The shell model in the complex-$k$ plane (the so-called Gamow shell model) has recently been formulated and applied to the structure of weakly bound, neutron-rich nuclei. The completeness relations of Newton and Berggren, which apply to the neutron case, are strictly valid for finite-range potentials. However, for long-range potentials, such as the Coulomb potential for protons, for which the arguments based on the Mittag-Leffler theory do not hold, the completeness still needs to be demonstrated. This has been done in this paper, both analytically and numerically. The generalized Berggren relations are then used in the first Gamow shell model study of nuclei having both valence neutrons and protons, namely, the lithium chain. The single-particle basis used is that of the Hartree-Fock-inspired potential generated by a finite-range residual interaction. The effect of isospin mixing in excited unbound states is discussed.

Measurements of the breakup and the neutron removal reactions of ${}^{16}\mathrm{C}$ have been made at 46 MeV∕A and the decay cross sections measured. A correlation between the cluster breakup channels and the reaction $\mathrm{Q}$ value suggests that the reaction mechanism is strongly linked to quasielastic processes. No enhancement of the two-body cluster breakup cross section is seen for ${}^{16}\mathrm{C}$. This result would indicate that ${}^{16}\mathrm{C}$ does not have a well developed cluster structure in the ground state, in agreement with recent calculations.

Results are presented on event-by-event electric charge fluctuations in central $\mathrm{Pb}+\mathrm{Pb}$ collisions at $20A,30A,40A,80A$, and $158A\mathrm{GeV}$. The observed fluctuations are close to those expected for a gas of pions correlated by global charge conservation only. These fluctuations are considerably larger than those calculated for an ideal gas of deconfined quarks and gluons. The present measurements do not necessarily exclude reduced fluctuations from a quark-gluon plasma because these might be masked by contributions from resonance decays.

We study the nucleon and diquarks in a nonlocal Nambu–Jona–Lasinio model. For certain parameters the model exhibits quark confinement, in the form of a propagator without real poles. After truncation of the two-body channels to the scalar and axial-vector diquarks, a relativistic Faddeev equation for nucleon bound states is solved in the covariant diquark–quark picture. The dependence of the nucleon mass on diquark masses is studied in detail. We find parameters that lead to a simultaneous reasonable description of pions and nucleons. Both the diquarks contribute attractively to the nucleon mass. Axial-vector diquark correlations are seen to be important, especially in the confining phase of the model. We study the possible implications of quark confinement for the description of the diquarks and the nucleon. In particular, we find that it leads to a more compact nucleon.

We propose a fully quantum-mechanical method of treating four-body nuclear breakup processes in scattering of a projectile consisting of three constituents, by extending the continuum-discretized coupled-channels method. The three-body continuum states of the projectile are discretized by diagonalizing the internal Hamiltonian of the projectile with the Gaussian basis functions. For ${}^6\mathrm{He}+{}^{12}\mathrm{C}$ scattering at 18 and $229.8\mathrm{MeV}$, the validity of the method is tested by convergence of the elastic and breakup cross sections with respect to increasing the number of the basis functions. Effects of the four-body breakup and the Borromean structure of ${}^6\mathrm{He}$ on the elastic and total reaction cross sections are discussed.

High-spin states in the nucleus ${}^{183}\mathrm{Tl}$ have been studied using the recoil decay tagging and recoil tagging techniques. The data have enabled new structures to be identified which are believed to be based on prolate $f_{7∕2}$, $h_{9∕2}$, and oblate $h_{9∕2}$ configurations. In addition, the prolate $i_{3∕2}$ structure has also been extended. The systematics of the newly identified structures will be discussed. The $\alpha$ decay of ${}^{183}\mathrm{Tl}$ has also been investigated. Examination of both delayed and prompt $\gamma$ rays in coincidence with the prominent $6333\text{−}\mathrm{keV}$ $\alpha$ decay, together with an investigation of the effects of the summing of $L$ electrons, allow assignment of transitions and the construction of tentative low-spin decay schemes for ${}^{179}\mathrm{Au}$ and ${}^{175}\mathrm{Ir}$.

We use a deformed quasiparticle random phase approximation formalism to describe simultaneously the energy distributions of the single $\beta$ Gamow-Teller strength and the two-neutrino double $\beta$ decay matrix elements. Calculations are performed in a series of double $\beta$ decay partners with $A=48$, 76, 82, 96, 100, 116, 128, 130, 136, and 150, using deformed Woods-Saxon potentials and deformed Skyrme Hartree-Fock mean fields. The formalism includes a quasiparticle deformed basis and residual spin-isospin forces in the particle-hole and particle-particle channels. We discuss the sensitivity of the parent and daughter Gamow-Teller strength distributions in single $\beta$ decay, as well as the sensitivity of the double $\beta$ decay matrix elements to the deformed mean field and to the residual interactions. Nuclear deformation is found to be a mechanism of suppression of the two-neutrino double $\beta$ decay. The double $\beta$ decay matrix elements are found to have maximum values for about equal deformations of parent and daughter nuclei. They decrease rapidly when differences in deformations increase. We remark on the importance of a proper simultaneous description of both double $\beta$ decay and single Gamow-Teller strength distributions. Finally, we conclude that for further progress in the field, it would be useful to improve and complete the experimental information on the studied Gamow-Teller strengths and nuclear deformations.

