The response of light drip line nuclei to spin-isospin dependent fields is investigated, using the self-consistent Hartree-Fock plus the random-phase approximation with Skyrme interactions. Including simultaneously both the isoscalar and isovector spin correlation, the random-phase-approximation response function is estimated in the coordinate space so as to take properly into account the continuum effect. The spin-orbit splitting, which plays an essential role in the spin-dependent response functions, is examined as a function of the mass number when we approach the drip line nuclei. It is found that the calculated $M1\mathrm{}$ peaks in ${}_6^8{\mathrm{C}}_2$ and ${}_2^8{\mathrm{He}}_6$ are much lower in energy than those expected from our knowledge of the $\beta$-stable nucleus ${}_6^{12}{\mathrm{C}}_6.$

The positions and widths of nuclear resonance states of the nuclei ${}^8\mathrm{Be},$ ${}^5\mathrm{He},$ and ${}^5\mathrm{Li}$ have been calculated in the microscopic cluster model using a real square integrable basis. The imposition of Gamow or scattering asymptotic boundary conditions onto the wave function is avoided. The approach is based on the notion of the continuum level density. This density is smoothed by the Strutinsky averaging procedure and it is calculated by making use of the eigenvalues of the full and the free Hamiltonian matrices. The continuum level density is connected to the S matrix and has a Breit-Wigner peak around the resonance energy. This approach is compared with the complex scaling method and with the exact calculation of the scattering phase shift.

Liquid-gas phase transition of finite nucleus is studied by means of microscopic reaction theory antisymmetrized molecular dynamics with momentum fluctuations. By calculating the time development of hot system in a potential well, thermodynamic variables, such as temperature and pressure and their relationship to the excitation energy of the system, are obtained. We see clearly the existence of three regions in calculated caloric curve, namely, liquid-dominant, plateau, and gas regions. The transition from liquid-dominant phase to gas phase begins with the cracking of hot liquid nucleus and disintegration into fragments. The property of plateau region strongly depends on the pressure of the system. The gas phase is well reproduced by van der Waals’ equation.

The elastic scattering of ${}^{16}\mathrm{O}{+}^{16}\mathrm{O}\mathrm{}$ has been measured at nine energies between $E_{\mathrm{lab}}=75\mathrm{}$ and 124 MeV. The data cover up to $100°$ in the c.m. and can be described in terms of phenomenological and folding model potentials which reproduce the main features observed. In agreement with studies at higher energies in this and similar systems, refractive effects are present in the angular distributions at all energies. In particular, the passage of Airy minima through $90°$ at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=40,$ 47.5, and 62 MeV explains the deep minima observed in the excitation function. The real part of the optical potential is found to vary very little with energy over the studied interval, but the imaginary part shows a rapid change in its shape at incident energy about 90 MeV. Nonetheless, the energy dependence of the volume integral of the real and imaginary parts is in agreement with dispersion relation predictions.

Inclusive light charged-particle emission spectra and cross sections from neutron bombardment of silicon were measured at $30°,$ $60°,$ $90°,$ and $135°$ over the neutron energy range from threshold to approximately 60 MeV. Source neutrons, continuous in energy, were provided by the spallation neutron source of the Los Alamos Weapons Neutron Research facility. Comparisons of our alpha-particle data with Hauser-Feshbach calculations, which include multistage emission processes and preequilibrium particle emission, indicate that the majority of alpha particles result from compound nuclear reactions. For proton and deuteron emission, direct and preequilibrium processes contribute significantly to the emission cross section. These data provide rigorous tests for the calculations while helping to guide the selection of input parameters such as nuclear level densities. The effects of assuming partial or complete isospin conservation are shown to be important for these reactions.

We present a G-matrix calculation of the effective nucleon-nucleon (NN) interaction for the distorted wave impulse approximation prediction of the cross section and polarization observables in ${(p,p}^{\prime })$ reactions. This interaction is based on a one-boson-exchange model of the free NN force that reproduces NN observables well. The G matrix includes the effects of Pauli blocking, nuclear binding, and strong relativistic mean-field potentials. To assess the quality of this interaction, we compare to 200-MeV measurements of the cross section and analyzing power for natural-parity inelastic transitions in ${}^{16}\mathrm{O},$ ${}^{28}\mathrm{Si},$ and ${}^{40}\mathrm{Ca}$ that span a variety of spins and nuclear densities, as well as to the interaction developed by Furnstahl and Wallace within a relativistic framework.

A study of the $\gamma$-ray decay of low-lying excited states in fragments produced in the spontaneous fission of ${}^{252}\mathrm{Cf}$ has revealed a significant correlation between the angles of emission of the $2_1^{+}\to 0_1^{+}$ transitions of complementary fragment pairs. Calculations of the amount of dealignment that is needed to reproduce the measured $a_2$ values, and a comparison with the results of previous fragment-$\gamma$ angular distribution measurements, suggests that at scission there may be significant population of $m\ne 0$ substates associated with the projection of the fragment spin vector on the fission axis. Fragments from the spontaneous fission of ${}^{248}\mathrm{Cm}$ emit $2_1^{+}\to 0_1^{+}\hspace{0.5em}\gamma$ rays that show markedly reduced interfragment correlations, suggesting that either a larger role is played by the relative angular momentum of the fragments, or that the dealignment introduced by the neutron emission and statistical $\gamma$ decay to the $2_1^{+}$ state is larger in ${}^{248}\mathrm{Cm}$ than ${}^{252}\mathrm{Cf}$ fission.

