A collective vector-boson model with broken SU(3) symmetry, in which the ground-state band and the lowest γ band belong to the same irreducible representation but are nondegenerate, is applied to several deformed even-even nuclei. The model description of ground and γ bands together with the corresponding $B\left(E2\mathrm{}\right)\mathrm{}$ transition probabilities is investigated within a broad range of SU(3) irreducible representations (λ,μ). The calculations show that the (λ,μ) characteristics of rotational nuclei depend to a great extent on the magnitude of the SU(3) splitting between the ground and γ bands. It is found that for weakly split spectra, the ground-γ band coupling scheme is realized relevantly within narrow regions of “favored” (λ,μ) multiplets, while in the cases of strong splitting a description in which the ground band is situated alone in an irreducible representation is favored. The obtained results are analyzed in terms of the band-mixing interactions. The possibility for a transition between the different collective SU(3) schemes is discussed.

We study the giant quadrupole resonances in the neutron drip line nucleus, ${}_8^{28}{\mathrm{O}}_{20},$ using the self-consistent Hartree-Fock calculation plus the random-phase approximation (RPA) with Skyrme interactions. Including simultaneously both the isoscalar and the isovector correlation, the RPA response function is calculated in the coordinate space so as to take into account properly the continuum effect. Though in neutron drip line nuclei the distribution of the quadrupole strength is much affected by the presence of the low-energy threshold strength, the isoscalar and the isovector correlation structure as well as the transition densities of the isoscalar giant resonance are in good agreement with those given by the collective model. In contrast, the transition density of the isovector giant resonance shows a clear deviation from that of the liquid-drop polarization mode.

We study the first excited state of ${}^4$He in a microscopic ${\{}^3\mathrm{H}{+p,}^3\mathrm{He}+n\}$ cluster model, including ${}^3$H and ${}^3$He distortions. The phenomenological ${}^1{S}_0$ ${}^3\mathrm{H}+p$ scattering phase shift is reasonably well reproduced. We localize a complex pole of the $S$ matrix between the ${}^3\mathrm{H}+p$ and ${}^3\mathrm{He}+n$ thresholds. The corresponding resonance parameters are $E_r=93\mathrm{}$ keV position relative to ${}^3\mathrm{H}+p$, and $\Gamma =390\mathrm{}$ keV width. A pole search is also performed in an extended $R$-matrix method, and a resonance is found with parameters $E_r=114\mathrm{}$ keV and $\Gamma =392\mathrm{}$ keV. The $R$-matrix approach gives several additional poles, some of which may be connected with an enhanced threshold effect.

By using the real-time Green's function method with a pair cutoff approximation up to the second order, the thermodynamical fluctuation effects of meson fields on the Zimanyi-Moszkowski model are investigated. We find that in the fluctuation effects on the effective mass of the nucleon, the pressures are considerable in the low-baryon-density region and/or the high-temperature regions. The results of the Zimanyi-Moszkowski model and the Welecka model beyond the mean-field approximation are compared.

The ${}^{10}$He nucleus, being a “maximal neutron-rich nucleus” in the ratio of neutrons to protons $\mathrm{}(p:n=1:4\mathrm{})\mathrm{}$ among nuclei observed so far, is investigated within the ${}^8\mathrm{He}+n+n$ model. The energy and decay width of the three-body system are solved by applying the complex scaling method to the ${}^8\mathrm{He}+n+n$ Hamiltonian, where the folding-type ${}^8\mathrm{He}-n$ potential is carefully chosen through the analysis of the experimental resonance energy 1.16 MeV of ${}^9$He and in comparison with the ${}^9\mathrm{Li}-n$ folding potential employed successfully in the description of the loosely bound ${}^{11}$Li system. The calculated result ${(E}_r=1.8\mathrm{}$ MeV, $\Gamma =1.4\mathrm{}$ MeV) of the ${}^{10}$He ground state corresponds well to the observed values.

