The neutron spin rotation induced by parity-violating (PV) components in the nucleon-nucleon potential is studied in $\overrightarrow{n}\text{−}d$ scattering at zero energy. Results are obtained corresponding to the Argonne $v_{18}$ two-nucleon and Urbana-IX three-nucleon strong-interaction potentials in combination with either the Desplanques-Donoghue-Holstein or pionless effective field theory models for the weak-interaction potential. We find that this observable is dominated by the contribution of the long-range part of the PV potential associated with pion exchange. Thus its measurement could provide a further constraint, complementary to that coming from measurements of the photon asymmetry in $\overrightarrow{n}\text{−}p$ radiative capture, on the strength of this component of the hadronic weak interaction.

The neutron-rich nucleus ${}^{30}\mathrm{Na}$ in the vicinity of the “Island of Inversion” was investigated using intermediate-energy Coulomb excitation. A single $\gamma$-ray transition was observed and attributed to the $3_1^{+}\to 2_{\mathrm{gs}}^{+}$ decay. A transition probability of $B(E2;2_{\mathrm{gs}}^{+}\to 3_1^{+})=147(21)\hspace{0.5em}{e}^2\hspace{0.5em}{\mathrm{fm}}^4$ was determined and found in agreement with a previous experiment and with large-scale shell-model calculations. Evidence for the strong excitation of the $4_1^{+}$ state predicted by the shell-model calculations was not observed.

Neutron-rich nuclei of ${}^{153,155}\mathrm{Nd}$ were studied from the spontaneous fission of ${}^{252}\mathrm{Cf}$. Eleven and nine new γ transitions were identified in ${}^{153}\mathrm{Nd}$ and ${}^{155}\mathrm{Nd}$, respectively. Rotational bands with the configurations of $\nu 5/2[642]$ and $\nu 3/2[521]$ were identified in ${}^{153}\mathrm{Nd}$ and ${}^{155}\mathrm{Nd}$, respectively. Excited states and γ transitions in ${}^{155}\mathrm{Nd}$ are reported for the first time here.

We present the first study to examine the validity of the relativistic impulse approximation (RIA) for describing elastic proton-nucleus scattering at incident laboratory kinetic energies lower than 200 MeV. For simplicity we choose a ${}^{208}\mathrm{Pb}$ target, which is a spin-saturated spherical nucleus for which reliable nuclear structure models exist. Microscopic scalar and vector optical potentials are generated by folding invariant scalar and vector scattering nucleon-nucleon ($\mathit{NN}$) amplitudes, based on our recently developed relativistic meson-exchange model, with Lorentz scalar and vector densities resulting from the accurately calibrated PK1 relativistic mean field model of nuclear structure. It is seen that phenomenological Pauli blocking (PB) effects and density-dependent corrections to $\sigma N$ and $\omega N$ meson-nucleon coupling constants modify the RIA microscopic scalar and vector optical potentials so as to provide a consistent and quantitative description of all elastic scattering observables, namely, total reaction cross sections, differential cross sections, analyzing powers and spin rotation functions. In particular, the effect of PB becomes more significant at energies lower than 200 MeV, whereas phenomenological density-dependent corrections to the $\mathit{NN}$ interaction also play an increasingly important role at energies lower than 100 MeV.

The experimental observation of hadrons correlated back-to-back with a (semi-)hard trigger in heavy-ion collisions has revealed a splitting of the away side correlation structure in a low to intermediate transverse momentum ($P_T$) regime. This is consistent with the assumption that energy deposited by the away side parton into the bulk medium produced in the collision excites a sonic shock wave (a Mach cone) that leads to away side correlation strength at large angles. A prediction that follows from assuming such a hydrodynamical origin of the correlation structure is that there is a sizable elongation of the shock wave in rapidity due to the longitudinal expansion of the bulk medium. Using a single-hadron trigger, this cannot be observed because of the unconstrained rapidity of the away side parton. Using a dihadron trigger, the rapidity of the away side parton can be substantially constrained and the longitudinal structure of the away side correlation becomes accessible. However, in such events several effects occur that change the correlation structure substantially: There is not only a sizable contribution due to the fragmentation of the emerging away side parton but also a systematic bias toward small energy deposition into the medium and hence a weak shock wave. In this article, both effects are addressed.

