A microscopic description of the excitation of isoscalar giant monopole resonance (ISGMR) and quadrupole resonance (ISGQR) in ${}^{28}\mathrm{Si},$ ${}^{40}\mathrm{Ca},$ ${}^{58}\mathrm{Ni},$ and ${}^{116}\mathrm{Sn}$ by 240 MeV bombarding energy $\alpha$ particles is provided based on self-consistent Hartree-Fock– (HF-) random-phase-approximation (RPA) approach and the distorted-wave Born approximation (DWBA). The folding model is used to obtain optical potentials from the HF ground-state density and a density dependent Gaussian nucleon-$\alpha$ interaction ${(V}_{\alpha n}).\mathrm{}$ The parameters of $V_{\alpha n}$ are determined by fitting experimentally measured angular distributions for the case of elastic scattering. Angular distributions of inelastically scattered $\alpha$ particles for ISGMR and ISGQR excitations of the target nucleus are obtained using the folding model DWBA and both microscopic (RPA) and hydrodynamical (collective model) transition densities (found from HF ground state densities). A possible overestimation of the energy weighted sum rules and shifts of centroid energies due to the collective-model-based DWBA reaction description is reported.

Shell corrections to the nuclear binding energy as a measure of shell effects in superheavy nuclei are studied within the self-consistent Skyrme-Hartree-Fock and relativistic mean-field theories. As a result of the presence of a low-lying proton continuum resulting in a free particle gas, special attention is paid to the treatment of the single-particle level density. To cure the pathological behavior of the shell correction around the particle threshold, a method based on the Green’s function approach has been adopted. It is demonstrated that for the vast majority of Skyrme interactions commonly employed in nuclear structure calculations, the strongest shell stabilization appears for $Z=124\mathrm{}$ and 126, and for $N=184.\mathrm{}$ On the other hand, in the relativistic approaches the strongest spherical shell effect appears systematically for $Z=120\mathrm{}$ and $N=172.\mathrm{}$ This difference probably has its roots in the spin-orbit potential. We have also shown that, in contrast to shell corrections which are fairly independent of the force, macroscopic energies extracted from self-consistent calculations strongly depend on the actual force parametrization used. That is, the A and Z dependence of the mass surface when extrapolating to unknown superheavy nuclei is prone to significant theoretical uncertainties.

Two new rotational bands have been observed in the ${}^{152}\mathrm{Dy}$ nucleus following experiments performed using the EUROGAM $\gamma$-ray spectrometer. Several transitions have been observed that link these new bands into the known single-particle states. Using the Doppler shift attenuation method, the quadrupole moment of the previously-known rotational sequence has been measured. The value of $Q_{\mathrm{band}}=3.85\mathrm{}\pm 0.06\hspace{0.5em}e\mathrm{b}$ confirms the deformed nature of this cascade. The structures of the three bands are discussed in terms of the occupation of both paired and unpaired orbitals, and are found to be in good agreement with theoretical calculations. The observation of two new bands further extends the concept of shape coexistence in the ${}^{152}\mathrm{Dy}$ nucleus.

The microcanonical multifragmentation model from [Al. H. Raduta and Ad. R. Raduta, Phys. Rev. C 55, 1344 (1997); 56, 2059 (1997); 59, 323 (1999)] is refined and improved by taking into account the experimental discrete levels for fragments with $A<~6$ and by including the stage of sequential decay of the primary excited fragments. The caloric curve is reevaluated and the heat capacity at constant volume curve is represented as a function of excitation energy and temperature. The sequence of equilibrated sources formed in the reactions studied by the ALADIN group ${(}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ at 600, 800, and 1000 MeV/nucleon bombarding energy) is deduced by fitting simultaneously the model predicted mean multiplicity of intermediate mass fragments ${(M}_{\mathrm{IMF}})$ and charge asymmetry of the two largest fragments ${(a}_{12})$ versus bound charge ${(Z}_{\mathrm{bound}})$ on the corresponding experimental data. The calculated HeLi isotopic temperature curves as a function of the bound charge are compared with the experimentally deduced ones.

