The initial conditions in the chemically nonequilibrated medium and Bjorken expanding medium at Relativistic Heavy Ion Collider (RHIC) are determined. With a set of rate equations describing the chemical equilibration of quarks and gluons based on perturbative QCD, we investigate the consequence for parton evolution at RHIC. With considering parton evolution, it is shown that the Debye screening mass and the inverse mean free-path of gluons reduce with increasing proper time in the QGP medium. The parton evolution affects the parton energy loss with detailed balance, both parton energy loss from stimulated emission in the chemically nonequilibrated expanding medium and in Bjorken expanding medium are linear dependent on the propagating distance rather than square dependent in the static medium. The energy absorption cannot be neglected at intermediate jet energies and small propagating distance of the energetic parton in contrast with that it is important only at intermediate jet energy in the static medium. This will increase the energy and propagating distance dependence of the parton energy loss and will affect the shape of suppression of moderately high $P_T$ hadron spectra.

Electric flux tubes are a well-known attribute of the quantum chromodynamic (QCD) vacuum in which they manifest confinement of electric color charges. Recently, experimental results appeared which suggest that not only do those objects persist at temperatures $T\approx T_c$ near the QCD phase transitions, but their decay is suppressed and the resulting clusters in Au-Au collisions are larger than in $\mathit{pp}$ collisions (i.e., in vacuum). This correlates well with recent theoretical scenarios that view the QCD matter in the $T\approx T_c$ region as a dual-magnetic plasma dominated by color-magnetic monopoles. In this view, the flux tubes are stabilized by dual-magnetic currents and are described by dual magnetohydrodynamics (DMHD). In this article, we calculate classically the dissipative effects in the flux tube. Such effects are associated with rescattering and finite conductivity of the matter. We derive the DMHD solution in the presence of dissipation and then estimate the lifetime of the electric flux tubes. The conclusion of this study is that a classical treatment leads to too short of a lifetime for the flux tubes.

We have studied the (ground-state) cluster radioactive decays within the preformed cluster model (PCM) of Gupta and collaborators [R. K. Gupta, in Proceedings of the 5th International Conference on Nuclear Reaction Mechanisms, Varenna, edited by E. Gadioli (Ricerca Scientifica ed Educazione Permanente, Milano, 1988), p. 416; S. S. Malik and R. K. Gupta, Phys. Rev. C 39, 1992 (1989)]. The relativistic mean-field (RMF) theory is used to obtain the nuclear matter densities for the double folding procedure used to construct the cluster-daughter potential with M3Y nucleon-nucleon interaction including exchange effects. Following the PCM approach, we have deduced empirically the preformation probability ${P_0}^{\mathrm{emp}}$ from the experimental data on both the $\alpha$- and exotic cluster-decays, specifically of parents in the trans-lead region having doubly magic ${}^{208}\mathrm{Pb}$ or its neighboring nuclei as daughters. Interestingly, the RMF-densities-based nuclear potential supports the concept of preformation for both the $\alpha$ and heavier clusters in radioactive nuclei. ${P_0}^{\alpha (\mathrm{emp})}$ for $\alpha$ decays is almost constant ($~$${10}^{-2}$–${10}^{-3}$) for all the parent nuclei considered here, and ${P_0}^{c(\mathrm{emp})}$ for cluster decays of the same parents decrease with the size of clusters emitted from different parents. The results obtained for ${P_0}^{c(\mathrm{emp})}$ are reasonable and are within two to three orders of magnitude of the well-accepted phenomenological model of Blendowske-Walliser for light clusters.

Excitation functions of elastic and inelastic ${}^7\mathrm{Be}+p$ scattering were measured in the energy range between 1.6 and 2.8 MeV in the c.m. An $R$-matrix analysis of the excitation functions provides strong evidence for new positive parity states in ${}^8\mathrm{B}$. A new $2^{+}$ state at an excitation energy of 2.55 MeV was observed, and a new $0^{+}$ state at 1.9 MeV is tentatively suggested. The $R$-matrix and time-dependent continuum shell model were used in the analysis of the excitation functions. The new results are compared to the calculations of contemporary theoretical models.

