The $\beta$-decay properties of neutron-rich ${}^{85}$Ga produced in proton-induced fission of ${}^{238}$U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Data consisted of $\beta -\gamma$ and $\beta -\gamma -\gamma$ coincidences were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station after high-resolution on-line mass separation. For the first time, the excited states in the $N=53$ isotone ${}^{85}$Ge were established from $\beta$-delayed $\gamma$ decay of ${}^{85}$Ga. The level scheme of the $N=52$ isotone ${}^{84}$Ge was improved and includes now 0${}^{+}$, 2${}^{+}$, (2)${}^{+}$, 4${}^{+}$, and (0)${}^{+}$ states populated in the $\beta$-delayed-neutron-$\gamma$ decay of ${}^{85}$Ga. Advanced shell-model calculations were used to analyze experimental data on ${}^{85}$Ge and ${}^{84}$Ge.

Complete fusion cross sections for ${}^7$Li+${}^{144,152}$Sm reactions have been measured at energies around the Coulomb barrier by offline $\gamma$-counting technique. Measured cross sections for the above two reactions are found to be similar at energies well above the Coulomb barrier, however, at sub-barrier energies the cross sections for the ${}^7$Li+${}^{152}$Sm system are much higher compared to the ${}^7$Li+${}^{144}$Sm system, manifesting the effect of target deformation. Cross sections for the present reactions at above-barrier energies are found to be larger than previously measured reactions involving ${}^6$Li projectile with the same targets, possibly due to smaller breakup probability of ${}^7$Li than ${}^6$Li. Coupled-channels calculations show that the experimental fusion cross sections for both the systems are enhanced at subbarrier energies and suppressed at above-barrier energies compared to the respective one-dimensional barrier penetration model predictions. The calculations by different models show that the measured complete fusion cross sections at above-barrier energies are suppressed up to $\sim$25% compared to the theoretical predictions. It also reveals that a large part of the suppression could be due to inelastic and transfer coupling.

The $\alpha$ decay of superheavy nuclei (SHN) is studied within the framework of the shell-model rate theory. The $\alpha$ half-lives are calculated in terms of the $\alpha$ clustering and resonance scattering amplitudes given by self-consistent models for the nuclear structure and reaction dynamics. The results and their systematics are compared with the available experimental data and with those data obtained from empirical models. The Brown relationship [B. A. Brown, Phys. Rev. C 46, 811 (1992)], which predicts a linear dependence of the $\log T_{\alpha }$ on $Z_d^{0.6}{Q}_{\alpha }^{-1/2}$, is used to obtain a relevant systematics for $\alpha$ half-lives of the observed SHN. Also, simple fit formulas are proposed for $\alpha$-half-time estimations with reduced standard errors. Comparison of experimental and calculated results provides insight into the accuracy of modern approaches for the structure of SHN with valence nucleons outside the doubly magic core.

Shear viscosity $\eta$ and entropy density $s$ of a hadronic resonance gas are calculated using the Chapman-Enskog and virial expansion methods using the $K$-matrix parametrization of hadronic cross sections which preserves the unitarity of the $T$ matrix. In the $\pi -K-N-\eta$ mixture considered, a total of 57 resonances up to 2 GeV were included. Comparisons are also made to results with other hadronic cross sections such as the Breit-Wigner (BW) and, where available, experimental phase shift parameterizations. Hadronic interactions forming resonances are shown to decrease the shear viscosity and increase the entropy density leading to a substantial reduction of $\eta /s$ as the QCD phase transition temperature is approached.

Background: The $\gamma$ process in supernova explosions is thought to explain the origin of proton-rich isotopes between Se and Hg, the so-called $p$ nuclei. The majority of the reaction rates for $\gamma$ process reaction network studies have to be predicted in Hauser-Feshbach statistical model calculations using global optical potential parametrizations. While the nucleon+nucleus optical potential is fairly well known, for the $\alpha$+nucleus optical potential several different parametrizations exist and large deviations are found between the predictions calculated using different parameter sets.

Purpose: By the measurement of elastic $\alpha$-scattering angular distributions at energies around the Coulomb barrier a comprehensive test for the different global $\alpha$+nucleus optical potential parameter sets is provided.

Methods: Between 20${}^{\circ }$ and 175${}^{\circ }$ complete elastic alpha scattering angular distributions were measured on the ${}^{113}$In $p$ nucleus with high precision at $E_{\mathrm{c}}.\mathrm{m}.=15.59$ and 18.82 MeV.

Results: The elastic scattering cross sections of the ${}^{113}$In($\alpha$,$\alpha$)${}^{113}$In reaction were measured for the first time at energies close to the astrophysically relevant energy region. The high precision experimental data were used to evaluate the predictions of the recent global and regional $\alpha$+nucleus optical potentials. Parameters for a local $\alpha$+nucleus optical potential were derived from the measured angular distributions.

