Neutron-rich matter at subnuclear densities may involve complex structures displaying a variety of shapes, such as spherical, slablike, and∕or rodlike shapes. These phases of the nuclear pasta are expected to exist in the crust of neutron stars and in core-collapse supernovae. The dynamics of core-collapse supernovae is very sensitive to the interactions between neutrinos and nucleons∕nuclei. Indeed, neutrino excitation of the low-energy modes of the pasta may allow for a significant energy transfer to the nuclear medium, thereby reviving the stalled supernovae shock. The linear response of the nuclear pasta to neutrinos is modeled via a simple semiclassical simulation. The transport mean free path for $\mu$ and $\tau$ neutrinos (and antineutrinos) is expressed in terms of the static structure factor of the pasta, which is evaluated using Metropolis Monte Carlo simulations.

A nonrelativistic potential-model version of the factorization assumption, used in perturbative QCD calculations of hadronic form factors, is used, along with the Born approximation valid at high energies, to derive a remarkably simple relationship between the impulse approximation contribution to the deuteron form factor at high-momentum transfer and the high-energy neutron-proton scattering amplitude. The relation states that the form factor at a given value of $Q^2$ is proportional to the scattering amplitude at a specific energy and scattering angle. This suggests that an accurate computation of the form factors at large $Q^2$ requires a simultaneous description of the phase shifts at a related energy, a statement that seems reasonable regardless of any derivation. Our form factor-scattering amplitude relation is shown to be accurate for some examples. However, if the potential consists of a strong short distance repulsive term and a strong longer-ranged attractive term, as typically occurs in many realistic potentials, the relation is found to be accurate only for ridiculously large values of $Q$. More general arguments, using only the Schrödinger equation, suggest a strong, but complicated, relationship between the form factor and scattering amplitude. Furthermore, the use of recently obtained soft potentials, along with an appropriate current operator, may allow calculations of form factors that are consistent with the necessary phase shifts.

In this paper we study the method of effective interaction as it is currently applied to few-body nuclear systems, i.e., the no-core approach. We have demonstrated that in the limit of very large model space, the no-core effective Hamiltonian is equivalent to the bare Hamiltonian transformed by a unitary transformation. This result is exact to second order in the norm of the two-body Lee-Suzuki similarity transformation operator. Using this result we propose a relation between the effective $A$-body wave function and the bare wave function. Verifying this proposition through numerical calculations we have found that the resulting wave function is a rather good approximation.

Isotopic and isotonic chains of superheavy nuclei are analyzed to search for spherical double shell closures beyond $Z=82$ and $N=126$ within the new effective field theory model of Furnstahl, Serot, and Tang for the relativistic nuclear many-body problem. We take into account several indicators to identify the occurrence of possible shell closures, such as two-nucleon separation energies, two-nucleon shell gaps, average pairing gaps, and the shell correction energy. The effective Lagrangian model predicts $N=172$ and $Z=120$ and $N=258$ and $Z=120$ as spherical doubly magic superheavy nuclei, whereas $N=184$ and $Z=114$ show some magic character depending on the parameter set. The magicity of a particular neutron (proton) number in the analyzed mass region is found to depend on the number of protons (neutrons) present in the nucleus.

The use of two proton-magic nuclei for both the projectile $(Z=28)$ and the target $(Z=50)$ in the “mirror” reaction types ${}^{58}\mathrm{Ni}+{}^{122}\mathrm{Sn}$ and ${}^{64}\mathrm{Ni}+{}^{116}\mathrm{Sn}$, leading to the same ${}^{180}\mathrm{Pt}$ compound nucleus, allows isolation of possible neutron-skin effects from both the target and the projectile. In these reactions, we studied the influence of neutron effects on the competition between fusion-fission, fusion-evaporation, and light-particle emission at equal compound-nucleus excitation energies and similar angular momentum distribution. The comparison of the experimental data, cross sections, and light-particle multiplicities, with the dynamical model HICOL and the statistical model GEMINI incorporating simple aspects of the dynamics, provides insights to the mechanisms of the studied reactions. Our study confirms that, at energy about $6\text{MeV}∕\text{nucleon}$, there is no influence of the entrance channel on the formation and on the decay of the compound nucleus produced by these reactions.

