The ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\overrightarrow{\mathrm{d}},\gamma ){}_{}{}^4{}_{}{}^{}\mathrm{He}$ reaction observables resulting from $M1\mathrm{}$, $E1\mathrm{}$, $M2\mathrm{}$ and $E2\mathrm{}$ transitions are studied quantitatively. The calculations are in agreement with recent data for the reaction vector ($A_y$) and tensor ($A_{\mathrm{yy}}$) analyzing powers at 5 MeV center of mass energy and also with the best available theoretical predictions for the ${}_{}{}^4{}_{}{}^{}\mathrm{He}D$ state wave function.

It is shown that the two-rotor model, like the interacting boson model, predicts an appreciable magnetic octupole strength for the $J^{\pi }=3^{+}$ member of the collective $K^{\pi }=1^{+}$ band, which was predicted and found experimentally to be mainly excited by the orbital component of the magnetic dipole operator. The importance of the present prediction for a complete understanding of the nature of this magnetic mode is emphasized.

We study the consequence of having different values for the delta isobar Landau-Migdal parameters, $g_{\mathrm{N}{\mathit{\Delta }}^{\mathcal{’}}}$ and $g_{\Delta \Delta }^{\mathcal{’}}$, from that of the nucleon parameter $g_{\mathrm{NN}{}^{\mathcal{’}}}$ on the high momentum properties of the spin-isospin responses and the pion condensation threshold of nuclei. Recent data on the spin responses prefer larger values for g’s. The facts that the pion condensate is not realized in nuclei and that the precritical phenomena are not observed by a significant amount provide the lower bound for $g_{\mathrm{N}{\mathit{\Delta }}^{\mathcal{’}}}$. We discuss also the sensitivities of the response functions on the choice of various quantities such as the effective mass and the coupling form factors.

An investigation of the ${\beta }^{\mathrm{-}}$ decay of 0.59 s ${}_{}{}^{145}{}_{}{}^{}\mathrm{Cs}$ into levels of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Ba}$ was undertaken to search for evidence of intrinsic reflection asymmetry in light rare-earth nuclei. $E_{\gamma }$, $I_{\gamma }$, γ-γ coincidence, angular correlation coefficients, and internal conversion coefficients were measured. The level scheme for ${}_{}{}^{145}{}_{}{}^{}\mathrm{Ba}$ up to 1.3 MeV has been constructed. The proposed spin and parity assignments are based upon the measured transition multipolarities and the γ?(hyγ angular correlation coefficients. The levels at 112, 175, 277, and 416 keV may be members of a decoupled K${=1/2\mathrm{}}^{\mathrm{-}}$ band with a decoupling parameter of -2 and a rotational parameter of 20 keV. The octupole deformed rotational structure which is observed in the light odd-A actinides is not readily identified in ${}_{}{}^{145}{}_{}{}^{}\mathrm{Ba}$.

The transition probability per unit time of a K shell internal conversion process is calculated in an intense laser field where the interaction energy of electrons with the laser field is comparable to the binding energy of the electrons in the atomic potential. The intense field K shell internal conversion coefficient is deduced and some numerical examples are given.