Isoscalar monopole modes in finite nuclei are studied in the framework of relativistic models currently used in ground state calculations. Response functions in the random phase approximation are calculated with nonlinear models for the first time. It is found that some effective Lagrangians having a bulk compression modulus in the range 280–350 MeV can predict correctly breathing mode energies in medium and heavy nuclei. It is pointed out that the parametrization NL1 ${(K}_{\infty }=211\mathrm{}\mathrm{MeV})$ leads to an anomalous behavior of the monopole response.

We carry out a study of the study of the $\mathrm{Q}\mathrm{}\mathrm{\cdot }\mathrm{}\mathrm{Q}$ interaction in a model space which consists of several nucleons in an open shell and all 2ħω excitations. This interaction is $-t({\chi }_0/2)\mathrm{Q}\mathrm{\cdot }\mathrm{Q},$ where for $t=1\mathrm{}$ we get the “accepted strength.” In the $0p$ space, the spectrum would scale with $t.\mathrm{}$ In this space, the $2_1^{+}$ and $2_2^{+}$ states of ${}^{10}\mathrm{Be}$ are degenerate, as are the [330] and [411] sets of ${J=0\mathrm{}}^{+},$ $1^{+},$ and $2^{+}$ triplets. When 2ħω admixtures are included, the degeneracies are removed. For $t>~1.8$ we have new ground state and a new $2_1^{+}$ state. These are states in which two particles are excited from the $0p$ to the $1s-0d$ shell. There is no mixing of these two-particle–two-hole (2p-2h) states with the other states. For these 2p-2h states the occupancy for $0s,$ $0p,$ $1s-0d,$ and $1p-0f$ are 4, 4, 2, and 0 respectively.

The structure of both low-lying and highly excited states and electromagnetic transitions in ${}^{206}\mathrm{Pb}$ and ${}^{205}\mathrm{Tl}$ has been studied within the framework of the shell model. The calculation predicts the occurrence of states in ${}^{206}\mathrm{Pb}$ with a structure homologous to parent states in ${}^{205}\mathrm{Tl},$ a phenomenon experimentally reported in these systems via $(p\to ,\alpha )$ reactions, in analogy with other regions of the mass table. This feature is not restricted to configurations where the two neutron holes are coupled to angular momentum zero, but also applies to higher configurations corresponding to angular momentum recoupling of the two neutron holes. The calculated results, obtained with both a modified surface delta interaction and Kuo-Herling interaction, are in good agreement with the experimental data, further supporting the ability of these interactions to describe nuclear properties in the lead region.

Coulomb energy differences between mirror nuclei with $A<~70$ are calculated within the framework of the nuclear shell model using an effective Coulomb plus isovector and isotensor interaction. Absolute binding energies for proton-rich nuclei are predicted by adding the calculated Coulomb shifts to experimentally measured binding energies for the neutron-rich mirror. The location of the proton drip line is investigated, as well as candidates for the exotic decay mode known as diproton emission. Taking into account the lifetimes of competing decay modes and limits imposed by experimental setups, it is concluded that the best candidates for the observation of correlated diproton emission are${}^{45}\mathrm{Fe},$ ${}^{48}\mathrm{Ni},$ and ${}^{63}\mathrm{Se}.$

The mixed-symmetry collective modes are investigated in Cr-Fe nuclei, by analyzing the realistic shell-model wave functions via the $H^n$-cooling method. It is clarified that the relatively low-lying mixed-symmetry states behave like doorway states. For these nearly spherical nuclei, the lowest mixed-symmetry state is shown to have $J^P{=2\mathrm{}}^{+}.$ An indication of the mixed-symmetry $3^{+}$ state is obtained. The sequence of the mixed-symmetry $2^{+},$ $1^{+},$ and $3^{+}$ levels and its nucleus dependence are discussed. Calculated $M1\mathrm{}$ and $M3\mathrm{}$ transitions in the low-energy region suggest that the mixed-symmetry $1^{+}$ and $3^{+}$ components are detectable. We investigate the $B\left(M1\mathrm{}\right)\mathrm{}$ distribution in a wider energy range, without breaking the isospin quantum number. It is confirmed that the mixed-symmetry $1^{+}$ component is well separated from the peak of the spin excitation. The isospin-raising component has a peak, well separated from the isospin-conserving one. The orbital angular-momentum contributes destructively to the spin excitations.

