We suggest a mechanism that may resolve a conflict between the precession of a neutron star and the widely accepted idea that protons in the bulk of the neutron star form a type II superconductor. We will show that if there is a persistent, nondissipating current running along the magnetic flux tubes the force between magnetic flux tubes may be attractive, resulting in a type I, rather than a type II, superconductor. If this is the case, the conflict between the observed precession and the canonical estimation of the Landau-Ginzburg parameter $\kappa >1/\sqrt{2}$ (which suggests type-II behavior) will automatically be resolved. We calculate the interaction between two vortices, each carrying a current $j$, and demonstrate that when $j>\frac{\hslash c}{2q\lambda }$, where $q$ is the charge of the Cooper pair and λ is the Meissner penetration depth, a superconductor is always type-I, even when the cannonical Landau-Ginzburg parameter κ indicates type II behavior. If this condition is met, the magnetic field is completely expelled from the superconducting regions of the neutron star. This leads to the formation of the intermediate state, where alternating domains of superconducting matter and normal matter coexist. We further argue that even when the induced current is small $j<\frac{\hslash c}{2q\lambda }$ the vortex Abrikosov lattice will nevertheless be destroyed due to the helical instability studied previously in many condensed matter systems. This would also resolve the apparent contradiction with the precession of the neutron stars. We also discuss some instances where anomalous induced currents may play a crucial role, such as in neutron star kicks, pulsar glitches, the toroidal magnetic field and the magnetic helicity.

We study a many fermion system in an equispaced nondegenerate single particle spectrum. Using methods of statistical mechanics, we reproduce Bethe's formula for the nuclear density of states along with low excitation corrections by Rademacher to Bethe's formula. We generalize the result for two species of particles and compare with recent results by Leboeuf.

Through a quantitative comparative study of the properties of deuteron and nucleon-nucleon interaction between the chiral quark model and the quark delocalization color screening model, we show that the σ-meson exchange used in the chiral quark model can be replaced by the quark delocalization and color screening mechanism.

One-dimensional nucleon-nucleon scattering is simulated by Monte Carlo techniques in the quasiclassical approximation of the Wigner representation. Nucleons are represented by minimum wave packets of approximate nucleon radii, their linear dispersion offset by intrinsic harmonic oscillation, inducing phase space spin in the nucleon Wigner function. A representative set of points evolve in four-dimensional phase space in deterministic classical and stochastic quantum momentum jumps. In the extended space, the inter-nucleon one-pion exchange potential is defined locally by the point coordinates. By the geometric analogy, cross sections are computed from collision distances considered as impact parameters. Results from the parameter free one-dimensional simulation show reasonable agreement with empirical data in the energy range 0.01 GeV to 5 GeV.

We present a semiclassical method to treat the proton breakup from a weakly bound state in an exotic nucleus. The Coulomb interactions among the proton, the core, and the target are treated to all orders, including the full-multipole expansion of the Coulomb potential. The nuclear proton-target interaction is also treated to all orders. The core-target interaction is included as an absorption. The method is semianalytical, thus allowing for a detailed understanding of the short-range and long-range effects of the interactions in the reaction dynamics. It explains also the origin of possible asymmetries in the core parallel momentum distributions when the full-multipole expansion of the Coulomb potential is used. Calculations are compared to results of other, fully numerical, methods and to experimental data to establish the accuracy and reliability of the method.

The global features of spectrum of highly excited light nonstrange mesons can be well understood within both chiral symmetry restoration scenario combined with the relation $M^2~J+n$ and within a nonrelativistic description based on the relation $M^2~L+n$. The predictions of these two alternative classifications for missing states are different and only future experiments can distinguish between the two. We elaborate and compare systematically the predictions of both schemes, which may serve as a suggestion for future experiments devoted to the search for missing states.

The ground-state bands of the neutron-rich ${}^{236}\mathrm{Th}$ and ${}^{242}\mathrm{U}$ nuclei were established up to spin 10 and 8, respectively, by in-beam γ-ray spectroscopy using the (${}^{18}\mathrm{O}$, ${}^{20}\mathrm{Ne}$) two-proton pickup reaction with a ${}^{238}\mathrm{U}$ and a ${}^{244}\mathrm{Pu}$ target. Deexcitation γ rays in ${}^{236}\mathrm{Th}$ and ${}^{242}\mathrm{U}$ were identified by selecting the kinetic energies of ${}^{20}\mathrm{Ne}$ using Si $\Delta E\text{−}E$ detectors. The excitation energies of the first $2^{+}$ states in U and Pu isotopes have local minima at $N\simeq 146$, suggesting the possibility that nuclei with $Z\simeq 92$ have a spherical shell closure of $N=164$. Calculation using the Koura-Yamada single-particle potential gives an energy gap of 1.8 MeV at $N=164$ for ${}^{256}\mathrm{U}$.

