The radiative neutron capture cross section of ${}^{207}\mathrm{Pb}$ has been measured at the CERN neutron time of flight installation n_TOF using the pulse height weighting technique in the resolved energy region. The measurement has been performed with an optimized setup of two C${}_6{D}_6$ scintillation detectors, which allowed us to reduce scattered neutron backgrounds down to a negligible level. Resonance parameters and radiative kernels have been determined for 16 resonances by means of an R-matrix analysis in the neutron energy range from 3 keV to 320 keV. Good agreement with previous measurements was found at low neutron energies, whereas substantial discrepancies appear beyond 45 keV. With the present results, we obtain an $s$-process contribution of 77±8% to the solar abundance of ${}^{207}\mathrm{Pb}$. This corresponds to an $r$-process component of $23\pm 8\%$, which is important for deriving the U/Th ages of metal poor halo stars.

Axial octupole and tetrahedral correlations in ${}^{80}\mathrm{Zr}$ and ${}^{98}\mathrm{Zr}$ have been investigated using the generator coordinate method, applied to a basis generated by Skyrme Hartree-Fock+BCS calculations. We focus on the possible presence of states with tetrahedral symmetry and their stability with respect to octupole vibrations. We show that pairing significantly reduces the stability of the tetrahedral configuration and that a shallow mean-field tetrahedral minimum coexists with an axial octupole minimum. The contributions to the correlation energies coming from the tetrahedral degree of freedom and octupole axial deformation are discussed.

The ratios of off-diagonal to diagonal conserved charge susceptibilities, e.g., ${\chi }_{\mathrm{BS}}/{\chi }_S,{\chi }_{\mathrm{QS}}/{\chi }_S$, related to the quark flavor susceptibilities, have proven to be discerning probes of the flavor carrying degrees of freedom in hot strongly interacting matter. Various constraining relations between the different susceptibilities are derived based on the Gell-Mann-Nishijima formula and the assumption of isospin symmetry. Using generic models of deconfined matter and results from lattice quantum chromodynamics, it is demonstrated that the flavor-carrying degrees of freedom at a temperature above $1.5T_c$ are quarklike quasiparticles. A new observable related by isospin symmetry to $C_{\mathrm{BS}}=-3{\chi }_{\mathrm{BS}}/{\chi }_S$ and equal to it in the baryon free regime is identified. This new observable, which is blind to neutral and nonstrange particles, carries the potential of being measured in relativistic heavy-ion collisions.

The contributions from the $\mathit{qqqq}\overline{q}$ components to the magnetic moments of the octet as well as the ${\Delta }^{++}$ and ${\Omega }^{-}$ decuplet baryons are calculated for the configurations that are expected to have the lowest energy if the hyperfine interaction depends on both spin and flavor. The contributions from the $u\overline{u},d\overline{d}$, and the $s\overline{s}$ components are given separately. It is shown that addition of $\mathit{qqqq}\overline{q}$ admixtures to the ground state baryons can improve the overall description of the magnetic moments of the baryon octet and decuplet in the quark model without SU(3) flavor symmetry breaking, beyond that of the different constituent masses of the strange and light-flavor quarks. The explicit flavor (and spin) wave functions for all the possible configurations of the $\mathit{qqqq}\overline{q}$ components with light and strange $q\overline{q}$ pairs are given for the baryon octet and decuplet. Admixtures of $~10\%$ of the $\mathit{qqqq}\overline{q}$ configuration where the flavor-spin symmetry is $[4]{}_{\mathit{FS}}[22]{}_F[22]{}_S$, which is likely to have the lowest energy, in particular reduces the deviation from the empirical values of the magnetic moments ${\Sigma }^{-}$ and the ${\Xi }^0$ compared with the static $\mathit{qqq}$ quark model.

Ultracold neutrons (UCN) with energy up to the Fermi potential were stored for the first time in a volume coated with diamondlike carbon. As a function of the UCN energy and wall temperature of the storage volume, we measured the wall loss parameter η and obtained $\eta =(3.1\pm 0.9)·{10}^{-4}$ at $T=290$ K and $\eta =(1.8\pm 0.2)·{10}^{-4}$ at $T=115$ K.

Constant contours of basic observables are discussed in the context of the interacting boson approximation (IBA) symmetry triangle. Contours that exhibit orthogonal crossing within the triangle are presented as a method for determining a set of parameter values for a particular nucleus and trajectories for isotopic chains. A set of contours that highlights a class of nuclei that are outside the two-parameter IBA-1 Hamitonian space is also presented.

