The eccentricity in coordinate space at midrapidity of the overlap zone in high-energy heavy-ion collisions predicted by the $k_{\perp }$-factorization formalism is generically larger than expected from scaling with the number of participants. We provide a simple qualitative explanation of the effect which shows that it is not caused predominantly by edge effects. We also show that it is quite insensitive to “details” of the unintegrated gluon distribution functions such as the presence of leading-twist shadowing and of an extended geometric scaling window. The larger eccentricity increases the azimuthal asymmetry of high transverse momentum particles. Finally, we point out that the longitudinal structure of the color glass condensate initial condition for hydrodynamics away from midrapidity is nontrivial but requires understanding of large-$x$ effects.

The effects of strong magnetic fields on neutron star matter are investigated in the quark-meson coupling (QMC) model. The QMC model describes a nuclear many-body system as nonoverlapping MIT bags in which quarks interact through self-consistent exchange of scalar and vector mesons in the mean-field approximation. The results of the QMC model are compared with those obtained in a relativistic mean-field (RMF) model. It is found that quantitative differences exist between the QMC and RMF models, whereas qualitative trends of the magnetic-field effects on the equation of state and composition of neutron star matter are very similar.

In the rest frame of a many-body system, used in the calculation of its static and scattering properties, the center of mass of a two-body subsystem is allowed to drift. We show, in a model-independent way, that drift corrections to the nucleon-nucleon potential are relatively large and arise from both one- and two-pion exchange processes. As far as chiral symmetry is concerned, corrections to these processes begin, respectively, at $\mathcal{O}(q^2)$ and $\mathcal{O}(q^4)$. The two-pion exchange interaction also yields a new spin structure, which promotes the presence of $P$ waves in trinuclei and is associated with profile functions that do not coincide with either central or spin-orbit ones. In principle, the new spin terms should be smaller than the $\mathcal{O}(q^3)$ spin-orbit components. However, in the isospin-even channel, a large contribution defies this expectation and gives rise to the prediction of important drift effects.

For the first time, complete quantal expressions are provided for the intrinsic components of the quadrupole tensor in the geometric Holstein-Primakoff representation of the IBA-1. These expressions are valid throughout the Casten triangle.

The Skyrme energy-density functional approach has been extended to study massive heavy-ion fusion reactions. Based on the potential barrier obtained and the parametrized barrier distribution the fusion (capture) excitation functions of a lot of heavy-ion fusion reactions are studied systematically. The average deviations of fusion cross sections at energies near and above the barriers from experimental data are less than 0.05 for $92\%$ of 76 fusion reactions with $Z_1{Z}_2<1200$. For the massive fusion reactions, for example, the ${}^{238}\mathrm{U}$-induced reactions and ${}^{48}\mathrm{Ca}+{}^{208}\mathrm{Pb}$, the capture excitation functions have been reproduced remarkably well. The influence of structure effects in the reaction partners on the capture cross sections is studied with our parametrized barrier distribution. By comparing the reactions induced by double-magic nucleus ${}^{48}\mathrm{Ca}$ and by ${}^{32}\mathrm{S}$ and ${}^{35}\mathrm{Cl}$, the “threshold-like” behavior in the capture excitation function for ${}^{48}\mathrm{Ca}$-induced reactions is explored and an optimal balance between the capture cross section and the excitation energy of the compound nucleus is studied. Finally, the fusion reactions with ${}^{36}\mathrm{S}$, ${}^{37}\mathrm{Cl}$, ${}^{48}\mathrm{Ca}$, and ${}^{50}\mathrm{Ti}$ bombarding ${}^{248}\mathrm{Cm}$, ${}^{247,249}\mathrm{Bk}$, ${}^{250,252,254}\mathrm{Cf}$, and ${}^{252,254}\mathrm{Es}$, as well as the reactions leading to the same compound nucleus with $Z=120$ and $N=182$, are studied further. The calculation results for these reactions are useful for searching for the optimal fusion configuration and suitable incident energy in the synthesis of superheavy nuclei.