Elastic scattering angular distributions of the weakly bound ${}^9\mathrm{Be}$ projectile from ${}^{208}\mathrm{Pb}$ have been measured for 11 beam energies ranging from 38 to $75\text{MeV}$. Analysis was carried out with the optical model, employing a double folded microscopic real potential with four different ${}^9\mathrm{Be}$ density functions. The surface strengths of the interaction potentials were consistent and all exhibited a threshold anomaly. However, the renormalization factor required to obtain an optimum fit to the data varied significantly depending upon which ${}^9\mathrm{Be}$ density function was used, cautioning that conclusions about the effect of breakup should not be based solely upon the value of this factor. Fusion cross sections predicted from these potentials were extracted using a barrier penetration model. Comparison with recently published experimental data suggests that the flux removed from complete fusion by breakup is balanced by the flux redirected into the partial fusion channel.

The reaction ${}^6\mathrm{He}+{}^{64}\mathrm{Zn}$ was studied in order to investigate the effects of the projectile neutron-halo structure on the reaction mechanism at energies around the Coulomb barrier. Elastic scattering angular distributions, transfer∕breakup angular distributions, and fusion excitation functions have been measured. Due to the low-recoil energy of the evaporation residues and the low intensity of the ${}^6\mathrm{He}$ beam, the fusion cross section was measured by detecting off-line the atomic x-ray emission which follows the electron capture decay of the evaporation residues. For comparison the reaction ${}^4\mathrm{He}+{}^{64}\mathrm{Zn}$ was studied using the same technique. The data for the reaction ${}^6\mathrm{He}+{}^{64}\mathrm{Zn}$ show that the transfer and breakup mechanisms account for almost $80\%$ of the total reaction cross section, moreover we do not observe an enhancement of the fusion cross section when compared with the ${}^4\mathrm{He}+{}^{64}\mathrm{Zn}$ reaction.

A new two parameter formula for yrast energies, which works best for soft rotors or transitional nuclei, is proposed and compared with existing data.

The reaction systems, ${}^{64}\mathrm{Zn}+{}^{58}\mathrm{Ni}$, ${}^{64}\mathrm{Zn}+{}^{92}\mathrm{Mo}$, ${}^{64}\mathrm{Zn}+{}^{197}\mathrm{Au}$, at 26, 35, and $47A\text{MeV}$, have been studied both in experiments with a $4\pi$ detector array, NIMROD, and with antisymmetrized molecular dynamics model calculations employing effective interactions corresponding to soft and stiff equation of state (EOS). Direct experimental observables, such as multiplicity distributions, charge distributions, energy spectra and velocity spectra, have been compared in detail with those of the calculations and a reasonable agreement is obtained for both EOS’s. No conclusive preference for either EOS has been observed. Neither of the above direct observables nor the strength of the elliptic flow are also sensitive to changes in the in-medium nucleon-nucleon cross sections. A detailed analysis of the central collision events revealed that multifragmentation with cold fragment emission is a common feature predicted for all reactions studied here. A possible multifragmentation scenario is presented; after the preequilibrium emission ceases in the composite system, cold light fragments are formed in a hotter gas of nucleons and stay cold until the composite system underdoes multifragmentation. For reaction with ${}^{197}\mathrm{Au}$ at $47A\text{MeV}$ a significant radial expansion takes place. For reactions with ${}^{58}\mathrm{Ni}$ and ${}^{92}\mathrm{Mo}$ at $47A\text{MeV}$ semitransparency becomes prominent. The differing reaction dynamics drastically change the kinematic characteristics of emitted fragments. This scenario gives consistent explanations for many existing experimental results in the Fermi energy domain.

Ternary fission of ${}^{252}\mathrm{Cf}$ was studied at Gammasphere with eight $\Delta E\times E$ particle telescopes. After Doppler correction, the $3368\text{keV}{2}^{+}\to 0^{+}$ transition in ${}^{10}\mathrm{Be}$ was found in coincidence with the ${}^{10}\mathrm{Be}$ fragments with no evidence for any $\gamma$ rays not Doppler shifted for ${}^{10}\mathrm{Be}$ with $>21\text{MeV}$ kinetic energy. The ratio of the first $2^{+}$ to ground-state population probabilities was estimated as $N\left(2^{+}\right)∕N\left(0^{+}\right)=0.160\pm 0.025$. The angular distribution for $3368\text{keV}$ $\gamma$ rays indicated the spin alignment of excited ${}^{10}\mathrm{Be}$ nuclei preferentially is parallel or antiparallel to their momentum.

