The inclusive energy distributions of the fragments ($3⩽Z⩽5$) emitted in the reaction ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ have been measured in the angular range $9^{°}$ to ${29}^{°}$, at the energies 117, 125, 145, and 160 MeV, respectively. The centroids of the fragments energy distributions follow Viola systematics, which suggest that the fragments are emitted from a fully energy relaxed composite—as expected for both FF and orbiting processes. The center of mass angular distributions of the fragments B, Be, and Li obtained at all the bombarding energies follow $1/\sin {\theta }_{\mathrm{c}.\mathrm{m}.}$ like variation—which further corroborates the conjecture of emission from fully equilibrated composite. The average $\langle Q\rangle$ values for the fragments B, Be, and Li are found to be independent of the center of mass emission angles, which further suggest that at all angles, the fragments are emitted from completely equilibrated source at all incident energies considered here. The yields of the fragments Li and Be are in agreement with statistical-model predictions. The enhanced yields of entrance channel fragment B indicate the survival of orbiting-like process in ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ system at these energies.

This study shows that isoscaling, usually studied in nuclear reactions, is a phenomenon common to all cases of fair sampling. Exact expressions for the yield ratio $R_{21}$ and approximate expressions for the isoscaling parameters $\alpha$ and $\beta$ are obtained and compared to experimental results. It is concluded that nuclear isoscaling is bound to contain a component due to sampling and, thus, a word of caution is issued to those interested in extracting information about the nuclear equation of state from isoscaling.

High precision measurements for back-angle quasi-elastic scattering of ${}^{16}\mathrm{O}$ from various target nuclei have been made, and are compared with coupled channels calculations to determine the diffuseness of the real part of the Woods-Saxon nuclear potential. The extracted diffuseness parameters are in the range of $0.60$ to $0.69$ fm, and agree well with previous results using a ${}^{32}\mathrm{S}$ projectile. The measured quasi-elastic energy spectra close to the barrier show both discrete peaks and a broad continuous structure with $Q$-values down to $-25$ MeV. These suggest the inadequacy of coupled channels calculations that include couplings only to low energy, discrete states of the colliding nuclei.

This work presents the cross sections for radioactive nuclide production in ${}^{56}\mathrm{Fe}$($p,x$) reactions determined in six experiments using 300, 500, 750, 1000, 1500, and 2600 MeV protons of the external beam from the ITEP U-10 proton accelerator. In total, 221 independent and cumulative yields of radioactive residuals of half-lives from 6.6 min to 312 d have been obtained. The radioactive product nuclide yields were determined by direct $\gamma$-spectrometry. The measured data have been compared with the experimental data obtained elsewhere by the direct and inverse kinematics methods and with calculation results of 15 different codes that simulated hadron-nucleus interactions: MCNPX (INCL, CEM2K, BERTINI, ISABEL), LAHET (BERTINI, ISABEL), CEM03 (.01, .G1, .S1), LAQGSM03 (.01, .G1, .S1), CASCADE-2004, LAHETO, and BRIEFF. Most of the data obtained here are in a good agreement with the inverse kinematics results and disprove the results of some earlier activation measurements that were quite different from the inverse kinematics measurements. The most significant calculation-to-experiment differences are observed in the yields of the $A<30$ light nuclei, indicating that further improvements in nuclear reaction models are needed, and pointing out as well to a necessity of more complete experimental measurements of such reaction products.

We study the near-threshold ${\eta }^{\text{'}}$ production mechanism in nucleon-nucleon and $\pi N$ collisions under the assumption that subthreshold resonance $N^{*}(1535)$ is predominant. In an effective Lagrangian approach that gives a reasonable description to the $\mathit{pN}\to \mathit{pN}\eta$ and ${\pi }^{-}p\to n\eta$ reactions, we find that the excitation of $N^{*}(1535)$ resonance from the t-channel π exchange makes the dominate contribution to the $\mathit{pN}\to \mathit{pN}{\eta }^{\text{'}}$ process, and a value of 6.5 for the ratio of $\sigma (\mathit{pn}\to \mathit{pn}{\eta }^{\text{'}})$ to $\sigma (\mathit{pp}\to \mathit{pp}{\eta }^{\text{'}})$ is predicted. A strongcoupling strength of $N^{*}(1535)$ to ${\eta }^{\text{'}}N$ ($g_{{\eta }^{\text{'}}{\mathit{NN}}^{*}}^2/4\pi =1.1$) is extracted from a combined analysis to $\mathit{pp}\to \mathit{pp}{\eta }^{\text{'}}$ and $\pi N\to N{\eta }^{\text{'}}$, and the possible implication to the intrinsic component of $N^{*}(1535)$ is explored.

