The ground-state spins and magnetic moments of neutron-rich ${}^{27}\mathrm{Mg}$, ${}^{29}\mathrm{Mg}$, and ${}^{31}\mathrm{Mg}$ were measured for the first time with laser and β-NMR spectroscopy at ISOLDE/CERN. The hyperfine structure of ${}^{27}\mathrm{Mg}$—observed in fluorescence—confirms previous assignments of the spin $I=1/2$ and reveals the magnetic moment ${\mu }_I({}^{27}\mathrm{Mg})=-0.4107(15){\mu }_N$. The hyperfine structure and nuclear magnetic resonance of optically polarized ${}^{29}\mathrm{Mg}$—observed in the asymmetry of its β decay after implantation in a cubic crystal—give $I=3/2$ and ${\mu }_I({}^{29}\mathrm{Mg})=+0.9780(6){\mu }_N$. For ${}^{31}\mathrm{Mg}$ they yield together $I=1/2$ and ${\mu }_I({}^{31}\mathrm{Mg})=-0.88355(15){\mu }_N$, where the negative magnetic moment provides evidence for a positive parity. The results for ${}^{27}\mathrm{Mg}$ and ${}^{29}\mathrm{Mg}$ agree well with shell-model calculations confined only to the $\mathit{sd}$ model space, whereas the ground state of ${}^{31}\mathrm{Mg}$ involves large contributions from neutrons in the $\mathit{pf}$ shell, which places this nucleus inside the “island of inversion.”

Results are presented for the polarization of the ejectile in quasi-elastic neutral-current neutrino (antineutrino) scattering off ${}^{12}\mathrm{C}$. A relativistic distorted-wave impulse-approximation model is used for the calculations where the bound state is obtained in the framework of the relativistic mean field theory and the final state interaction is taken into account in the scattering state by means of a relativistic optical potential. The sensitivity to the strange-quark content of the nucleon weak current is discussed.

We systematically study total reaction cross sections of carbon isotopes with $N=6\text{−}16$ on a proton target for wide range of incident energies. An emphasis is put on the difference from the case of a carbon target. The calculations include the reaction cross sections of ${}^{19,20,22}\mathrm{C}$ at $40A$ MeV, the data of which have recently been measured at RIKEN. The Glauber theory is used to calculate the reaction cross sections. To describe the intrinsic structure of the carbon isotopes, we use a Slater determinant generated from a phenomenological mean-field potential, and construct the density distributions. To go beyond the simple mean-field model, we adopt two types of dynamical models: One is a core$+n$ model for odd-neutron nuclei, and the other is a core$+n+n$ model for ${}^{16}\mathrm{C}$ and ${}^{22}\mathrm{C}$. We propose empirical formulas which are useful in predicting unknown cross sections.

Recently we measured the ratio of $K$-shell internal conversion coefficients, ${\alpha }_K$, for the 127.5-keV $E3$ transition in ${}^{134}\mathrm{Cs}$ and the 661.7-keV $M4$ transition in ${}^{137}\mathrm{Ba}$. We here report a measurement of the 165.9-keV $M1$ transition in ${}^{139}\mathrm{La}$, based on which we convert our earlier ratio measurement into individual ${\alpha }_K$ values for the transitions in ${}^{134}\mathrm{Cs}$ and ${}^{137}\mathrm{Ba}$. These results continue to confirm the Dirac-Fock calculations of internal conversion coefficients that incorporate the atomic $K$-shell vacancy.

