We study the finite temperature-density phase diagram of an attractive fermionic system that supports two-body (dimer) and three-body (trimer) bound states in free space. Using interactions characteristic for nuclear systems, we obtain the critical temperature $T_{c2}$ for the superfluid phase transition and the limiting temperature $T_{c3}$ for the extinction of trimers. The phase diagram features a Cooper-pair condensate in the high-density, low-temperature domain which, with decreasing density, crosses over to a Bose condensate of strongly bound dimers. The high-temperature, low-density domain is populated by trimers whose binding energy decreases toward the density-temperature domain occupied by the superfluid and vanishes at a critical temperature $T_{c3}>T_{c2}$.

Systematic α-nucleus folding potentials are used to analyze α-decay half-lives of superheavy nuclei. Preformation factors of about several percent are found for all nuclei under study. The systematic behavior of the preformation factors and the volume integrals of the potentials allows predictions of α-decay energies and half-lives for unknown nuclei. Shell closures can be determined from measured α-decay energies using the discontinuity of the volume integral at shell closures. For the first time a double shell closure is predicted for $Z_{\mathrm{magic}}=132,N_{\mathrm{magic}}=194$, and $A_{\mathrm{magic}}=326$ from the systematics of folding potentials. The calculated α-decay half-lives remain far below 1 ns for superheavy nuclei with double shell closure and masses $A>300$ independent of the precise knowledge of the magic proton and neutron numbers.

Low energy collisions of very heavy nuclei (${}^{238}\mathrm{U}+{}^{238}\mathrm{U}$, ${}^{232}\mathrm{Th}+{}^{250}\mathrm{Cf}$, and ${}^{238}\mathrm{U}+{}^{248}\mathrm{Cm}$) have been studied within the realistic dynamical model based on multidimensional Langevin equations. Large charge and mass transfer was found to result from the “inverse quasi-fission” process leading to the formation of the surviving superheavy long-lived neutron-rich nuclei. In many events, the lifetime of the composite system consisting of two touching nuclei turns out to be rather long; sufficiently long for the spontaneous formation of positrons to occur from a super-strong electric field—a fundamental QED process.

We report relative measurements of the $\overrightarrow{n}-\overrightarrow{d}$ longitudinal spin-dependent total cross-section difference $(\Delta {\sigma }_L){}_d$, at $E_n$(lab) = 5.0, 6.88, and 9.0 MeV. The deuteron target was polarized via dynamic nuclear polarization at 250 mK in a 2.5-T external magnetic field. The target polarization was monitored by nuclear magnetic resonance and was calibrated by a $(\Delta {\sigma }_L){}_d$ measurement at $E_n$(lab) = 1.18 MeV. The polarized neutron beams were produced through the ${}^3\mathrm{H}$$(\overrightarrow{p},\overrightarrow{n})$${}^3\mathrm{He}$ and ${}^2\mathrm{H}$$(\overrightarrow{d},\overrightarrow{n})$${}^3\mathrm{He}$ reactions. The neutron polarizations were determined either by direct measurement or from known or calculated polarization-transfer coefficients. The results for $(\Delta {\sigma }_L){}_d$ show agreement with theoretical calculations based on nucleon-nucleon potential models but are not of sufficient precision to distinguish the presence or absence of three-nucleon force contributions to the cross sections.

The high-spin structure of ${}^{170}\mathrm{Hf}$ was investigated using the EUROBALL spectrometer. The previously known level scheme was extended in the low-spin region as well as to higher spins, and several new bands were discovered. In particular, two bands were identified which show the characteristics of triaxial superdeformation. One of these bands is strongly populated, and its excitation energy and spins are established. Configuration assignments are made to the normal-deformed bands based on comparisons of their properties with cranked shell model calculations. The results for the very high spin states provide important input for such calculations.

This work uses a simple model to understand the properties of isoscaling. Using a generalized percolation model, it is first shown that isoscaling is a general property of fragmenting systems. In particular, it is found that the usual isoscaling property can be seen as a limit case of bond percolation in lattices in D dimensions, with N colors, with independent probabilities for each color, and for any regular topology. The effect of introducing correlations is also studied.

