A detailed $\alpha$-decay study was performed for ${}^{189m,g}$Bi produced in the reaction of ${}^{95}$Mo on ${}^{96}$Mo at 418 MeV. Evaporation residues were selected in-flight using the Argonne fragment mass analyzer and implanted into a double sided silicon strip detector. The correlation technique between implants and subsequent decays was used to observe new weak $\alpha$ branches of ${}^{189}$Bi to excited states in ${}^{185}$Tl. A more precise value of 182(8) keV for the excitation energy of the $\pi s$${}_{1/2}$ intruder state in ${}^{189}$Bi was determined. The $\alpha$ decay of the ${}^{189}$Bi (9/2${}^{-})$ ground state to the $\pi d_{3/2}$ level at 284 keV was observed for the first time. In addition, the $\alpha$ decay of ${}^{188}$Bi was remeasured. Reduced widths for the $\alpha$ decays of odd-$A$ ${}^{189-197m,g}$Bi nuclei to states in their Tl daughters are discussed.

From the time differential angular correlation measurement of the 94-63 keV cascade ${\mathrm{in}}^{169}$Tm, a pure M1 character of the 94 keV γ ray is suggested in contrast to the 4% E2 admixture observed in conversion coefficient measurements. Our result indicates “penetration effects” on the internal conversion processes for the 94 keV transition. The observation of penetration effects for a K-allowed unhindered transition is probably the first. The magnetic moment of the 379 keV state has been remeasured, and the value [μ=(3.04±0.14)μ${}_N$] is in close agreement with the theoretical prediction (4.5${\mu }_N$).

The nucleus ${}^{198}$Au has been studied with an energy resolution of 11 keV via the ${}^{197}$Au${\mathrm{}(d,p)\mathrm{}}^{198}$Au reaction at an incident deuteron energy of 22 MeV. The angular distributions, measured at 10 angles, permit one to clearly characterize the $l=1\mathrm{}$ and 3 transfers. Data concerning the $l$ values and spectroscopic strengths have been obtained; a comparison is made, for negative-parity levels, between these results and theoretical energies, spins, and strengths calculated in the framework of extended supersymmetry. The results are also compared to those of a previous transfer study of ${}^{196}$Au, and to another theoretical calculation.

We study finite nuclei within the relativistic mean field approach with density dependent couplings (RMFD) based on the relativistic Brueckner-Hartree-Fock (RBHF) results on nuclear matter. We take the linear relativistic mean-field Lagrangian with mesons σ, ω, δ, and ρ, whose coupling constants with nucleons are determined so as to reproduce the RBHF results of nuclear matter at various densities and proton fractions. We apply the RMFD approach to various nuclei with spherical shape including unstable ones in the periodic table. We find satisfactory results on the nuclear properties. We emphasize here that the proton and neutron effective masses are largely different from each other as the proton fraction is decreased from $Y_p=0.5\mathrm{}$, which forces us to include the isovector scalar meson δ in our approach.

The energy systematics of even-$A$, neutron-deficient polonium isotopes have been previously observed down to $A=194\mathrm{}$. The low-lying states display a gradual approach to the equal spacings of a harmonic vibrator, exceeding this limit for the first time in ${}^{194}$Po. We have successfully modeled these energy systematics using the particle-core model and have applied the quasiparticle random phase approximation to extract microscopic wave functions for the collective $2_1^{+}$ states and predict ${B(E2;2\mathrm{}}_1^{+}\to 0_1^{+})$ values. We are able to explain the Po trends in terms of the overlaps of the wave functions of valence particles, overlaps which are enhanced when particles occupy the high-$j$ proton ${1h}_{9/2}$ and neutron ${1i}_{13/2}$ orbitals. We find little evidence for particle-hole excitations across the $Z=82\mathrm{}$ shell gap.

Energy levels in $N=50\mathrm{}$ nuclei are calculated allowing single-particle excitations from the $p_{1/2}$ and $g_{9/2}$ shells into the $d_{5/2}$, $s_{1/2}$, $d_{3/2}$, and $g_{7/2}$ shells. Important parts of the interaction are determined by least-squares fits to known levels. Agreement with experiment is very good. The high-spin particle-hole states appear to be mainly yrast levels in mass 93 and higher, but are not in ${}^{90}\mathrm{Zr}$.