A new computational method for solving the configuration-space Faddeev equations for three-nucleon systems has been developed. This method is based on the spline decomposition in the angular variable and a generalization of the Numerov method for the hyperradius. The $s$-wave calculations of the inelasticity and phase shift as well as breakup amplitudes for $n\text{−}d$ and $p\text{−}d$ breakup scatterings for lab energies 14.1 and $42.0\text{MeV}$ were performed with the Malfliet-Tjon I-III potential. In the case of $n\text{−}d$ breakup scattering the results are in good agreement with those of the benchmark solution [J. L. Friar, B. F. Gibson, G. Berthold, W. Glöckle, Th. Cornelius, H. Witala, J. Haidenbauer, Y. Koike, G. L. Payne, J. A. Tjon, and W. M. Kloet, Phys. Rev. C 42, 1838 (1990); J. L. Friar, G. L. Payne, W. Glöckle, D. Hüber, and H. Witala, Phys. Rev. C 51, 2356 (1995)]. In the case of $p\text{−}d$ quartet breakup scattering disagreement for the inelasticities reaches up to $6\%$ as compared with those of the Pisa group [A. Kievsky, M. Viviani, and S. Rosati, Phys. Rev. C 64, 024002 (2001)]. The calculated $p\text{−}d$ amplitudes fulfill the optical theorem with a good precision.

The cross section and polarization for nucleon elastic scattering from ${}^{16}\mathrm{O}$ has a minimum at large angles and low energies that cannot be fitted with phenomenological or microscopic local optical potentials. Inclusion of exchange terms, e.g., knock-on and heavy-ion exchange, also failed to reproduce this minimum. However, it has been well fitted previously with a parity dependent (local) optical potential. It is shown here that this parity dependence simulates, at least in part, the nonlocality due to channel coupling.

Within a quantum molecular dynamics model we calculate the largest Lyapunov exponent (LLE), the density fluctuation, and the mass distribution of fragments for a series of nuclear systems at different initial temperatures. It is found that the LLE peaks at the temperature (“critical temperature”) where the density fluctuation reaches a maximal value and the mass distribution of fragments is best fitted by the Fisher’s power law from which the critical exponents for mass and charge distribution are obtained. The time-dependent behavior of the LLE and density fluctuation is studied. We find that the time scale of the density fluctuation is much longer than that of the inverse LLE, which indicates that chaotic motion can be well developed during the process of fragment formation. The finite-size effect on “critical temperature” for nuclear systems ranging from calcium to superheavy nuclei is also studied.

The $t+{}^3\mathrm{He}$ cluster structures in ${}^6\mathrm{Li}$ were investigated by using the ${}^7\mathrm{Li}\left({}^3\mathrm{He},\alpha \right)$ reaction at $450\text{MeV}$ and at ${\theta }_L=0°$. A binary decay into $t+{}^3\mathrm{He}$ with a branching ratio of $0.8\pm 0.2$ from a broad state at $E_x=21\text{MeV}$ in ${}^6\mathrm{Li}$ was observed by measuring $t$ and ${}^3\mathrm{He}$ decay particles. From the measured angular correlations and with the analysis of the spectral shape by using the Breit-Wigner formula, the $21\text{−}\text{MeV}$ resonance was decomposed into the ${}^{1}P$ $\left(T=0\right)$ state at $E_x=18.0\pm 0.5\text{MeV}$ with $\Gamma \left(\text{FWHM}\right)=5.0\pm 0.5\text{MeV}$ (where FWHM means full width at half maximum), and the ${}^{3}P$ $\left(T=1\right)$ state at $E_x=22\pm 1\text{MeV}$ with $\Gamma =8\pm 1\text{MeV}$.

