Relativistic mean-field theory is combined with a method based on the analytic continuation of the coupling-constant method to determine the energies and widths of single-particle resonant states in the Sn isotopes. It is shown that, as for the bound levels, there exists clear shell structure in the resonant levels. In particular, an isospin dependence of pseudospin symmetry is clearly shown in the resonant states and is consistent with that observed in the bound states. The splittings of energies and widths between pseudospin doublets are correlated with the quantum numbers of the single-particle states, as well as the nuclear mass number. A phenomenon similar to the behavior of energy and width splittings between the pseudospin doublets also appears for the spin partners and the proton orbits.

Experimental energy spectrum and $B(E2)$ values in ${}^{68}\mathrm{Ni}$ and ${}^{90}\mathrm{Zr}$ indicate a double-magic character in these neutron-rich nuclei with $N$ or $Z=40$. The data nevertheless do not show any pronounced irregularity in two-nucleon separation energy. To understand the underlying physics, we carry out both shell-model and mean-field calculations. The shell-model calculation can reproduce all the observations well. It is understood from the mean-field results for ${}^{68}\mathrm{Ni}$ that the shell gap at $N=40$ disappears because of dynamical correlations of the isovector $J=0$ pairing interaction. In ${}^{90}\mathrm{Zr}$, however, such a dynamic process with the $J=0$ pairing appears not important because of the strong contribution of the $J>0$ interaction. We study also level schemes in the Ni isotopes and $N=$ 50 isotones. We predict a new band built on the $0_2^{+}$ state in both ${}^{68}\mathrm{Ni}$ and ${}^{90}\mathrm{Zr}$. The states of this band are dominated by two-particle-two-hole excitations from the $\mathit{fp}$ shell to the intruder $g_{9/2}$ orbit.

We outline a formalism to carry out time dependent Hartree-Fock (TDHF) calculations of fusion cross sections for spherical+deformed nuclei. The procedure incorporates the dynamic alignment of the deformed nucleus into the calculation of the fusion cross section. The alignment results from multiple $E2/E4$ Coulomb excitation of the ground state rotational band. Implications for TDHF fusion calculations are discussed. TDHF calculations are done in an unrestricted three-dimensional geometry using modern Skyrme force parametrizations.

We report results from shell-model studies of muon capture on ${}^{40}\mathrm{Ca}$ to low-lying levels of ${}^{40}\mathrm{K}$. We discuss the comparison among calculated capture rates, measured capture rates, and analogous transitions in ($e,e^{\text{'}}$) scattering in terms of the particle-hole structure of the ${}^{40}\mathrm{Ca}$-${}^{40}\mathrm{K}$ nuclei. We highlight the ${}^{40}\mathrm{Ca}$$(0^{+},0)\to$${}^{40}\mathrm{K}$$(0^{-},2626)$ axial charge transition and its sensitivity to the induced pseudoscalar coupling $g_p$ of the proton's weak interaction. In addition, we address the hindrance of unique first-forbidden transitions due to particle-hole interactions and the emergence of allowed Gamow-Teller transitions due to ground-state correlations. Last, we examine the longitudinal alignment of ${}^{40}\mathrm{K}$ recoils following muon capture and discuss this possibility for independently determining the induced coupling $g_p$.

The rare earth nuclei from $N=92$ to $N=108$ display a very regular pattern of empirically extracted interactions of the last protons with the last neutrons. The simplicity of the empirical systematics suggests that a simple interpretation should be possible. We discuss calculations of these proton-neutron ($p\text{−}n$) interactions with a zero-range δ force.

Excited states in ${}^{161}\mathrm{Re}$ were populated using the ${}^{106}\mathrm{Cd}$(${}^{58}\mathrm{Ni}$, $p2n$) reaction at a beam energy of 270 MeV, resulting in the first observation of γ rays emitted from this nucleus. The reaction products were separated from scattered beam and fission fragments by the gas-filled recoil separator RITU, and were implanted in the double-sided silicon strip detectors of the GREAT spectrometer. Prompt γ rays were detected by the JUROGAM Ge detector array and were assigned to ${}^{161}\mathrm{Re}$ based on α- and proton-decay tagging of the implanted reaction products. The near-yrast high-spin level structure, which was delineated to spins around $39/2$, is discussed in the context of the total Routhian surface formalism. The level scheme is interpreted in terms of the alignment of $h_{9/2}/f_{7/2}$ neutrons at lower spins, followed by excitations involving the $\pi h_{11/2}$ subshell at higher spins.