We study the properties of the superdeformed (SD) bands of ${}^{195}$Pb and ${}^{193}$Hg by the cranked Hartree-Fock-Bogoliubov method. Our calculations reproduce the flat behavior of the dynamical moment of inertia of two of the SD bands of ${}^{195}$Pb measured recently. We discuss possible configuration assignments for the observed bands 3 and 4 of ${}^{195}$Pb. We also calculate the two interacting SD bands of ${}^{193}$Hg. Our analysis confirms the merit of density-dependent pairing forces as compared to seniority pairing interactions.

The influence of quadrupole and hexadecapole residual interactions on rotational bands is investigated in a single-$j$ shell model. An exact shell-model diagonalization of the quadrupole-plus-hexadecapole Hamiltonian demonstrates that the hexadecapole-hexadecapole interaction can sometimes produce a staggering of energy levels in the yrast sequence; however, long and regular $\Delta I=2\mathrm{}$ sequences are not obtained. The shell-model results are discussed in terms of the intrinsic deformations extracted by means of the self-consistent Hartree-Fock method. The angular momentum dependence of intrinsic quadrupole and hexadecapole moments $Q_{2\mu }$ and $Q_{4\mu }$ is investigated.

The proton spectra of the giant quadrupole resonance decay in ${}^{40}$Ca is analyzed. The decay mechanism of this excitation is studied by the inclusion of the semidirect, preequilibrium, and statistical modes through the chaining evolution of the particle-hole configurations. Strong evidence for the contribution of preequilibrium decay of the giant resonance is established.

Temperature dependent shell corrections are calculated taking into account the continuum spectrum of a finite depth mean field potential. The effect of the continuum is split up into a discret term which includes Gamow resonances and an integral along a contour in the complex energy plane. The resonances appear in the formalism in the same manner as bound states and at low temperatures they give the main part of the contribution due to the continuum. The method is applied to the particular case of ${}^{208}$Pb. The temperature for which the shell corrections are washed out completly is estimated at $T\approx 2.5$ MeV.

The ground states of Hg and Pb isotopes are studied in the framework of deformed relativistic mean field theory with pairing interactions in the BCS theory. We show that the neutron and proton gap parameters strongly depend on deformation, and demonstrate that it is crucially important to solve the gap equations for each deformation in order to discuss the shape and the charge radius of these isotopes. The oblate shape and the charge radius of neutron deficient Hg isotopes are well reproduced. Our calculations suggest that the atomic number 82 stays a magic number for all the Pb isotopes we studied, and well reproduce the isotope shifts of Pb isotopes.

The structure of nuclei in the lower half of the $\mathrm{fp}$ shell is investigated by the spectral distribution method using the modified Kuo-Brown interaction. This interaction recently showed success in reproducing observed properties through detailed shell model studies. Spectral distribution studies avoid explicit diagonalization and hold promise for applications to astrophysics.

We describe the properties of the neutron-rich nuclei around $N=28\mathrm{}$ in the shell mode framework. The valence space includes the $\mathrm{sd}$ shell for protons and the $\mathrm{pf}$ shell for neutrons without any restriction. Good agreement is found with the available experimental data. The $N=28\mathrm{}$ shell closure persists, even if eroded by the large neutron excess. The calculations predict that ${}^{40}$S and ${}^{42}$S are deformed with $\beta =0.29\mathrm{}$ and $\beta =0.32\mathrm{}$ respectively.

It is shown that the $\Delta I=2\mathrm{}$ staggering in the isolated rotational band of axial nuclei may be explained by the nonaxial distortion of a self-consistent field under rotation. The method for obtaining the effective rotational Hamiltonian from the microscopic Routhian has been developed by using the mean field approach with the exact diagonalization in the space of intruder orbitals and the perturbation theory for low-$j$ ones. The rotational dynamics of the simplest effective Hamiltonian, resulting in staggering, has been analyzed in its parameter space. The parameters are estimated in the axially deformed oscillator potential with and without pairing. The close connection of the phenomenon with the single-particle configurations of the superdeformed bands is discussed.

$E4\mathrm{}$, $E6\mathrm{}$, and $M5\mathrm{}$ transitions in the ${1f}_{7/2}$-shell nuclei, for which anomalous effective charges are required to reproduce experiment, are discussed by using the effective transition operators which are calculated within the framework of the first-order perturbation theory. The correlated operators thus obtained consist of one-body and two-body transition operators, the former of which is considered to be the origin of effective charges, while the latter cannot be incorporated into the idea of effective charges. The two-body contributions are very important in those higher-multipole transitions, to the extent that the concept of effective charge breaks down, and they are found indispensable in achieving reasonable agreement with experiment.