The isovector giant dipole resonance (GDR) of an $\alpha$ cluster in ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$, and its analogs in ${}^{6,7}\mathrm{Be}$ and ${}^{6,7}\mathrm{He}$ were searched for by using the ${}^{6,7}\mathrm{Li}\left(p,p^{\prime }\right)$, ${}^{6,7}\mathrm{Li}\left({}^3\mathrm{He},t\right)$, and ${}^{6,7}\mathrm{Li}\left({}^7\mathrm{Li},{}^7\mathrm{Be}\right)$ reactions at the incident energies of 300, 450, and $455\text{MeV}$, respectively. New dipole resonances were found at $E_x=27.0\pm 1.5\text{MeV}$ in ${}^6\mathrm{Li}$ and at $E_x=29.0\pm 1.5\text{MeV}$ in ${}^7\mathrm{Li}$, both with widths (full width at half maximum) of $12\pm 2\text{MeV}$. In ${}^6\mathrm{He}$, ${}^6\mathrm{Be}$, ${}^7\mathrm{He}$, and ${}^7\mathrm{Be}$, the dipole resonances with a width of $12\pm 2\text{MeV}$ were observed at $E_x=24.0\pm 1.5,23.5\pm 1.5,18.0\pm 1.5$, and $28.0\pm 1.5\text{MeV}$, respectively. The resonance shapes were reproduced well with the GDR shape observed in the ${}^4\mathrm{He}\left(\gamma ,n\right)$ reactions. The averaged value for the ratios of the resonance cross section in $A=6$ to that in $A=7$ for each element was $1.2\pm 0.3$. The averaged value for the ratios of the resonance cross section to the GDR cross section in the respective target nuclei was $0.44\pm 0.08$, which was consistent with the ratios of the GDR cross section in ${}^4\mathrm{He}$ to that in ${}^{6,7}\mathrm{Li}$ reported in the photonuclear reactions. The excitation energies for the dipole resonances in $A=6$ and 7 nuclei relative to the separation energies of an $\alpha$ particle in ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$, respectively, agreed well with the excitation energy for the GDR in ${}^4\mathrm{He}\left(\sim 26\text{MeV}\right)$. We conclude that the resonances observed in ${}^{6,7}\mathrm{Li}$ are consistent with the GDR of the $\alpha$ cluster and the resonances in ${}^{6,7}\mathrm{He}$ and ${}^{6,7}\mathrm{Be}$ are consistent with the analogs of the GDR in the $\alpha$ cluster. The $Q$ value for the excitation of the GDR of the $\alpha$ cluster in $A=7$ nuclei is deeper by $1.6\pm 0.3\text{MeV}$ on the average than that in $A=6$.

The fragment yield ratios were investigated in the fission of ${}^{238,233}\mathrm{U}$ targets induced by $14\text{MeV}$ neutrons. The isoscaling behavior was typically observed for the isotopic chains of fragments ranging from the proton-rich to the most neutron-rich ones. The observed high sensitivity of neutron-rich heavy fragments to the target neutron content suggests fission as a source of neutron-rich heavy nuclei for present and future rare ion beam facilities, allowing studies of nuclear properties towards the neutron drip line and investigations of the conditions for nucleosynthesis of heavy nuclei. The breakdowns of the isoscaling behavior around $N=62$ and $N=80$ manifest the effect of two shell closures on the dynamics of scission. The shell closure around $N=64$ can be explained by the deformed shell. The investigation of isoscaling in the spontaneous fission of ${}^{248,244}\mathrm{Cm}$ further supports such conclusion. The $Z$ dependence of the isoscaling parameter exhibits a structure which can be possibly related to details of scission dynamics. The fission isoscaling studies can be a suitable tool for the investigation of possible new pathways to synthesize still heavier nuclei.

In this work we study the effects of temperature on the equations of state obtained within a relativistic model, with and without $\beta$ equilibrium over a wide range of densities. We also compare the results of the equation of state, effective mass, and strangeness fraction for the TM1, NL3, and GL sets of parameters. We have checked that TM1 and NL3 are not appropriate for the description of neutron and protoneutron stars.

The relativistic mean-field effective interaction with density-dependent meson-nucleon couplings DD-ME1 is tested in the calculation of deformed nuclei. Ground-state properties of six isotopic chains $\left(60⩽Z⩽70\right)$ in the region of rare-earth nuclei are calculated by using the relativistic Hartree-Bogoliubov (RHB) model with the DD-ME1 mean-field interaction, and with the Gogny D1S force for the pairing interaction. Results of fully self-consistent RHB calculations for the total binding energies, charge isotope shifts, and quadrupole deformation parameters are compared with the available empirical data.

A recently developed two-level mixing model of superdeformed decay is applied to evaluate the tunneling width between the superdeformed and normally deformed potential wells in ${}^{192}\mathrm{Pb}$ and ${}^{194}\mathrm{Pb}$. Estimates are made of level densities and $\gamma$ decay widths for levels in the normally deformed well, which are required for evaluation of the model. Experimental quasicontinuum results are used to suggest a spin-dependent reduction of the energy gap in the level spectrum, resulting in approximately constant level densities and decay widths in the normal well over the decay-out region for each isotope. However, it transpires that the model’s prediction of the tunneling width is nearly independent of the normally deformed state widths for both isotopes. This observation is used to extract potential barrier heights for the two nuclei that depend mainly on experimentally determined values.