The finite-temperature Hartree-Fock-Bogoliubov equations are solved for ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ with the pairing-plusquadrupole interaction. Although the static shape is spherical at zero temperature, raising the temperature induces a second-order phase transition to a prolate deformed shape. The onset of deformation is related to the thermal destruction of the pairing gap.

The hole left in the center of the Pb nucleus by the removal of one proton is filled in to within 50% by rearrangement. Therefore, the charge distribution difference between Pb and Tl and the Pb(e,e'p)Tl cross section can only be interpreted in terms of the $3s$ wave function after this strong rearrangement is taken into account.

We propose a U(15) ⊗ U(30) boson-fermion symmetry scheme based on the coupling of a $j=\frac{1}{2}, \frac{3}{2}, \frac{5}{2}, \frac{7}{2}, \mathrm{and} \frac{9}{2}$ particle with even-even core nucleus described by the interacting boson model including $g$ bosons. The single-particle structure of the rotational bands in the SU(3) limit of the U(15) ⊗ U(30) symmetry scheme is compared, for the ${}_{}{}^{185}{}_{}{}^{}\mathrm{W}$ nucleus, with that of the Nilsson model and contrasted with the U(6) ⊗ U(20)-SU(3) scheme used by Warner. From the present exercise it appears that $g$ bosons are needed for a complete description of the low lying rotational bands of the ${}_{}{}^{185}{}_{}{}^{}\mathrm{W}$ nucleus.

We calculate the one-photon decay rate of the polyelectron ${\mathrm{P}}^{++\mathrm{-}}$ in the ground state to be 8.8×${10}^{\mathrm{-}2}$ ${\sec }^{\mathrm{-}1}$. Implications for possible explanations of the anomalous peaks observed in heavy-ion collisions are briefly discussed.

The cross sections for the electric-dipole radiative-capture reaction ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(α,γ${)}^7$Be are calculated with an approximation procedure (approximate-resonating-group-method procedure) in which the antisymmetrization of the wave function is simply represented by the adoption of an intercluster renormalized function obtained by operating on the resonating-group relative-motion function with the square root of the norm operator. The result shows that this procedure does yield values for the capture cross-section factor in excellent agreement with the resonating-group-method results. By studying the properties of the approximate-resonating-group-method wave functions, we find that, in this capture reaction, the nuclear potential is sampled at all energies and should be properly considered even at astrophysical low energies around 10 keV. In addition, based again on approximate-resonating-group-method results, we have shown that the macroscopic capture-reaction models of Iwinski et al. using analytical-continuation techniques and of Buck et al. using Gaussian-type effective local potentials are not sufficiently accurate for the computation of cross-section factors because of the fact that the details of the nuclear interaction are not well accounted for.

The physical concepts of the hybrid and exciton models are reexamined and shown to constitute fundamentally different approaches to preequilibrium reactions. The difference in cross section predictions obtained from the models is not attributable—as has often been argued—to inappropriate exciton distribution functions in higher order terms or multiple chance emission. It rather rests with the question of whether or not configuration mixing is assumed to take place during equilibration and what is assumed about hole interactions. A simplified but realistic example is given to illustrate these points, and a test against experimental data is proposed to decide which model is the more appropriate to use.

It is shown in the WKB approximation that a nonlocal energy-independent potential of the Frahn-Lemmer–type can be determined from its phase shifts given at all energies and angular momenta. A numerical illustration is presented. The extension of the method to more general nonlocal energy-independent potentials is discussed.

A separable approximation for the ${}_{}{}^1{}_{}{}^{}\mathrm{S}_0^{}{}_{}{}^{}$, ${}_{}{}^1{}_{}{}^{}\mathrm{P}_1^{}{}_{}{}^{}$, ${}_{}{}^3{}_{}{}^{}\mathrm{P}_0^{}{}_{}{}^{}$, and ${}_{}{}^3{}_{}{}^{}\mathrm{P}_1^{}{}_{}{}^{}$ channels of the N-N Reid soft core and Argonne potentials, based on the use of Gamow states, is presented. The on- and off-shell scattering amplitudes obtained from these separable forms are compared with the corresponding exact ones. Excellent agreement is obtained, which makes the Gamow separable approximation a successful and unambiguous method to construct separable approximations for local realistic N-N interactions.

The ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$(d,d’${)}^{91}$${\mathrm{Zr}}^{\mathrm{*}}$ reaction has been investigated at 17 MeV incident energy. Up to 4.8 MeV excitation, 73 levels, some of them new, were identified. Angular distributions associated to ∼40 levels were attributed to pure L=2, 3, or 5 excitations, concentrated in energy regions where the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ core exhibits $2^{+}$, $3^{\mathrm{-}}$, and $5^{\mathrm{-}}$ states. The partial deformation parameters ${\beta }_L^{\mathcal{’}}$ obtained show agreement with those from low energy proton scattering for L=2, but there is a systematic difference for L=3 and L=5, which is discussed. Attention is drawn to the high excitation probability of the first excited state of ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$, as measured by the ${\beta }_2$≃0.18 value obtained, a factor of ∼2 above all other values for nuclei with A=90±2.

Previous large-angle investigations of atomic Rayleigh and Delbrück scattering in the few MeV energy range have been extended to small scattering angles. Rayleigh predictions obtained by combining the second-order S matrix for inner shells with the modified form factor for outer shells are accurate to better than 3%. Tentative estimates of Coulomb correction terms for the Delbrück amplitudes are obtained from the experimental differential cross sections using (i) general properties of scattering amplitudes, (ii) information from pair production valid at small angles, and (iii) rather firm arguments concerning signs and relative magnitudes of the scattering amplitudes at large angles and assumptions about the relative magnitudes of the Coulomb correction amplitudes at intermediate energies.

We investigate the capabilities of a semimicroscopic optical model potential involving fewer adjustable parameters than phenomenological models and test the sensitivity of this potential to various rotational band assumptions. Our analysis of the model capabilities is performed using experimental elastic, inelastic, and total cross sections as well as experimental neutron strength functions. We compare our calculations to these experiments and to the predictions of a phenomenological model. Our sensitivity study is performed for the first three rotational bands of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$. The two main ingredients of our calculations are the microscopic optical-model potential of Jeukenne, Lejeune, and Mahaux and nuclear densities from Hartree-Fock-Bogoliubov calculations using the density-dependent force $D_1$.

Differential cross sections for proton elastic scattering from ${}_{}{}^{42}{}_{}{}^{}$,44,48Ca have been measured at seven energies in the laboratory energy range from 21.0 to 48.4 MeV, and for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at six energies between 25.0 and 45.0 MeV. Measurements were made at 2.5° intervals from 10° to 90° (laboratory angles), and at 5.0° intervals between 90° and 170°. Relative errors in the data are typically between 3% and 4%; the scale errors are also 3%. The data have been analyzed by both nonrelativistic and relativistic optical models. The optical potential parameters were used to calculate nuclear matter radius information for the calcium isotopic series, which is compared to previous results.

We use a microscopic model in which we start from two nuclei approaching each other; at the end, the nuclear matter breaks up into a few composite pieces and nucleons. The initial stage is described by hard collisions; clusters are produced by the mean field, when hard collisions are over. Representative results are shown.

Excited states in ${}_{}{}^{195}{}_{}{}^{}\mathrm{Bi}$ were populated by the ${}_{}{}^{182}{}_{}{}^{}\mathrm{W}$${(}^{19}$F,6n) and ${}_{}{}^{169}{}_{}{}^{}\mathrm{Tm}$${(}^{30}$Si,4n) reactions. The subsequent γ-ray emission was studied using in-beam spectroscopic methods including excitation functions, γ-ray angular distributions, γ-γ-t coincidence, conversion electron, and pulsed-beam-γ timing measurements. Three isomeric states were located in ${}_{}{}^{195}{}_{}{}^{}[J^{\pi }$,$t_{1/2}$,E]: ${\left[\mathrm{}\right((13/2\mathrm{})\mathrm{}}^{+}$), 32±2 ns, 888 keV]; ${\left[\mathrm{}\right((25/2\mathrm{})\mathrm{}}^{+}$), 80±10 ns, 2196 keV]; and ${\left[\mathrm{}\right((29/2\mathrm{})\mathrm{}}^{\mathrm{-}}$), 750±50 ns, 2311+Δ keV]. The structure of the observed states is interpreted within the shell-model framework. Systematic features of excited state energies and transition rates in the odd-A bismuth isotopes are discussed. A comparison of intruder states analogous to those in odd-A antimony nuclei of the Z=50 transition region is made.