Charge-changing and fragment production cross sections at $0^{°}$ have been obtained for interactions of 290, 400, and 650 MeV/nucleon ${}^{40}\mathrm{Ar}$ beams, 650 and 1000 MeV/nucleon ${}^{35}\mathrm{Cl}$ beams, and a 1000 MeV/nucleon ${}^{48}\mathrm{Ti}$ beam. Targets of C, ${\mathrm{CH}}_2$, Al, Cu, Sn, and Pb were used. Using standard analysis methods, we obtained fragment cross sections for charges as low as 8 for Cl and Ar beams and as low as 10 for the Ti beam. Using data obtained with small-acceptance detectors, we report fragment production cross sections for charges as low as 5, corrected for acceptance using a simple model of fragment angular distributions. With the lower-charged fragment cross sections, we can compare the data to predictions from several models (including NUCFRG2, EPAX2, and PHITS) in a region largely unexplored in earlier work. As found in earlier work with other beams, NUCFRG2 and PHITS predictions agree reasonably well with the data for charge-changing cross sections, but these models do not accurately predict the fragment production cross sections. The cross sections for the lightest fragments demonstrate the inadequacy of several models in which the cross sections fall monotonically with the charge of the fragment. PHITS, despite its not agreeing particularly well with the fragment production cross sections on average, nonetheless qualitatively reproduces some significant features of the data that are missing from the other models.

Experimental constraints are useful tools in helping to decide, among a number of candidates, which is the more suitable equation of state for nuclear matter. In this work we compare nonrelativistic Skyrme-type and relativistic Walecka-type models when they are used to describe processes related to binary system instabilities and phases coexistence. In general, nonrelativistic and relativistic models predict somewhat different behaviors, but we found that one of the parametrizations of the density-dependent hadronic model shows some similarities with nonrelativistic models in many of the features addressed in our investigation. We have checked that, once experimental data obtained in heavy-ion collisions are extrapolated to account for symmetric and neutron matter, some of the models discussed in the present work, both relativistic and nonrelativistic, should be ruled out.

We compute the spin-independent structure functions of the forward virtual-photon Compton tensor of the proton at one loop using heavy baryon chiral perturbation theory and dispersion relations. We study the relation between both approaches. We use these results to generalize some sum rules to virtual photon transfer momentum and relate them with sum rules in deep inelastic scattering. We then compute the leading chiral term of the polarizability correction to the Lamb shift of hydrogen and muonic hydrogen. We obtain $-87.05/n^3\mathrm{Hz}$ and $-0.148/n^3\mathrm{meV}$ for the correction to the hydrogen and muonic hydrogen Lamb shift, respectively.

We investigated the negative-parity states and electromagnetic transitions in ${}^{151,153}\mathrm{Ho}$ and ${}^{151,153}\mathrm{Dy}$ within the framework of the interacting boson fermion model 2 (IBFM-2). Spin assignments for some states with uncertain spin are made based on this calculation. Calculated excitation energies, electromagnetic transitions, and branching ratios are compared with available experimental data and a good agreement is obtained. The model wave functions were used to study β decays from Ho to Dy isotones, and the calculated $\log \mathit{ft}$ values are close to the experimental data.

The spectra of seven $p$-shell $\Lambda$ hypernuclei are calculated with effective interactions derived from the new Nijmegen ESC04 baryon-baryon interaction. The results of interactions ESC04A and ESC04B compare well with the known experimental levels, whereas those of ESC04C and ESC04D do not. The primary difference between the two pairs of potentials is the ratio of triplet to singlet strength in the central potential. The ${}_{\Lambda }^{16}\mathrm{O}$ results indicate that the tensor interaction is too weak and/or the spin-orbit odd interaction is too strong for all potentials. In addition the $\Lambda N\text{−}\Sigma N$ coupling potentials have an unusual radial behavior. The calculations provide a natural explanation for the reduction of the spin-spin interaction of phenomenological interactions from the beginning to the end of the shell.