The possibility of ferromagnetic and antiferromagnetic phase transitions in symmetric nuclear matter is analyzed within the framework of a Fermi liquid theory with the effective Gogny interaction. It is shown that at some critical density nuclear matter with the D1S effective force undergoes a phase transition to the antiferromagnetic spin state (opposite directions of neutron and proton spins). The self-consistent equations of spin polarized nuclear matter with the D1S force have no solutions corresponding to ferromagnetic spin ordering (the same direction of neutron and proton spins) and, hence, the ferromagnetic transition does not appear. The dependence of the antiferromagnetic spin polarization parameter as a function of density is found at zero temperature.

The natural $\alpha$-decay of ${}^{180}\mathrm{W}$ has been unambiguously detected for the first time. The $\alpha$ peak is found in a ($\gamma$, $\beta$, and neutron)-free background spectrum. This has been achieved by the simultaneous measurement of phonon and light signals with the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) cryogenic detectors. A half-life of $T_{1∕2}=(1.8\pm 0.2)\times {10}^{18}\text{years}$ and an energy release of $Q=[2516.4\pm 1.1\left(\mathrm{stat.}\right)\pm 1.2\left(\mathrm{sys.}\right)]\mathrm{keV}$ have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.

We explore how nuclear modifications to the nucleon parton distributions affect production of high-transverse-momentum hadrons in deuteron-nucleus collisions. We calculate the charged hadron spectra to leading order using standard fragmentation functions and shadowing parametrizations. We obtain the $d+\mathrm{Au}$ to $pp$ ratio both in minimum bias collisions and as a function of centrality. The minimum bias results agree reasonably well with the BRAHMS data while the calculated centrality dependence underestimates the data and is a stronger function of $p_T$ than the data indicate.

We study the structure of the baryon resonances $\Lambda \left(1405\right)$ and $\overline{\Lambda }\left(1405\right)$ in $J∕\psi$ four-body decays $J∕\psi \to \Sigma \overline{\Sigma }\pi \pi$ in the framework of a coupled channel chiral unitary approach. With still sufficient freedom for model parameters, the $\Lambda \left(1405\right)$ and $\overline{\Lambda }\left(1405\right)$ resonances are generated by simultaneously taking the meson baryon and meson antibaryon final state interactions into account. The $\pi \Sigma \left(\pi \overline{\Sigma }\right)$ invariant mass distributions peak around 1410 MeV, which favors the assertion that the $\Lambda \left(1405\right)\left[\overline{\Lambda }\left(1405\right)\right]$ is a superposition of the two $\Lambda \left(1405\right)\left[\overline{\Lambda }\left(1405\right)\right]$ states which dominantly couple to $\overline{K}N\left(K\overline{N}\right)$ and $\pi \Sigma \left(\pi \overline{\Sigma }\right)$, respectively. We also calculate the amplitude for isospin $I=1$ which gives hints of a possible $I=1$ baryon resonance in the energy region of the $\Lambda \left(1405\right)$, which up to now has not been observed.

High-spin states in doubly odd ${}^{170}\mathrm{Re}$ have been populated via the ${}^{142}\mathrm{Nd}({}^{32}\mathrm{S},p3n\gamma )$ reaction at beam energies of 155 and 166 MeV. $\mathrm{K}X\text{−}\gamma$ and $\gamma \text{−}\gamma$ coincidences have been measured using a detector array consisting of 12 high-purity germanium detectors with BGO suppressors. A rotational band is identified and assigned to ${}^{170}\mathrm{Re}$ for the first time. This band is proposed to be built on the $\pi h_{11∕2}\otimes \nu i_{13∕2}$ two-quasiparticle configuration by comparing the band properties with known bands in neighboring nuclei and the cranked-shell model calculations.

Dipole and quadrupole excitations in the semimagic $N=50$ nucleus ${}^{88}\mathrm{Sr}$ were investigated at the superconducting Darmstadt electron linear accelerator S-DALINAC with bremsstrahlung of an end-point energy of $6.8\mathrm{MeV}$. Many new dipole excitations could be identified, and their reduced excitation probabilities were determined. The experimental findings are discussed in the context of quasiparticle-phonon-model and shell-model calculations. A breaking of the $N=50$ core is essential to describe the structure of the observed excitations. The two-phonon quadrupole-octupole $J^{\pi }=1^{-}$ state exhibits unusual features which are presently not understood.

A model of nuclear level decay in a plasma environment is described. Nuclear excitation and decay by photon processes, nuclear excitation by electron capture, and decay by internal conversion are taken into account. The electrons in the plasma are described by a relativistic average atom model for the bound electrons and by a relativistic Thomas-Fermi-Dirac model for the free electrons. Nuclear decay of isomeric level may be enhanced through an intermediate level lying above the isomer. An enhanced nuclear decay rate may occur for temperatures far below the excitation energy of the transition to the intermediate level. In most cases, the enhancement factor may reach several decades.