We analyze the renormalization of the $\mathit{NN}$ interaction at low energies and the deuteron bound state through the chiral two-pion-exchange potential assumed to be valid from zero to infinity. The short distance van der Waals singularity structure of the potential as well as the requirement of orthogonality conditions on the wave functions determine that after renormalization, in the ${}^1{S}_0$ singlet channel and in the ${}^3{S}_1\text{−}{}^3{D}_1$ triplet channel, one can use the deuteron binding energy, the asymptotic $D/S$ ratio, and the $S$-wave scattering lengths as well as the chiral potential parameters as independent variables. We use then the asymptotic wave function normalization $A_S$ of the deuteron and the singlet and triplet effective ranges to determine the chiral constants yielding $c_1,c_3$, and $c_4$. The role of finite cutoff corrections, the loss of predictive power due to uncertainties in the input data, and the connection to one-pion-exchange distorted wave perturbative approaches is also discussed.

A method for calculation of Gamow-Teller transition rates is developed by using the concept of the Projected Shell Model (PSM). The shell model basis is constructed by superimposing angular-momentum-projected multiquasiparticle configurations, and nuclear wave functions are obtained by diagonalizing the two-body interactions in these projected states. Calculation of transition matrix elements in the PSM framework is discussed in detail, and the effects caused by the Gamow-Teller residual forces and by configuration-mixing are studied. With this method, it may become possible to perform a state-by-state calculation for β-decay and electron-capture rates in heavy, deformed nuclei at finite temperatures. Our first example indicates that, while experimentally known Gamow-Teller transition rates from the ground state of the parent nucleus are reproduced, stronger transitions from some low-lying excited states are predicted to occur, which may considerably enhance the total decay rates once these nuclei are exposed to hot stellar environments.

The recently published experimental data on $K^{+}\Lambda$ photoproduction by the SAPHIR, CLAS, and LEPS Collaborations are analyzed by means of a multipole approach. For this purpose the background amplitudes are constructed from appropriate Feynman diagrams in a gauge-invariant and crossing-symmetric fashion. The results of our calculation emphasize the lack of mutual consistency between the SAPHIR and CLAS data previously found by several independent research groups, whereas the LEPS data are found to be more consistent with those of CLAS. The use of SAPHIR and CLAS data, individually or simultaneously, leads to quite different resonance parameters that, therefore, could lead to different conclusions on “missing resonances.” Fitting to the SAPHIR and LEPS data simultaneously indicates that the $S_{11}(1650),P_{13}(1720),D_{13}(1700),D_{13}(2080),F_{15}(1680)$, and $F_{15}(2000)$ resonances are required, whereas fitting to the combination of CLAS and LEPS data leads alternatively to the $P_{13}(1900),D_{13}(2080),D_{15}(1675),F_{15}(1680)$, and $F_{17}(1990)$ resonances. Although yielding different results in most cases, both SAPHIR and CLAS data indicate that the second peak in the cross sections at $W~1900$ MeV originates from the $D_{13}(2080)$ resonance with a mass between 1911 and 1936 MeV. Furthermore, in contrast to the results of currently available models and the Table of Particle Properties, both data sets do not exhibit the need for a $P_{11}(1710)$ resonance. The few data points available for target asymmetry cannot be described by the models proposed in the present work.

The improved quark mass density-dependent model (IQMDD) based on soliton bag model is studied at finite temperature. Applying the finite temperature field theory, the effective potential of the IQMDD model and the bag constant $B(T)$ have been calculated at different temperatures. It is shown that there is a critical temperature $T_C\simeq 110\mathrm{MeV}$. We also calculate the soliton solutions of the IQMDD model at finite temperature. It turns out that when $T<T_C$, there is a bag constant $B(T)$ and the soliton solutions are stable. However, when $T>T_C$ the bag constant $B(T)=0$ and there is no soliton solution, therefore, the confinement of quarks are removed quickly.

We investigate the composition and the equation of state of the kaon condensed phase in neutrino-free and neutrino-trapped star matter within the framework of the Brueckner-Hartree-Fock approach with three-body forces. We find that neutrino trapping shifts the onset density of kaon condensation to a larger baryon density, and reduces considerably the kaon abundance. As a consequence, when kaons are allowed, the equation of state of neutrino-trapped star matter becomes stiffer than the one of neutrino free matter. The effects of different three-body forces are compared and discussed. Neutrino trapping turns out to weaken the role played by the symmetry energy in determining the composition of stellar matter, and thus reduces the difference between the results obtained by using different three-body forces.

Spin polarized states in nuclear matter with Skyrme effective forces are studied on the base of a Fermi liquid theory for a wide range of isospin asymmetries and densities. There are a few possible scenarios of spin ordered phase transitions: (a) nuclear matter with SLy4 interaction undergoes at some critical density a phase transition to a spin polarized state with the oppositely directed spins of neutrons and protons; (b) for SkI5 interaction, a spin polarized state with the like-directed neutron and proton spins is formed; (c) nuclear matter with SkI3 interaction under increasing density, at first, undergoes a phase transition to the state with the opposite directions of neutron and proton spins, which goes over at larger density to the state with the same direction of nucleon spins. Spin polarized states at strong isospin asymmetry are accompanied by the long tails in the density profiles of the neutron spin polarization parameter near the critical density, if the energy gain of the transition from the nonpolarized state to a polarized one is the decreasing function of isospin asymmetry (SLy4 force). If the energy gain is increased with isospin asymmetry, there are no long tails in the density distribution of the neutron spin polarization parameter (SkI3, SkI5 forces).

