Background: A microscopic description of nuclei is important to understand the nuclear shell model from fundamental principles. This is difficult to achieve for more than the lightest nuclei without an effective approximation scheme.

Purpose: Define and evaluate an approximation scheme that can be used to study nuclei that are described as two particles attached to a closed (sub-)shell nucleus.

Methods: The equation-of-motion coupled-cluster formalism has been used to obtain ground- and excited-state energies. This method is based on the diagonalization of a non-Hermitian matrix obtained from a similarity transformation of the many-body nuclear Hamiltonian. A chiral interaction at the next-to-next-to-next-to leading order (N${}^3$LO) using a cutoff at 500 MeV was used.

Results: The ground-state energies of ${}^6$Li and ${}^6$He were in good agreement with a no-core shell-model calculation using the same interaction. Several excited states were also produced with overall good agreement. Only the $J^{\pi }=3^{+}$ excited state in ${}^6$Li showed a sizable deviation. The ground-state energies of ${}^{18}$O, ${}^{18}$F, and ${}^{18}$Ne were converged but underbound compared to experiment. Moreover, the calculated spectra were converged and comparable to both experiment and shell-model studies in this region. Some excited states in ${}^{18}$O were high or missing in the spectrum. It was also shown that the wave function for both ground and excited states separates into an intrinsic part and a Gaussian for the center-of-mass coordinate. Spurious center-of-mass excitations are clearly identified.

Conclusions: Results are converged with respect to the size of the model space and the method can be used to describe nuclear states with simple structure. Especially the ground-state energies were very close to what has been achieved by exact diagonalization. To obtain a closer match with experimental data, effects of three-nucleon forces, the scattering continuum, as well as additional configurations in the coupled-cluster approximations are necessary.

An influence of the repulsive interactions on matter properties is considered within the excluded volume van der Waals hadron-resonance gas model. Quantitative results are presented for matter at the chemical freeze-out in central nucleus-nucleus collisions at relativistic energies. In particular, it is shown that repulsive interactions connected to the nonzero size of created particles lead to a significant decrease of the collision energy at which the net-baryon density has a maximum. A position of the transition point from baryon-to-meson dominated matter depends on the difference between baryon and meson hard-core radiuses.

Analytic calculations are presented of the contribution to the anomalous magnetic moment of a muon from the channels of annihilation of an electron-positron pair to a pair of charged pi mesons, with radiative correction connected with the final state, as well as corrections to the lowest-order kernel. The result with pointlike pi-meson assumptions is $a_{\mathrm{point}}=a_{\mathrm{point}}^{\left(1\right)}+\Delta a_{\mathrm{point}}$, $a_{\mathrm{point}}^{\left(1\right)}=7.0866\times {10}^{-9}$, $\Delta a_{\mathrm{point}}=-2.4\times {10}^{-10}.$ Taking into account the pion form factor in the frames of the Nambu-Jona-Lasinio (NJL) approach leads to $a_{NJL}=a_{NJL}^{\left(1\right)}+\Delta a_{NJL}$, $a_{NJL}^{\left(1\right)}=5.48\times {10}^{-8}$, $\Delta a_{NJL}=-3.43\times {10}^{-9}$.

In the neutron-star crust, nonuniform structure of nuclear matter—called the “pasta” structure—is expected. From recent studies of giant flares in magnetars, these structures might be related to some observables and physical quantities of the neutron-star crust. To investigate the above quantities, we numerically explore the pasta structure with a fully three-dimensional geometry and study the properties of low-density nuclear matter, based on the relativistic mean-field model and the Thomas-Fermi approximation. We observe typical pasta structures for fixed proton number fraction and two of them for cold catalyzed matter. We also discuss the crystalline configuration of “pasta.”

The neutron-rich nucleus ${}^{117}$Rh was synthesized in the fission of a relativistic ${}^{238}$U beam produced at the GSI laboratory in Darmstadt, Germany. An isomeric state with $t_{1/2}=138\left(17\right)$ ns decaying by a single $\gamma$ ray was observed, providing the first information on the excited states in this nucleus. The experimental data are discussed in terms of systematics and interpreted by using the Woods-Saxon deformed shell model and triaxial-rotor-plus-particle calculations. The origin of the isomer is explained as being due to a hindered $E2$ transition to the ground state.