The decay properties of the new isotope ${}^{282}113$ and its daughter nuclei have been measured in the ${}^{237}\mathrm{Np}$(${}^{48}\mathrm{Ca}$, $3n$)${}^{282}113$ reaction. During an irradiation with a beam dose of $1.1\times {10}^{19}244$-MeV ${}^{48}\mathrm{Ca}$ projectiles, two decay chains originating from the odd-odd isotope ${}^{282}113$ $(E_{\alpha }=10.63\pm 0.08\mathrm{MeV},T_{\alpha }={73}_{-29}^{+134}\mathrm{ms})$ were produced in the complete fusion reaction with a cross section of $0.9_{-0.6}^{+1.6}$ pb; these properties are all in agreement with expectations based on the results of previous experiments.

Using both the absolute and relative surrogate techniques, the ${}^{236}\mathrm{U}$($n,f$) cross section was deduced over an equivalent neutron energy range of 0 to 20 MeV. A 42 MeV ${}^3\mathrm{He}$ beam from the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory was used to perform a (${}^3\mathrm{He}$,α) pickup reaction on targets of ${}^{235}\mathrm{U}$ ($J^{\pi }=7/2^{-}$) and ${}^{238}\mathrm{U}$ ($J^{\pi }=0^{+}$) and the fission decay probabilities were determined. The ${}^{235}\mathrm{U}$(${}^3\mathrm{He}$,$\alpha f$) and ${}^{238}\mathrm{U}$(${}^3\mathrm{He}$,$\alpha f$) were surrogates for ${}^{233}\mathrm{U}$($n,f$) and ${}^{236}\mathrm{U}$($n,f$), respectively. The cross sections extracted using the surrogate method were compared to directly measured cross sections. The sensitivity of these cross sections to the $J^{\pi }$-population distributions was explored.

A consistent folding model analysis of the ($\Delta S=0,\Delta T=1$) charge exchange $(p,n)$ reaction measured with ${}^{48}\mathrm{Ca}$, ${}^{90}\mathrm{Zr}$, ${}^{120}\mathrm{Sn}$, and ${}^{208}\mathrm{Pb}$ targets at the proton energies of 35 and 45 MeV is done within a two-channel coupling formalism. The nuclear ground state densities given by the Hartree-Fock-Bogoliubov formalism and the density-dependent CDM3Y6 interaction were used as inputs for the folding calculation of the nucleon optical potential and $(p,n)$ form factor. To have an accurate isospin dependence of the interaction, a complex isovector density dependence of the CDM3Y6 interaction has been carefully calibrated against the microscopic Brueckner-Hartree-Fock calculation by Jeukenne, Lejeune, and Mahaux before being used as folding input. Since the isovector coupling was used to explicitly link the isovector part of the nucleon optical potential to the cross section of the $(p,n)$ reaction exciting the 0${}^{+}$ isobaric analog states in ${}^{48}\mathrm{Sc}$, ${}^{90}\mathrm{Nb}$, ${}^{120}\mathrm{Sb}$, and ${}^{208}\mathrm{Bi}$, the newly parametrized isovector density dependence could be well tested in the folding model analysis of the $(p,n)$ reaction. The isospin- and density-dependent CDM3Y6 interaction was further used in the Hartree-Fock calculation of asymmetric nuclear matter, and a realistic estimation of the nuclear symmetry energy was made.

The proportionality between single charge-exchange reaction cross sections in the forward direction as found, for example, from $(p,n)$ and $({}^3\mathrm{He}$,$t)$ and from $(n,p)$ and $(d,{}^2\mathrm{He}$) reactions, and the Gamow-Teller (GT) strength into the same final nuclear states has been studied and/or assumed often in the past. Using the most physically justified theory we have at our disposal and for the specific example of the ${}^{76}\mathrm{Ge}$-${}^{76}\mathrm{Se}$ system that may undergo double β decay, we demonstrate that the proportionality is a relatively good assumption for reactions changing a neutron into a proton, i.e., ${}^{76}\mathrm{Ge}(p,n){}^{76}\mathrm{As}$. In this channel, the main contribution to the GT strengths comes from the removal of a neutron from an occupied single-particle (SP) state and the placement of a proton into an unoccupied SP state having either the same state quantum numbers or those of the spin-orbit partner. In contrast to this, in the second leg of the double β decay, a single proton must be taken from an occupied SP state and a neutron placed into an unoccupied one. This second process often is Pauli forbidden in medium-heavy nuclei and can only be effected if the Fermi surface is smeared out. Such is the case for ${}^{76}\mathrm{Se}(n,p){}^{76}\mathrm{As}$. Our results suggest that one may not always assume a proportionality between the forward-angle cross sections of the charge-exchange reactions and the GT strength in any such medium-heavy nuclei. The discrepancy originates from a pronounced effect of the radial dependence of the nucleon-nucleon ($\mathit{NN}$) interaction in connection with the Pauli principle on the cross sections in the $(n,p)$ reaction channel. Such a radial dependence is completely absent in the GT transition operator.