Low-spin states were studied in ${}^{30}\mathrm{Al}$ following the β decay of ${}^{30}\mathrm{Mg}$ produced in the fragmentation of 140-MeV/AMU ${}^{48}\mathrm{Ca}$. Analysis of the $\beta \text{−}\gamma$ and $\beta \text{−}\gamma \text{−}\gamma$ coincidences revealed a new $1^{+}$ state at 2413 keV, confirmation of the level scheme, and a more accurate half-life measurement of 315(6) ms for the ${}^{30}\mathrm{Mg}$ ground state. Higher-spin states were investigated in the reaction of ${}^{14}\mathrm{C}$ on ${}^{18}\mathrm{O}$ at 22 MeV. Protons and deuterons were detected in a segmented E-ΔE Si telescope in coincidence with one or two γ rays in the FSU Ge detector array. A comparison of the resulting level and decay scheme with predictions of the $\mathit{sd}$ shell model shows good agreement with all but six of the states in both excitation energy and γ-decay branching ratios. The root-mean-square deviations in energy of these states using the older USD and newer USDA and USDB interactions were 265, 176, and 173 keV, respectively. The remaining six states are well described as $4^{-}$ to $7^{-}$ states, similar in relative energy to those in ${}^{28}\mathrm{Al}$ but shifted down by about 1200 keV. These states also agree well with the predictions of shell-model calculations using the WBP interaction. A comparison of the lowest $4^{-}$ states in even A Na, Al, and P isotopes shows a systematic decrease in energy with increasing N and with decreasing Z. The energies of the $4^{-}$ states are almost identical in nuclei with the same $N\text{−}Z$ values.

Nonstatistical event-by-event mean-$p_t$ fluctuations in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=130$ and $200$ GeV are analyzed in the multiphase transport model (AMPT) with string melting, and the results are compared with STAR data. The analysis suggests that in-medium elastic parton scattering may contribute greatly to the mean-$p_t$ fluctuations in relativistic heavy-ion collisions. Furthermore, it is demonstrated that nonstatistical event-by-event mean-$p_t$ fluctuations can be used to probe the initial partonic dynamics in these collisions. The comparison shows that with an in-medium elastic parton-scattering cross section ${\sigma }_p=10$ mb, AMPT with string melting can well reproduce $\sqrt{s_{\mathit{NN}}}=130$ GeV data on the centrality dependence of nonstatistical event-by-event mean-$p_t$ fluctuations. The comparison also shows that the fluctuation data for $\sqrt{s_{\mathit{NN}}}=200$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions can be well reproduced with ${\sigma }_p$ between 6 and 10 mb.

Following suggestions that the energy associated with Coulomb correlations and a possible charge-symmetry breaking of nuclear forces might largely cancel the Coulomb-exchange term, we refit the HFB-14 mass model without the Coulomb-exchange term to essentially all the mass data. The resulting mass model, HFB-15, gives a better fit to the 2149 mass data, ${\sigma }_{\mathrm{rms}}$ falling from 0.729 to 0.678 MeV. The improvement in the energy differences between mirror nuclei is particularly striking: the Nolen-Schiffer anomaly, which is strong for HFB-14, is essentially eliminated. As for the extrapolation to highly neutron-rich nuclei, the HFB-15 model differs significantly from HFB-14, with up to 15 MeV less binding being predicted. However, the differences in the predicted values of differential quantities such as the neutron-separation energies, β-decay energies and fission barriers are very much smaller.

Experiments with cold Fermi atoms can be tuned to probe strongly-interacting fluids that are very similar to the low-density neutron matter found in the crusts of neutron stars. In contrast to traditional superfluids and superconductors, matter in this regime is very strongly paired, with gaps of the order of the Fermi energy. We compute the $T=0$ equation of state and pairing gap for cold atoms and low-density neutron matter as a function of the Fermi momentum times the scattering length. Results of quantum Monte Carlo calculations show that the equations of state are very similar. The neutron matter pairing gap at low densities is found to be very large but, except at the smallest densities, significantly suppressed relative to cold atoms because of the finite effective range in the neutron-neutron interaction.

We study the relation between the finite-range (meson-exchange) and zero-range (point-coupling) representations of effective nuclear interactions in the relativistic mean-field framework. Starting from the phenomenological interaction DD-ME2 with density-dependent meson-nucleon couplings, we construct a family of point-coupling effective interactions for different values of the strength parameter of the isoscalar-scalar derivative term. In the meson-exchange picture this corresponds to different values of the σ-meson mass. The parameters of the isoscalar-scalar and isovector-vector channels of the point-coupling interactions are adjusted to nuclear matter and ground-state properties of finite nuclei. By comparing results for infinite and semi-infinite nuclear matter, ground-state masses, charge radii, and collective excitations, we discuss constraints on the parameters of phenomenological point-coupling relativistic effective interaction.