As a unique feature, the ${}^{229}$Th nucleus has an isomeric transition in the vacuum ultraviolet that can be accessed by optical lasers. The interference effects occurring in the interaction between coherent optical light and an ensemble of ${}^{229}$Th nuclei are investigated theoretically. We consider the scenario of nuclei doped in vacuum ultraviolet transparent crystals and take into account the effect of different doping sites and therefore different lattice fields that broaden the nuclear transition width. This effect is shown to come into interplay with interference effects due to the hyperfine splitting of the ground and isomeric nuclear states. We investigate possible experimentally available situations involving two-, three- and four-level schemes of quadrupole sublevels of the ground and isomeric nuclear states coupling to one or two coherent fields. Specific configurations which offer clear signatures of the isomer excitation advantageous for the more precise experimental determination of the transition energy are identified. Furthermore, it is shown that population trapping into the isomeric state can be achieved. This paves the way for further nuclear quantum optics applications with ${}^{229}$Th such as nuclear coherent control.

The formation of the QCD vacuum with nonzero winding number $Q_w$ during relativistic heavy-ion collisions breaks the parity and charge-parity symmetry. A new kind of field configuration can separate charge in the presence of a background magnetic field—the “chiral magnetic effect.” The strong magnetic field and the QCD vacuum can both completely be produced in the noncentral nuclear-nuclear collision. Based on the theory of Kharzeev, McLerran, and Warringa, we use the Wood-Saxon nucleon distribution to replace that of the uniform distribution to improve the magnetic field calculation method of the noncentral collision. The chiral magnetic field distribution at Large Hadron Collider (LHC) energy regions are predicted. We also calculate the contributions to the magnetic field of the total charge given by produced quarks.

${}^{116}\mathrm{Ru}$ and ${}^{118}\mathrm{Ru}$ have been studied via $\beta$-delayed $\gamma$-ray spectroscopy of nuclei produced in fragmentation reactions at the Radioactive Ion-Beam Factory (RIBF) facility. Level schemes with positive-parity states up to spin $J=6$ have been constructed. The results have been discussed in terms of the interacting boson model, the algebraic collective model, and total Routhian surfaces. We conclude that the very neutron-rich nuclei still show many features associated with triaxial $\gamma$-soft nuclei, represented by the O(6) symmetry, but are approaching a spherical structure, the U(5) symmetry, with increasing neutron number towards the $N=82$ shell closure. In ${}^{118}\text{Ru}$, hints of a shape transition in the ground state have been observed.

We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory (SNO). By exploiting particle identification information obtained from the proportional counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis of the SNO data resulted in a total flux of active neutrino flavors from ${}^8\mathrm{B}$ decays in the Sun of $(5.25\pm 0.16{(\mathrm{stat}.)}_{-0.13}^{+0.11}(\mathrm{syst}.))\times {10}^6{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$, while a two-flavor neutrino oscillation analysis yielded $\Delta m_{21}^2=(5.6_{-1.4}^{+1.9})\times {10}^{-5}{\mathrm{eV}}^2$ and ${\tan }^2{\theta }_{12}=0.{427}_{-0.029}^{+0.033}$. A three-flavor neutrino oscillation analysis combining the SNO result with results of all other solar neutrino experiments and reactor neutrino experiments yielded $\Delta m_{21}^2=(7.{46}_{-0.19}^{+0.20})\times {10}^{-5}{\mathrm{eV}}^2$, ${\tan }^2{\theta }_{12}=0.{443}_{-0.025}^{+0.030}$, and ${\sin }^2{\theta }_{13}=(2.{49}_{-0.32}^{+0.20})\times {10}^{-2}$.

We apply thermal field theory methods to compute microscopically the nucleon self-energy arising from one-pion exchange in isospin-symmetric nuclear matter and neutron matter. A self-consistent numerical scheme is introduced and its convergence is demonstrated. The repulsive contribution from the Fock exchange diagram to the energy per nucleon in symmetric nuclear matter is obtained.