The symmetry energy and the isoscaling properties of the fragments produced in the multifragmentation of ${}^{40}\mathrm{Ar}$, ${}^{40}\mathrm{Ca}+{}^{58}\mathrm{Fe}$, ${}^{58}\mathrm{Ni}$ reactions at 25, 33, 45, and 53 MeV/nucleon were investigated within the framework of statistical multifragmentation model. The isoscaling parameters α, from the primary (hot) and secondary (cold) fragment yield distributions, were studied as a function of excitation energy, isospin (neutron-to-proton asymmetry), and fragment symmetry energy. It is observed that the isoscaling parameter α decreases with increasing excitation energy and decreasing symmetry energy. The parameter α is also observed to increase with increasing difference in the isospin of the fragmenting system. The sequential decay of the primary fragments into secondary fragments, when studied as a function of excitation energy and isospin of the fragmenting system, show very little influence on the isoscaling parameter. The symmetry energy, however, has a strong influence on the isospin properties of the hot fragments. The experimentally observed scaling parameters can be explained by symmetry energy that is significantly lower than that for the ground-state nuclei near saturation density. The results indicate that the properties of hot nuclei at excitation energies, densities, and isospin away from the normal ground-state nuclei could be significantly different.

Nuclear forces violating parity and time reversal invariance ($\mathcal{P},\mathcal{T}$-odd) produce $\mathcal{P},\mathcal{T}$-odd nuclear moments, for example, the nuclear Schiff moment. In turn, this moment can induce the electric dipole moment in the atom. The nuclear Schiff moment is predicted to be enhanced in nuclei with static quadru pole and octupole deformation. The analogous suggestion of the enhanced contribution to the Schiff moment from the soft collective quadrupole and octupole vibrations in spherical nuclei is tested in this article in the framework of the quasiparticle random phase approximation with separable quadrupole and octupole forces applied to the odd ${}^{217-221}\mathrm{Ra}$ and ${}^{217-221}\mathrm{Rn}$ isotopes. In this framework, we confirm the existence of the enhancement effect due to the soft modes, but only in the limit when the frequencies of quadrupole and octupole vibrations are close to zero. According to the QRPA, in realistic cases the enhancement in spherical nuclei is strongly reduced by a small weight of the corresponding “particle + phonon” component in a complicated wave function of a soft nucleus. The perspectives of a better description of the structure of heavy soft nuclei are discussed.

We calculate total masses and radii of neutron stars for pure neutron matter and nuclear matter in β equilibrium. We apply a relativistic nuclear matter equation of state derived from Dirac-Brueckner-Hartree-Fock calculations. We use realistic nucleon-nucleon interactions defined in the framework of the meson exchange potential models. Our results are compared with other theoretical predictions and recent observational data. Suggestions for further study are discussed.

The total cross section for radiative neutron capture on a proton, $\mathit{np}\to d\gamma$, is evaluated at big-bang nucleosynthesis (BBN) energies. The electromagnetic transition amplitudes are calculated up to next-to-leading-order within the framework of pionless effective field theory with dibaryon fields. We also calculate the $d\gamma \to \mathit{np}$ cross section and the photon analyzing power for the $d\overrightarrow{\gamma }\to \mathit{np}$ process from the amplitudes. The values of low-energy constants that appear in the amplitudes are estimated by a Markov Chain Monte Carlo analysis using the relevant low-energy experimental data. Our result agrees well with those of other theoretical calculations except for the $\mathit{np}\to d\gamma$ cross section at some energies estimated by an $R$-matrix analysis. We also study the uncertainties in our estimation of the $\mathit{np}\to d\gamma$ cross section at relevant BBN energies and find that the estimated cross section is reliable to within $~1$% error.