We discuss in detail the coupled-channels approach for large-angle quasi-elastic scattering in massive systems, where many degrees of freedom may be involved in the reaction. We especially investigate the effects of single-, double-, and triple-phonon excitations on the quasi-elastic scattering for ${}^{48}\mathrm{Ti}$, ${}^{54}\mathrm{Cr}$, ${}^{56}\mathrm{Fe}$, ${}^{64}\mathrm{Ni}$, and ${}^{70}\mathrm{Zn}+{}^{208}\mathrm{Pb}$ systems, for which the experimental cross sections have been measured recently. We show that the present coupled-channels calculations well account for the overall width of the experimental barrier distribution for these systems. In particular, it is shown that the calculations taking into account single-quadrupole phonon excitation in ${}^{48}\mathrm{Ti}$ and triple-octupole phonon excitations in ${}^{208}\mathrm{Pb}$ reasonably well reproduce the experimental quasi-elastic cross section and barrier distribution for the ${}^{48}\mathrm{Ti}+{}^{208}\mathrm{Pb}$ reaction. However, ${}^{54}\mathrm{Cr}$, ${}^{56}\mathrm{Fe}$, ${}^{64}\mathrm{Ni}$, and ${}^{70}\mathrm{Zn}+{}^{208}\mathrm{Pb}$ systems seem to require the double-quadrupole phonon excitations in the projectiles to reproduce the experimental data.

We investigate a (3+1)-dimensional hydrodynamic expansion of the hot and dense system created in head-on collisions of Pb+Pb/Au+Au at beam energies from 5 to 200 GeV/nucleon. An equation of state is used that incorporates a critical end point (CEP) in line with the lattice data. The necessary initial conditions for the hydrodynamic evolution are taken from a microscopic transport approach, the ultrarelativistic quantum molecular dynamics (UrQMD) model. We compare the properties of the initial state and the full hydrodynamic calculation with an isentropic expansion employing an initial state from a simple overlap model. We find that the specific entropies ($S/A$) from both initial conditions are very similar and only depend on the underlying equation of state. Using the chiral (hadronic) equation of state, we investigate the expansion paths for both initial conditions. Defining a critical area around the critical point, we show at what beam energies one can expect to have a sizable fraction of the system close to the critical point. Finally, we emphasize the importance of the equation of state of strongly interacting matter in the (experimental) search for the CEP.

New recent experimental α decay half-lives have been compared with the results obtained from previously proposed formulas depending only on the mass and charge numbers of the α emitter and the $Q_{\alpha }$ value. For the heaviest nuclei they are also compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulas. The correct agreement allows us to make predictions for the α decay half-lives of other still unknown superheavy nuclei from these analytic formulas using the extrapolated $Q_{\alpha }$ of G. Audi, A. H. Wapstra, and C. Thibault [Nucl. Phys. A729, 337 (2003)].

We suggest, on general principles, that the isotopic distributions and thus isoscaling are affected by an entropic symmetry term, which is present even when the symmetry energy term is absent.

The neutron capture cross sections of the Zr isotopes have important implications in nuclear astrophysics and for reactor design. The small cross section of the neutron magic nucleus ${}^{90}\mathrm{Zr}$, which accounts for more than 50% of natural zirconium represents one of the key isotopes for the stellar $s$-process, because it acts as a bottleneck in the neutron capture chain between the Fe seed and the heavier isotopes. The same element, Zr, also is an important component of the structural materials used in traditional and advanced nuclear reactors. The ($n,\gamma$) cross section has been measured at CERN, using the n_TOF spallation neutron source. In total, 45 resonances could be resolved in the neutron energy range below 70 keV, 10 being observed for the first time thanks to the high resolution and low backgrounds at n_TOF. On average, the ${\Gamma }_{\gamma }$ widths obtained in resonance analyses with the $R$-matrix code SAMMY were 15% smaller than reported previously. By these results, the accuracy of the Maxwellian averaged cross section for $s$-process calculations has been improved by more than a factor of 2.