The effects of symmetry energy softening of relativistic mean field (RMF) models on the properties of matter with neutrino trapping are investigated. It is found that the effects are less significant than those in the case without neutrino trapping. The weak dependence of the equation of state on the symmetry energy is shown as the main reason for this finding. Using different RMF models the dynamical instabilities of uniform matters, with and without neutrino trapping, have been also studied. The interplay between the dominant contribution of the variation of matter composition and the role of effective masses of mesons and nucleons leads to higher critical densities for matter with neutrino trapping. Furthermore, the predicted critical density is insensitive to both the number of trapped neutrinos as well as the RMF model used in the investigation. It is also found that additional nonlinear terms in the Horowitz-Piekarewicz and Furnstahl-Serot-Tang models prevent another kind of instability, which occurs at relatively high densities, because the effective σ meson mass in their models increases as a function of matter density.

A determination by noble gas mass spectrometry of ${}^{22}\mathrm{Ne}$ production through the combined reactions ${}^{19}\mathrm{F}$($\alpha ,n$)${}^{22}\mathrm{Na}$(${\beta }^{+}$)${}^{22}\mathrm{Ne}$ and ${}^{19}\mathrm{F}$($\alpha ,p$)${}^{22}\mathrm{Ne}$ on natural calcium fluoride is made for the first time. Six samples of U-rich fluorite from a fluorspar deposit in Mexico were used to determine the ${}^{22}{\mathrm{Ne}}_{\mathrm{nucl}}{/}^4{\mathrm{He}}_{\mathrm{rad}}$ ratio generated by the spontaneous decay of U during the last 32 Ma. The obtained ratio (1.33 ± 0.11) $\times {10}^{-5}$ (95% confidence), is compared to other experimental data on natural uranium oxides and theoretical values.

A γ-soft analog of the confined β-soft rotor model is developed by using a γ-independent displaced infinite-well β potential in the Bohr Hamiltonian, for which exact separation of variables is possible. Level schemes interpolating between the E(5) critical point symmetry (with $R_{4/2}=E(4_1^{+})/E(2_1^{+})=2.20$) and the O(5) γ-soft rotor (with $R_{4/2}=2.50$) are obtained; these exhibit a crossover of excited $0^{+}$ bandheads that lead to agreement with the general trends of $0_2^{+}$ states in this region and is observed experimentally in ${}^{128,130}\mathrm{Xe}$.

The proton emission induced by polarized photons is studied in the energy range above the giant resonance region and below the pion emission threshold. Results for the ${}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}$, and ${}^{40}\mathrm{Ca}$ nuclei are presented. The sensitivity of various observables to final-state interaction, meson exchange currents, and short-range correlations is analyzed. We found relevant effects due to the virtual excitation of the Δ resonance.

The ${}^{220}\mathrm{Th}$ level scheme has been considerably extended from an experiment using the ${}^{26}\mathrm{Mg}+{}^{198}\mathrm{Pt}$ reaction at 128 MeV. The evaporation residues from this very fissile system were selected with the HERCULES detector system and residue-gated $\gamma$ rays were measured with Gammasphere. The simplex feature (alternating-parity levels) persists up to the highest spins observed ($23\hslash$), but the nucleus exhibits a more vibrational-like behavior than the heavier Th isotopes. In addition, a doubling of the negative-parity, odd-spin states is seen as well as a staggering of the $B(E1)/B(E2)$ ratios. A new interpretation based on a picture of tidal waves on a reflection-asymmetric nuclear surface is proposed.