Conclusions: Predictions for the reaction cross sections of ${}^{113}$In($\alpha ,\gamma$)${}^{117}$Sb and ${}^{113}$In($\alpha$,n)${}^{116}$Sb at astrophysically relevant energies were given using the global and local optical potential parametrizations.

We explore the properties of medium-mass and heavy nuclear clusters embedded in a gas of nucleons with the help of Skyrme-Hartree-Fock microscopic calculations at zero temperature. Two alternative representations of clusters are introduced, namely coordinate-space and energy-space clusters. We parametrize their density profiles in spherical symmetry in terms of basic properties of the energy density functionals used and propose an analytical, Woods-Saxon density profile whose parameters depend, not only on the composition of the cluster, but also on that of the nucleon gas. We study the clusters' energies with the help of the local-density approximation, validated through our microscopic results. We find that the volume energies of coordinate-space clusters are determined by the saturation properties of matter, while the surface energies are strongly affected by the presence of the gas. We conclude that both the density profiles and the cluster energies are strongly affected by the gas and discuss implications for the nuclear equation of state and related perspectives. Our study provides a simple but microscopically motivated modeling of the energetics of clusterized matter at subsaturation densities for applications of astrophysical interest.

It has been shown on selected data that heavy ion sub-barrier fusion is of compound nucleus nature. Data subjected to a simple energy scaling demonstrate either the lack of or greatly reduced fusion enhancement. Within the proposed approach, the sub-barrier fusion cross-section could be easily predictable.

Self-consistent random-phase approximation is rederived in a consistent way with the help of the coupled cluster ground state wave function truncated at the two-body level. An exact killing operator for this wave function is introduced allowing for a detailed discussion of the approximation scheme. Several exactly solvable models are reanalyzed under this new perspective giving rise to a quantitative evaluation of the performances of this many-body method.

A new implementation of the finite amplitude method (FAM) for the solution of the relativistic quasiparticle random-phase approximation (RQRPA) is presented, based on the relativistic Hartree-Bogoliubov (RHB) model for deformed nuclei. The numerical accuracy and stability of the FAM–RQRPA is tested in a calculation of the monopole response of ${}^{22}$O. As an illustrative example, the model is applied to a study of the evolution of monopole strength in the chain of Sm isotopes, including the splitting of the giant monopole resonance in axially deformed systems.

The high spin structure of ${}^{201}$Tl has been studied by $\gamma$-ray spectroscopic method using the ${}^{198}$Pt(${}^7$Li,4$n$)${}^{201}$Tl reaction at 45 MeV beam energy. The level scheme of ${}^{201}$Tl has been considerably extended through the observation of 31 new transitions. Several new band structures have been established. The 9/2${}^{-}$ oblate band has been significantly extended beyond the particle alignment frequencies. The band structures and the other excited states have been compared with the neighboring odd-$A$ Tl isotopes and with the even-even core nucleus ${}^{200}$Hg. The total Routhian surface calculations have been performed to study the deformation and shape changes as a function of spin in this nucleus.

We have performed a systematical investigation on the new or improved data of $\alpha$ decay in recent experiments, including neutron-deficient nuclei around the proton drip line and superheavy nuclei. By using the double-folding integral of the effective nucleon-nucleon interaction plus the density distributions of the $\alpha$ particle and the daughter nucleus, the deformed $\alpha$-core potential is constructed. The $\alpha$ decay half-lives are then obtained within the modified two-potential approach. These obtained $\alpha$ decay half-lives are found to be in good agreement with the corresponding experimental data. This shows that the present model and formulas of $\alpha$ decay are valid for some new mass ranges.

Bulk viscosity effects on the collective flow harmonics in heavy-ion collisions are investigated, on an event-by-event basis, using a newly developed 2+1 Lagrangian hydrodynamic code named v-usphydro, which implements the smoothed particle hydrodynamics algorithm for viscous hydrodynamics. A new formula for the bulk viscous corrections present in the distribution function at freeze-out is derived, starting from the Boltzmann equation for multi-hadron species. Bulk viscosity is shown to enhance the collective flow Fourier coefficients from $v_2\left(p_T\right)$ to $v_5\left(p_T\right)$ when $p_T\sim 1$–2.5 GeV, even when the bulk viscosity to entropy density ratio, $\zeta /s$, is significantly smaller than $1/\left(4\pi \right)$.

