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A radiofrequency quadrupole (RFQ) ion beam cooler and buncher has been developed to deliver bunched beams with low transverse emittance, energy spread, and time spread to the BECOLA collinear laser spectroscopy system at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The beam cooler and buncher contains new features which enhance performance, especially for high count rate beams, as well as simplifying construction, maintenance, and operation. The transverse emittance, energy spread, and time spread of the bunched beam, as well as buncher efficiency are reported, showcasing the capabilities of the BECOLA facility to perform collinear laser spectroscopy measurements with bunched rare isotope beams at NSCL and at the future Facility for Rare Isotope Beams (FRIB).

The Facility for Rare Isotope Beams (FRIB) is a major new scientific user facility under construction in the United States for nuclear science research with beams of rare isotopes [1]. FRIB is funded by the United States Department of Energy Office of Science (DOE-SC) and is located on the campus of Michigan State University (MSU), in East Lansing, Michigan, USA. FRIB will support the mission of the Office of Nuclear Physics in the DOE-SC. The total FRIB project cost is $730 million and the facility is scheduled to be completed by 2022. The project has passed the 75% complete mark and is managed toward early completion in 2021. FRIB is estimated to provide access to 80% off all isotopes of elements lighter than uranium.

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.

New high-spin levels have been identified in the nucleus 120Pd from analysis of the coincidence gamma rays observed in the 238U(α, f γ γ γ ) reaction. Recoiling fragments were detected with the Rochester heavy-ion detector array, CHICO, in coincidence with gamma-rays using Gammasphere. An A=110-130 mass-gated γ − γ − γ cube from this experiment was constructed and analyzed for coincident gamma-rays in several nuclei near A=120. New results for neutron-rich 118Pd and 120Pd have been obtained. The 120Pd level scheme was extended to spin of 10+ by building on the new low-energy gamma rays identified in decay studies of 120Rh. The details of the 118Pd level scheme derived from this work are compared to previous work. The systematics of the yrast levels in even-even Pd and Cd isotopes are presented and the symmetry of energy levels around N = 68 is discussed. A new 10+ level in 124Cd has been observed. The population intensity of even-even neutron-rich Cd isotopes is deduced, indicating that nuclides near 120Cd are preferentially populated following alpha-induced fission of 238U.

The structure of magic neutron-rich nickel isotopes produced in the fragmentation of a 140 A MeV 86 Kr beam was investigated. For the first time four gamma transitions were assigned to the decay of the I π = 8 + , T 1 / 2 = 590 −110 +180 ns isomer, thus establishing the 0 + – 2 + – 4 + – 6 + – 8 + ground-state band in 76 Ni. The previously unknown 2 + and 4 + levels belonging to the ground-state band in 74 Ni were identified in the β decay of 74 Co ( T 1 / 2 = 30 ( 3 ) ms ) . The decay properties of 72 Co → 72 Ni were verified and confirmed on the basis of γ – γ coincidence data. The relevance of the measured level properties for the magicity of 78 Ni is analyzed with the help of advanced shell-model predictions.

New half-lives for neutron-rich ruthenium, rhodium and palladium isotopes close to the r-process path along the N=82 closed shell have been measured at the National Superconducting Cyclotron Laboratory at Michigan State University. The studied isotopes are close to the critical A=118-126 mass region in the astrophysical r-process, where incorrect nuclear structure development towards the shell closure may have the most pronounced effect on the abundances of elements produced. Neutron-rich nuclei were produced by fragmentation of a 120-MeV per nucleon 136 Xe beam on Be and were separated by the A1900 fragment separator. The nuclei of interest were implanted into a double-sided Si strip detector at the center of the MSU β counting system. Charge states and fully- stripped isotopes were distinguished by a measurement of the total kinetic energy of each implant. Our measured half-lives will provide first clues on whether our understanding of nuclear structure evolution in this mass region is correct.

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.

The first fully on-line use of the angular distribution of beta emission in detection of NMR of nuclei oriented at low temperatures is reported. The magnetic moments of the single valence particle, intermediate mass, isotopes 67Ni(nup(-1)(1/2);1/2(-)) and 69Cu(pip(1)(3/2);3/2(-)) are measured to be +0.601(5) m(N) and +2.84(1) m(N), respectively, revealing only a small deviation from the neutron p(1/2) single-particle value in the former and a large deviation from the proton p(3/2) single-particle value in the latter. Quantitative interpretation is given in terms of core polarization and meson-exchange currents.