The ${\beta }^{\mathrm{-}}$ decays of ${}_{}{}^{35}{}_{}{}^{}\mathrm{P}$, ${}_{}{}^{37}{}_{}{}^{}\mathrm{S}$, ${}_{}{}^{38}{}_{}{}^{}\mathrm{S}$, and ${}_{}{}^{38}{}_{}{}^{}\mathrm{Cl}$ were studied both experimentally and via shell-model calculations. The four decaying nuclei were formed by bombardment of 81% enriched ${}_{}{}^{36}{}_{}{}^{}\mathrm{S}$ by triton and deuteron beams. Gamma-ray spectroscopy was carried out with Ge detectors, either bare or surrounded by a Compton suppression NaI(Tl) shield. One new Gamow-Teller decay was observed in ${}_{}{}^{35}{}_{}{}^{}\mathrm{P}$ decay, and one new first-forbidden decay was observed in ${}_{}{}^{38}{}_{}{}^{}\mathrm{S}$ decay. Otherwise γ-ray measurements of $E_{\gamma }$ and $I_{\gamma }$ (and limits on $I_{\gamma }$ for unobserved transitions) were improved significantly over previous results. Shell-model studies were undertaken in order to bring these beta decay results to bear on an understanding of the shell structure in the (sd) to (fp) transition region at A=40. An interaction was constructed in the 1$d_{5/2}$, 1$d_{3/2}$, 2$s_{1/2}$, 1$f_{7/2}$, 1$f_{5/2}$, 1$p_{3/2}$, 1$p_{1/2}$ model space. This interaction started from the Wildenthal ‘‘USD’’ (sd) interaction and the van Hees-Glaudemans (fp) interaction, which were connected by the cross-shell Millener-Kurath interaction. Certain important two-body matrix elements and single-particle energies were adjusted to fit experimental binding energies in A=40, 41, 42. This interaction was then used to calculate level spectra for the daughter nuclei ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$, ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$, ${}_{}{}^{38}{}_{}{}^{}\mathrm{Cl}$, and ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$ as well as Gamow-Teller and unique first-forbidden beta decays leading to these nuclei. The techniques used in these relatively large scale calculations are discussed in detail, as are the results.

The isotope shift and hyperfine structure of the optical Sn I resonance transition 5$p^2$ ${}_{}{}^3{}_{}{}^{}\mathrm{P}_0^{}{}_{}{}^{}$→5p6s ${}_{}{}^3{}_{}{}^{}\mathrm{P}_1^{}{}_{}{}^{}$ at λ=286.3 nm have been studied for 18 Sn nuclei including two isomers. Laser-induced resonance fluorescence from a collimated atomic beam of tin was observed using a tunable continuous wave dye laser with frequency doubler. The electromagnetic nuclear moments and changes of the mean square charge radii of the nuclear charge distributions were determined. The results are discussed with respect to the information they provide on the nuclear structure of the nuclei investigated; they are compared with various theoretical models.

Those two-pion-exchange three-nucleon forces which arise from nuclear processes that involve only pions and nucleons are calculated. Among the processes which contribute are pion seagulls (e.g., nucleon-antinucleon pair terms) and overlapping, retarded pion exchanges. The resulting potential is shown to be a (v/c${)}^2$ relativistic correction, and satisfies nontrivial constraints from special relativity. The relativistic ambiguities found before in treatments of relativistic corrections to the one-pion-exchange nuclear charge operator and two-body potential are also present in the three-nucleon potential. The resulting three-nucleon force differs from the original Tucson-Melbourne potential only in the presence of several new nonlocal terms, and in the specification of the choice of ambiguity parameters in the latter potential.

We employ the hybrid soliton model of the nucleon consisting of a topological meson field and deeply bound quarks to investigate the behavior of the quarks in soliton matter as a function of density. To organize the calculation, we place the solitons on a spatial lattice. The model suggests the transition of matter from a color insulator to a color conductor above a critical density of a few times normal nuclear density. There is no latent heat associated with the transition.

The high-spin yrast levels (with $J_{\max {}^{\pi }{=14\mathrm{}}^{+})}$ in the nuclei ${}_{}{}^{68}{}_{}{}^{}$,70,72,74Ge and ${}_{}{}^{70}{}_{}{}^{}$,72,74,76Se are studied in the framework of the variation-after-projection method in conjunction with the Hartree-Fock-Bogoliubov ansatz for the trial wave functions, employing realistic effective interactions. The overall agreement between the experimental and the calculated values for the level energies, static quadrupole moments, as well as the reduced E2 transition probabilities is reasonably good.

We examine the influence of angular momentum on the threshold temperature of a nucleus in a toroidal shape of equilibrium. The presence of high angular momentum lowers the threshold temperature at which the toroidal equilibrium begins to appear.