Quasielastic (QE) and transfer excitation function measurements have been carried out for the ${}^{16}\mathrm{O},{\hspace{0.5em}}^{19}\mathrm{F}{+}^{232}\mathrm{Th}$ systems at ${\theta }_{\mathrm{lab}}=170\mathrm{}°$ over a wide energy range above and below the Coulomb barrier. The data were analyzed to obtain the representation of fusion barrier distributions as well as the mean square compound nuclear spin values $\left(〈l^2〉\right),$ which are found to compare well with the results of the standard fusion model (CCDEF) calculations. Further, the back-angle transfer cross-section data as a function of the bombarding energy were transformed to give the transfer probabilities as a function of the distance of closest approach for $1p,$ $2p,$ $1\alpha ,$ and $1p1\alpha$ transfer channels. The experimental “slope parameters” derived from these data were compared with the predictions of the semiclassical model calculations. It is found that the results for single nucleon or single cluster transfers are well explained by the semiclassical model, whereas for multinucleon or cluster transfers, the calculations underpredict the transfer probabilities.

It is recalled that spin observables in the strangeness-exchange reaction $\overline{p}\overrightarrow{p}\overline{\Lambda }\Lambda$ are not independent, but are related to each other by simple algebraic relations. This provides constraints on the existing data on polarization and spin-correlation coefficients and also on forthcoming data obtained using a polarized proton target.

We examine the time-reversal-violating nuclear “Schiff moment” that induces electric dipole moments in atoms. After presenting a self-contained derivation of the form of the Schiff operator, we show that the distribution of Schiff strength, an important ingredient in the ground-state Schiff moment, is very different from the electric-dipole-strength distribution, with the Schiff moment receiving no strength from the giant dipole resonance in the Goldhaber-Teller model. We then present shell-model calculations in light nuclei that confirm the negligible role of the dipole resonance and show the Schiff strength to be strongly correlated with low-lying octupole strength. Next, we turn to heavy nuclei, examining recent arguments for the strong enhancement of Schiff moments in octupole-deformed nuclei over that of ${}^{199}\mathrm{Hg},$ for example. We concur that there is a significant enhancement while pointing to effects neglected in previous work (both in the octupole-deformed nuclides and ${}^{199}\mathrm{Hg})$ that may reduce it somewhat, and emphasizing the need for microscopic calculations to resolve the issue. Finally, we show that static octupole deformation is not essential for the development of collective Schiff moments; nuclei with strong octupole vibrations have them as well, and some could be exploited by experiment.

We discuss the implications of finite size effects on the determination of the order of a phase transition which may occur in infinite systems. We introduce a specific model to which we apply different tests. They are aimed to characterize the smoothed transition observed in a finite system. We show that the microcanonical ensemble may be a useful framework for the determination of the nature of such transitions.

We find that the excitation energies of single analog states for odd-even nuclei in the $f_{7/2}$ shell with ${J=j=7/2\mathrm{}}^{-}$ and the ${J=0\mathrm{}}^{+}$ double analog states in the even-even nuclei are fairly well described by the formulas $E^{*}\mathrm{}(j,T+1\mathrm{})=b(T+X)\mathrm{}$ and $E^{*}{(0\mathrm{}}^{+},T+2)=2b(T+X+0.5\mathrm{}),$ respectively, where $T=|N-Z|/2\mathrm{}$ is usually the ground-state isospin. Comparisions are made with single j-shell calculations and also those involving configuration mixing.

Cluster expansion of the many-body Schrödinger wave function is manifested through the projected Faddeev-Yakubovsky equations. It is shown that using these equations one can formulate a systematic expansion for the wave function of finite systems in a translational invariant manner. The solution of the N-body problem at a given order becomes equivalent to solving the few-body Faddeev-Yakubovsky equations. The first two orders in this expansion are given explicitly and then solved for the case of N bosons interacting through the nucleon-nucleon Afnan-Tang S3 and Malfliet-Tjon MT-V potentials.