The $(W,Q^2)$ dependence of the ratio of inclusive electron scattering cross sections for ${}^{15}\mathrm{N}$/${}^{12}\mathrm{C}$ was determined in the kinematic ranges $0.8<W<2$ GeV and $0.2<Q^2<1$ GeV${}^2$ using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratios exhibit only slight resonance structure, in agreement with a simple phenomenological model and an extrapolation of deep-inelastic scattering ratios to low $Q^2$. Ratios of ${}^4\mathrm{He}$/${}^{12}\mathrm{C}$ using 1.6 to 2.5 GeV electrons were measured with very high statistical precision and were used to correct for He in the N and C targets. The $(W,Q^2)$ dependence of the ${}^4\mathrm{He}$/${}^{12}\mathrm{C}$ ratios is in good agreement with that of the phenomenological model and exhibit significant resonance structure centered at $W=0.94,1.23$, and 1.5 GeV.

We present the first measurement of the Σ beam asymmetry in η photoproduction on the neutron in the photon energy range from threshold to 1.5 GeV. Data have been collected by using the tagged and linearly polarized photon beam and the large solid angle apparatus of the GRAAL facility. Neutron data have been selected among η photoproduction events on the deuteron in the quasi-free kinematics approximation. Proton data, extracted in the same way, are within errors identical to those previously obtained on free protons at the GRAAL facility, except for a few points falling in certain energy bins. This difference is, however, well understood in terms of the Fermi motion of the nucleons in the deuteron. We take the consistency of free and quasi-free proton data as an indication that nuclear effects are negligible also for neutron data. The ETAMAID model, in which a strong coupling of the $D_{15}(1675)$ resonance to the $\eta$-neutron channel is introduced, can explain the proton data very well, but it cannot describe the beam asymmetry for the neutron.

The charged-current quasielastic scattering of muon neutrino on the oxygen target is analyzed for neutrino energy up to 2.5 GeV using the relativistic distorted-wave impulse approximation (RDWIA). The inclusive cross sections $d^2\sigma /{\mathit{dQ}}^2$, calculated within the RDWIA, are lower than the relativistic Fermi gas model results in the range of the square of four-momentum transfer $Q^2⩽0.2$ (GeV/$c$)${}^2$. We also studied the nuclear-model dependence of the neutrino energy reconstruction accuracy using the charged-current quasielastic events with no detector effects and background. We found that for one-track events the accuracy is nuclear model dependent for neutrino energy up to 2.5 GeV.

One of the key uncertainties in our understanding of the astrophysical $\mathit{rp}$ process is the extent to which even-even $N=Z$ nuclei such as ${}^{68}\mathrm{Se}$ and ${}^{72}\mathrm{Kr}$ act as waiting points in the process because of the next nucleus in the proton-capture chain being proton unbound. For these specific cases, much of the argument is based on the nonobservation of ${}^{69}\mathrm{Br}$ and ${}^{73}\mathrm{Rb}$ following projectile fragmentation. An examination of the nuclear structure involved, and the high population of low-lying isomers in the mirror nuclei, ${}^{69}\mathrm{Se}$ and ${}^{73}\mathrm{Kr}$ in fragmentation, suggests that this nonobservation may be down to a shadowing mechanism where the majority of the population goes to the isomer that proton decays before the ground state can be reached. Strong conclusions on the extent to which the ${}^{69}\mathrm{Br}$ and ${}^{73}\mathrm{Rb}$ are unbound may therefore be unsafe. The possible astrophysical implications of this are discussed along with the relevance of this shadowing mechanism to the search for exotic nuclei in fragmentation.