Neutron total and capture reaction cross-section measurements for ${}^{206}\mathrm{Pb}$ were performed at the GELINA neutron time-of-flight facility in the energy range from 1 to 620 keV. The resonance parameters corresponding to 304 excited nuclear levels in ${}^{207}\mathrm{Pb}$ were determined from the data using the R-matrix formalism. The results are compared to existing data. From the capture data photon strength functions have been deduced. No evidence has been found for a previously reported enhancement of the $M1$ transition strength, nor for a strong enhancement of the s-wave doorway state in the photon channel. The neutron capture cross section of ${}^{206}\mathrm{Pb}$ is of importance in stellar evolution calculations of the formation of the elements by neutron capture. Maxwellian-averaged neutron capture cross sections have been calculated at different stellar temperatures ranging up to 100 keV and compared with the results of previous work and evaluated data libraries.

We extract the $Q\text{−}\overline{Q}$ potential by using the thermodynamic quantities obtained in lattice gauge calculations. The potential is tested and found to give spontaneous dissociation temperatures that agree well with those from lattice gauge spectral function analysis. Using such a $Q\text{−}\overline{Q}$ potential, we examine the quarkonium states in a quark-gluon plasma and determine the “quark drip lines” which separate the region of bound color-singlet $Q\overline{Q}$ states from the unbound region. The characteristics of the quark drip lines severely limit the region of possible bound $Q\overline{Q}$ states with light quarks to temperatures close to the phase transition temperature. Bound quarkonia with light quarks may exist very near the phase transition temperature if their effective quark mass is of the order of 300–400 MeV and higher.

We study the role of pions on the ground states of finite nuclei with explicit treatment of pions by variation after charge and parity projection based on the relativistic chiral mean-field (CPPCMF) model. This CPPCMF model has been applied to ${}^4\mathrm{He}$ and demonstrated to provide good ground-state properties within a spherical pion field ansazt. We further apply this model to heavier nuclei up to ${}^{56}\mathrm{Ni}$ in this article. We find that pions play dominant role also for properties of ${}^{12}\mathrm{C}$. However, this pionic effect is significantly suppressed in ${}^{16}\mathrm{O}$ due to the Pauli blocking effect. We find that pionic correlations reflect largely the particle configurations in the shell structure. As for the heavier nuclei, the pionic energy systematics as a function of nuclear mass number are clearly separated into two groups, the LS and $\mathit{jj}$ closed-shell nuclei. The large amount of pionic contributions are obtained for $\mathit{jj}$ closed-shell nuclei as compared with those for LS closed-shell nuclei. This fact may indicate that the pion plays an important role on the formation of the $\mathit{jj}$ magic numbers. The pionic contributions are reduced approximately as $A^{-2/3}$ with the nuclear mass number. We discuss the reason of this reduction of the pionic energy with the nuclear mass and propose to improve our present ansatz of dealing with pions for heavier nuclei.

High spin states up to spin $41/2\hslash$ were populated in ${}^{139}\mathrm{Nd}$ using the heavy ion fusion evaporation reaction. The low spin states below $19/2^{-}$ indicate a triaxial shape. Two dipole bands, one negative parity and the other positive parity, have been identified in the present work. The configurations of different high spin states are discussed from a systematic comparison with neighboring $N=79$ odd mass isotopes. The observed dipole bands are compared with the results of the tilted axis cranking calculations.

A simple expression for the Coulomb interaction of two deformed, arbitrarily oriented, axially symmetric nuclei is obtained. An accurate approximation for the nuclear part of the interaction between these nuclei has been proposed. The properties of the total potentials between nuclei with prolate-prolate, prolate-oblate, and oblate-oblate deformations at various orientations are discussed. The particularities of the total potentials for the systems leading to superheavy elements are considered in detail. The influence of quadrupole and hexadecapole deformations of both nuclei at various orientations on the barrier height and potential pocket properties is studied.

We consider the development of Cooper pairs in a self-consistent Hartree-Fock mean field for the even Sm isotopes. Results are presented at the level of a BCS treatment, a number-projected BCS treatment and an exact treatment using the Richardson ansatz. For a fixed value of the pairing strength, projected BCS captures much of the pairing correlation energy that is absent from BCS, but still misses a sizable component, typically of order 1 MeV. Furthermore, because it does not average over the properties of the fermion pairs, the exact Richardson solution permits a more meaningful definition of the Cooper wave function and of the fraction of pairs that are collective.

The electromagnetic decay properties of high-spin states in ${}^{52}\mathrm{Mn}$ have been studied through various experiments with the GASP and EUROBALL arrays plus the ISIS light charged-particle detector and the Neutron Wall. From γ-γ particles coincidence measurements, spins, and parities of these states and branching ratios of their decay γ rays have been determined. Using the Doppler-shift attenuation method the mean life of some states have been established. These results are compared with large-scale shell-model calculations in the full $\mathit{fp}$ shell.