The relative differential cross section for the elastic scattering of neutrons by protons was measured at an incident neutron energy $E_n=14.9$ MeV and for center-of-mass scattering angles ranging from about ${60}^{°}$ to ${180}^{°}$. Angular distribution values were obtained from the normalization of the integrated data to the $n$-$p$ total elastic scattering cross section. Comparisons of the normalized data to the predictions of the Arndt et al. phase-shift analysis, those of the Nijmegen group, and with the ENDF/B-VII.0 evaluation are sensitive to the value of the total elastic scattering cross section used to normalize the data. The results of a fit to a first-order Legendre polynomial expansion are in good agreement in the backward scattering hemisphere with the predictions of the Arndt et al. phase-shift analysis, those of the Nijmegen group, and to a lesser extent, with the ENDF/B-VII.0 evaluation. A fit to a second-order expansion is in better agreement with the ENDF/B-VII.0 evaluation than with the other predictions, in particular when the total elastic scattering cross section given by Arndt et al. and the Nijmegen group is used to normalize the data. A Legendre polynomial fit to the existing $n$-$p$ scattering data in the 14 MeV energy region, excluding the present measurement, showed that a best fit is obtained for a second-order expansion. Furthermore, the Kolmogorov-Smirnov test confirms the general agreement in the backward scattering hemisphere and shows that significant differences between the database and the predictions occur in the angular range between ${60}^{°}$ and ${120}^{°}$ and below ${20}^{°}$. Although there is good overall agreement in the backward scattering hemisphere, more precision small-angle scattering data and a better definition of the total elastic cross section are needed for an accurate determination of the shape and magnitude of the angular distribution.

Castillejo-Dalitz-Dyson (CDD) poles are known to be connected with bound states and resonances. We discuss a new type of CDD pole associated with primitives i.e., poles of the $P$ matrix that correspond to zeros of the $D$ function on the unitary cut. The Low scattering equation is generalized for amplitudes with primitives. The relationship between the CDD poles and the primitives is illustrated by a description of the $S$-wave nucleon-nucleon phase shifts.

An analysis of all available $\alpha$-particle-induced reaction cross sections on nuclei within the mass number range $121⩽A⩽197$, below the Coulomb barrier, is carried out. This analysis leads to an optical potential that describes the $\alpha$-particle elastic scattering at low energies as well and both elastic-scattering and reaction data for $45⩽A⩽124$. The energy dependence of the surface imaginary potential depth is proved to be essential for understanding $\alpha$-particle interaction behavior below the Coulomb barrier.

We have remeasured and have redetermined the $g$ factor for the $4_1^{+}$ state in ${}^{68}\mathrm{Zn}$ following inconsistencies between earlier measurements and a recent result. We have reanalyzed several former measurements by applying an alternative analysis procedure, which allows for determining the precession effect separately for each gamma detector implying less uncertainties in the background subtraction for the relevant spectra. In addition, all measured $g$-factor and $B(E2)$ data for the first $2^{+}$ and $4^{+}$ states in all stable even-$A$ Zn isotopes and the radioactive ${}^{62}\mathrm{Zn}$, are compared with new large-scale shell model calculations based on the most advanced effective interaction in the $\mathit{fpg}$-shell model space.

We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with $N/A=$ 0.54 and 0.57 as well as isobaric systems with $N/A=$ 0.5 and 0.58. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due to the Coulomb repulsion. We also demonstrate clearly the dominance of Coulomb repulsion over symmetry energy.

Compound nucleus spin distribution has been calculated for several fission reaction systems induced by nucleons and heavy ions. Determination of the spin distribution for these systems is based upon the comparison between the experimental data of the fission fragment angular distributions as well as the prediction of the standard saddle-point statistical model (SSPSM). For the systems, the two cases, namely with and without neutron emission corrections were considered. This method is used for the first time to determine compound nucleus spin distribution. Afterwards, our theoretical results have been compared with the data obtained from the coupled-channel technique as well as the Wong model, and satisfactory agreements were found. Furthermore, we have introduced a semiclassical approximation relation for the compound nucleus spin distribution of these systems.

Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar $H$-shell burning. In particular, the strengths of low-energy resonances with $E<200$ keV in ${}^{25}\mathrm{Mg}$($p,\gamma$)${}^{26}\mathrm{Al}$ determine the production of ${}^{26}\mathrm{Al}$ and a precise knowledge of these nuclear data is highly desirable. Absolute measurements at such low energies are often very difficult and hampered by $\gamma$-ray background as well as changing target stoichiometry during the measurements. The latter problem can be partly avoided using higher-energy resonances of the same reaction as a normalization reference. Hence the parameters of suitable resonances have to be studied with adequate precision. In the present work we report on new measurements of the resonance strengths $\omega \gamma$ of the $E=214$, $304$, and $326$ keV resonances in the reactions ${}^{24}\mathrm{Mg}$($p,\gamma$)${}^{25}\mathrm{Al}$, ${}^{25}\mathrm{Mg}$($p,\gamma$)${}^{26}\mathrm{Al}$, and ${}^{26}\mathrm{Mg}$($p,\gamma$)${}^{27}\mathrm{Al}$, respectively. These studies were performed at the LUNA facility in the Gran Sasso underground laboratory using multiple experimental techniques and provided results with a higher accuracy than previously achieved.

Excited states in ${}^{145}\mathrm{Cs}$, populated following the spontaneous fission of ${}^{248}\mathrm{Cm}$, were studied by means of prompt-$\gamma$ spectroscopy, using the EUROGAM2 multidetector array. A new level scheme of ${}^{145}\mathrm{Cs}$ was proposed. We identified a decoupled band corresponding to $1/2[550]$ proton configuration and interpreted the ground-state band as a mixed configuration of $1/2[440]$ and $3/2[422]$ proton orbitals. Quasiparticle-rotor calculations performed for ${}^{145}\mathrm{Cs}$ support such assignments. The electric dipole moment in ${}^{145}\mathrm{Cs}$, $D_0=0.013(4)$ efm, is smaller than in lighter Cs isotopes, which suggests that octupole correlations in Cs isotopes decrease at the neutron number $N=90$, similarly as observed in the ${}^{146}\mathrm{Ba}$ and ${}^{147}\mathrm{La}$ isotones.

Possibilities of transfer-induced fission of new isotopes of superheavy nuclei with charge numbers $103-108$ are studied for the first time in the reactions ${}^{48}\mathrm{Ca}+{}^{244,246,248}\mathrm{Cm}$ at energies near the corresponding Coulomb barriers. The predicted cross sections are found to be measurable with the detection of three-body final states.

Halo phenomena in deformed nuclei are investigated within a deformed relativistic Hartree Bogoliubov (DRHB) theory. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Contributions of the halo, deformation effects, and large spatial extensions of these systems are described in a fully self-consistent way by the DRHB equations in a spherical Woods-Saxon basis with the proper asymptotic behavior at a large distance from the nuclear center. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nucleus ${}^{44}\mathrm{Mg}$. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the occurrence of this decoupling effects are discussed.

The study of the bremsstrahlung photon emission accompanying fragments produced in the spontaneous fission of heavy nuclei by a fully quantum approach is presented for the first time. This kind of problem requires the knowledge of wave functions of the fissioning system leading to a wide distribution of couples of fragments that are the products of fission. With the aim of obtaining these wave functions, the interaction potential between the emitted fragment and residual nucleus is calculated by a standard approach. A new procedure was performed that allows an increase in the accuracy of calculations of radial integrals in the far asymptotic region and the achievement of the convenient convergence in calculations of the spectra. The total probability of the emitted photons in the spontaneous fission of ${}^{252}\mathrm{Cf}$ was calculated in such a way. We obtained good agreement between theory and experimental data up to 38 MeV for the bremsstrahlung spectrum of photons while the calculation of the total probability of photon emission accompanying fragments was performed up to an energy of 60 MeV. The analysis of contributions in the bremsstrahlung spectrum accompanying the emission of light, medium, and heavy fragments in the fission of ${}^{252}\mathrm{Cf}$ is presented.