The electric quadrupole transition from the first $2^{+}$ state to the ground $0^{+}$ state in ${}^{18}\mathrm{C}$ was studied through a lifetime measurement by an upgraded recoil shadow method applied to inelastically scattered radioactive ${}^{18}\mathrm{C}$ nuclei. The measured mean lifetime is $18.9\pm 0.9(\mathrm{stat})\pm 4.4(\mathrm{syst})$ ps, corresponding to a $B$($E2;2_1^{+}\to 0_{\mathrm{g}.\mathrm{s}.}^{+}$) value of $4.3\pm 0.2\pm 1.0\hspace{0.17em}{e}^2$ fm${}^4$, or about 1.5 Weisskopf units. The mean lifetime of the first $2^{+}$ state in ${}^{16}\mathrm{C}$ was remeasured to be $18.3\pm 1.4\pm 4.8$ ps, about four times shorter than the value reported previously. The discrepancy between the two results was explained by incorporating the γ-ray angular distribution measured in this work into the previous measurement. These transition strengths are hindered compared to the empirical transition strengths, indicating that the anomalous hindrance observed in ${}^{16}\mathrm{C}$ persists in ${}^{18}\mathrm{C}$.

We analyze α inelastic scattering on ${}^{12}\mathrm{C}$ exciting the $0_2^{+}$ state at the incident energy of $E_{\alpha }=240$ MeV using the eikonal wave Born approximation and investigate what determines the oscillation pattern appearing in the inelastic angular distribution. We present an interpretation for the results obtained by the present author and his collaborator [Phys. Rev. C 74, 054606 (2006)] that the oscillation pattern in inelastic angular distribution is almost independent of the nuclear radius of ${}^{12}\mathrm{C}$($0_2^{+}$).

Model independent formulas are derived for the beam analyzing power $A_y$ and beam to meson spin transfers in $\mathit{pp}\to \mathit{pp}\omega$, taking into consideration all six threshold partial wave amplitudes $f_1,\dots ,f_6$ covering the $\mathit{Ss}$, $\mathit{Sp}$, and $\mathit{Ps}$ channels. It is shown that the lowest three partial wave amplitudes $f_1,f_2,f_3$ can be determined empirically without any discrete ambiguities. Partial information with regard to the amplitudes $f_4,f_5,f_6$ covering the $\mathit{Ps}$ channel may be extracted, if the measurements are carried through at the double differential level.

The photoproduction process of neutral kaons on a liquid deuterium target is investigated near the threshold region, $E_{\gamma }=0.8\text{−}1.1$ GeV. $K^0$ events are reconstructed from positive and negative pions, and differential cross sections are derived. Experimental momentum spectra are compared with those calculated in the spectator model using a realistic deuteron wave function. Elementary amplitudes as given by recent isobar models and a simple phenomenological model are used to study the effect of the new data on the angular behavior of the elementary cross section. The data favor a backward-peaked angular distribution of the elementary $n(\gamma ,K^0)\Lambda$ process, which provides additional constraints on current models of kaon photoproduction. The present study demonstrates that the $n(\gamma ,K^0)\Lambda$ reaction can provide key information on the mechanism of the photoproduction of strangeness.

Recent calculations with an effective isospin-dependent contact interaction show the possibility of the crossover from superfluidity of neutron Cooper pairs in the ${{}^1\mathrm{S}}_0$ pairing channel to Bose-Einstein condensation (BEC) of di-neutron bound states in dilute nuclear matter. The density and spin correlation functions are calculated for a di-neutron condensate in asymmetric nuclear matter with the aim of finding the possible features of the BCS-BEC crossover. It is shown that the zero-momentum transfer spin correlation function satisfies the sum rule at zero temperature. In symmetric nuclear matter, the density correlation function changes sign at low momentum transfer across the BCS-BEC transition, and this feature can be considered as a signature of the crossover. At finite isospin asymmetry, this criterion gives too large a value for the critical asymmetry ${\alpha }_c^d~0.9$, at which the BEC state is quenched. Therefore, it can be trusted for the description of the density-driven BCS-BEC crossover of neutron pairs only at small isospin asymmetry. This result generalizes the conclusion of the study in Phys. Rev. Lett. 95, 090402 (2005), where the change of sign of the density correlation function at low momentum transfer in two-component quantum fermionic atomic gas with the balanced populations of fermions of different species was considered as an unambiguous signature of the BCS-BEC transition.