We examine the nuclear medium effect on the charge symmetry breaking (CSB) caused by isospin mixing of two neutral vector mesons interacting with nucleons in neutron matter. It is found that isospin mixing is strongly enhanced in neutron matter as the neutron density increases and the charge symmetry is broken to a large extent. We illustrate the influence of the enhanced CSB for bulk quantities by calculating the mass of a fictitious neutron star composed of only neutrons. For the stars with central densities around the normal density of nuclear matter, the masses are reduced by as much as 35% in comparison with those emerging from an ordinary relativistic nuclear model with no CSB considered. The effect of CSB is attenuated for stars with higher central densities which actual neutron stars are supposed to have, although the charge symmetry remains broken to a large extent.

Differential cross sections and spin observables $A_y,$ ${\mathrm{iT}}_{11},$ $T_{20},$ and $T_{22}$ are calculated for the $p{d}^3\mathrm{H}{\pi }^{+}$ reaction in a $p\overrightarrow{p}d{\pi }^{+}\hspace{0.5em}$ model at energies near threshold. The results are compared with experimental data for the reactions $\overrightarrow{p}{d}^3\mathrm{He}{\pi }^0$ and $\overrightarrow{d}{p}^3\mathrm{He}{\pi }^0.$ Good agreement of these predictions with the data for the proton analyzing powers is obtained, and for most of the other observables satisfactory agreement is found. Effects of various assumptions in the model are investigated and discussed.

An intrinsic-state formalism for the interacting boson model IBM-4 is presented. A basis of deformed bosons is introduced which allows the construction of a general trial wave function that has Wigner’s spin-isospin SU(4) symmetry as a particular limit. Intrinsic-state calculations are compared with exact ones, showing good agreement.

Measurements of elastic and inelastic scattering cross sections have been performed for 2.5 and 4.1 MeV neutrons incident on ${}^{155,156,157,158,160}\mathrm{Gd}.$ Angular distributions have been measured at both energies for the $0^{+},$ $2^{+},$ and $4^{+}$ members of the ground-state (gs) band of the even-even isotopes and for the ${3/2}^{-},$ ${5/2}^{-},$ and ${7/2}^{-}$ levels of the gs band of the even-odd isotopes. Angular distributions for inelastic scattering from the ${9/2}^{-}$ level of the gs band of ${}^{155}\mathrm{Gd}$ and ${}^{157}\mathrm{Gd}$ have also been measured at 4.1 MeV. These results together with previously measured s- and p-wave strength functions, potential scattering radii, and elemental total cross sections have been combined in an analysis based on coupled-channel semimicroscopic optical model potential (OMP) and statistical model calculations. The deformed OMP, an extension of our earlier work [E. Bauge, J.P. Delaroche, and M. Girod, Phys. Rev. C 48, 1118 (1998)], is built using a complex density-dependent effective interaction and deformed matter densities deduced from unconstrained, axially symmetric Hartree-Fock-Bogoliubov (HFB) calculations based on the Gogny force. The HFB calculations which describe quite nicely a wealth of results from electron scattering and Coulomb excitations measurements, lead to semimicroscopic OMP predictions in good agreement with the neutron scattering and reaction measurements. A phenomenological OMP analysis is also performed to compare the global properties of both potentials.

The similarity between ${}^6\mathrm{He}{+}^4\mathrm{He}$ and ${}^6\mathrm{Li}{+}^4\mathrm{He}$ elastic scattering data suggests that a previously performed coupled-discretized-continuum channels (CDCC) analysis of ${}^6\mathrm{Li}{+}^4\mathrm{He}$ might be applicable to recently published data for the elastic scattering of ${}^6\mathrm{He}$ from ${}^4\mathrm{He}$ at the three c.m. energies of 11.6, 15.9, and 60.4 MeV. A two-body cluster $\alpha +2n$ structure of ${}^6\mathrm{He}$ was assumed and couplings to the first excited state of ${}^6\mathrm{He}$ at the excitation energy of 1.8 MeV as well as to the states in the continuum were taken into account by means of the CDCC method. The calculations based on the previously performed CDCC analysis of polarized ${}^6\mathrm{Li}{+}^4\mathrm{He}$ scattering at a c.m. energy of 11.1 MeV provide a satisfactory description of the angular distributions of elastically scattered ${}^6\mathrm{He}$ even at backward angles. This result suggests that the large angle scattering has a much smaller two-neutron transfer component than is commonly believed to be present.