Fusion-evaporation cross sections were measured in the two systems ${}^{48}\mathrm{Ca}+{}^{90,96}\mathrm{Zr}$ in an energy range from well below to well above the Coulomb barrier. The sub-barrier fusion of ${}^{48}\mathrm{Ca}+{}^{90}\mathrm{Zr}$ is reproduced by coupled-channels calculations including the lowest quadrupole and octupole vibrations of ${}^{90}\mathrm{Zr}$, and using a Woods-Saxon potential with a standard diffuseness parameter a = 0.68 fm. However, the fusion cross sections are overestimated above the barrier. The low-energy slope of the excitation function for ${}^{48}\mathrm{Ca}+{}^{96}\mathrm{Zr}$ is steeper. This implies a larger diffuseness parameter a = 0.85 fm. Fusion cross sections are well fit in the whole energy range, and the effect of the strong octupole vibration in ${}^{96}\mathrm{Zr}$ is predominant. The extracted fusion barrier distributions are reasonably well reproduced by calculations for both systems. A comparison with previous data for ${}^{40}\mathrm{Ca}+{}^{90,96}\mathrm{Zr}$ is made in an attempt to clarify the role of transfer couplings in sub-barrier fusion.

We explore the range of values of the in-medium width of a ρ-meson at rest which is compatibale with the QCD sum rule approach in a nuclear medium assuming vector meson dominance and a Brown-Rho scaling law of the ρ-meson mass with the chiral condensate. The lower and upper bounds for the in-medium width are found to be strongly increasing with the decreasing mass of the ρ-meson (increasing nuclear density). We also study the bounds for the in-medium width in models not satisfying the Brown-Rho scaling law. It is shown that the in-medium width depends on how rapidly the mass decreases in comparison to the change of the quark condensate. The bounds for the in-medium width increase with density only if the relative change of the quark condensate is stronger than the relative decrease in mass. This is important for experimental tests of the Brown-Rho scaling paradigm and other dropping ρ-mass scenarios.

Nonuniform structures of mixed phases at the first-order phase transition to charged kaon condensation are studied using a density functional theory within the relativistic mean-field model. Including electric field effects and applying the Gibbs conditions in a proper way, we numerically determine density profiles of nucleons, electrons, and condensed kaons. Importance of charge screening effects is elucidated and thereby we show that the Maxwell construction is effectively justified. Surface effect is also studied to figure out its effect on the density profiles.

Excited states in ${}^{109}\mathrm{Mo}$, populated in the spontaneous fission of ${}^{248}\mathrm{Cm}$, were studied using the EUROGAM2 array. Octupole deformation reported previously in ${}^{109}\mathrm{Mo}$ was not confirmed. Spin and parity of the ground state were changed. A new band found in this work suggests the ${5/2}^{+}$[402] neutron configuration for the ground state. In the 222.2 keV band, the 110.8 and 138.9 keV transitions are of M1 + E2 instead of E1 multipolarity, as reported previously. The 222.2 keV band is explained as the ${7/2}^{-}$[523] neutron configuration.

Adiabatic and configuration-fixed constrained triaxial relativistic mean field (RMF) approaches are developed for the first time. A new phenomenon, the existence of multiple chiral doublets (MχD), i.e., more than one pair of chiral doublet bands in one single nucleus, is suggested for ${}^{106}\mathrm{Rh}$ based on the triaxial deformations and their corresponding proton and neutron configurations.

A three-body model of ${}^{14}\mathrm{C}$ $+n+n$ is applied to study the energy spectrum and the hindered E2 transition in ${}^{16}\mathrm{C}$. A realistic two-nucleon potential is used for the valence neutrons. Both spin-singlet and spin-triplet components for the neutrons are taken into account. The three-body problem with a Pauli constraint is solved in a stochastic variational method. For the $n\text{−}$${}^{14}\mathrm{C}$ potential chosen to reproduce the properties of ${}^{15}\mathrm{C}$, the low-lying energy spectrum agrees reasonably well with experiment, but the ground state is predicted to be about 1 MeV high. The calculated $B(E2$; $2_1^{+}\to 0_1^{+})$ value is about twice the measured value if the polarization charge of the valence neutrons is taken to be the same as that required to fit the ${}^{15}\mathrm{C}$ data. The correlated motion of the valence neutrons is displayed through the two-neutron density distribution.

A study of the dependence of the giant dipole resonance γ-ray yield from different functional forms of the symmetry term for the nucleon-nucleon interaction potential has been performed through the semiclassical molecular dynamics approach CoMD-II. We studied central and midperipheral reactions in the charge/mass asymmetric system ${}^{40}\mathrm{Ca}+{}^{48}\mathrm{Ca}$ at 45 MeV/nucleon. The calculations show that the balance between the dynamical and the statistical emission is very sensitive to the “stiffness” of the symmetry term. This sensitivity could be highlighted by measuring the degree of coherence and the anisotropy ratio related to the dynamically emitted radiation.

We report the first study of restoration of rotational symmetry and fluctuations of the quadrupole deformation in the framework of relativistic mean-field models. A model is developed that uses the generator coordinate method to perform configuration mixing calculations of angular-momentum-projected wave functions, calculated in a relativistic point-coupling model. The geometry is restricted to axially symmetric shapes, and the intrinsic wave functions are generated from the solutions of the constrained relativistic mean-field + BCS equations in an axially deformed oscillator basis. A number of illustrative calculations are performed for the nuclei ${}^{194}\mathrm{Hg}$ and ${}^{32}\mathrm{Mg}$, in comparison with results obtained in nonrelativistic models based on Skyrme and Gogny effective interactions.