The calculated $Q$ values and half widths of α-decay of superheavy elements using both the S-matrix and the WKB methods are analyzed. The calculations are carried out using the microscopically derived α-daughter potentials for the parents appearing in the α-decay chain of super heavy element ($A=277,Z=112$). Both the S-matrix and the WKB methods though yield comparable results for smaller, in fact negative log ${\tau }_{1/2}$ values, the former is superior. However, for the case of positive log ${\tau }_{1/2}$ it is found that the S-matrix method though exact, runs into some numerical difficulties.

The formation of superheavy nucleus ${}^{270}\mathrm{Hs}$ via the 4n evaporation channel of fusion reactions ${}^{26}\mathrm{Mg}+{}^{248}\mathrm{Cm}$, ${}^{30}\mathrm{Si}+{}^{244}\mathrm{Pu}$, ${}^{36}\mathrm{S}+{}^{238}\mathrm{U}$, and ${}^{48}\mathrm{Ca}+{}^{226}\mathrm{Ra}$ is studied using a two-parameter Smoluchowski equation. The evaporation residual cross sections of the reactions ${}^{48}\mathrm{Ca}+{}^{226}\mathrm{Ra}$ and ${}^{36}\mathrm{S}+{}^{238}\mathrm{U}$ are obviously enhanced because of their large negative $Q$ values. The enhancement is due to the fact that the excitation energy corresponding to the maximum yield of the evaporation residue depends on the reaction $Q$ value, and the maximum cross section sensitively depends on the increment of this excitation energy relative to the effective threshold energy of which the channel for fission after 4n emission opens.

High-resolution transmission and capture time-of-flight measurements of ${}^{127}\mathrm{I}$ and ${}^{129}\mathrm{I}$ have been carried out at the 150 MeV pulsed neutron source at the Geel electron linear accelerator (GELINA) facility of the Institute for Reference Materials and Measurements. Below 10 keV, the individual resonances were analyzed with the Reich-Moore approximation of the $R$-matrix theory. The resonance parameters (energy and partial widths) and the potential scattering length $R_0^{\prime }$ were determined using the resonance shape analysis technique. Within the 3.5–100 keV neutron energy range, the capture and total cross sections were interpreted in terms of average resonance parameters with the Hauser-Feshbach formalism with width fluctuations. This work has delivered a consistent set of ${}^{127,129}\mathrm{I}$ $s$- and $p$-wave average resonance parameters (neutron strength function $S_l$, mean level spacing $D_l$, and average radiation width $\langle \Gamma {\gamma }_{{}_l}\rangle$).

The dynamics at the critical point of a general first-order quantum phase transition in a finite system is examined from an algebraic perspective. Suitable Hamiltonians are constructed whose spectra exhibit coexistence of states corresponding to two degenerate minima in the energy surface separated by an arbitrary barrier. Explicit expressions are derived for wave functions and observables at the critical point.

High-spin band structures in neutron-rich ${}^{105}\mathrm{Mo}$ have been investigated by measuring prompt γ rays emitted by the spontaneous fission fragments of ${}^{252}\mathrm{Cf}$ with the Gammasphere detector array. The yrast band has been confirmed and five new collective bands are observed. The three bands based on the 246.3-, 332.0-, and 310.0-keV levels are proposed as the single-neutron excitation bands built on the ${3/2}^{+}$[411], ${1/2}^{+}$[411], and ${5/2}^{+}$[413] Nilsson orbitals, respectively. The other two bands with band head levels at 870.5 and 1534.6 keV are candidates for one-phonon $K=9/2$ and two-phonon $K=13/2$ γ-vibrational bands, respectively. Systematic comparison of these bands with bands in neighboring nuclei are discussed.

We establish an analytical link between the level density obtained by means of the Strutinsky averaging method and the semiclassical level density. This link occurs only in the so-called asymptotic limit. It turns out that the Strutinsky method amounts to an approximation to the semiclassical method. This approximation contains an unavoidable remainder that constitutes an intrinsic noise in comparison to the semiclassical method. Thus, the problem of the dependency of the Strutinsky procedure on the two free smoothing parameters of the averaging is intimately connected to this noise. However, we demonstrate that the noise of the method is small in the average density of states and in the average energy, whereas it might be non-negligible in the shell correction itself. To improve this method, we give a rule that consists simply of minimizing the relative error for the average energy.