In this article we study the surface tension and the curvature energy of three-flavor quark matter in equilibrium under weak interactions within the Nambu–Jona-Lasinio model. We include the effect of color superconductivity and describe finite size effects within the multiple reflection expansion framework. Our calculations result in large values of the surface tension which disfavor the formation of mixed phases at the hadron-quark interphase inside a hybrid star.

We calculate the reaction cross sections for ${}^6\mathrm{Li}$ and ${}_{\Lambda }^7\mathrm{Li}$ on a ${}^{12}\mathrm{C}$ target at $100\mathrm{MeV}/\mathrm{nucleon}$ using the Glauber theory. To this end, we assume a two-body cluster structure for ${}^6$Li and ${}_{\Lambda }^7\mathrm{Li}$, and employ the few-body treatment of the Glauber theory, that is beyond the well known optical limit approximation. We show that the reaction cross section for ${}_{\Lambda }^7\mathrm{Li}$ is smaller than that for ${}^6$Li by about 4%, reflecting the shrinkage effect of the $\Lambda$ particle.

Using an improved scission-point model, the mass distributions are calculated for induced fission of even Hg isotopes with mass numbers $A=174\text{to}196$. With increasing $A$ of a fissioning ${}^A$Hg nucleus the mass distribution evolves from symmetric for ${}^{174}$Hg, to asymmetric for isotopes close to ${}^{180}$Hg, and back to more symmetric for ${}^{192,194,196}$Hg. In the fissioning Hg isotopes their excitation energy weakly influences the shape of the mass distribution. In ${}^{180,184}$Hg, the mass distributions of fission fragments remain asymmetric even at high excitation energies.

With growing multiplicity, the $pp$ and $pA$ collisions enter the domain where the macroscopic description (thermodynamics and hydrodynamics) becomes applicable. We discuss this situation, first with simplified thought experiments, then with some idealized representative cases, and finally address the real data. For clarity, we do not do it numerically but analytically, using the Gubser solution. We found that the radial flow is expected to increase from central $AA$ to central $pA$, while the elliptic flow decreases, with higher harmonics being comparable. We extensively study the magnitude and distribution of the viscous corrections, in Navier-Stokes and Israel-Stuart approximations, ending with higher gradient resummation proposed by Lublinsky and Shuryak. We found that those corrections grow from $AA$ to $pA$ to $pp$, but remain tractable even for $pp$.

Using an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, we have studied the connection between the symmetry energy and features of the dynamical dipole mode in fusion reactions with the charge-asymmetric entrance channel. The yield and angular distribution of the prompt photon emission are extracted by a bremsstrahlung approach. The experimental data of ${}^{36}$Ar + ${}^{96}$Zr at 16 MeV/nucleon and ${}^{32}$S + ${}^{100}$Mo at 9.3 MeV/nucleon are compared with IBUU model calculations, and the soft symmetry energy is found to describe the data reasonably well.

We demonstrate that high-quality total radiation width (${\Gamma }_{\gamma }$) data are a virtually untapped resource for testing and improving nuclear models. To this end, we obtained unprecedentedly large sets of ${\Gamma }_{\gamma }$ values for all six $s$- and $p$-wave $J^{\pi }$ values for ${}^{95}$Mo neutron resonances. We show that ${\Gamma }_{\gamma }$ distributions simulated in the framework of the nuclear statistical model are in sharp disagreement with the data. Simulations modified to include doorway effects resulted in much better agreement. These results call into question the reliability of the nuclear statistical model.

We present a method to evaluate the $\overline{K}$ absorption width in the bound $\overline{K}NN$ system. Most calculations of this system ignore this channel and only consider the $\overline{K}N\to \pi \Sigma$ conversion. Other works make a qualitative calculation using perturbative methods. Since the $\Lambda \left(1405\right)$ resonance is playing a role in the process, the same resonance is changed by the presence of the absorption channels and we find that a full nonperturbative calculation is called for, which we present here. We employ the fixed center approximation to Faddeev equations to account for $\overline{K}$ rescattering on the $\left(NN\right)$ cluster and we find that the width of the states found previously for $S=0$ and $S=1$ increases by about 30 MeV due to the $\overline{K}NN$ absorption, to a total width of about 80 MeV.

Odd-even staggering (OES) appears in many areas of nuclear physics and is generally associated with the pairing term in the nuclear binding energy. To explore this effect, we use the improved statistical multifragmentation model to populate an ensemble of hot primary fragments, which are then de-excited using the Weisskopf-Ewing statistical emission formalism. The yields are then compared to experimental data. Our results show that, before secondary decay, OES appears only in the yields of even mass fragments and not in the yields of odd mass fragments. De-excitation of the hot fragments must be taken into account to describe the data, suggesting that the OES in fragment yields is a useful criterion for validating or adjusting theoretical de-excitation models.