We prove the existence theorem for a scalar density functional (DF) for nuclei. The theorem is a direct consequence of the rotational invariance of the nuclear Hamiltonian. Since the DF depends only on scalar densities, practical predictions of ground state (g.s.) energies reduce to one-dimensional, radial calculations.

Possible configurations in which excitons can be excited are demonstrated and discussed. A pre-equilibrium model code was developed in the framework of exciton and hybrid models using specified exciton configurations. The calculations were restricted to proton induced reactions at energies below 100 MeV. Results support the suggestion that a hole exists just below the Fermi energy before the reaction is initiated. A reduction in the relative abundance of high energy particles in the emission spectra may arise from the existence of such a hole state in the initial reaction phase and a subsequent thermalization among excitons during the phase lifetime. All suggested particle configurations give similar final results; the distinction among them lies in how and when the emissions occur. A “memory” factor is given for the particle configurations to determine to what extent the configuration can “remember” the entrance channel.

The equation of state (EOS) for nuclear and neutron rich matter is investigated in a relativistic mean field (RMF) model. New shell states are found that minimize the free energy per baryon, calculated in a spherical Wigner-Seitz (WS) approximation, over a significant range of baryon densities. These shell states, that have both inside and outside surfaces, minimize the Coulomb energy of large proton number configurations at the expense of a larger surface energy. This is related to a possible depression in the central density of super heavy nuclei. As the baryon density increases, we find the system changes from normal nuclei, to shell states, and then to uniform matter.

In the present article we investigate the onset of the pasta phase with different parametrizations of the nonlinear Walecka model. At zero temperature two different methods are used, one based on coexistent phases and the other on the Thomas-Fermi approximation. At finite temperature only the coexistence phases method is used. $\mathit{npe}$ matter with fixed proton fractions and in $\beta$ equilibrium is studied. The pasta phase decreases with the increase of temperature. The internal pasta structure and the beginning of the homogeneous phase vary depending on the proton fraction (or the imposition of $\beta$ equilibrium), on the method used, and on the chosen parametrization. It is shown that a good parametrization of the surface tension with dependence on the temperature, proton fraction, and geometry is essential to describe correctly large isospin asymmetries and the transition from pasta to homogeneous matter.

The equal filling approximation, a procedure widely used in mean-field calculations to treat the dynamics of odd nuclei in a time-reversal invariant way, is justified as the consequence of a variational principle over an average energy functional. The ideas of statistical quantum mechanics are employed in the justification. As an illustration of the method, the ground and lowest-lying states of some octupole deformed radium isotopes are computed.

Microscopic structure of the low-lying isovector dipole excitation mode in neutron-rich ${}^{26,28,30}\mathrm{Ne}$ is investigated by performing deformed quasiparticle-random-phase-approximation (QRPA) calculations. The particle-hole residual interaction is derived from a Skyrme force through a Landau-Migdal approximation. We obtain the low-lying resonance in ${}^{26}\mathrm{Ne}$ at around 8.6 MeV. It is found that the isovector dipole strength at $E_x<10$ MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule. This excitation mode is composed of several QRPA eigenmodes, one is generated by a $\nu (2s_{1/2}^{-1}2p_{3/2})$ transition dominantly and the other mostly by a $\nu (2s_{1/2}^{-1}2p_{1/2})$ transition. The neutron excitations take place outside of the nuclear surface reflecting the spatially extended structure of the $2s_{1/2}$ wave function. In ${}^{30}\mathrm{Ne}$, the deformation splitting of the giant resonance is large, and the low-lying resonance overlaps with the giant resonance.