The existence of a subshell gap at neutron number N =40 is investigated in the odd-mass Ni and Cu isotopes using the Particle-Core Coupling Model (PCM). The calculated properties are in good agreement with the existing experimental data, suggesting that 68 Ni is a good core for the adjacent nuclei. Evaluation of the 2 + 1 excitation energies, two-neutron separation energies, and pairing properties of the Ni isotopes reveals discontinuities at neutron number N =40. These data support the existence of a significant neutron subshell gap at N =40, for Z =28. The systematic behavior of the proton single-particle energies extracted from the particle-core coupling calculations for the odd-mass Cu isotopes is discussed in terms of monopole shifts. The effect is consistent with the existence of a neutron subshell gap at N =40.

Two new systems, to measure lifetimes of nuclear levels in the picosecond range that decay by E0 transitions, have been developed at the UNISOR on-line isotope separator facility. These systems make use, for the first time, of fast coincidences involving characteristic X-rays. The first of the two systems involves specifically the X-rays originating from the internal conversion process, while the second involves X-rays resulting from both the internal conversion and electron capture processes.

The decay properties of rp‐process nuclei in the vicinity of 100Sn have been studied at the National Superconducting Cyclotron Laboratory (NSCL). The measured β‐decay half‐life for 100Sn is 0.55−0.31+0.70 s, in agreement with a previous measurement. In 98In, the β‐decay of the ground state plus that of a long lived isomer were observed with half‐lives of 47(13) ms and 0.66(40) s respectively. The half‐life of 96Cd, measured for the first time, is 1.03−0.21+0.24 s; however, the existence of a predicted isomeric state in this nucleus could not be confirmed. Additionally, a gamma cascade de‐exciting a μ‐isomer in the odd‐odd nucleus 96Ag was observed. The implications of the measured half‐life of 96Cd on the calculated rp‐process final abundances are discussed.

Excited states in the neutron-rich 121, 123, 125Ag were studied via the fragmentation of a 136Xe beam at 120MeV/nucleon in a thick 9Be target. The levels in 121Ag were populated in the $ \beta$ decay of 121Pd while those assigned to 123, 125Ag were identified via isomer spectroscopy. The transitions identified in 121Ag are consistent with the $ \gamma$ -rays reported in 117, 119Ag . The newly observed transitions were placed in the level schemes of 123, 125Ag based on the analysis of $ \gamma$ - $ \gamma$ coincidences and the systematics. We attribute the onset of isomerism in the 123, 125Ag isotopes to the drop in energy of the negative-parity levels similar to the 5- state in the even-even Cd cores. The proposed level scheme for 125Ag is well described by the NuShellX shell model calculations.

The structures of the odd-neutron nuclides {sup 119,121}Te have been investigated following beta decay of {sup 119,121}I. Gamma-ray and conversion-electron singles and coincidence measurements have been performed on mass separated sources using Ge gamma-ray detectors and Si(Li) electron detectors and a mini-orange positron filter. New levels and branching ratios have been determined for both nuclides. {ital E}0 components have been identified on {ital M}1 and {ital M}1/{ital E}2 transitions in {sup 119}Te and interpreted as arising from coupling of particle-hole intruder states with the odd neutron.

The structure of the $^{56,58,60}\mathrm{Cr}$ nuclei was investigated at Gammasphere using both deep inelastic and fusion-evaporation reactions. As a result of this work, expanded level schemes are now available for these three neutron-rich, even-even isotopes. Experimental signatures were found for both single-particle and collective excitations whose relative importance varies with neutron number. Together with recent structural information on the odd-$A$ $^{55,57,59}\mathrm{Cr}$ neighbors, the present data highlight the changing role of the ${g}_{9/2}$ orbital with neutron number. Comparisons with shell-model calculations using the recently developed GXPF1A interaction and with total Routhian surface calculations are presented.

