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Background: Mainly because of its long half-life and despite its scientific relevance, spectroscopic measurements of Lu176 forbidden β decays are very limited and lack formulation of shape factors. A direct precise measurement of its Q value is also presently unreported. In addition, the description of forbidden decays provides interesting challenges for nuclear theory. The comparison of precise experimental results with theoretical calculations for these decays can help to test underlying models and can aid the interpretation of data from other experiments. Purpose: Perform the first precision measurements of Lu176β-decay spectra and attempt the observation of its electron capture decays, as well as perform the first precision direct measurement of the Lu176β-decay Q value. Compare the shape of the precisely determined experimental β spectra to theoretical calculations, and compare the end point energy to that obtained from an independent Q value measurement. Method: The Lu176β-decay spectra measurements and the search for electron capture decays were performed with an experimental setup that employed lutetium-containing scintillator crystals and a NaI(Tl) spectrometer for coincidence counting. The β decay Q value was determined via high-precision Penning trap mass spectrometry (PTMS) with the LEBIT facility at the National Superconducting Cyclotron Laboratory. The β-spectrum calculations were performed within the Fermi theory formalism with nuclear structure effects calculated using a shell model approach. Results: Both β transitions of Lu176 were experimentally observed and corresponding shape factors formulated in their entire energy ranges. The search for electron capture decay branches led to an experimental upper limit of 6.3×10-6 relative to its β decays. The Lu176β-decay and electron capture Q values were measured using PTMS to be 1193.0(6) and 108.9(8) keV, respectively. This enabled precise β end point energies of 596.2(6) and 195.3(6) keV to be determined for the primary and secondary β decays, respectively. The conserved vector current hypothesis was applied to calculate the relativistic vector matrix elements. The β-spectrum shape was shown to significantly depend on the Coulomb displacement energy and on the value of the axial vector coupling constant gA, which was extracted according to different assumptions. Conclusion: The implemented self-scintillation method has provided unmatched observations of Lu176, independently validated by the first direct measurements of its β-decay Q value by Penning trap mass spectrometry. Theoretical study of the main β transition led to the extraction of very different effective gA and log10f values, showing that a high-precision description of this transition would require a realistic nuclear structure with nucleus deformation.

We performed a Penning trap mass measurement of $^{61}{\rm Zn}$ at the National Superconducting Cyclotron Laboratory and NuShellX calculations of the $^{61}{\rm Zn}$ and $^{62}{\rm Ga}$ structure using the GXPF1A Hamiltonian to obtain improved estimates of the $^{61}{\rm Zn}(p,\gamma)^{62}{\rm Ga}$ and $^{60}{\rm Cu}(p,\gamma)^{61}{\rm Zn}$ reaction rates. Surveying astrophysical conditions for type-I X-ray bursts with the code MESA, implementing our improved reaction rates, and taking into account updated nuclear masses for $^{61}{\rm V}$ and $^{61}{\rm Cr}$ from the recent literature, we refine the neutrino luminosity from the important mass number $A=61$ urca cooling source in accreted neutron star crusts. This improves our understanding of the thermal barrier between deep heating in the crust and the shallow depths where extra heat is needed to explain X-ray superbursts, as well as the expected signature of crust urca neutrino emission in light curves of cooling transients., Comment: Submitted

We report high-precision mass measurements of ^{50-55}Sc isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for ^{53-55}Sc. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers N=32 and N=34 above proton-magic Z=20. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the N=32 isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic ^{52}Ca. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in ^{55}Sc at N=34. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing N=32 neutron shell gap energies but were highly disparate in the description of the N=34 isotone.