The Porter-Thomas distribution is a key prediction of the Gaussian orthogonal ensemble in random matrix theory. It is routinely used to provide a measure for the number of levels that are missing in a given resonance analysis. The Porter-Thomas distribution is also of crucial importance for estimates of thermonuclear reaction rates where the contributions of certain unobserved resonances to the total reaction rate need to be taken into account. In order to estimate such contributions by randomly sampling over the Porter-Thomas distribution, the mean value of the reduced width must be known. We present mean reduced width values for protons and $\alpha$ particles of compound nuclei in the $A=28–67$ mass range. The values are extracted from charged-particle elastic scattering and reaction data that were measured at the Triangle Universities Nuclear Laboratory over several decades. Our new values differ significantly from those previously reported that were based on a preliminary analysis of a smaller data set. As an example for the application of our results, we present new thermonuclear rates for the ${}^{40}$Ca($\alpha$,$\gamma$)${}^{44}$Ti reaction, which is important for ${}^{44}$Ti production in core-collapse supernovae, and compare with previously reported results.

A multireflection time-of-flight mass spectrograph, competitive with Penning trap mass spectrometers, has been built at RIKEN. We have performed a first online mass measurement, using ${}^8$Li${}^{+}$ ($T_{1/2}=838$ ms). A new analysis method has been realized, with which, using only ${}^{12}$C${}^{+}$ references, the mass excess of ${}^8$Li was accurately determined to be 20 947.6(15)(34) keV ($\delta m/m=6.6\times {10}^{-7}$). The speed, precision, and accuracy of this first online measurement exemplifies the potential for using this new type of mass spectrograph for precision measurements of short-lived nuclei.

The $\alpha$-cluster states of ${}^{22}$Ne are studied within the framework of the semimicroscopic algebraic cluster model (SACM). The band structure, energy spectrum, as well as $E2$ and $E1$ transitions are calculated and are compared with the experimental data. The results are also compared with those obtained from two microscopic models: the deformed-basis antisymmetrized molecular dynamics approach and the generator-coordinate method. It is found that the prominent bands obtained in the latter frameworks all have equivalents in the SACM, and the agreement between the calculated spectroscopic properties is rather good, especially for positive-parity states.

Multinucleon transfer processes in heavy-ion reactions at energies slightly above the Coulomb barrier are investigated in a fully microscopic framework of the time-dependent Hartree-Fock (TDHF) theory. Transfer probabilities are calculated from the TDHF wave function after collision using the projection operator method which has recently been proposed by Simenel [Phys. Rev. Lett. 105, 192701 (2010)]. We show results of the TDHF calculations for transfer cross sections of the reactions of ${}^{40,48}\mathrm{Ca}+{}^{124}\mathrm{Sn}$ at $E_{\mathrm{lab}}=170$, 174 MeV, ${}^{40}\mathrm{Ca}+{}^{208}\mathrm{Pb}$ at $E_{\mathrm{lab}}=235$, 249 MeV, and ${}^{58}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ at $E_{\mathrm{lab}}=328.4$ MeV, for which measurements are available. We find the transfer processes show different behaviors depending on the $N/Z$ ratios of the projectile and the target and the product of the charge numbers, $Z_{\mathrm{P}}{Z}_{\mathrm{T}}$. When the projectile and the target have different $N/Z$ ratios, fast transfer processes of a few nucleons towards the charge equilibrium of the initial system occur in reactions at large impact parameters. As the impact parameter decreases, a neck formation is responsible for the transfer. A number of nucleons are transferred by the neck breaking when two nuclei dissociate, leading to transfers of protons and neutrons in the same direction. Comparing cross sections by theory and measurements, we find the TDHF theory describes the transfer cross sections of a few nucleons reasonably. As the number of transferred nucleons increases, the agreement becomes less accurate. The TDHF calculation overestimates transfer cross sections accompanying a large number of neutrons when more than one proton are transferred. Comparing our results with those by other theories, we find the TDHF calculations give qualitatively similar results to those of direct reaction models such as grazing and Complex WKB.