The empirical data for the charge (proton) density differences and the isotope shifts of the even Ca nuclei are analyzed by means of a simple phenomenological model. The role of short and long range correlations in the description of the data is examined. Certain types of short and long range correlations are accounted for. Short range correlations are approximated through a Jastrow-type correlation function while for long range correlations the fluctuations of the nuclear surface are considered. The analysis shows that the combined effects of these correlations improves the description of the experimental data.

The yrast spectra with $J_{\max }^{\pi }{=10\mathrm{}}^{+},B\left(E2\mathrm{}\right)\mathrm{}$ transition probabilities and $Q_{J^{+}}$ values are calculated for even-even xenon isotopes by carrying out variation-after-projection calculations in conjunction with a Hartree-Fock-Bogoliubov (HFB) ansatz employing a pairing-plus-quadrupole-quadrupole effective interaction operating in a reasonably large valence space outside the ${}^{100}\mathrm{Sn}$ core. Our calculations reveal that the systematics of low-lying yrast states in these isotopes are intricately linked with the manner in which neutrons tend to occupy the various valence orbits. The results on $B\left(E2\mathrm{}\right)\mathrm{}$ transition probabilities predict a dip in the isotopes ${}^{114,116,120,124,128}\mathrm{Xe},$ which might be construed to imply different structures for ${}^{114,116,120,124,128}\mathrm{Xe}$ as compared to their neighbors. Besides this, our results also reveal that both the HFB technique and the quadrupole-quadrupole-plus-pairing model of the two-body interaction are fairly reliable in this mass region.

A complete set ${(iT}_{11}{,T}_{20}{,T}_{21}{,T}_{22})$ of analyzing powers (AP’s) has been obtained for the single nucleon transfer reaction ${}^{12}\mathrm{C}{(}^6\mathrm{Li}{,}^7\mathrm{Li}{)}^{11}$C. In addition, ${\mathrm{iT}}_{11}$ and $T_{21}$ AP data have been obtained for ${}^{12}\mathrm{C}{(}^6\mathrm{Li}{,}^7\mathrm{Be}{)}^{11}$B. A finite range distorted wave Born approximation calculation provides a qualitatively good description of the ground-state transfer data ${\mathrm{iT}}_{11},$ but is out of phase at small angles. It describes the magnitude but not the detail of the rank-2 AP over the measured angular range. A coupled-channels Born approximation (CCBA) analysis describes the elastic, inelastic, and ground-state transfer reaction cross section and AP data well. The excited-state transfer cross section description is also good, but the AP data are less well described. CCBA calculations indicate that coupling to states in ${}^6$Li and ${}^{12}$C is not crucial to the description, but that coupling in the final state between the ground and first excited states of ${}^7$Li or ${}^7$Be is needed to describe the small-angle oscillations in the ground-state transfer ${\mathrm{iT}}_{11}$ data.

Measurements of energy spectra for protons, deuterons, tritons, and α particles in coincidence with heavy evaporation residues were made with a large logarithmic detector array which covered the angular range of 3° to 24°. We performed detailed comparisons with statistical calculations which model the evaporative decay of a compound nucleus formed in the collisions. We found out that it was possible to account for the observed energy spectra of the light particles and their relative yields if one assumes initial evaporation from a highly deformed composite system (dinuclear) which at a later stage in the cascade relaxes into a normal compound nucleus.