Two-neutron knockout reactions from nuclei in the proximity of the proton dripline have been studied using intermediate-energy beams of neutron-deficient ${}^{34}\mathrm{Ar}$, ${}^{30}\mathrm{S}$, and ${}^{26}\mathrm{Si}$. The inclusive cross sections, and also the partial cross sections for the population of individual bound final states of the ${}^{32}\mathrm{Ar}$, ${}^{28}\mathrm{S}$ and ${}^{24}\mathrm{Si}$ knockout residues, have been determined using the combination of particle and γ-ray spectroscopy. Similar to the two-proton knockout mechanism on the neutron-rich side of the nuclear chart, these two-neutron removal reactions from already neutron-deficient nuclei are also shown to be consistent with a direct reaction mechanism.

The $g$ factor of the $2_1^{+}$ state in ${}^{70}\mathrm{Ge}$ was remeasured using a different experimental approach. Furthermore, for the first time an experimental value (although with a large uncertainty) was obtained for the $g$ factor of the $2_2^{+}$ state in ${}^{70}\mathrm{Ge}$. All this was accomplished by employing the technique of α transfer to an energetic ${}^{66}\mathrm{Zn}$ ion beam in inverse kinematics combined with transient magnetic fields in ferromagnetic gadolinium. The value of the $g(2_1^{+})$ factor obtained ranges from +0.32(11) to +0.43(12), subject to certain assumptions. This range of values is in general agreement with the range of values in the literature, where Coulomb excitation and different IMPAC techniques were used. Lifetimes of several low-lying states were redetermined using the Doppler-Shift-Attenuation-Method. The deduced $B(E2)$ values and the $g(2_1^{+})$ factor are discussed within the framework of large-scale full $\mathit{fp}$ shell model calculations with a closed ${}^{40}\mathrm{Ca}$ core and including excitations from the $f_{7/2}$ orbital. The results are compared with recent data for ${}^{68}\mathrm{Ge}$ and ${}^{68}\mathrm{Zn}$.

Angular distributions for the ${}^{11}\mathrm{B}+{}^{25}\mathrm{Mg}$ elastic scattering, ${}^{25}\mathrm{Mg}$(${}^{11}\mathrm{B}$,${}^{12}\mathrm{C}$)${}^{24}\mathrm{Na}$ proton pickup, and ${}^{25}\mathrm{Mg}$(${}^{11}\mathrm{B}$,${}^{10}\mathrm{Be}$)${}^{26}\mathrm{Al}$ stripping reactions have been measured at $E_{{}^{11}\mathrm{B}}=35$ MeV. The angular distributions have been analyzed by the distorted-waves Born approximation calculations using the code fresco. The spectroscopic factors for the overlaps $\langle$${}^{25}\mathrm{Mg}$$|$${}^{26}\mathrm{Al}$$\rangle ,\langle$${}^{25}\mathrm{Mg}$$|$${}^{24}\mathrm{Na}$$\rangle$ for the ground state and excited states of ${}^{26}\mathrm{Al}$ and ${}^{24}\mathrm{Na}$ have been obtained and compared to previous measurements and shell-model calculations.

The vector manifestation (VM) fixed-point scenario found in the Harada-Yamawaki hidden local symmetry effective theory makes a striking prediction that as the fireball expands and cools from $T_c$ down toward the freeze-out temperature $T_{\mathrm{freeze}\text{−}\mathrm{out}}$ in heavy-ion collisions, what we refer to as “hadronic freedom” sets in which hadrons do not interact or barely interact. We suggest that this scenario is testable at the BNL relativistic heavy in collider, and as a specific example, we provide an astonishingly simple prediction in terms of the V.M for the ${\rho }^0/{\pi }^{-}$ ratio measured in peripheral collisions. We suggest that this hadronic freedom has already been observed in the STAR peripheral collisions, in which the ${\rho }^0$ mesons were reconstructed by following their pion decay products back to the vertex where they are formed. In this scenario, the measured ${\rho }^0/{\pi }^{-}$ ratio can be reproduced in these special circumstances only because the “flash temperature” $T_{\mathrm{flash}}$ at which the ρ mesons go on-shell is equal to the freeze-out temperature. In more central collisions with lower freeze-out temperatures, the rescattering of the pions is expected to destroy the possibility of this reconstruction.

The problem of freeze-out (FO) in relativistic heavy-ion reactions is addressed. We develop and analyze an idealized one-dimensional model of FO in a finite layer, based on the covariant FO probability. The resulting post FO phase-space distributions are discussed for different FO probabilities and layer thicknesses.