The decay of ${}^{10}\mathrm{C}$ excited states to the $2p+2\alpha$ exit channel has been studied using inelastic excitation of a secondary ${}^{10}\mathrm{C}$ beam. The decay sequences leading to the $2p+2\alpha$ final state are determined for the previously known levels and for a newly found level at $E^{*}=8.4$ MeV. A state at $E^{*}=6.57$ MeV is shown to undergo two-proton decay to ${}^8{\mathrm{Be}}_{\mathrm{g}.\mathrm{s}.}$ with strong $p$-$p$ correlations consistent with the ${}^1\mathrm{S}$ phase shift. Based on the lack of such correlations for other two-proton decays, this indicates that the correlations are associated with structure of the parent level.

The partial width for decay of a resonance into three fragments is largely determined at distances where the energy is smaller than the effective potential producing the corresponding wave function. At short distances the many-body properties are accounted for by preformation or spectroscopic factors. We use the adiabatic expansion method combined with the WKB approximation to obtain the indispensable cluster model wave functions at intermediate and larger distances. We test the concept by deriving conditions for the minimal basis expressed in terms of partial waves and radial nodes. We compare results for different effective interactions and methods. Agreement is found with experimental values for a sufficiently large basis. We illustrate the ideas with realistic examples from α emission of ${}^{12}\mathrm{C}$ and two-proton emission of ${}^{17}\mathrm{Ne}$. Basis requirements for accurate momentum distributions are briefly discussed.

The Euroball array has been used to search for linking transitions between the superdeformed (SD) and the normal deformed (ND) wells in ${}^{151}\mathrm{Tb}$. Many $\gamma$ rays in the energy range 2–4 MeV have been observed in coincidence with the yrast SD band. It is proposed that the highest energy transition of 3748 keV and the strongest line (2818 keV) of the previously observed transitions both decay from the same SD level as their links with the ND states have been identified. The current spectra have insufficient statistics to completely identify the decay point in the SD band. Theoretical calculations covering SD bands in the $A\approx 150$ region enable the two possible spin assignments to be compared with experimental data on proposed links in ${}^{149}\mathrm{Gd}$ and ${}^{152}\mathrm{Dy}$. It is concluded that the energy of the lowest SD band member in ${}^{151}\mathrm{Tb}$ has an excitation energy of 12861 keV and a spin of $65/2^{+}$.

We propose a decomposition of the scattering amplitude into shadow and surface components for proton scattering against calcium isotopes as targets at 21 MeV. We account for spin-orbit coupling effects for the optical potential in the nonrelativistic limit. Our calculations show very good agreement with experimental trends.

We develop a semiclassical procedure to calculate breakup reaction products’ angular and energy distributions in the laboratory frame of reference. The effects of the Coulomb and nuclear interaction potentials on the classical trajectories, as well as bound-bound, bound-continuum, and continuum-continuum couplings, are included. As an example we consider the ${}^8\mathrm{B}+{}^{58}\mathrm{Ni}$ system at $E_{\mathrm{lab}}=26$ MeV and find very good agreement with the available experimental data.