Detailed measurements of the elastic scattering of ${}^{16}\mathrm{O}$ ions from ${}^{12}\mathrm{C}$ have been carried out at seven energies from 62 to 124 MeV, at center-of-mass angles from about $10°$ to about $145°.$ A coherent optical model analysis of these data has been performed using both the Woods-Saxon and the folding-model potentials. The extracted results are consistent with analyses of data at higher energies for this and similar light heavy-ion systems. Some model-independent spline forms for the real potentials were also investigated.

An isotopic spin dependent lattice-gas model is employed to investigate several characteristics of nuclear fragmentation observed in intermediate energy heavy ion collisions. In addition to the isotopic spin dependent nearest neighbor interaction the Coulomb interaction between protons, expected to be important for heavy systems, is also taken into account. The model is used to calculate a number of fragmentation observables with special emphasis on the dependence of particle emission on the isospin content of the disassembling system.

We have studied fragmentation processes of ${}^{208}\mathrm{Pb}$ projectiles at 1.0 and 158 GeV/nucleon and of ${}^{197}\mathrm{Au}$ projectiles at 10.6 GeV/nucleon in collisions with targets ranging from ${\mathrm{CH}}_2$ to Pb. This is the first time projectile fragmentation has been investigated in such a large projectile energy range with the same experimental technique and with high statistical significance. For our experiments we used stacks of thin CR-39 and BP-1 nuclear track detectors. This experimental method allows measurement of the trajectories and charges of all particles with charge numbers $Z>~6$ or $Z>~7$ depending on the detection threshold. Yield spectra for the fragment charge Z and the charge sum of the detected fragments show significant target and energy dependences, which originate from different excitation energy spectra of the projectile residues in collision with light target nuclei, especially for the hydrogen target, and additionally from contributions by electromagnetic dissociation in collisions with heavy target nuclei at high beam energies. The characteristics of the breakup of the prefragment in a multifragmentation reaction were investigated based on charge correlations. No significant target dependence was observed for the different energies. This shows that the memory in the special entrance channel of the reaction is lost before the excited prefragment breaks up into smaller particles.

Tagged linearly polarized photons have been used at the Mainz Microtron (MAMI) for simultaneous measurements of the $p(\overrightarrow{\gamma },p){\pi }^0$ and $p(\overrightarrow{\gamma },{\pi }^{+})n$ reaction channels to study the $\gamma \overrightarrow{N}\Delta \mathrm{}\left(1232\right)\mathrm{}$ transition. The energy dependence of the magnetic dipole $M_{1+}^{3/2}$ and electric quadrupole $E_{1+}^{3/2}$ amplitudes have been extracted from these data in the photon energy range from $270$ to 420 MeV. The $E2/M1\mathrm{}$ ratio for the $\gamma \overrightarrow{N}\Delta \mathrm{}\left(1232\right)\mathrm{}$ transition has been determined to be $-(2.5\mathrm{}\pm {0.1}_{\mathrm{stat}}\pm {0.2}_{\mathrm{sys}})\%$ at the resonance position $({\delta }_{33}=90\mathrm{}°).\mathrm{}$

An experiment has been performed to search for superdeformed (SD) states in ${}^{149,150}\mathrm{Dy}.$ While no evidence for discrete superdeformed states has been observed, a superdeformed ridge with a separation of $\Delta E_{\gamma }=52\mathrm{}$ keV with a total intensity of $1.8\pm 0.5\%$ that of ${}^{150}\mathrm{Dy}$ has been observed. An upper limit of 0.8% (0.9%), of the intensity of ${}^{150}\mathrm{Dy}$ ${(}^{149}\mathrm{Dy}),$ is placed for observation of the most intense discrete line states. The relative weakness in the SD population is suggested to be due to a rapid decrease in the depth of the superdeformed minimum, as one moves away from doubly magic ${}^{152}\mathrm{Dy}.$