The ${}^{28}\mathrm{Si}$($p,t$)${}^{26}\mathrm{Si}$ reaction has been studied to resolve a controversy surrounding the properties of the ${}^{26}\mathrm{Si}$ level at 5.914 MeV and its contribution to the ${}^{25}\mathrm{Al}$($p,\gamma$)${}^{26}\mathrm{Si}$ reaction rate in novae, which affects interpretations of galactic ${}^{26}\mathrm{Al}$ observations. Recent studies have come to contradictory conclusions regarding the spin of this level ($0^{+}$ or $3^{+}$), with a $3^{+}$ assignment implying a large contribution by this level to the ${}^{25}\mathrm{Al}$($p,\gamma$)${}^{26}\mathrm{Si}$ reaction rate. We have extended our previous study [Bardayan et al., Phys. Rev. C 65, 032801(R) (2002)] to smaller angles and find the angular distribution of tritons populating the 5.914-MeV level in the ${}^{28}\mathrm{Si}$($p,t$)${}^{26}\mathrm{Si}$ reaction to be consistent with either a $2^{+}$ or $3^{+}$ assignment. We have calculated reaction rates under these assumptions and used them in a nova nucleosynthesis model to examine the effects of the remaining uncertainties in the ${}^{25}\mathrm{Al}$($p,\gamma$)${}^{26}\mathrm{Si}$ rate on ${}^{26}\mathrm{Al}$ production in novae.

Borexino is an experiment for low-energy neutrino spectroscopy at the Gran Sasso underground laboratories. It is designed to measure the monoenergetic ${}^7\mathrm{Be}$ solar neutrino flux in real time, via neutrino-electron elastic scattering in an ultrapure organic liquid scintillator. Borexino has the potential to also detect neutrinos from the $\mathit{pep}$ fusion process and the CNO cycle. For this measurement to be possible, radioactive contamination in the detector must be kept extremely low. Once sufficiently clean conditions are met, the main background source is ${}^{11}\mathrm{C}$, produced in reactions induced by the residual cosmic muon flux on ${}^{12}\mathrm{C}$. In the process, a free neutron is almost always produced. ${}^{11}\mathrm{C}$ can be tagged on an event-by-event basis by looking at the threefold coincidence with the parent muon track and the subsequent neutron capture on protons. This coincidence method has been implemented on the Borexino Counting Test Facility data. We report on the first event-by-event identification of in situ muon-induced ${}^{11}\mathrm{C}$ in a large underground scintillator detector. We measure a ${}^{11}\mathrm{C}$ production rate of 0.130 ± 0.026(stat) ± 0.014(syst) day${}^{-1}$ ton${}^{-1}$, in agreement with predictions from both experimental studies performed with a muon beam on a scintillator target and ab initio estimations based on the ${}^{11}\mathrm{C}$ producing nuclear reactions.

The one-neutron knockout reaction ${}^9\mathrm{Be}$(${}^{57}\mathrm{Cr}$,${}^{56}\mathrm{Cr}$+γ)X has been measured in inverse kinematics with an intermediate-energy beam. Cross sections to individual states in ${}^{56}\mathrm{Cr}$ were partially untangled through the detection of the characteristic γ-ray transitions in coincidence with the reaction residues. The experimental inclusive longitudinal momentum distribution and the yields to individual states are compared to calculations that combine spectroscopic factors from the full $\mathit{fp}$ shell model and nucleon-removal cross sections computed in a few-body eikonal approach.

Two different three-body models are compared with a fully antisymmetrized microscopic three-cluster model. The local model makes use of local effective interactions involving forbidden states among the three particles. In the semi-microscopic model, nonlocal two-body interactions are derived within the resonating-group method from the same nucleon-nucleon effective forces as in the microscopic model. In both cases, calculations are performed in hyperspherical coordinates with the Lagrange-mesh method. The role of forbidden states and their elimination are discussed. The models are applied to an $\alpha \alpha n$ description of ${}^9\mathrm{Be}$ and an $\alpha \mathit{nn}$ description of ${}^6\mathrm{He}$. The local model results are affected by almost forbidden states and may be unrealistic for ${}^9\mathrm{Be}$. A comparison of the microscopic and semi-microscopic models shows that the effect of exchanges involving the three clusters is weak. An overbinding of ${}^9\mathrm{Be}$ cannot be avoided with nucleon-nucleon forces reproducing $\alpha n$ and $\alpha \alpha$ scattering properties. On the contrary, ${}^6\mathrm{He}$ is underbound under the same conditions. This can probably be attributed to a lack of three-nucleon forces.