The even $^{52\ensuremath{-}56}\mathrm{Ti}$ isotopes have been studied with intermediate-energy Coulomb excitation and absolute $B(E2;{0}^{+}\ensuremath{\rightarrow}{2}_{1}^{+})$ transition rates have been obtained. These data confirm the presence of a subshell closure at neutron number $N=32$ in neutron-rich nuclei above the doubly magic nucleus $^{48}\mathrm{Ca}$ and provide no direct evidence for the predicted $N=34$ closure. Large-scale shell model calculations with the most recent effective interactions are unable to reproduce the magnitude of the measured strengths in the semimagic Ti nuclei and their strong variation with neutron number.

The structure and decay of neutron‐rich r‐process nuclides has been studied by a variety of means that take advantage of enhanced selectivity to permit identification of exotic nuclides. New level structures are presented for 134,135Sb along with data for Ag isomers and Cd yrast structures. Some of the properties measured play an important role in calculations of the yields of elements and isotopes produced in r‐process nucleosynthesis that takes place at high temperature in the presence of large densities of neutrons.

An experiment was performed at the National Superconducting Cyclotron Laboratory at Michigan State University to investigate β‐ and isomer decay properties of several isotopes in the vicinity of 78Ni. The identification of an (8+) isomer in 76Ni was confirmed and its deexcitation cascade identified; the β‐decay of 71–73Co was reinvestigated and that of 74Co studied for the first time. First evidence of β‐delayed neutron emission in neutron‐rich cobalt isotopes was also obtained. Preliminary results are reported.

The possible occurrence of sub‐shell gaps at N = 32 and N = 34 in neutron‐rich titanium isotopes is discussed in light of new experimental results from (i) deep‐inelastic reactions measured with Gammasphere at the ATLAS facility at Argonne National Laboratory and from (ii) intermediate‐energy Coulomb excitation performed at the National Superconducting Cyclotron Laboratory at Michigan State University.

Details regarding the $\ensuremath{\beta}$-decay properties of $^{54,55,56}\mathrm{Sc}$ are reported and compared with shell model predictions. The low-energy level structures of even-even $^{54,56}\mathrm{Ti}$ are presented, and the systematic variation of the energy of the first excited ${2}_{1}^{+}$ state is discussed in light of proposed shell closures at $N=32,34$ for the neutron-rich $\mathrm{Ti}$ isotopes.

Gamma rays from neutron-rich nuclei in the vicinity of $Z=20$, $N=28$ have been studied at Gammasphere using deep-inelastic reactions induced by a $330\text{\ensuremath{-}}\mathrm{MeV}$ $^{48}\mathrm{Ca}$ beam on a thick $^{238}\mathrm{U}$ target. The yrast $\ensuremath{\gamma}$-ray cascade of $^{56}\mathrm{Ti}$ was identified for the first time and the location in energy of the ${2}^{+}$, ${4}^{+}$, and ${6}^{+}$ states was determined. The low-spin $^{56}\mathrm{Ti}$ yrast structure does not support the presence of a subshell closure at $N=34$ as suggested on the basis of other data on nuclei in the region as well as shell model calculations with a recently proposed interaction.

$\ensuremath{\beta}$ decay of ${}^{56,57,58}\mathrm{V}$ has been used to populate low-energy levels of ${}^{56,57,58}\mathrm{Cr},$ respectively. The low-energy levels of the even-even Cr isotopes and $\ensuremath{\beta}$-decay half-lives and branching ratios of the parent V isotopes are compared to results of shell-model calculations. The Cr energy level calculations were completed in the full $\mathrm{pf}$-model space, using several different interactions. The systematic variation of ${E(2}_{1}^{+}),$ which is indicative of a subshell closure at $N=32,$ was best reproduced in calculations using a pf-shell-model interaction based on effective two-body matrix elements with some replacement by the G matrix.

We report on the low‐energy structure of the neutron‐rich, even‐even nuclides 54Ti32, 56Cr32, and 58Cr34 studied via β‐delayed γ‐ray spectroscopy. The systematic variation of the excitation energy of first excited 2+ states in the even‐even 24Cr and 22Ti isotopes provides evidence of a subshell closure at N = 32 for neutron‐rich nuclides having Z ⩽ 24. Shell model calculations, which correctly account for the appearance of the N = 32 subshell, also predict a new shell closure at N = 34 for Ti and Ca isotopes.