The thermodynamic partition function for a gas of color-singlet bags consisting of fundamental and adjoint particles in both $\mathrm{U}(N_c)$ and $\mathrm{SU}(N_c)$ group representations is reviewed in detail. The constituent particle species are assumed to satisfy various thermodynamic statistics. The gas of bags is probed to study the phase transition for nuclear matter in extreme conditions. These bags are interpreted as the Hagedorn states, and they are the highly excited hadronic states produced below the phase transition point to the quark-gluon plasma (QGP). The hadronic density of states has the Gross-Witten critical point and exhibits a third-order phase transition from a hadronic phase dominated by the discrete low-lying hadronic mass spectrum particles to another hadronic phase dominated by the continuous Hagedorn states. The Hagedorn threshold production is found just above the highest known experimental discrete low-lying hadronic mass spectrum. The subsequent Hagedorn phase undergoes a first-order deconfinement phase transition to an explosive QGP. The role of the chiral phase transition in the phases of the discrete low-lying mass spectrum and the continuous Hagedorn mass spectrum is also considered. It is found to be crucial in the phase transition diagram. Alternative scenarios are briefly discussed for the Hagedorn gas undergoing a higher order phase transition through multiple processes of internal color-flavor structure modification.

We calculate leading-order dilepton yields from a quark-gluon plasma that has a time-dependent anisotropy in momentum space. Such anisotropies can arise during the earliest stages of quark-gluon plasma evolution due to the rapid longitudinal expansion of the created matter. Two phenomenological models for the proper-time dependence of the parton hard momentum scale, $p_{\mathrm{hard}}$, and the plasma anisotropy parameter, ξ, are constructed that describe the transition of the plasma from its initial nonequilibrium state to an isotropic thermalized state. The first model constructed interpolates between 1+1 dimensional free streaming at early times and 1+1 dimensional ideal hydrodynamical expansion at late times. In the second model we include the effect of collisional broadening of the parton distribution functions in the early-time pre-equilibrium stage of plasma evolution. We find for both cases that for fixed initial conditions high-energy dilepton production is enhanced by pre-equilibrium emission. When the models are constrained to fixed final pion multiplicity the dependence of the resulting spectra on the assumed plasma isotropization time is reduced. Using our most realistic collisionally broadened model we find that high-transverse-momentum dilepton production would be enhanced by at most 40% at the Relativistic Heavy Ion Collider and 50% at the CERN Large Hadron Collider if one assumes an isotropization/thermalization time of 2 fm/$c$. Given sufficiently precise experimental data this enhancement could be used to determine the plasma isotropization time experimentally.

Results on $\Lambda ,\overline{\Lambda },{\Xi }^{-}$, and ${\overline{\Xi }}^{+}$ production in central $\mathrm{Pb}+\mathrm{Pb}$ reactions at $20A,30A,40A,80A$, and 158$A$ GeV are presented. The energy dependence of transverse mass spectra, rapidity spectra, and multiplicities is discussed. Comparisons to string hadronic models (UrQMD and HSD) and statistical hadron gas models are shown. Although the latter provide a reasonable description of all particle yields, the first class of models fails to match the ${\Xi }^{-}$ and ${\overline{\Xi }}^{+}$ multiplicities.

The hadronization of an expanding partonic fireball is studied within the parton-hadron-string-dynamics (PHSD) approach, which is based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice QCD results in thermodynamic equilibrium. Apart from strong parton interactions, the expansion and development of collective flow is driven by strong gradients in the parton mean fields. An analysis of the elliptic flow $v_2$ demonstrates a linear correlation with the spatial eccentricity ε as in ideal hydrodynamics. The hadronization occurs by quark-antiquark fusion or three-quark/three-antiquark recombination, which is described by covariant transition rates. Since the dynamical quarks become very massive, the formed resonant “pre-hadronic” color-dipole states ($q\overline{q}$ or $\mathrm{qqq}$) are of high invariant mass, too, and sequentially decay to the ground-state meson and baryon octets increasing the total entropy. This solves the entropy problem in hadronization in a natural way. The resulting particle ratios turn out to be in line with those from a grand-canonical partition function at temperature $T\approx 170$ MeV rather independent from the initial temperature and indicate an approximate strangeness equilibration.