Coupled-channel and dispersive-optical model analyses of published neutron scattering and reaction data for ${}^{27}\mathrm{Al}$, ${}^{59}\mathrm{Co}$, and ${}^{93}\mathrm{Nb}$ at incident energies between 0.1 and $80\mathrm{MeV}$ have been performed. The resulting potentials are used to place constraints on the determination of the spin-spin interaction from published spin-spin cross-section measurements. For the three nuclei, the strength of the central real spin-spin potential, which was taken to have a surface plus volume shape, was found to be small. Volume integrals for this central potential component were determined to be in the $4–7\mathrm{MeV}{\mathrm{fm}}^3$ range and to decrease somewhat as mass number increases.

The breakup of ${}^{11}\mathrm{Be}$ on ${}^{12}\mathrm{C}$ at $67\mathrm{MeV}∕\text{nucleon}$ is analyzed in a semiclassical framework. The resulting time-dependent Schrödinger equation is solved numerically by expanding the projectile wave function upon a three-dimensional spherical mesh. The nuclear interaction between the projectile fragments and the target are modeled by optical potentials. The low-lying ${\frac{5}{2}}^{+}$ resonance of ${}^{11}\mathrm{Be}$ induces a narrow peak in the breakup cross section. The nuclear interactions between the projectile and the target are found to be responsible for the transition towards this resonance. The good agreement with recent experimental data confirms the validity of the model and leads us to suggest that nuclear induced breakup of halo nuclei may be used as a quantitative probe of their internal structure.

A method allowing analysis of the overpopulation of phase space in heavy ion collisions in a model-independent way is proposed within the hydrodynamic approach. It makes it possible to extract a chemical potential of thermal pions at freeze-out, irrespective of the form of freeze-out (isothermal) hypersurface in Minkowski space and transverse flows on it. The contributions of resonance (with masses up to $2\mathrm{GeV}$) decays to spectra, interferometry volumes, and phase-space densities are calculated and discussed in detail. The estimates of average phase-space densities and chemical potentials of thermal pions are obtained for SPS and RHIC energies. They demonstrate that multibosonic phenomena at those energies might be considered as a correction factor rather than as a significant physical effect. The analysis of the evolution of the pion average phase-space density in chemically frozen hadron systems shows that it is almost constant or slightly increases with time while the particle density and phase-space density at each space point decreases rapidly during the system’s expansion. We found that, unlike the particle density, the average phase-space density has no direct link to the freeze-out criterion and final thermodynamic parameters, being connected rather to the initial phase-space density of hadronic matter formed in relativistic nucleus-nucleus collisions.

We examine cross sections for the processes $\gamma N\to NK\overline{K}$ in the framework of a phenomenological Lagrangian. We include contributions from $\Lambda$ and $\Sigma$ resonances up to spin $3∕2$, as well as those from an exotic ${\Theta }^{+}$. We allow the ${\Theta }^{+}$ to have spin $1∕2$ or $3∕2$, with either positive or negative parity in each case. We also allow the state to be either isovector or isoscalar. We find that the scenario that most closely matches observations at Jefferson Laboratory requires a moderately large coupling of the ${\Theta }^{+}$ to $N{K}^{*}$.

Stellar cross sections of importance with respect to the termination of the $s$-process reaction chain have been determined for the two cases, ${}^{208}\mathrm{Pb}(\mathit{n},\gamma ){}^{209}\mathrm{Pb}$ and ${}^{209}\mathrm{Bi}(\mathit{n},\gamma ){}^{210}\mathrm{Bi}^g$, yielding $kT=30\mathrm{keV}$ values of $⟨\sigma v⟩∕v_T=0.31\pm 0.2\mathrm{mb}$ and $2.54\pm 0.14\mathrm{mb}$, respectively. The measurements were carried out by activation of Pb and Bi samples in a quasistellar neutron spectrum using gold as a cross section standard. With this technique the uncertainties reported in previous works could be considerably reduced. The measurements are complemented by a discussion of the recycling at the termination point of the $s$-process neutron capture chain in a $3M_{☉}$ and $[\mathrm{Fe}∕\mathrm{H}]=-1.3$ asymptotic giant branch star. At this metallicity, AGB stars give rise to the maximum production of $s$-process lead. The sensitivity of the isotopic lead abundances is discussed with respect to the remaining cross section uncertainties. The information obtained in this work is also of relevance for an assessment of the $\alpha$ activity due to a buildup of ${}^{210}\mathrm{Po}$ in $\mathrm{Pb}∕\mathrm{Bi}$ cooled fast reactor systems.

The ${}^2\mathrm{H}({}^{124}\mathrm{Sn},p)$ reaction has been measured at 562 MeV (4.5 A MeV). Differential cross sections were measured from ${\theta }_{\mathrm{c}.\mathrm{m}}=7°\text{–}61°$. Angular momentum transfers and spectroscopic factors determined using finite range DWBA calculations are in good agreement with earlier measurements performed in normal kinematics.