A new excited state at 2164 keV has been identified in 72Ni with tentative spin and parity of 4+ based on comparison to shell model calculations. This level is suggested to be populated via the ?-decay of an isomeric state in 72Co, and is postulated to be one of the key states that play a role in the disappearance of isomers in Ni. The known low-energy levels in 72Ni are compared with results of shell model calculations using the NR78 interaction to follow the seniority of the observed states. In addition, the half-life of the 8+ isomer in 76Ni has been measured as 630(90) ns and the full cascade of transitions from this isomer has been verified experimentally in this work.

The g factors of the ${2}_{1}^{+}$ states of the stable, even-even Mo isotopes ${}^{92,94,96,98,100}\mathrm{Mo}$ were measured using the transient field method. While ${}^{92}{\mathrm{Mo}}_{50}$ has a g factor consistent with that of the $\ensuremath{\pi}{g}_{9/2}^{2}$ configuration, the g factor of ${}^{94}\mathrm{Mo}$ is about 60% of the hydrodynamic model value, $Z/A.$ As further pairs of neutrons are added, the heavier isotopes ${}^{96,98,100}\mathrm{Mo}$ show a monotonic increase in ${g(2}^{+})$ to values that exceed $Z/A$ for ${}^{98}\mathrm{Mo}$ and ${}^{100}\mathrm{Mo}.$ The systematic behavior of the ${g(2}_{1}^{+})$ values for the Mo isotopes, as one moves away from the neutron shell closure at $N=50,$ is compared with the shell model, a collective model with pairing corrections and IBM-2 calculations.

The neutron-rich argon isotope ${}^{43}\mathrm{Ar}$ has been studied by quasielastic and inelastic proton scattering performed in inverse kinematics. The measured inelastic angular distribution for the second excited state is in good agreement with an $L=2$ transition. Assuming this transition to be $E2,$ yields a ${\ensuremath{\beta}}_{2}$ value for this state of $0.25\ifmmode\pm\else\textpm\fi{}0.03$ when compared with distorted-wave Born approximation calculations. This value is comparable to the one reported for the stable isotope ${}^{40}\mathrm{Ar}.$ Moreover it is similar to those measured by Coulomb excitation for the neighboring even-even isotopes ${}^{42}\mathrm{Ar}$ and ${}^{44}\mathrm{Ar}$ indicating that the structure of the argon isotopes is stable as a function of neutron number.

Gamma rays have been identified in the decay of isomers in 125,126,127Cd, 123,124,125Ag, 121Pd, 120Rh, and 117Ru that provide information about the low-energy structures of these nuclei. In turn, comparison of low-energy levels in the Cd and Te isotones reveals that, whereas the yrast structures in the Te isotopes rise smoothly as N approaches the closed shell at 82, the 15/2- to 11/2- transitions level off as N exceeds 76. This is identified as the point where the Cd isotopes undergo a phase transition and become “neutron rich”.

Detailed nuclear structure studies of 20⩽N⩽28, 14⩽Z⩽20 nuclides have been limited until recently due to the lack of a good production mechanism. With the advent of projectile fragmentation facilities these nuclides can now be produced, separated, and studied in detail using several different techniques. Two recent experiments conducted at the NSCL have provided information on the β decays of 39,40,41P, 40,41,42,43S, and 42,43,44,45Cl, which will be used to establish level schemes for the daughter nuclides. These will provide a better understanding of the systematic change from spherical to deformed shapes within the proton sd and neutron fp shells. Presented here are preliminary results from these experiments with an emphasis placed on the structure of the deformed nucleus 40S.

Fine structure in the α decay of 192Po has been studied in the reaction of 36Ar on 160Dy at 176 MeV. Evaporation residues were selected in-flight using the Argonne Mass Analyzer and implanted into a double sided silicon strip detector. The correlation technique between implants and subsequent decays was used to observe fine structure in the α decay of 192Po leading to the identification of an excited 0+ state in 188Pb at 571(31) keV. The half-life of 192Po has been determined to be 33.2(14) ms. The observation of a low-lying 0+ state is discussed in terms of proton particle-hole pair excitations across the Z=82 shell gap. The small hindrance factor to the excited 0+ state relative to the ground state supports the picture of shape coexistence in light even-even Po isotopes.