The heavy residues emitted following the interaction of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been measured for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ bombarding energies from 12 to 35 MeV. The gross characteristics of the residue spectra are in qualitative agreement with a fusion-evaporation mechanism. Beginning at Coulomb barrier energies, it is found that the total fusion cross section diverges from the total reaction cross section obtained from optical model fits to ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O elastic scattering data. The importance of the process which limits the ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O fusion cross section is attested to by the fact that only 60% of the total reaction strength can be accounted for by fusion at our highest bombarding energies. A comparison of the total fusion cross sections as a function of center-of-mass energy for the ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O and ${}_{}{}^7{}_{}{}^{}$Li${+\mathrm{}}^{16}$O entrance channels reveals essentially identical total fusion cross section excitation functions. This result contrasts sharply with the results obtained in an earlier study of ${}_{}{}^6{}_{}{}^{}$,7Li-induced reactions on ${}_{}{}^{12}{}_{}{}^{}$,13C nuclei. In the earlier study, fusion cross sections which were projectile dependent and target independent were observed. Finally, the critical angular momenta have been extracted from the ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O total fusion cross sections. When compared with the critical angular momenta obtained from an earlier study of the ${}_{}{}^{10}{}_{}{}^{}$B${+\mathrm{}}^{12}$C entrance channel, a common limitation is found with increasing ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ excitation energy. This result is in sharp contrast with the result of an earlier study of entrance channels which form the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ compound nucleus, a compound system only one neutron removed from ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$.

The electromagnetic dissociation of ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$, ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ target nuclei was inferred from measurements of cross sections for the one-neutron removal reaction. Beams of 2.1 GeV/nucleon ${}_{}{}^1{}_{}{}^{}\mathrm{H}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, 1.8 GeV/nucleon ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, and 1.7 GeV/nucleon ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ projectiles were used. Beam intensities were monitored using the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(RHI,X${)}^{11}$C reaction, where RHI represents relativistic heavy ion beams. The experimental cross sections in excess of the estimated nuclear contributions are generally well described by use of the Weizsaaumlcker-Williams method for calculating the electromagnetic dissociation contributions but increase more slowly as the projectile charge is increased. Cross sections for one-neutron removal reactions are large for the heavier projectiles, ranging up to 707 mb. For these cases a high percentage is from the electromagnetic dissociation process.

The influence of the nuclear mean field on the nucleons emitted from heavy ion collisions in the energy range 400–800 MeV per nucleon is investigated in an analytical approach. Simple expressions for the kinetic flow tensor and the triple differential momentum distribution of these nucleons are obtained, which lead to a sizable flow angle, and to a characteristic structure of the momentum distribution in the reaction plane.

The inelastic excitation of the ${\mathrm{}(1/2)\mathrm{}}^{+}$ (871 keV) state of ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ in the reaction of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ on ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ is described by a time-dependent quantum mechanical model with two diabatic states and a classical treatment of the radial relative motion. The structures in the angle-integrated cross section are interpreted as caused by the barriers of the angular momentum-dependent potentials. The transition strength is enhanced by the Landau-Zener effect between the levels considered.

We have measured the sub-barrier fusion cross sections for ${}_{}{}^{16}{}_{}{}^{}$,17,18O on ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and we present the data and the experimental method in detail. The data were analyzed with a one-dimensional potential barrier inversion model, a two-dimensional incoming wave boundary condition model, and a two-dimensional Wentzel-Kramers-Brillouin model. We find that a multidimensional model is necessary to describe the enhanced fusion cross sections in oxygen and the two-dimensional incoming wave boundary condition model suggests that a complete description of the fusion, inelastic, and elastic cross sections is possible.

By means of a cascade model calculation, it is shown that medium mass fragment production in proton-induced reactions very likely proceeds via the breakup of the residual nuclear system rather than coalescence. The reaction trajectory of the excited nuclear system is found to enter the mechanical instability region with S/A∼0.4, well below the average S/A of 1.6–2.0 observed experimentally for heavy fragments in proton-induced reactions. We estimate the increase in entropy generated by passage through the mechanical instability region of nuclear matter by means of two simple models. The predicted final entropy is comparable to what is found experimentally.