We investigate the thermodynamic equation of state of isospin-symmetric nuclear matter with microscopic nuclear forces derived within the framework of chiral effective field theory. Two- and three-body nuclear interactions constructed at low-resolution scales form the basis for a perturbative calculation of the finite-temperature equation of state. The nuclear force models and many-body methods are benchmarked against bulk properties of isospin-symmetric nuclear matter at zero temperature, which are found to be well reproduced when chiral nuclear interactions constructed at the lowest resolution scales are employed. The calculations are then extended to finite temperatures, where we focus on the liquid-gas phase transition and the associated critical point. The Maxwell construction is applied to construct the physical equation of state, and the value of the critical temperature is determined to be $T_c=17.2$–19.1 MeV, in good agreement with the value extracted from multifragmentation reactions of heavy ions.

Direct determination of the neutrino mass is at the present time one of the most important aims of experimental and theoretical research in nuclear and particle physics. A possible way of detection is through neutrinoless double-electron capture, $0\nu \mathrm{ECEC}$. This process can only occur when the energy of the initial state matches precisely that of the final state. We present here a calculation of prefactors (PFs) and nuclear matrix elements (NMEs) within the framework of the microscopic interacting boson model (IBM-2) for ${}^{124}\mathrm{Xe}$, ${}^{152}\mathrm{Gd}$, ${}^{156}\mathrm{Dy}$, ${}^{164}\mathrm{Er}$, and ${}^{180}\mathrm{W}$. From the PF and NME we calculate the expected half-lives and obtain results that are of the same order as those of $0\nu {\beta }^{+}{\beta }^{+}$ decay, but considerably longer than those of $0\nu {\beta }^{-}{\beta }^{-}$ decay.

The ${\beta }^{-}\mathrm{-decay}$ rates of neutron-rich Zr and Mo isotopes are investigated within the deformed quasiparticle random-phase approximation with realistic nucleon-nucleon interactions. Axially symmetric deformations are considered in the calculations from a mean-field description of a quasiparticle picture and of both particle-hole and particle-particle excitations. The Brückner $G$ matrix obtained with charge-dependent Bonn nucleon-nucleon forces is employed for residual particle-particle and particle-hole interactions. Contributions from both allowed Gammow-Teller and first-forbidden transitions are calculated and the sensitivity of the calculated results to the particle-particle strength is discussed. The calculated $\beta$-decay half-lives show a good agreement with the available experimental data. Moreover, predictions of $\beta$-decay half-lives are made for some extremely neutron-rich isotopes, which could be useful for future experiments.

The formation of $\alpha \mathrm{-particle}$ clusters on the surface of heavy nuclei is described in a generalized relativistic mean-field model with explicit cluster degrees of freedom. The effects on the size of the neutron skin of Sn nuclei and ${}^{208}\mathrm{Pb}$ are investigated as a function of the mass number and the isospin-dependent part of the effective interaction, respectively. The correlation of the neutron skin thickness with the difference of the neutron and proton numbers and with the slope of the nuclear symmetry energy is modified as compared to the mean-field calculation without $\alpha$-cluster correlations.

The magic nature of the ${}^{54}\mathrm{Ca}$ nucleus is investigated in light of recent experimental results. We employ both Hartree-Fock-Bogoliubov and Hartree-Fock (HF)+BCS methods using Skyrme-type SLy5, SLy5+T, and T44 interactions. The evolution of the single-particle spectra is studied for the $N=34$ isotones: ${}^{60}\mathrm{Fe}$, ${}^{58}\mathrm{Cr}$, ${}^{56}\mathrm{Ti}$, and ${}^{54}\mathrm{Ca}$. An increase is obtained in the neutron spin-orbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes ${}^{54}\mathrm{Ca}$ a magic nucleus candidate. Quasiparticle random-phase approximation calculations on top of HF+BCS are performed to investigate the first $J^{\pi }=2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the mean-field part of the calculations. The first $2^{+}$ states indicate a subshell closure for both ${}^{52}\mathrm{Ca}$ and ${}^{54}\mathrm{Ca}$ nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in ${}^{52}\mathrm{Ca}$ and ${}^{54}\mathrm{Ca}$ nuclei.

Fusion barrier distributions have been obtained from the measurement of the quasi-elastic scattering excitation functions at a backward angle in the reactions of ${}^{6,7}\mathrm{Li}$ with ${}^{209}\mathrm{Bi}$. Comparisons have been carried out among barrier distributions, obtained from quasi-elastic scattering by considering elastic + inelastic and elastic + inelastic + [breakup(BU) and/or transfer] and also from fusion excitation function measurements. It has been observed that representations of barrier distributions obtained from elastic + inelastic + [breakup(BU) and/or transfer] and from fusion excitation functions are in good agreement showing the importance of the inclusion breakup channels for the correct fusion barrier representations in the ${}^{6,7}\mathrm{Li}+{}^{209}\mathrm{Bi}$ reactions. The observed discrepancy in the resultant barrier distributions with and without including breakup and/or transfer has been interpreted in terms of the capture barrier distribution. The results obtained from the continuum discretized coupled channels calculations also follow the fusion barrier distributions which have been obtained from the fusion excitation functions measurements. It has been observed that the inclusion of direct breakup $\alpha$ with the elastic and inelastic channels in quasi-elastic scattering play an important role in explaining consistently the fusion barrier distributions for both the ${}^{6,7}\mathrm{Li}+{}^{209}\mathrm{Bi}$ systems.

During therapeutic treatments using ions such as carbon, nuclear interactions between the incident ions and nuclei present in organic tissues may occur, leading to the attenuation of the incident beam intensity and to the production of secondary light charged particles. As the biological dose deposited in the tumor and the surrounding healthy tissues depends on the beam composition, an accurate knowledge of the fragmentation processes is thus essential. In particular, the nuclear interaction models have to be validated using experimental double differential cross sections which are still very scarce. An experiment was realized in 2011 at GANIL to obtain these cross sections for a 95-MeV/nucleon carbon beam on different thin targets for angles raging from 4${}^{\circ }$ to 43${}^{\circ }$. To complete these data, a new experiment was performed in September 2013 at GANIL to measure the fragmentation cross section at zero degree for a 95-MeV/nucleon carbon beam on thin targets. In this work, the experimental setup will be described, the analysis method detailed, and the results presented.

The quantized Skyrme model is applied to the $\pi N$ scattering problem, especially the $P_{11}$ wave amplitude. The field fluctuation and the zero mode are consistently taken into account, and the quantum correction to the Born term is calculated. It is found that this $1/N_c$ correction is comparable with the Born term and is crucially important for the $\pi N$ scattering problem in the Skyrme model.

A recently introduced analytical model for the nuclear density profile [P. Papakonstantinou, J. Margueron, F. Gulminelli, and Ad. R. Raduta, Phys. Rev. C 88, 045805 (2013)] is implemented in the extended Thomas-Fermi energy density functional. This allows us to (i) shed a new light on the issue of the sign of surface symmetry energy in nuclear mass formulas, which is strongly related to the nonuniformity of the isospin asymmetry in finite nuclei, as well as to (ii) evaluate the in-medium corrections to the nuclear cluster energies in thermodynamic conditions relevant for the description of the (proto)neutron star crust. The ground-state configurations of the model are compared to Hartree-Fock calculations in spherical symmetry for some selected isotopic chains, and systematic errors are quantified. The in-medium modification of the nuclear mass due to the presence of a gas component is shown to strongly depend both on the density and the asymmetry of the nucleon gas. This shows the importance of accounting for such effects in the realistic modelizations of the equation of state for core-collapse supernovae and protoneutron stars.

Background: Optical potentials are crucial ingredients for the prediction of nuclear reaction rates needed in simulations of the astrophysical $\gamma$ process. Associated uncertainties are particularly large for reactions involving $\alpha$ particles. This includes $(\gamma ,\alpha )$ reactions which are of special importance in the $\gamma$ process.

Purpose: The measurement of $(\alpha ,n)$ reactions allows for an optimization of currently used $\alpha$-nucleus potentials. The reactions ${}^{165}\mathrm{Ho}$$(\alpha ,n)$ and ${}^{166}\mathrm{Er}$$(\alpha ,n)$ probe the optical model in a mass region where $\gamma$ process calculations exhibit an underproduction of $p$ nuclei which is not yet understood.

Method: To investigate the energy-dependent cross sections of the reactions ${}^{165}\mathrm{Ho}$$(\alpha ,n)$ and ${}^{166}\mathrm{Er}$$(\alpha ,n)$ close to the reaction threshold, self-supporting metallic foils were irradiated with $\alpha$ particles using the FN tandem Van de Graaff accelerator at the University of Notre Dame. The induced activity was determined afterwards by monitoring the specific $\beta$-decay channels.

Results: Hauser-Feshbach predictions with a widely used global $\alpha$ potential describe the data well at energies where the cross sections are almost exclusively sensitive to the $\alpha$ widths. Increasing discrepancies appear towards the reaction threshold at lower energy.

Conclusions: The tested global $\alpha$ potential is suitable at energies above 14 MeV, while a modification seems necessary close to the reaction threshold. Since the $\gamma$ and neutron widths show non-negligible impact on the predictions, complementary data are required to judge whether or not the discrepancies found can be solely assigned to the $\alpha$ width.

The total reaction cross section is an essential quantity in particle and heavy-ion transport codes when determining the mean free path of a transported particle. Many transport codes determine the distance a particle is transported before it collides with the target or is stopped in the target material, with the Monte Carlo (MC) method using semiempirical parametrization models for the total reaction cross sections. In order to improve the well-known Kox and Shen models of total reaction cross sections and allow the models to be used at energies below 30 MeV/nucleon, we propose a modified parametrization of the transparency parameter. We also report that the Kox and Shen models have a projectile-target asymmetry and should be used so that the lighter nucleus is always treated as the projectile.

We present evidence for the nuclear ripples superimposed on the Airy structure of the nuclear rainbow, which is similar to the meteorological rainbow. The mechanism of the nuclear ripples is also similar to that of the meteorological rainbow, which is caused by the interference between the externally reflective waves and refractive waves. The nuclear ripple structure was confirmed by analyzing the elastic angular distribution in ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ rainbow scattering at $E_L=115.9$ MeV using the coupled channels method by taking account of coupling to the excited states of ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ with a double folding model derived from a density-dependent effective nucleon-nucleon force with realistic wave functions for ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$. The coupling to the excited states plays the role of creating the external reflection.

The isotopic behavior of the fusion cross sections and barrier curvature at energies near and below the barrier are explored using the proximity formalism. For this purpose, various versions of the proximity potentials are used to calculate the nuclear part of the interaction potential. Our study has been restricted to the isotopic systems which obey the condition of $0.5\le N/Z\le 1.6$ for their compound nuclei. The obtained results show that the barrier curvature and the fusion cross section follow a similar behavior at near- and below-barrier energies. In fact, these quantities decrease nonlinearly (second order) with the addition of a neutron. In the present study, the energy dependence of the fusion cross sections is also discussed for the considered isotopic systems.

Fission fragments resulting from the fission of target-like nuclei produced in the ${}^{40}\mathrm{Ar}+{}^{197}\mathrm{Au}$ reaction at 35 MeV/u are measured in coincidence with the emitted light charged particles (LCPs). Comparison of the $N/Z$ composition of the LCPs at middle and large angles in the laboratory frame shows that particles emitted at smaller angles, which contain a larger contribution from dynamical emission, are more neutron rich. A moving-source model is used to fit the energy spectra of the hydrogen isotopes. A hierarchy from proton to deuteron and triton is observed in the multiplicity ratio between the intermediate velocity source and the compound nucleus source. This ratio is sensitive to the dynamical emission at early stages of the reaction and to statistical emission lasting up to the scission point. Calculations with the improved quantum molecular dynamics (ImQMD) transport-model qualitatively support the picture that more free and bound neutrons are emitted during the early stage, showing a clear dependence of $N/Z$ on the parametrization of the symmetry energy. The time-dependent isospin composition of the emitted particles thus may be used to probe the symmetry energy at subsaturation densities.