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 region near Z=28, N=40 is a subject of great interest for nuclear structure studies due to spectroscopic signatures in $^{68}$Ni suggesting a subshell closure at N=40. Trends in nuclear masses and their derivatives provide a complementary approach to shell structure investigations via separation energies. Penning trap mass spectrometry has provided precise measurements for a number of nuclei in this region, however a complete picture of the mass surfaces has so far been limited by the large uncertainty remaining for nuclei with N > 40 along the iron and cobalt chains. Here we present the first Penning trap measurements of $^{68,69}$Co, performed at the Low-Energy Beam and Ion Trap facility at the National Superconducting Cyclotron Laboratory. In addition, we perform ab initio calculations of ground state and two-neutron separation energies of cobalt isotopes with the valence-space in-medium similarity renormalization group approach based on a particular set of two- and three-nucleon forces which predict saturation in infinite matter. We discuss the importance of these measurements and calculations for understanding the evolution of nuclear structure near $^{68}$Ni., 7 pages, 6 figures

Using high-precision Penning trap mass spectrometry at the Low Energy Beam and Ion Trap facility at the National Superconducting Cyclotron Laboratory we have measured the $Q$ values of the fourth-order forbidden $\ensuremath{\beta}$ decay and electron capture of $^{50}\mathrm{V}$ and the double electron capture $Q$ value of $^{50}\mathrm{Cr}$ with the results ${Q}_{\ensuremath{\beta}}(^{50}\mathrm{V})=1038.1(1)$ keV, ${Q}_{\mathrm{EC}}(^{50}\mathrm{V})=2208.7(1)$ keV, and ${Q}_{2\mathrm{EC}}(^{50}\mathrm{Cr})=1170.5(1)$ keV. In addition, we have measured the atomic masses of $^{46,47,49,50}\mathrm{Ti},^{50,51}\mathrm{V}$, and $^{50,52--54}\mathrm{Cr}$, reducing uncertainties by factors of up to three compared with the most recent atomic mass evaluation $(Ame2016)$ [Chin. Phys. C 41, 030003 (2017)]. Our results are in good agreement with $Ame2016$ for $^{46,47,49,50}\mathrm{Ti}$ and $^{50,54}\mathrm{Cr}$ and show deviations of up to $\ensuremath{\sim}1\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{4pt}{0ex}}(2.5\ensuremath{\sigma})$ for $^{50,51}\mathrm{V}$ and $^{50,54}\mathrm{Cr}$.

We report the mass measurement of ^{56}Cu, using the LEBIT 9.4 T Penning trap mass spectrometer at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of ^{56}Cu is critical for constraining the reaction rates of the ^{55}Ni(p,γ) ^{56}Cu(p,γ) ^{57}Zn(β^{+}) ^{57}Cu bypass around the ^{56}Ni waiting point. Previous recommended mass excess values have disagreed by several hundred keV. Our new value, ME=-38626.7(7.1) keV, is a factor of 30 more precise than the extrapolated value suggested in the 2012 atomic mass evaluation [Chin. Phys. C 36, 1603 (2012)CPCHCQ1674-113710.1088/1674-1137/36/12/003], and more than a factor of 12 more precise than values calculated using local mass extrapolations, while agreeing with the newest 2016 atomic mass evaluation value [Chin. Phys. C 41, 030003 (2017)CPCHCQ1674-113710.1088/1674-1137/41/3/030003]. The new experimental average, using our new mass and the value from AME2016, is used to calculate the astrophysical ^{55}Ni(p,γ) and ^{56}Cu(p,γ) forward and reverse rates and perform reaction network calculations of the rp process. These show that the rp-process flow redirects around the ^{56}Ni waiting point through the ^{55}Ni(p,γ) route, allowing it to proceed to higher masses more quickly and resulting in a reduction in ashes around this waiting point and an enhancement to higher-mass ashes.

