The SO(8) fermion pair model in its original version is unable to describe rigid axial rotation. Using the Hartree-Bogolyubov intrinsic state within an exact Schwinger realization of SO(8) we show that this can be remedied by introducing a cubic quadrupole interaction. Prolate and oblate minima are found and the degeneracy of the γ band with the ground-state band is removed. The new interaction can be understood from a renormalization of the quadrupole operator. An analogy with the liquid drop model, where the quadrupole moment is expanded in the shape coordinates ${\alpha }_{\mu }$, shows that the higher-order correction is of order 1/Ω.

Nuclear structure effects are shown to play a significant role in determining the pion asymmetries expected for the excitation of isospin mixed states. As an example, the ${\pi }^{+}$/${\pi }^{\mathrm{-}}$ ratio for excitation of the giant dipole resonance region in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is calculated. It is shown that, at the peak of the angular distribution (${\theta }_{\mathrm{lab}=30\mathrm{}}$°), no significant deviation from unity is expected for the pion ratio if the isospin mixing is at the level of 5%.

The low-lying spectrum of the neutron-rich doubly-odd nucleus ${}_{}{}^{40}{}_{}{}^{}\mathrm{Cl}$ is studied with a shell-model space consisting of all configurations of neutron and proton 0$d_{3/2}$ and 0$f_{7/2}$ orbitals, a space which emphasizes the effects of multiparticle-multihole excitations. The effective interaction among the valence particles was obtained from a systematic fit to the low-lying spectra of nuclei within the model space. The model predictions are compared with other shell-model calculations which emphasize spaces characterized by many orbits but only 0ħω configurations, as well as with the limited available experimental data.

We give some applications of the optical theorem (and its extensions) to charge exchange reactions of pions between isobaric analog states of nuclear targets, based on isospin invariance. We then derive an inequality, valid in the strong absorption limit, to give a bound on reaction channels which may be contributing to the isotensor optical potential, at pion energies near the 3,3 resonance. We further show that coupling to pion absorption on T=1 pairs may provide a major component of this potential.

We compute the effects of nuclear binding in the Drell-Yan process pA→${\mu }^{+}$${\mu }^{\mathrm{-}}$+X using a relativistic nuclear model. Comparisons are made for A=He, Fe, and Au.

Charge exchange reactions at intermediate energies represent an important tool to investigate spin-isospin excitations of the nucleon as well as in nuclei. We report on a calculation of the tensor polarization response of the reaction d→+p→(2p)+Δ°, studied with a tensor polarized deuteron beam. The model considers simple π and ρ exchange including minimal short-range correlations by eliminating the δ function in the spin-spin part. We compare our results to first preliminary polarization data as well as to differential cross sections of reactions such as p+p→${\Delta }^{++}$+n with unpolarized protons.

New Nilsson (κ,μ) parameter sets for the proton N=4, 5, and 6 harmonic oscillator shells are deduced for the A≊120–140 mass region by fitting a potential-energy-surface calculation, using the Nilsson-Strutinsky method, to 28 experimental bandhead energies. The results from both the standard and the fitted Nilsson (κ,μ) parameter sets are compared with experimental bandhead energies. The fitted (κ,μ) parameter sets achieve a significant improvement in the bandhead energies over this region. In addition, calculated single-particle levels using both the Woods-Saxon and the Nilsson potentials are compared.

The components of the three-body model of the deuteron wave function corresponding to the configuration in which the two nucleons interact while the pion acts as spectator are calculated. These components represent the probability to find a real pion inside the deuteron and comprise approximately 0.25% of the total deuteron wave function. The components are parametrized in terms of simple functions, thus facilitating their use in physical applications like the electromagnetic production of pions in the deuteron. This probability must be added to the probability in which a nucleon is the spectator and the second nucleon interacts with the pion. That probability is known to be 0.21% in our model; therefore the total probability to find a real pion inside the deuteron is 0.46%.

Using a coherent state phase space representation the distribution function corresponding to many-particle harmonic oscillator wave functions is obtained in explicit analytic form. A density matrix expansion is performed and found to produce good approximations to the exact results.

The neutron decay of the giant multipole resonance region from 9 to 15 MeV of excitation energy in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ has been studied. Neutron branching ratios for the decay to the ground state or to the low-lying excited states of ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ were measured as a function of the excitation energy of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ and compared to Hauser-Feshbach calculations. While the neutron branching ratios from the isoscalar quadrupole resonance are reproduced by the calculations, the ratios from excitation energies above 12.5 MeV show a large excess with respect to the statistical predictions.

A multidetector setup with large solid angle coverage has been used to measure the particle and fragment emission associated with the production of intermediate mass fragments in reactions of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ on ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Ag}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ at bombarding energies $30 \mathrm{MeV}\le \frac{E}{A}\le 84 \mathrm{MeV}$. It is found that the cross sections, the element distributions, and the multiplicites of intermediate mass fragments are strongly correlated with the excitation energy $E_x$ deposited in the composite system and that multifragment emission sets in at $E_x\cong 300$ MeV.

