude.