A detailed analysis of the wide excitation function of nuclear stopping has been conducted within a transport model, isospin-dependent quantum molecular dynamics model, and an overall good agreement with the INDRA and FOPI Collaborations’ experimental data has been achieved. It is found that the mean value of isotropy in central heavy-ion collision (HIC) reaches a minimum near-Fermi energy and approaches a maximum at around 300–400$A$ MeV. This suggests that, in statistical average, the equilibration is far from being reached, even in central HIC especially near Fermi energy. A hierarchy in the stopping of fragments, which favors heavy fragments to penetrate, provides a robust restriction on the global trend of nuclear stopping and could serve as a probe for nuclear equations of state.

Collective flow in collisions between lead nuclei at the CERN Large Hadron Collider (LHC) are influenced by random initial state fluctuations, especially for odd harmonics. Here we extend fluctuation studies to longitudinal fluctuations, which may have significant effect on the rapidity distribution of odd harmonics. Furthermore center-of-mass rapidity fluctuations are measurable, but not yet analyzed. Here in the PACIAE parton and hadron molecular dynamics model we make an analysis of initial state fluctuations. As previous analyses have discussed mainly the effects of fluctuations on eccentricity and the elliptic flow we pay particular attention to the fluctuations of the center-of-mass rapidity of the system, which is conservatively estimated in our model as $\Delta y_{\mathrm{c}.\mathrm{m}.}=0.1$, by neglecting all pre-equilibrium emission effects that increase the $y_{\mathrm{c}.\mathrm{m}.}$ fluctuations.

The subshell effect for nuclei with proton number $Z\sim$ 64 has been known for many years. The most economic way to consider this effect is to use the effective valence proton number. In this Brief Report we extract effective valence proton numbers for nuclei in this region by using the systematics of the first $2^{+}$ energies ($E_{2_1^{+}}$) of even-even nuclei, the ratios of the first $4^{+}$ and $6^{+}$ state energies with respect to $E_{2_1^{+}}$ ($R_4$ and $R_6$), the $B\left(E2\right)$ values, the quadrupole deformation parameters $e_2$, and anomalous $g$ factors of the $2_1^{+}$ state for even-even nuclei. It is noticed that these physical quantities saturate when $N_{\mathrm{p}}{N}_{\mathrm{n}}$, the product of the valence proton number and the valence neutron number, is large enough; on the other hand, they go to saturation at different “speeds.” We show that the subshell effect is more evident for $E_{2_1^{+}}$ and yrast state energy ratios ($R_4$ and $R_6$), and relatively less for other quantities.

The U(5) to SU(3) evolution of the nuclear structure in the even ${}^{144-156}$Nd isotopes has been investigated in the framework of the interacting boson approximation (IBA-2) model, taking into account the effect of the partial $Z=64$ subshell closure on the structure of the states of a collective nature. The analysis, which led to a satisfactory description of excitation energy patterns, quadrupole moments, and decay properties of the states (even when important $M1$ components were present in the transitions), is extended to the available data on $g$ factors, in ${}^{144-150}$Nd. Their values are reasonably reproduced by the calculations.

Extensive calculations on isoscaling behavior with the sequential-decay model $gemini$ are performed for the medium-to-heavy nuclei in the mass range $A=60$–120 at excitation energies up to 3 MeV/nucleon. The comparison between the products after the first-step decay and the ones after the entire-steps decay demonstrates that there exists a strong sequential decay effect on the final isoscaling parameters and the apparent temperature. Results show that the apparent symmetry energy coefficient ${\gamma }_{\text{app}}$ does not reflect the initial symmetry energy coefficient $C_{\text{sym}}$ embedded in the mass calculation in the present gemini model.

We suggest that the number of correlated nucleon pairs in an arbitrary nucleus can be estimated by counting the number of proton-neutron, proton-proton, and neutron-neutron pairs residing in a relative $S$ state. We present numerical calculations of those amounts for the nuclei ${}^4$He, ${}^9$Be, ${}^{12}$C, ${}^{27}$Al, ${}^{40}$Ca, ${}^{48}$Ca, ${}^{56}$Fe, ${}^{63}$Cu, ${}^{108}$Ag, and ${}^{197}$Au. The results are used to predict the values of the ratios of the per-nucleon electron-nucleus inelastic scattering cross section to the deuteron in the kinematic regime where correlations dominate.

Excited states in ${}^{56}$Cr have been populated after ${}^{48}$Ca(${}^{11}$B,p2n) reactions at a beam energy of 32 MeV. The Cologne plunger device surrounded by a $\gamma$-detector array of one EUROBALL cluster detector and five Ge detectors was employed to determine lifetimes with the recoil distance Doppler shift method. $\gamma \gamma$-coincidence data were analyzed using the differential decay curve method and precise lifetimes for the first $2^{+}$ and $4^{+}$ state of $\tau =5.49\left(14\right)$ ps and $\tau =3.15\left(11\right)$ ps, respectively, were extracted. The corresponding B(E2; $2^{+}\to 0^{+})=11.33\left(31\right)$ W.u. quantifies with a high accuracy the puzzling discrepancy between experimental B(E2) values in $N=32$ isotones and theoretical results from large-scale shell model calculations employing modern effective nucleon-nucleon interactions.

Elastic scattering angular distributions for ${}^7$Be, ${}^9$Be, and ${}^{10}$Be isotopes on ${}^{12}$C target were measured at laboratory energies of 18.8, 26.0, and 23.2 MeV, respectively. The analysis was performed in terms of optical model potentials using Woods-Saxon and double-folding form factors. Also, continuum discretized coupled-channels calculations were performed for ${}^7$Be and ${}^9$Be $+{}^{12}$C systems to infer the role of breakup in the elastic scattering. For the ${}^{10}$Be $+{}^{12}$C system, bound states coupled-channels calculations were considered. Moreover, total reaction cross sections were deduced from the elastic scattering analysis and compared with published data on other weakly and tightly bound projectiles elastically scattered on the ${}^{12}$C target, as a function of energy.

We present a number of independent flow observables that can be measured using multiparticle azimuthal correlations in heavy-ion collisions. Some of these observables are already well known, such as $v_2\left\{2\right\}$ and $v_2\left\{4\right\}$, but most are new—in particular, joint correlations among $v_1$, $v_2$, and $v_3$. Taken together, these measurements will allow for a more precise determination of the medium properties than is currently possible. In particular, by taking ratios of these observables, we construct quantities that are less sensitive to the hydrodynamic response of the medium and thus more directly characterize the initial-state fluctuations of the event shape, which may constrain models for early-time, nonequilibrium QCD dynamics. We present predictions for these ratios using two Monte Carlo models and compare them to available data.

Each and every energy-dependent partial-wave analysis is parametrizing the pole positions in a procedure defined by the way the continuous energy dependence is implemented. These pole positions are, henceforth, inherently model dependent. To reduce this model dependence, we use only one, coupled-channel, unitary, fully analytic method based on the isobar approximation to extract the pole positions from each available member of the worldwide collection of partial-wave amplitudes, which are understood as nothing more but a good energy-dependent representation of genuine experimental numbers assembled in a form of partial-wave data. In that way, the model dependence related to the different assumptions on the analytic form of the partial-wave amplitudes is avoided, and the true confidence limit for the existence of a particular resonant state, at least in one model, is established. The way the method works and first results are demonstrated for the $S_{11}$ partial wave.

In Had$\check{\mathrm{z}}$imehmedović et al. [Phys. Rev. C 84, 035204 (2011)] we have used the Zagreb realization of Carnegie-Melon-Berkeley coupled-channel, unitary model as a tool for extracting pole positions from the world collection of partial-wave data, with the aim of eliminating model dependence in pole-search procedures. In order that the method is sensible, we in this paper discuss the stability of the method with respect to the strong variation of different model ingredients. We show that the Zagreb CMB procedure is very stable with strong variation of the model assumptions and that it can reliably predict the pole positions of the fitted partial-wave amplitudes.

In this work, masses and radii of neutron stars are considered to investigate the effect of nuclear symmetry energy on astrophysical observables. A relativistic mean-field model with density-dependent meson-baryon coupling constants is employed in describing the equation of state of dense nuclear matter, and the density dependencies of the symmetry energies are quoted from the recent phenomenological formulas obtained from heavy-ion data at subnuclear saturation densities. Since hyperons can take part in the $\beta$-equilibrium of the dense matter inside neutron stars, we include hyperons in our estimation and their roles are discussed in combination with that of the nuclear symmetry energy.

The $\alpha$-particle energy spectra have been measured in coincidence with fission fragments over a wide range of relative angles with respect to fragment emission direction in the ${}^{11}$B (62 MeV) $+$ ${}^{232}$Th reaction. The $\alpha$-particle multiplicity spectra have been fitted with moving source model to extract the prescission (${\alpha }_{\mathrm{pre}}$) and near-scission (${\alpha }_{\mathrm{nse}}$) components. The present results, along with available data from the literature over a wide range of $Z^2/A$ and the excitation energy of a compound system, have been analyzed to develop certain global features of the pre- and near-scission emission characteristics. It is seen that ${\alpha }_{\mathrm{pre}}$ values when normalized to $E_{\mathit{CN}}^{2.3}$ ($E_{\mathit{CN}}$ is the compound nucleus excitation energy) show a systematic linearly increasing trend with the $\alpha$-particle emission $Q$ value ($Q_{\alpha }$). The fraction of near-scission multiplicity is observed to be nearly the same at around 10% of the total prescission multiplicity for all the systems.

We present a method that offers perspectives to perform fully antisymmetrized simulations for inhomogeneous bulk fermion matter. The technique bears resemblance to classical periodic boundary conditions, using localized single-particle states. Such localized states are an ideal tool to discuss phenomena where spatial localization plays an important role. The antisymmetrization is obtained introducing a doubly periodic structure in the many-body fermion wave functions. This results in circulant matrices for the evaluation of expectation values, leading to a computationally tractable formalism to study fully antisymmetrized bulk fermion matter. We show that the proposed technique is able to reproduce essential fermion features in an elegant and computationally advantageous manner.

Measurements of ${}^9$Be + $\alpha$ resonant scattering have been performed using the thick-target approach with a ${}^4$He gas volume and a large-area silicon strip detector. ${}^9$Be beam energies in the range 12 to 21.4 MeV were used to measure the ${}^{13}$C excitation energy spectrum between 13.2 and 16.2 MeV. An $R$-matrix analysis has been performed to characterize the spins and widths of ${}^{13}$C resonances, some of which have been proposed to be associated with a 3$\alpha +n$ molecular band.

The azimuthal angle ($\phi$) dependence of the Coulomb barrier parameters (height $V_b$ and position $R_b$) are studied in the framework of the double-folding model with the realistic M3Y nucleon-nucleon interaction. Different pairs of axially symmetric, deformed nuclei are considered. For the interaction between medium and heavy nuclei, the maximum percentage of $\phi$ dependence is studied as a function of relative orientations of the interacting nuclei. It appreciably increases as the values of the deformation parameters increase and is sensitive to the hexadecapole deformation. The smallest $\phi$ variation is found for the relative orientations ${\theta }_P={\theta }_T={90}^{\circ }$. The $\phi$ variation of the Coulomb barrier parameters, as calculated in the present paper, is completely different in both magnitude and behavior from those deduced in the widely used proximity approach.

Heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) are well described by the (nearly ideal) hydrodynamics for average events. In the present paper we study initial state fluctuations appearing on an event-by-event basis and the propagation of perturbations induced by them. We found that (i) fluctuations of several of the lowest harmonics have comparable magnitudes and (ii) that at least all odd harmonics are correlated in phase, (iii) thus indicating the local nature of fluctuations. We argue that such local perturbations should be the source of the “tiny bang,” a pulse of sound propagating from it. We identify its two fundamental scales as (i) the “sound horizon” (analogous to the absolute ruler in cosmic microwave background and galaxy distributions) and (ii) the “viscous horizon” separating damped and undamped harmonics. We then qualitatively describe how one can determine them from the data and thus determine two fundamental parameters of the matter: the (average) speed of sound and viscosity. The rest of the paper explains how one can study mutual coherence of various harmonics. For that, one should go beyond the two-particle correlations to three (or more) particles. Mutual coherence is important for the picture of propagating sound waves.

We report on $K^{*0}$ production at midrapidity in Au $+$ Au and Cu $+$ Cu collisions at $\sqrt{s_{NN}}=62.4$ and 200 GeV collected by the Solenoid Tracker at the Relativistic Heavy Ion Collider detector. The $K^{*0}$ is reconstructed via the hadronic decays $K^{*0}\to K^{+}{\pi }^{-}$ and $\overline{K^{*0}}\to K^{-}{\pi }^{+}$. Transverse momentum, $p_T$, spectra are measured over a range of $p_T$ extending from 0.2 GeV$/c$ up to 5 GeV$/c$. The center-of-mass energy and system size dependence of the rapidity density, $dN/dy$, and the average transverse momentum, $\langle p_T\rangle$, are presented. The measured $N\left(K^{*0}\right)/N\left(K\right)$ and $N\left(\phi \right)/N\left(K^{*0}\right)$ ratios favor the dominance of rescattering of decay daughters of $K^{*0}$ over the hadronic regeneration for the $K^{*0}$ production. In the intermediate $p_T$ region ($2.0<p_T<4.0$ GeV$/c$), the elliptic flow parameter, $v_2$, and the nuclear modification factor, $R_{\mathrm{CP}}$, agree with the expectations from the quark coalescence model of particle production.

The stellar reaction ${}^{26}$Si($p,\gamma$)${}^{27}$P was studied in the Coulomb dissociation of ${}^{27}$P. Two known resonance levels in ${}^{27}$P were excited and a candidate for the third excited state was found in the ${}^{26}$Si $p$ relative energy spectrum. The $E$2 resonance strengths $\omega \gamma$ were obtained to be $(6.5\pm 1.3)\times {10}^{-11}$, $(6.0\pm 1.1)\times {10}^{-10}$, and $(1.10\pm 0.27)\times {10}^{-10}$ MeV. The total ($E2+M$1) $\omega \gamma$ value for the first excited state was evaluated to be $1.9_{-1.1}^{+1.9}\times {10}^{-9}$ MeV with the help of the shell model. The error was estimated from the deviation of theoretical predictions with the same shell model from experimental strengths obtained in the present study for ${}^{27}$P and earlier ones for the mirror nucleus ${}^{27}$Mg. The astrophysical reaction rate for the ${}^{26}$Si($p,\gamma$)${}^{27}$P reaction was also calculated and compared with previous estimations.