The Doppler-shift attenuation method was applied to measure the lifetime of the 4.03 MeV state in ${}^{19}\mathrm{Ne}$. By utilizing a ${}^3\mathrm{He}$-implanted Au foil as a target, the state was populated using the ${}^{20}\mathrm{Ne}$(${}^3\mathrm{He}$, $\alpha$)${}^{19}\mathrm{Ne}$ reaction in inverse kinematics at a ${}^{20}\mathrm{Ne}$ beam energy of 34 MeV. De-excitation γ rays were detected in coincidence with α particles. At the 1σ level, the lifetime was determined to be ${11}_{-3}^{+4}$ fs and at the 95.45% confidence level the lifetime is ${11}_{-7}^{+8}$ fs.

Incoherent pion electroproduction on the deuteron is studied from threshold up to the second resonance region with special emphasis on the influence of the final-state interaction, in particular on polarization observables. The elementary $\gamma N\to \pi N$ amplitude is taken from the MAID-2003 model. The final-state interaction is included by considering complete rescattering in the final $\mathit{NN}$ and $\pi N$ subsystems. Investigated in detail is their influence on the structure functions governing the semi-exclusive differential cross section, where besides the scattered electron only the produced pion is detected. For charged pion-production the effect of $\mathit{NN}$ rescattering is moderate whereas $\pi N$ rescattering is almost negligible, except very close to threshold. $\mathit{NN}$ rescattering appears much stronger in neutral pion production for which the primary mechanism is the elimination of a significant spurious coherent contribution in the impulse approximation. Sizeable effects are also found in some of the polarization structure functions for beam and/or target polarizations.

The decay properties of ${}^{290}116$ and ${}^{291}116$, and the dependence of their production cross sections on the excitation energies of the compound nucleus, ${}^{293}116$, have been measured in the ${}^{245}\mathrm{Cm}$ (${}^{48}\mathrm{Ca}$, $\mathit{xn}$)${}^{293-x}116$ reaction. These isotopes of element 116 are the decay daughters of element 118 isotopes, which are produced via the ${}^{249}\mathrm{Cf}+{}^{48}\mathrm{Ca}$ reaction. We performed the element 118 experiment at two projectile energies, corresponding to ${}^{297}118$ compound nucleus excitation energies of $E^{*}=29.2\pm 2.5$ and $34.4\pm 2.3$ MeV. During an irradiation with a total beam dose of $4.1\times {10}^{19}$ ${}^{48}\mathrm{Ca}$ projectiles, three similar decay chains consisting of two or three consecutive $\alpha$ decays and terminated by a spontaneous fission (SF) with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even-even isotope ${}^{294}118$ ($E_{\alpha }=11.65\pm 0.06$ MeV, $T_{\alpha }=0.{89}_{-0.31}^{+1.07}$ ms) produced in the $3n$-evaporation channel of the ${}^{249}\mathrm{Cf}+{}^{48}\mathrm{Ca}$ reaction with a maximum cross section of $0.5_{-0.3}^{+1.6}$ pb.

A fully gauge-invariant (pseudoscalar) meson photoproduction amplitude off a nucleon including the final-state interaction is derived. The approach based on a comprehensive field-theoretical formalism developed earlier by one of the authors replaces certain dynamical features of the full interaction current by phenomenological auxiliary contact currents. A procedure is outlined that allows for a systematic improvement of this approximation. The feasibility of the approach is illustrated by applying it to both the neutral and charged pion photoproductions.

The conditions under which nuclear collective modes couple to plasmon modes in asymmetric nuclear matter (ANM) neutralized by electrons, which is of interest for the study of neutron stars and supernovae, are investigated. The calculations were performed within a relativistic mean-field approach to nuclear matter, and the Coulomb field was included. We show that the coupling may be so strong that it affects the onset of the nuclear mode at low densities and may also affect its isovector/isoscalar character.