The forward-to-backward asymmetry of neutrons emitted in the ${}^{40}$Ca$\left(\gamma {,n}_0\right)$ reaction was measured at photon energies in the range of 27–50 MeV. An energy-dependent asymmetry was observed that is interpreted as evidence of interference between the isovector quadrupole resonance and the giant dipole resonance. Data analysis in terms of semiclassical and direct-semidirect models estimate the isovector quadrupole resonance to be at an excitation energy of $31.0\pm 1.5$ MeV, with a width of $16.0\pm 1.5$ MeV, and exhausting most of the energy-weighted sum rule for the isovector quadrupole resonance.

Cross sections have been measured for 65 MeV ${\pi }^{+}$ scattering to the ${}^{10}$B ground and first four excited states. The 1.74 MeV excited state results provide the first measurement of the energy dependence of the isovector spin-flip strength parameter. Our analysis indicates that the observed empirical enhancement of the isovector spin-flip strength has little or no dependence on energy at and below resonance. A mass dependence for the empirical enhancement factor may exist.

The attenuation cross sections measured in transmission experiments at the alternating-gradient synchrotron for $K^{+}$ on ${}^6\mathrm{Li}$, C, Si, and Ca at $p_L$ = 488, 531, 656, and 714 MeV/$c$ are reanalyzed in order to derive total $\left({\sigma }_T\right)$ and reaction $\left({\sigma }_R\right)$ cross sections. The effect of plural (Molière) scattering is properly accounted for, leading to revised values of ${\sigma }_T.$ We demonstrate the model dependence of these values, primarily due to the choice of $K^{+}$ nuclear optical potential used to generate the necessary Coulomb-nuclear and nuclear elastic corrections. Values of ${\sigma }_R$ are also derived, for the first time, from the same data and exhibit a remarkable degree of model independence. The derived values of ${\sigma }_T$ and ${\sigma }_R$ exceed those calculated by the first-order $t\rho$ optical potential for C, Si, and Ca, but not for ${}^6\mathrm{Li}$, particularly at 656 and 714 MeV/$c$ where the excess is 10–25%. Relative to ${}^6\mathrm{Li}$, this excess is found to be nearly energy independent and its magnitude of 15–25% is not reproduced by any nuclear medium effect studied so far.

A prominent and wide resonance centered at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=32.5\mathrm{}$ MeV has recently been found in the ${(0\mathrm{}}_2^{+}{,0\mathrm{}}_2^{+})$ inelastic channel of the ${}^{12}$C${+}^{12}$C reaction. It has been suggested that it corresponds to a 6$\alpha$-particle-chain state in ${}^{24}$Mg. In the present work we study ${}^{12}$C${+}^{12}$C excitation functions between center-of-mass energies of 30 and 35 MeV in steps of 250 keV for weakly populated outgoing channels. We present the inelastic channels to the states above the $\alpha$-particle decay threshold, ${(0\mathrm{}}_1^{+}{,0\mathrm{}}_2^{+})$, ${(0\mathrm{}}_1^{+}{,3\mathrm{}}_1^{-})$, and ${(0\mathrm{}}_1^{+}{,4\mathrm{}}_1^{+})$, and the one- and two-nucleon transfer channels. In the inelastic and the transfer channels we observe correlated intermediate-width structures at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=31\mathrm{}$, 32.5, and 33.5 MeV, whose widths are appreciably smaller than the width measured in the ${(0\mathrm{}}_2^{+}{,0\mathrm{}}_2^{+})$ channel. Our $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=32.5\mathrm{}$ MeV angular distribution of the ${(0\mathrm{}}_1^{+}{,0\mathrm{}}_2^{+})$ channel exhibits oscillatory behavior and, unlike that of the ${(0\mathrm{}}_2^{+}{,0\mathrm{}}_2^{+})$ channel, does not display enhancement around ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=90\mathrm{}°$. Data were collected via the kinematic coincidence technique. For data reduction we use a novel approach allowing for the extraction of results on nonbinary channels.

We examine the average cluster distribution as a function of lattice probability for a very small $\mathrm{}(L=6\mathrm{})\mathrm{}$ lattice and determine the scaling function of three-dimensional percolation.  The behavior of the second moment, calculated from the average cluster distribution of $L=6\mathrm{}$ and $L=63\mathrm{}$ lattices, is compared to power-law behavior predicted by the scaling function. We also examine the finite-size scaling of the critical point and the size of the largest cluster at the critical point. This analysis leads to estimates of the critical exponent $\nu$ and the ratio of critical exponents $\beta /\nu$.