We study the balance energy ($E_{\mathrm{bal}}$) as a function of combined system mass for different colliding geometries, which range from central to semiperipheral ones. We find that $E_{\mathrm{bal}}$ follows a power law behavior ($\propto A^{\tau }$) at all colliding geometries. We also study the effect of momentum dependent interactions on $E_{\mathrm{bal}}$ as well as on its mass dependence. We find that the inclusion of momentum dependent interactions changes the value of $\tau$ drastically at peripheral geometries in agreement with other calculations.

We have measured the ${}^{149}\mathrm{Sm}(n,\alpha ){}^{146}\mathrm{Nd}$ cross section at 6.0 MeV to be $0.12\pm 0.018$ mb. This is the first reported result for this cross section in the MeV region and so should be helpful for constraining nuclear data evaluations (which differ by a factor of 40 for this reaction at this energy) and for testing and improving nuclear models. The experiment was performed at the at the 4.5-MV Van de Graaff accelerator of Peking University. Neutrons were produced via the ${}^2\mathrm{H}(d,n){}^3\mathrm{He}$ reaction using a deuterium gas target, and absolute neutron flux was determined with a small ${}^{238}\mathrm{U}$ fission chamber. Alpha particles were detected using a two-section gridded ionization chamber in which two large-area ${}^{149}\mathrm{Sm}{}_2{\mathrm{O}}_3$ samples were placed back-to-back so that the cross section and forward/backward ratio were measured for nearly the entire 4$\pi$ solid angle. The data were compared to statistical-model predictions using the code talys. Good agreement between the measured and theoretical cross sections could be obtained with a small modification of the $\alpha$-optical potential parameters from their default values in talys. However, we were not able to reproduce the measured forward/backward ratio. In addition, using the previously reported ${}^{147}\mathrm{Sm}(n,\alpha ){}^{144}\mathrm{Nd}$ cross section at 6.0 MeV together with our new result, good agreement was found between the measured and predicted cross-section ratio for these two isotopes. Finally, none of the existing evaluated data libraries are in agreement with our new data to within the experimental uncertainties.

Recent progress in experimental techniques allows us to study very exotic systems like neutron-rich nuclei in the vicinity of ${}^{78}\mathrm{Ni}$. The spectroscopy of this region can nowadays be studied theoretically in the large scale shell model calculations. In this work, we perform a shell model study of odd copper nuclei with $N=40–50$, in a large valence space with the ${}^{48}\mathrm{Ca}$ core, using a realistic interaction derived from the CD-Bonn potential. We present the crucial importance of the proton core excitations for the description of spectra and magnetic moments, which are for the first time correctly reproduced in theoretical calculations. Shell evolution from ${}^{68}\mathrm{Ni}$ to ${}^{78}\mathrm{Ni}$ is discussed in detail. A weakening of the $Z=28$ gap when approaching the $N=50$ shell closure, suggested by the experimental evidence, is confirmed in the calculations.

A novel method which allows us to find observables at many energies simultaneously in a multichannel scattering problem using just a single diagonalization of the total Hamiltonian matrix in some $L_2$ basis is developed. The approach is based on the multichannel generalization of ideas due to Lifshits and Birman-Krein on the tight relationship between a spectral shift function and a single-channel $S$ matrix in the combination with $L_2$ discretization of the continuum. As a clear illustration for the efficiency of the suggested method, the differential cross sections of neutron scattering off heavy nuclei in the case of a complex nonlocal interaction potential as well as energy dependence of partial $\mathit{NN}$ phase shifts and mixing parameters for the two-nucleon scattering with tensor force are calculated.

A systematic study of the low-lying structure of $N=27$, $28,$ and $29$ isotones is performed within the shell model framework using the SDPF-U interaction [F. Nowacki and A. Poves, Phys. Rev. C 79, 014310 (2009)]. For each isotonic chain, correlation energy is found to increase while moving away from the stability line. Spherical shapes as well as small values of correlation energy are associated with the isotopes of ${}_{20}$Ca and ${}_{19}$K discussed in this study. Neutron intruder states appear at low excitation energy in the ${}_{18}$Ar and ${}_{17}$Cl studied isotopes. Coexistence between spherical and prolate deformed states is a systematic feature in ${}_{16}$S isotopes. Below $Z=16$ most of the studied nuclei are characterized by intruder ground states. The major role played by protons in determining the structure of $N\simeq 28$ nuclei is shown.