Two-dimensional low-$p_T$ dihadron correlations in azimuthal angle $\varphi$ and pseudorapidity $\eta$ in high-energy heavy-ion collisions are investigated within both the HIJING Monte Carlo model and an event-by-event $(3+1)$D ideal hydrodynamic model. Without final-state interaction and collective expansion, dihadron correlations from HIJING simulations have a typical structure from minijets that contains a near-side two-dimensional peak and an away-side ridge along the $\eta$ direction. In contrast, event-by-event $(3+1)$D ideal hydrodynamic simulations with fluctuating initial conditions from the $\mathrm{HIJING}+\mathrm{AMPT}$ model produce a strong dihadron correlation that has an away-side as well as a near-side ridge. Relics of intrinsic dihadron correlation from minijets in the initial conditions still remain as superimposed on the two ridges. By varying initial conditions from $\mathrm{HIJING}+\mathrm{AMPT}$, we study effects of minijets, nonvanishing initial flow, and longitudinal fluctuation on the final-state dihadron correlations. With a large rapidity gap, one can exclude near-side correlations from minijet relics and dihadron correlations can be described by the superposition of harmonic flows up to the sixth order. When long-range correlations with a large rapidity gap are subtracted from short-range correlations with a small rapidity gap, the remaining near-side short-range dihadron correlation is shown to result mainly from relics of minijets. Low-transverse-momentum hadron yields per trigger $(p_T^{\mathrm{trig}}<4\mathrm{GeV}/c,p_T^{\mathrm{asso}}<2\mathrm{GeV}/c)$ owing to this short-range correlation in central heavy-ion collisions are enhanced over that in peripheral heavy-ion collisions and $p+p$ collisions, while widths in azimuthal angle remain the same, in qualitative agreement with experimental data. The enhancement owing to influence by the transverse expansion of the bulk medium is also shown to increase with centrality and colliding energy but to be insensitive to the kinetic freeze-out temperature.

Background: Collectivity has been inferred in ${}^{64}\mathrm{Cr}$ based on measurements of the excitation energy of the first excited $2^{+}$ state and $B(E2;2_1^{+}\to 0_1^{+})$ value. However, the energy of the $2_1^{+}$ state in ${}^{64}\mathrm{Cr}$ is not precisely known.

Purpose: The objective was to precisely determine the energy of the $2_1^{+}\to 0_1^{+}$ transition in ${}^{64}\mathrm{Cr}$ following the $\beta$ decay of ${}^{64}\mathrm{V}$.

Method: ${}^{64}\mathrm{V}$ ions were produced by projectile fragmentation at the National Superconducting Cyclotron Laboratory and stopped in a double-sided Si strip detector. ${}^{64}\mathrm{V}$ isomeric and $\beta$-delayed $\gamma$ rays were detected in an ancillary array of high-purity Ge detectors in order to determine the energies of excited states in ${}^{64}\mathrm{V}$ and ${}^{64}\mathrm{Cr}$.

Results: The first excited $2^{+}$ state in ${}^{64}\mathrm{Cr}$ was populated following the $\beta$ decay of ${}^{64}\mathrm{V}$, and an energy of 430(2) keV was determined. Additionally, an isomeric state in ${}^{64}\mathrm{V}$ with an energy of 81.0(7) keV and a half-life less than 1 $\mu$s was discovered.

Conclusion: The excitation energy of the $2_1^{+}$ state in ${}^{64}\mathrm{Cr}$ has been precisely determined and an isomeric state is identified in ${}^{64}\mathrm{V}$ for the first time.

Properties of neutron-rich ${}^{22}\mathrm{C}$ are studied using the mean-field approach with Skyrme energy density functionals. Its weak binding and large total reaction cross section, which are suggested by recent experiments, are simulated by modifying the central part of Skyrme potential. Calculating $E1$ strength distribution by using the random-phase approximation, we investigate developments of low-lying electric dipole $\left(E1\right)$ strength and the contribution of core excitations of ${}^{20}\mathrm{C}$. As the neutron Fermi level approaches the zero-energy threshold (${\varepsilon }_F\gtrsim -1$ MeV), we find that the low-lying $E1$ strength exceeds the energy-weighted cluster sum rule, which indicates the importance of core excitations with the $1d_{5/2}$ orbit.