The dynamical cluster-decay model (DCM), with effects of deformations and orientations of nuclei included in it, is used to study the decay of the hot and rotating compound nucleus ${}^{105}$Ag${}^{*}$ formed in a ${}^{12}\mathrm{C}+{}^{93}\mathrm{Nb}$ reaction at near and below barrier energies. The only parameter of the model is the neck-length parameter, which varies smoothly with the temperature of the compound nucleus, and its value remains within the range of validity ($\sim$2 fm) of the proximity potential. The emissions of both the observed light particles ($A_2=1–4$) representing the evaporation residue (ER) and the (energetically favored) intermediate mass fragments (IMFs; $5\le A_2\le 13$), together with the so far unobserved fission channel, are considered as the dynamical collective mass motions of preformed fragments or clusters through the barrier. A best fit to data is shown to be obtained only if a large noncompound-nucleus (nCN) contribution, calculated as a quasifission or capture process, is allowed in the DCM. Another interesting result is that the one-neutron contribution is large, rather the largest, when best fits are attempted only for the ER cross sections, but, in turn, it reduces to zero or becomes relatively small if the data on the total fusion cross section ${\sigma }_{\mathrm{fus}}$, i.e., ${\sigma }_{\mathrm{ER}}+{\sigma }_{\mathrm{IMFs}}$, are considered. Furthermore, the fusion-fission (ff) cross section ${\sigma }_{\mathrm{ff}}$, consisting of symmetric and near-symmetric fragments, at the considered three energies of the experiment, is predicted to be of the order of 10${}^1$ to 10${}^3$ mb, depending on the choice of neck-length parameter for fission region. Further experimental studies are called for both the nCN and ff channels in this reaction.

We have used the ${}^{13}$B($d,p$)${}^{14}$B reaction in inverse kinematics to study the properties of states in ${}^{14}$B, the lightest particle-bound $N=9$ isotone. The spectroscopic information, including spins, parities, and spectroscopic factors for the states observed in ${}^{14}$B are used to deduce the wave functions for the low-lying negative parity $\nu \left(\mathit{sd}\right)$ levels, as well as provide information about the evolution of the effective neutron $1s_{1/2}-0d_{5/2}$ single-particle energies. The data confirm that the ground and first-excited states are predominantly $s$ wave in character and are single-neutron halo states. The effective single-particle energies are found to match the trends set by other $N=9$ isotones.

A recent measurement of Coulomb excitation of the ${}^{224}\mathrm{Ra}$ projectile has determined $E3$ strengths for the first time in this region. The critical-point character of ${}^{224}\mathrm{Ra}$ is confirmed by these new results.

The ${}^{18}$Ne($\alpha$,$p$)${}^{21}$Na reaction provides a pathway for breakout from the hot CNO cycles to the $rp$ process in type-I x-ray bursts. To better determine this astrophysical reaction rate, the resonance parameters of the compound nucleus ${}^{22}$Mg have been investigated by measuring the resonant elastic scattering of ${}^{21}$Na+$p$. An 89 MeV ${}^{21}$Na radioactive ion beam was produced at the CNS Radioactive Ion Beam Separator and bombarded an 8.8 mg/cm${}^2$ thick polyethylene target. The recoiled protons were measured at scattering angles of ${\theta }_{\mathrm{c}.\mathrm{m}.}\approx 175{}^{\circ }$ and 152${}^{\circ }$ by three $\Delta E$-$E$ silicon telescopes. The excitation function was obtained with a thick-target method over energies $E_x$(${}^{22}$Mg) = 5.5–9.2 MeV. The resonance parameters have been determined through an $R$-matrix analysis. For the first time, the $J^{\pi }$ values for ten states above the $\alpha$ threshold in ${}^{22}$Mg have been experimentally determined in a single consistent measurement. We have made three new $J^{\pi }$ assignments and confirmed seven of the ten tentative assignments in the previous work. The ${}^{18}$Ne($\alpha$,$p$)${}^{21}$Na reaction rate has been recalculated, and the astrophysical impact of our new rate has been investigated through one-zone postprocessing x-ray burst calculations. We find that the ${}^{18}$Ne($\alpha$,$p$)${}^{21}$Na rate significantly affects the peak nuclear energy generation rate and the onset temperature of this breakout reaction in these phenomena.