Spallation of ${}^{27}\mathrm{Al}$ and ${}^{56}\mathrm{Fe}$ by 800 MeV protons was investigated at the WNR facility of the Los Alamos National Laboratory. Production cross sections for a considerable number of residual nuclei were determined for both targets by use of three different methods. Because of the specific time structure of the WNR beams it was possible to observe both the prompt γ radiation resulting from the final stage of the spallation reaction and the γ radiation due to the decay of short-lived residual nuclei by delayed γ-ray spectroscopy. The activity of long-lived residual nuclei was measured several weeks after the irradiation with a calibrated high-purity Ge γ-ray detector. In the prompt γ-ray spectrum it was possible to observe the transitions from the first excited $2^{+}$ state to the ground state for all even-even nuclei strongly populated in the spallation reactions and, from these data, to deduce the production cross sections of these mostly stable nuclei in addition to the short- and long-lived residual nuclei mentioned before. In this way production cross sections for 36 nuclides from the proton interactions with ${}^{56}\mathrm{Fe}$ and for 12 nuclides in the case of ${}^{27}\mathrm{Al}$ could be measured; in addition, meaningful upper limits were obtained for a number of further nuclides in both cases. The results are in reasonable agreement with previous measurements obtained by different methods; for a number of nuclides, production cross sections were determined for the first time. The present data as well as the results of all previous measurements are compared with the predictions of the semiempirical systematics and with quantum molecular dynamics calculations.

Double charge exchange cross sections have been measured at ${\theta }_L=5\mathrm{}°$ and $T_{\pi }=$ 230, 180, and 140 MeV for targets of ${}^{60,62,64}$Ni. Results are compared with previous data at 292 MeV and with a generalized seniority model.

The electrofission cross section of ${}^{239}\mathrm{Pu}\mathrm{}(e,f)\mathrm{}$ is measured between 7 and 12 MeV. The data are analyzed by means of the virtual photon formalism, assuming that $E1,$ $E2\mathrm{}$ $\mathrm{}(T=0\mathrm{}),$ and $M1\mathrm{}$ transitions are involved. Using known estimates for the $E1\mathrm{}$ and $E2\mathrm{}$ $\mathrm{}(T=0\mathrm{})\mathrm{}$ fission strengths, it is deduced an $M1\mathrm{}$ fission strength of $19\pm 4{\mu }_N^2$ concentrated near the fission barrier (between 5.4 and 5.8 MeV). The levels of the ${}^{239}\mathrm{Pu}$ transition nucleus are theoretically obtained; a bunch of positive-parity levels shows up between 5.5 and 5.9 MeV, which might well be associated with the deduced $M1\mathrm{}$ strength, since the $E2\mathrm{}$ strength is negligible in this energy interval.

Velocity spectra of evaporation residues produced in the ${}^{35}{\mathrm{C}\mathrm{l}+}^{12}\mathrm{C}$ reaction have been measured at bombarding energies of 125, 140, and 154 MeV using time-of-flight techniques. These distributions were used to identify evaporation residues and to separate complete fusion and incomplete fusion components. The results show the presence of small contributions of incomplete fusion components which appear to be due to a cluster transfer reaction mechanism. Angular distributions and total and complete fusion evaporation residue cross sections were extracted at 70, 90, 110, 125, 140, and 154 MeV. The complete fusion cross sections and the deduced critical angular momenta are compared with other experimental data and the predictions of existing models.

A search for narrow, deeply bound pionic atom states via atomic radiative capture of negative pions in a target of ${}^{208}$Pb was carried out for pion kinetic energies of 20 and 25 MeV. Although no clear signature of any such gamma ray emission could be observed in the data, fits of the gamma ray spectra between the energies of 12 and 42 MeV involving a quadratic background together with a pair of peaks $(1s$, $2p)$ whose relative intensity was taken from theory yielded an overall strength for the peaks which are consistent (to a 67% confidence level) with radiative capture whose integrated cross section is 20.0 $\pm$ 10.0 $\mu$b/sr at 90$°$ for 20 MeV incident pions. A lower probability (40% confidence level) result was obtained when the fit was carried out without the peaks included, just the continuum background.

The dependence of the spin polarization on the incident angle of the primary beam has been measured for ${}^{12}$B fragments produced in the fragmentation of an ${}^{18}$O beam on a Nb target at 80 MeV/nucleon. A change in sign of the spin polarization was observed with a change in sign of the incident angle of the projectile. This result is in agreement with the kinematical model presented recently to qualitatively describe the mechanism for the production of spin-polarized fragments following intermediate-energy heavy-ion reactions. The resonance curve for ${}^{12}$B has also been measured using a technique of multiple adiabatic fast passage with continuous implantation. This technique is briefly compared to the single-pass adiabatic fast passage method employed with beam-on/beam-off data acquisition.