We have measured the half-life of ${}^{14}\mathrm{O}$, a superallowed $(0^{+}\to 0^{+})$ β decay isotope. The ${}^{14}\mathrm{O}$ was produced by the ${}^{12}\mathrm{C}$(${}^3\mathrm{He}$,$n$)${}^{14}\mathrm{O}$ reaction using a carbon aerogel target. A low-energy ion beam of ${}^{14}\mathrm{O}$ was mass separated and implanted in a thin beryllium foil. The beta particles were counted with plastic scintillator detectors. We find $t_{1/2}=70.696\pm 0.052$ s. This result is $1.5\sigma$ higher than an average value from six earlier experiments, but agrees more closely with the most recent previous measurement.

The neutron capture cross section of ${}^{209}\mathrm{Bi}$ has been measured at the CERN n_TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of γ-rays, internal electron conversion, and the isomeric state in bismuth, have been taken into account. γ-Ray absorption effects inside the sample have been corrected by employing a nonpolynomial weighting function. Because ${}^{209}\mathrm{Bi}$ is the last stable isotope in the reaction path of the stellar $s$-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by α decays. In the relevant stellar range of thermal energies between $\mathit{kT}=5$ and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. At this low temperature an important part of the heavy Pb-Bi isotopes are supposed to be synthesized by the $s$-process in the He shells of low mass, thermally pulsing asymptotic giant branch stars. With the improved set of cross sections we obtain an $s$-process fraction of 19±3% of the solar bismuth abundance, resulting in an $r$-process residual of 81±3%. The present ($n,\gamma$) cross-section measurement is also of relevance for the design of accelerator driven systems based on a liquid metal Pb/Bi spallation target.

A medium-spin isomer in ${}^{197}\mathrm{Au}$ is identified with $t_{1/2}=150(5)$ ns following a multinucleon transfer reaction between an 850-MeV ${}^{136}\mathrm{Xe}$ beam and a ${}^{198}\mathrm{Pt}$ target. The transitions identified here are considered and possible configurations for the associated levels discussed. In addition, a newly observed out-of-beam transition in ${}^{195}\mathrm{Au}$ is briefly reported.

The PHOBOS experiment at the BNL Relativistic Heavy Ion Collider has measured the total multiplicity of primary charged particles as a function of collision centrality in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=$ 19.6, 130, and 200 GeV. An approximate independence of $\langle N_{\mathrm{ch}}\rangle /\langle N_{\mathrm{part}}/2\rangle$ on the number of participating nucleons is observed, reminiscent of “wounded nucleon” scaling ($N_{\mathrm{ch}}\propto N_{\mathrm{part}}$) observed in proton-nucleus collisions. Unlike $p+A$, the constant of proportionality does not seem to be set by the $\mathit{pp}/\overline{p}p$ data at the same energy. Rather, there seems to be a surprising correspondence with the total multiplicity measured in $e^{+}{e}^{-}$ annihilations, as well as the rapidity shape measured over a large range. The energy dependence of the integrated multiplicity per participant pair shows that $e^{+}{e}^{-}$ and $A+A$ data agree over a large range of center-of-mass energies ($\sqrt{s}>20$ GeV), and $\mathit{pp}/\overline{p}p$ data can be brought to agree approximately with the $e^{+}{e}^{-}$ data by correcting for the typical energy taken away by leading particles. This is suggestive of a mechanism for soft particle production that depends mainly on the amount of available energy. It is conjectured that the dominant distinction between $A+A$ and $p+p$ collisions is the multiple collisions per participant, which appears to be sufficient to substantially reduce the energy taken away by leading particles.

We discuss results obtained in the study of shape coexistence in the neutron-deficient ${}^{72-78}\mathrm{Kr}$ isotopes. The method that we used is based on the mixing of axial mean-field configurations after their projection on particle number and angular momentum. The calculations are performed with a Skyrme interaction and a density-dependent pairing interaction. Although our calculation reproduces qualitatively and quantitatively many of the global features of these nuclei, such as coexistence of prolate and oblate shapes, their strong mixing at low angular momentum, and the deformation of collective bands, the ordering of our calculated low-lying levels is at variance with experiment. We analyze the role of the single-particle spectrum of the underlying mean field for the spectrum of collective excitations.