The surprising absence of the $N=34$ subshell closure in the exotic nucleus ${}^{56}\mathrm{Ti}$ is highlighted by examining the experimental single neutron energies along the $N=28$ isotopes, which are extracted from previously existing data on single-neutron transfer reactions on stable isotones and nuclear masses. The results point out the role of the monopole effect of the tensor force on the $f_{7/2}\text{−}{f}_{5/2}$ splitting and confirm the prediction of the reduction of this splitting in the $Z>20$ isotones. In addition, the importance of making similar measurements of the distribution of single neutron and single neutron hole strength in the exotic $Z<20\hspace{0.5em}N=28$ isotones is discussed. Measurements of the ($d,p$) reaction and the neutron knockout reaction on the exotic nucleus ${}^{46}\mathrm{Ar}$ have provided proof of principle for the necessary reactions, and advances presently taking place in detector technology will soon provide the tools necessary for reliably mapping the distribution of neutron strength in detail.

We discuss the influence of different initial conditions for the stress tensor and the effect of bulk viscosity on the expansion and cooling of the fireball created in relativistic heavy ion collisions. In particular, we explore the evolution of longitudinal and transverse components of the pressure and the extent of dissipative entropy production in the one-dimensional, boost-invariant hydrodynamic model. We find that a bulk viscosity consistent with recent estimates from lattice QCD further slows the equilibration of the system; however, it does not significantly increase the entropy produced.

Multiplicity fluctuations of positively, negatively, and all charged hadrons in the forward hemisphere were studied in central Pb+Pb collisions at $20A,30A,40A,80A$, and $158A$ GeV. The multiplicity distributions and their scaled variances ω are presented as functions of their dependence on collision energy as well as on rapidity and transverse momentum. The distributions have bell-like shapes and their scaled variances are in the range from 0.8 to 1.2 without any significant structure in their energy dependence. No indication of the critical point in fluctuations are observed. The string-hadronic ultrarelativistic quantum molecular dynamics (UrQMD) model significantly overpredicts the mean, but it approximately reproduces the scaled variance of the multiplicity distributions. The predictions of the statistical hadron-resonance gas model obtained within the grand-canonical and canonical ensembles disagree with the measured scaled variances. The narrower than Poissonian multiplicity fluctuations measured in numerous cases may be explained by the impact of conservation laws on fluctuations in relativistic systems.

A new set of equations for relativistic viscous hydrodynamics that captures both weak-coupling and strong-coupling physics to second order in gradients has been developed recently. We apply this framework to bulk physics at the Relativistic Heavy Ion Collider (RHIC), both for standard (Glauber-type) as well as for color-glass-condensate (CGC) initial conditions and show that the results do not depend strongly on the values for the second-order transport coefficients. Results for multiplicity, radial flow and elliptic flow are presented, and we quote the ratio of viscosity over entropy density for which our hydrodynamic model is consistent with experimental data. For CGC initial conditions, early thermalization does not seem to be required in order for hydrodynamics to describe charged hadron elliptic flow.

The low-energy bare-nucleus cross section for ${}^9\mathrm{Be}(p,\alpha ){}^6\mathrm{Li}$ has been extracted by means of the Trojan horse method (THM) applied to the ${}^2\mathrm{H}({}^9\mathrm{Be}$, $\alpha ,{}^6\mathrm{Li})n$ reaction at a beam energy of ${}^9\mathrm{Be}$ of 22.35 MeV. For the first time, we assume an intermediate process, ${}^9\mathrm{Be}+{}^2\mathrm{H}\to {}^9\mathrm{Be}+p+n$, and considered this process as one criterion of the quasifree condition. Accordingly, sequential decay processes were eliminated. The derived astrophysical $S(E)$ factor for the two-body process ${}^9\mathrm{Be}(p,\alpha ){}^6\mathrm{Li}$ is compared with that obtained from direct experiments. We have found good agreement between the two results, leading to an improved determination of the $S(E)$ with $S(0)=21.0\pm 0.8$ MeV b. Furthermore, the electron screening potential energy $U_e=676\pm 86$ eV has also been extracted in a model-independent way by comparing the direct and THM data. The value is significantly higher than that predicted by current theoretical models, whereas it is lower than $\mathit{Ue}\simeq 830$ eV, which was extracted from direct measurements with inclusion of the $E_{\mathrm{c}.\mathrm{m}.}=-23$ keV subthreshold resonance.