We report on results of a kinematically complete neutron-deuteron breakup experiment performed at Triangle Universities Nuclear Laboratory using an $E_n=13$ MeV incident neutron beam. The ${}^1{S}_0$ neutron-neutron scattering length $a_{\mathit{nn}}$ has been determined for four production angles of the neutron-neutron final-state interaction configuration. The absolute cross-section data were analyzed with rigorous three-nucleon calculations. Our average value of $a_{\mathit{nn}}=-18.7\pm 0.7$ fm is in excellent agreement with $a_{\mathit{nn}}=-18.6\pm 0.4$ fm obtained from capture experiments of negative pions on deuterons. We also performed a shape analysis of the final-state interaction cross-section enhancements by allowing the normalization of the data to float. From these relative data, we obtained an average value of $a_{\mathit{nn}}=-18.8\pm 0.5$ fm, in agreement with the result obtained from the absolute cross-section measurements. Our result deviates from the world average of $a_{\mathit{nn}}=-16.7\pm 0.5$ fm determined from previous kinematically complete neutron-deuteron breakup experiments, including the most recent one carried out at Bonn. However, this low value for $a_{\mathit{nn}}$ is at variance with theoretical expectation and other experimental information about the sign of charge-symmetry breaking of the nucleon-nucleon interaction. In agreement with theoretical predictions, no evidence was found of significant three-nucleon force effects on the neutron-neutron final-state interaction cross sections.

Implementation of Dyson boson mapping is discussed in connection with effective Hamiltonians. A feature of the mapping technique, when implemented in an ideal boson basis, is the possible appearance of spurious states. These spurious states typically signal the overcompleteness of the basis. Without truncation, no contamination of the physical states and spectrum takes place. However, in practice one may be required to select from the ideal boson basis the dominant components for a given interaction. It is shown that the correspondence between a perturbative expansion, $á\mathit{la}$ Bloch-Horowitz, and Dyson boson mapping allows for the identification of spurious states. The proposed method is applied to the mapping of a bi-fermionic Hamiltonian.

The contribution of the three-body correlations to the binding energy of symmetric nuclear matter is calculated, within the continuous version of the hole-line expansion, by means of the direct matrix inversion method. For the nucleon-nucleon interactions considered in this paper, we find that at the three-hole-line level, the saturation curve is fairly close to the saturation curve obtained within the standard version. The role of the various contributions to the binding energy is discussed in detail.

One of the most remarkable results to emerge from heavy-ion collisions over the past two decades is the striking regularity shown by particle yields at all energies. This has led to several very successful proposals describing particle yields over a very wide range of beam energies, reaching from $1A$ GeV up to 200A GeV, using only one or two parameters. A systematic comparison of these proposals is presented here. The conditions of fixed energy per particle, baryon+anti-baryon density, normalized entropy density as well as percolation model are investigated. The results are compared with the most recent chemical freeze-out parameters obtained in the thermal-statistical analysis of particle yields. The sensitivity and dependence of the results on parameters is analyzed and discussed. It is shown that in the energy range above the top energy of the BNL Alternating Gradient Synchrotron within present accuracies, all chemical freeze-out criteria give a fairly good description of the particle yields. However, the low energy heavy-ion data favor the constant energy per particle as a unified condition of chemical particle freeze-out. This condition also shows the weakest sensitivity on model assumptions and parameters.

We present the centrality-dependent measurement of multiplicity and pseudorapidity distributions of charged particles and photons in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=62.4$ GeV. The charged particles and photons are measured in the pseudorapidity region $2.9\le \eta \le 3.9$ and $2.3\le \eta \le 3.7$, respectively. We have studied the scaling of particle production with the number of participating nucleons and the number of binary collisions. The photon and charged particle production in the measured pseudorapidity range has been shown to be consistent with energy-independent limiting fragmentation behavior. Photons are observed to follow a centrality-independent limiting fragmentation behavior, while for charged particles it is centrality dependent. We have carried out a comparative study of the pseudorapidity distributions of positively charged hadrons, negatively charged hadrons, photons, pions, and net protons in nucleus-nucleus collisions and pseudorapidity distributions from p+p collisions. From these comparisons, we conclude that baryons in the inclusive charged particle distribution are responsible for the observed centrality dependence of limiting fragmentation. The mesons are found to follow an energy-independent behavior of limiting fragmentation, whereas the behavior of baryons is energy dependent.