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Abstract: A collinear laser-spectroscopy (CLS) system in the BEam COoler and LAser spectroscopy (BECOLA) facility was constructed at National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The BECOLA facility will be used to advance measurements of nuclear properties of low-energy rare isotope beams generated via in-flight reactions and subsequent beam thermalization in a buffer gas. The CLS studies at BECOLA will complement laser spectroscopy studies of charge radii and nuclear moments mostly obtained so far at Isotope SeOn Line (ISOL) facilities. Commissioning tests of the CLS system have been performed using an offline ion source to produce stable-ion beams. The tests set the ground work for experiments at the future Facility for Rare Isotope Beams (FRIB) as well as experiments at the current Coupled Cyclotron Facility at NSCL. [Copyright &y& Elsevier]

Abstract: The electric quadrupole coupling constant of the ground state of , ) in a tetragonal KH2PO4 single crystal was measured to be using the β-ray detecting nuclear quadrupole resonance technique. The electric quadrupole moment of 37K was determined to be , where the known electric quadrupole coupling constant of stable 39K in the KH2PO4 crystal was used as a reference. The present experimental result is larger than that predicted by shell-model calculations in the sd or the sd and fp model spaces. A possible variation of effective charges was explored to explain the discrepancy. [Copyright &y& Elsevier]

The β decay of neutron-rich nuclei in the π1f7/2 and νpf shells has been studied at the NSCL to track the development of new proposed shell closures at N=32 and 34 due to the monopole migration of the ν1f5/2 orbital. From a measurement of absolute γ-ray intensities following the β decay of odd-odd nuclei, the β-decay branching ratios to levels in the even-even daughters can be deduced. The branching ratios, especially to the 0+ daughter ground state, can be used to assign spins and parities to the parent ground states. The interpretation of these assignments for odd-odd nuclei in a single-particle limit can be used to track the migration of the ν1f5/2 single-particle state. [Copyright &y& Elsevier]

32Mg lies within a region of deformed nuclei commonly referred to as the “island of inversion”. The β decay of 33Al and 33Mg has been studied to learn about nuclear structure near 32Mg. Decay curves and precise half-life measurements are presented for both species. Gamma-ray spectra from correlated 33Al decay events are also presented. The β-decay properties of 33Al are shown to be well-described by an sd shell model calculation, suggesting that the ground state of 33Al lies primarily outside the island of inversion. [Copyright &y& Elsevier]

The level structure of 5422Ti32 has been explored for the first time by combining β-decay measurements from fragmentation products with prompt γ-ray spectroscopy following deep inelastic reactions. The latter technique was also instrumental in tracing 52Ti30 to higher spin. The data provide new tests of effective interactions for full pf-shell calculations in neutron-rich nuclei above 48Ca. The data indicate the presence of a significant subshell gap at N=32 and comparisons between theory and experiment suggest an additional shell closure at N=34 in Ca and Ti isotopes. [Copyright &y& Elsevier]

Abstract: The performance characteristics of two charge-exchange cells (CECs) with horizontal and vertical cell configurations were determined by neutralizing a 10-keV rubidium ion beam in a potassium vapor. The neutralization efficiency and the fluorescence line shape of the 5s 2P3/2 (D2) transition in neutral 85Rb were investigated as a function of the reservoir temperature used to control the potassium vapor density. The CECs exhibited similar neutralization performance and at neutralization efficiencies greater than 25–50% an asymmetric line shape of the rubidium D2 fluorescent signal was observed. The asymmetry was attributed to inelastic channels in the charge-exchange process. The rubidium D2 fluorescence line shape was fitted with a multiple Voigt function, which quantitatively models the inelastic channels. In the present Rb+ + K charge-exchange process, the optimum neutralization efficiency to accurately determine the centroid of the Rb D2 resonance line shape was obtained by fitting single Voigt functions to the resonance spectra obtained at neutralization efficiencies where inelastic processes were negligible. [Copyright &y& Elsevier]

Abstract: First experimental evidence for a high-spin isomer () in 97Cd, a waiting point in the astrophysical rapid proton capture process, is presented. The data were obtained in β-decay studies at NSCL using the new RF Fragment Separator system and detecting β-delayed protons and β-delayed γ rays. Decays from ground and isomeric states were disentangled, and proton emission branches were determined for the first time. We find half-lives of 1.10(8) s and 3.8(2) s, and β-delayed proton emission branches of 12(2)% and 25(4)% were deduced for the ground and isomeric states, respectively. With these results, the nuclear data needed to determine an rp-process contribution to the unknown origin of solar 96Ru are in place. When the new data are included in astrophysical rp-process calculations, one finds that an rp-process origin of 96Ru is unlikely. [Copyright &y& Elsevier]

Abstract: The level structures of 55V and 55Ti, the two nuclei with a single nucleon outside the semi-magic 54 22Ti32 core, have been investigated in order to provide new tests of full pf-shell calculations with the GXPF1A interaction. The addition of a proton does not appear to affect the shell gap significantly, although comparisons between calculations and experiment at high spins () indicate the need for a larger model space for an accurate description of the data in this regime. The energy separation between the and orbitals in neutron-rich Ti isotopes is not large enough to result in an shell gap. However, comparisons between the 55Ti data and the calculations argue for the presence of a sizable gap in 54Ca. [Copyright &y& Elsevier]

Abstract: The structure of magic neutron-rich nickel isotopes produced in the fragmentation of a 86Kr beam was investigated. For the first time four gamma transitions were assigned to the decay of the , isomer, thus establishing the ground-state band in 76Ni. The previously unknown and levels belonging to the ground-state band in 74Ni were identified in the β decay of 74Co . The decay properties of 72Co→ 72Ni were verified and confirmed on the basis of coincidence data. The relevance of the measured level properties for the magicity of 78Ni is analyzed with the help of advanced shell-model predictions. [Copyright &y& Elsevier]

The regions around the doubly magic nuclei 100Sn and 78Ni are of great interest from a nuclear structure standpoint. These nuclei also play a key role in the astrophysical rp- and r-processes, respectively. Recently, nuclei in these regions were studied at the Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. [Copyright &y& Elsevier]