Under the assumption that the ground state of a many-body system is formed by a condensate of quartets, the structure of these quartets, as well as the equations that describe the excitations of such a system, are obtained. It is shown that such a description can be applied to well deformed nuclei. In particular, it is found that the one- and three-body excitations will have a description that is similar to the one provided by the Nilsson model. Some experimental differences are predicted.

The ${}_{}{}^{106}{}_{}{}^{}$,108,110,112,11 ${}_{}{}^4{}_{}{}^{}$,116Cd(p,t) reactions have been investigated at $E_{\mathrm{p}=26\mathrm{}}$ MeV. Enhancement factors for the ground-state to ground-state transitions have been extracted and compared with predictions for two-nucleon transfer strengths. No evidence for a sizable admixture of the intruder configurations in the ground states is deduced from this experiment.

Elastic scattering of monoenergetic tagged photons from natural barium and cerium targets was measured at 135° for excitations between 4.5 and 9.0 MeV. The data were used to infer the respective total absorption cross sections below neutron emission threshold, and the results are compared with (γ,n) measurements and with the predictions of a quasiparticle-phonon calculation in ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$. The low energy dipole absorption is found to be generally consistent with an extrapolation of the tail of the E1 giant resonance, and to be substantially underestimated by the quasiparticle-phonon theory.

Half-lives have been measured for the neutron-rich nuclei ${}_{}{}^{123}{}_{}{}^{}\mathrm{Ag}$ and ${}_{}{}^{123\mathrm{-}125}{}_{}{}^{}$,127,128Cd at an on-line mass separator. The results are compared with recent model calculations. The data near Z=50 are consistent with the systematic pattern of discrepancies between the theoretical and new empirical values already observed in the rare-earth region and near Z=28. The results imply that additional effects associated with proton shell structure may need to be included in the model.

The optical isotope shift in the 6$s^2$-6s6p (λ=460 nm) atomic resonance transition of ${}_{}{}^{82}{}_{}{}^{}\mathrm{Sr}$ ($t_{1/2}$=24 d) has been measured to be 418(2.5) MHz. The weak atomic beam of ${}_{}{}^{82}{}_{}{}^{}\mathrm{Sr}$ was detected using the photon burst technique. The extracted value for the change in nuclear mean square radius is compared to predictions using the droplet model.

Differential cross sections for the reactions ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(γ,${\pi }^{+}$${)\mathrm{}}^{10}$Be ${}_{\mathrm{}(\mathrm{g}.\mathrm{s}.\mathrm{})\mathrm{}}{}^{}{}_{}{}^{}$ and ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(γ,${\pi }^{+}$${)\mathrm{}}^{10}$Be ${}_{\mathrm{}\left(1\mathrm{s}\mathrm{t}\right)\mathrm{}}{}^{}{}_{}{}^{}$ have been deduced from measured electroproduction yields at $E_{\mathrm{e}=185\mathrm{}}$ MeV and ${\mathrm{theta}}_{\pi }$=30?(de–150°. The experimental results are compared with a calculation made in distorted wave impulse approximation. Substantial discrepancies between the theory and the experiment are observed.

Making use of the underlying shell model picture of the interacting boson model, we derive some relations between the electromagnetic and hadronic density operators.

It is pointed out that the absolute B(M1) strengths for transitions between low lying states of collective nuclei provide a useful constraint on the possible parametrization of Hamiltonians within the framework of the interacting boson approximation. Some specific examples of recent calculations are cited where, despite good agreement with experimental energies and B(E2) values, some inconsistencies arise when the predictions for low lying M1 strengths are compared with the empirical values.

The possible occurrence of abnormal nuclear states associated with neutral pion condensation has been studied in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ within a Jastrow-type variational approach using an effective interaction to simulate Δ mixing into the nucleon states. The role played by short range correlations and Δ excitations in producing ${\pi }^0$ condensation is discussed.