We report the determination of the Q(EC) value of the mirror transition of (11)C by measuring the atomic masses of (11)C and (11)B using Penning trap mass spectrometry. More than an order of magnitude improvement in precision is achieved as compared to the 2012 Atomic Mass Evaluation (Ame2012) [Chin. Phys. C 36, 1603 (2012)]. This leads to a factor of 3 improvement in the calculated Ft value. Using the new value, Q(EC)=1981.690(61) keV, the uncertainty on Ft is no longer dominated by the uncertainty on the Q(EC) value. Based on this measurement, we provide an updated estimate of the Gamow-Teller to Fermi mixing ratio and standard model values of the correlation coefficients.

We report the first direct measurement of the (14)O superallowed Fermi β-decay QEC value, the last of the so-called "traditional nine" superallowed Fermi β decays to be measured with Penning trap mass spectrometry. (14)O, along with the other low-Z superallowed β emitter, (10)C, is crucial for setting limits on the existence of possible scalar currents. The new ground state QEC value, 5144.364(25) keV, when combined with the energy of the 0(+) daughter state, Ex(0(+))=2312.798(11) keV [F. Ajzenberg-Selove, Nucl. Phys. A523, 1 (1991)], provides a new determination of the superallowed β-decay QEC value, QEC(sa)=2831.566(28) keV, with an order of magnitude improvement in precision, and a similar improvement to the calculated statistical rate function f. This is used to calculate an improved Ft value of 3073.8(2.8) s.

A new technique has been developed at TRIUMF's TITAN facility to perform in-trap decay spectroscopy. The aim of this technique is to eventually measure weak electron capture branching ratios (ECBRs) and by this to consequently determine GT matrix elements of $\beta\beta$ decaying nuclei. These branching ratios provide important input to the theoretical description of these decays. The feasibility and power of the technique is demonstrated by measuring the ECBR of $^{124}$Cs., Comment: 9 pages, 9 figures

The first direct mass measurement of {6}He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of {8}He was determined with improved precision over our previous measurement. The obtained masses are m({6}He)=6.018 885 883(57) u and m({8}He)=8.033 934 44(11) u. The {6}He value shows a deviation from the literature of 4σ. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16) fm for {6}He and {8}He, respectively. We present a detailed comparison to nuclear theory for {6}He, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces.

To extract the effective neutrino Majorana mass from an observed 0νββ decay, precise knowledge of the involved nuclear matrix element is required. This poses a challenge to nuclear structure models. In particular, calculations based on the proton‐neutron Quasiparticle Random Phase Approximation show significant discrepancies with experimental electron capture (EC) rates of the intermediate nucleus even when tuned on 2νββ decay rates. However, EC branching ratios (BR) are in many cases not well known because the strengths of these decay branches are at the sensitivity limit of traditional experimental techniques. Here, we present a novel approach at TITAN/TRIUMF to measure EC‐BR and to overcome shortcomings of previous methods. We also present results of a first proof‐of‐principle experiment which represents the very first observation of an electron capture in a Penning trap.

A new long-lived isomeric state in (65)Fe has been discovered with Penning trap mass spectrometry and high-precision mass measurements of the neutron-rich isotopes (63-65)Fe and (64-66)Co have been performed with the Low-Energy Beam and Ion Trap Facility at the NSCL. For the new isomer in (65)Fe an excitation energy of 402(5) keV has been determined from the measured mass difference between the isomeric and ground states. The mass uncertainties of all isotopes have been reduced by a factor of 10-100 compared to previous results. In the case of (64)Co the previous mass value was found to deviate by about 5 standard deviations from the new measurement.

The mass of the short-lived radio nuclide 38Ca (T(1/2) = 440 ms) has been measured with the 9.4-T Penning trap mass spectrometer of the Low-Energy Beam and Ion Trap Facility. A mass uncertainty of deltam = 280 eV has been achieved, corresponding to deltam/m = 8 x 10(-9). The result makes 38Ca, a superallowed beta emitter, a new candidate to test the conserved-vector-current hypothesis. The experiment is also the first demonstration that short-lived radioactive isotopes produced by projectile fragmentation of relativistic heavy-ion beams can be slowed down and prepared such that precision experiments of this kind are possible.