We observed the 19 keV neutron decay from the 3.388-MeV state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ by measuring ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$-neutron coincidences in colinear geometry at several angles. The ratio of this yield to the yield of particle-stable ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ nuclei is a measure of the excitation energy of ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ fragments produced in the reaction. The extreme kinematic focusing of the 19-keV decay enabled us to obtain the dependence of this ratio on fragment kinetic energy. For ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ nuclei emitted with kinetic energies $\frac{E}{A}\lesssim 15$ MeV the ratio is surprisingly constant; for ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ nuclei of higher kinetic energy it decreases monotonically.

The eikonal model has been formulated in terms of the participant and spectator probabilities. It has been used to relate the number of collisions, the numbers of participants from both the projectile and the target, and the energy in the zero-degree detector. It is found by comparison with the recent data that the transverse energy or the charged-particle multiplicity is directly proportional to the total number of participant nucleons rather than to the number of collisions.

Incorporating final-state correlation effects, we have reinvestigated the ${\gamma }^1\mathrm{H}\to K^{+}\Lambda$ elementary process. Our model not only resolves the persisting trouble of the small $\mathrm{KN}\Lambda$ coupling constant, but also yields agreement with cross-section data at higher energies. Using our amplitudes, we calculate angular distributions for the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(\gamma , K^{+}){}_{\Lambda }{}^{16}{}_{}{}^{}\mathrm{N}$. While the forward cross section increases with increasing energy, the total cross section is almost constant from $E_{\gamma }=1.2\mathrm{}$ through 2 GeV, suggesting that rather low photon energies hold promise for exploration of hypernuclear excitations.

The $0^{+}$(p→,p→’${)0\mathrm{}}^{\mathrm{-}}$ reaction has been used as an example to elucidate the importance of the energy dependence of the nucleon-nucleon (NN) interaction on nucleon-nucleus (NA) spin observables. Because of its simplicity the $0^{+}$→$0^{\mathrm{-}}$ transition is specially suited for the study of energy-dependent corrections. For this transition inclusion of corrections induced by energy dependence results in large modifications in the behavior of certain spin observables. Thus we conclude for the $0^{+}$→$0^{\mathrm{-}}$ transition that calculations neglecting energy-dependent corrections are not only inconsistent but can lead to qualitatively incorrect conclusions. We argue that corrections arising from the energy dependence studied will be small for stretched states. Finally, we propose a simple procedure that will allow one to study the importance of corrections arising from the energy dependence of a proposed NN interaction in a systematic way.

The method discussed here is related to the extension of the Vlasov approach to study isovector collective modes. We analyze dipole, quadrupole, and octupole resonances in ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. Full quantum random phase approximation results are well reproduced. A collision term is added through a relaxation time approach. It is shown that the widths of the giant resonances are dominated by an interplay between Landau damping and collision damping. A quite fair agreement with recent quadrupole data is found. Some temperature in the reference state is introduced, in order to study the behavior of collective motions built on excited states. We get a moderate increase of the widths and a clear quenching of the strengths. A shift of the resonance energy is also observed, actually very sensitive to the residual interaction used.

Mass number, atomic number, energy, and angular distributions have been measured for the projectile-like fragments from the damped reaction ${}_{}{}^{238}{}_{}{}^{}$U${+}^{48}$Ca at $E_{\mathrm{lab}=425\mathrm{}}$ MeV. Correlations in the measured two-dimensional probability distribution P(A,Z) are discussed along with the general dissipative features of the damped reaction mechanism. The first and second moments of the observed atomic and mass number distributions are compared with those of other asymmetric reaction systems. Although the ${}_{}{}^{238}{}_{}{}^{}$U${+}^{48}$Ca system is highly asymmetric, its potential energy surface in the vicinity of the injection point has a nearly zero gradient resulting in a negligible drift in the proton number. The proton drifts observed in reactions of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ with five different projectiles vary systematically with the potential gradient. The mass and charge data are compared with quantitative predictions by a dynamical reaction model based on nucleon exchange. The theoretical model gives a reasonable account of the mass and charge distributions for the ${}_{}{}^{238}{}_{}{}^{}$U${+}^{48}$Ca reaction but fails systematically to predict experimental drifts when the driving forces are large.

Particle-particle correlations (p-p and α-α) vs relative momentum ($P_{\mathrm{rel}}$) are reported (${\theta }_{\mathrm{lab}\mathrm{\approxeq }19.5}$°) for the reaction 140 MeV ${}_{}{}^{16}{}_{}{}^{}$O${+}^{27}$Al. A plot of the Galilean invariant cross section indicates that evaporative emission dominates the gross proton production even at this forward angle. The observed anticorrelation between two protons for small values of $P_{\mathrm{rel}}$ is analyzed to give an evaporation lifetime in the range of 1–5×${10}^{\mathrm{-}21}$ s. The α-α correlation is completely different; it seems to arise from preformed ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$.

The single-closed-shell nucleus ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$ was studied using the ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$${(}^{18}$O,4n) reaction. High-spin deformed states in ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$ were observed up to the (${22}^{+}$) state, and the backbending phenomenon was found. Constancy in the moment of inertia for the high-spin states was observed. The calculation based on the spin-projection Hartree-Bogoliubov model reproduces well the experimental data. The backbending phenomenon in ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$ is explained as due to the band crossing between the intruder g band and the intruder aligned (ν$h_{11/2}$${)}^2$ band.