In order to test the statistical model’s ability to predict the behavior of relatively light mass systems $\left(A\approx 67\right)$ with large angular momenta, two matched heavy ion nuclear reactions were used to $\mathrm{produce}{\hspace{0.5em}}^{67}{\mathrm{Ga}}^{*}$ composite nuclei at an excitation energy of 127 MeV. Light charged particles (protons, deuterons, tritons, and $\alpha$ particles) were used as probes to characterize the composite systems and track the deexcitation processes. From these measurements, energy spectra, cross sections, angular distributions, anisotropy ratios, and particle multiplicities were deduced. Measuring many degrees of freedom provides a stringent test for the statistical models. What is found is that models which did well in predicting the behavior of heavy composite systems $\left(A\approx 150\right),$ are unable to simultaneously reproduce energy spectra, angular distributions, and particle multiplicities for the lighter systems $\left(A\approx 67\right),$ where angular momentum plays a dominant role. This implies that more rigorous models and/or additional physics are needed to understand the behavior of the hot, high-spin nuclear matter in this mass region.

We present measurements from Brookhaven AGS Experiment 864 of neutron invariant multiplicity in $11.5A$ GeV/c $\mathrm{Au}+\mathrm{Pb}$ collisions. The measurements span a rapidity range from center of mass to beam rapidity ${(y}_{\mathrm{beam}}=3.2)$ and are presented as a function of event centrality. The results are compared with E864 measurements of proton invariant multiplicity and an average $n/p$ ratio at hadronic freeze-out of $1.19\pm .08$ is determined for the rapidity range $y=1.6\mathrm{}$ to $y=\mathrm{2.4.}\mathrm{}$ We discuss briefly the implications of this ratio within a simple equilibrium model of the collision system.

The Schwinger-Dyson formalism is used to check the consistency of instanton model solutions for the quark propagator with recent models of confining gluon propagators. We find that the models are not consistent. A major discrepancy is the absence of a vector condensate in the instanton model that is present in the solutions with nonperturbative confining gluons.

The cross section for $n\overrightarrow{p}d\gamma$ is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The $E1\mathrm{}$ amplitude is computed up to ${\mathrm{N}}^3\mathrm{LO}$ and depends only upon nucleon-nucleon phase shift data. In contrast, the $M1\mathrm{}$ contribution is computed up to next-to-leading order, and the four-nucleon-one-magnetic-photon counterterm that enters is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to $E\sim 1\mathrm{MeV}$ is estimated to be $\lesssim 4\%.$

Strength functions for the isoscalar giant monopole and quadrupole resonances in ${}^{154}\mathrm{Sm}$ have been measured with inelastic scattering of 240 MeV α particles at small angles. The $E0\mathrm{}$ strength distribution containing ${(104\mathrm{}}_{-20}^{+15\mathrm{}})\%$ of the energy-weighted sum rule (EWSR) is consistent with two peaks at $E_x=12.1\mathrm{}\pm 0.4\mathrm{MeV}$ and $15.5\pm 0.3\mathrm{MeV}$ containing $(36\mathrm{}\pm 10)\%$ and $(68\mathrm{}\pm 9)\%$ of the EWSR and the $E2\mathrm{}$ strength distribution containing ${(103\mathrm{}}_{-20}^{+18\mathrm{}})\%$ of the EWSR is consistent with three peaks at $E_x=11.3\mathrm{}\pm 0.2\mathrm{MeV},$ $14.5\pm 0.5\mathrm{MeV},$ and $17.5\pm 0.5\mathrm{MeV}$ containing $(44\mathrm{}\pm 7)\%,$ $(44\mathrm{}\pm 8)\%,$ and $(15\mathrm{}\pm 8)\%,$ respectively, of the EWSR.

A general expression is discussed for pion probability distributions coming from relativistic heavy ion collisions. The general expression contains as limits (1) the disoriented chiral condensate (DCC), (2) the negative binomial distribution and Pearson type-III distribution, (3) a binomial or Gaussian result, and (4) a Poisson distribution. This general expression approximates other distributions such as a signal-to-noise laser distribution. Similarities and differences of the DCC distribution with these other distributions are studied. A connection with the theory of disordered systems will be discussed which includes spin glasses, randomly broken objects, and random and chaotic maps.

We investigate the degree to which the concept of superscaling, initially developed within the framework of the relativistic Fermi gas model, applies to inclusive electron scattering from nuclei. We find that data obtained from the low-energy loss side of the quasielastic peak exhibit the superscaling property; i.e., the scaling functions $f\left({\psi }^{\prime }\right)$ are not only independent of momentum transfer (the usual type of scaling: scaling of the first kind), but coincide for $A>~4$ when plotted versus a dimensionless scaling variable ${\psi }^{\prime }$ (scaling of the second kind). We use this behavior to study the as yet poorly understood properties of the inclusive response at large electron energy loss.

The medium spin, near yrast states of the $\mathrm{fpg}$ shell nuclei ${}^{58}\mathrm{Ni},$ ${}^{61}\mathrm{Cu},$ and ${}^{61}\mathrm{Zn}$ have been studied following the fusion evaporation of a ${}^{24}\mathrm{Mg}$ beam and a ${}^{40}\mathrm{Ca}$ target. Discrete transitions were unambiguously identified using the AYEBALL gamma-ray array in conjunction with the Argonne fragment mass analyzer and a split anode ionization chamber. The decay schemes of ${}_{28}^{58}\mathrm{Ni},$ ${}_{29}^{61}\mathrm{Cu},$ and ${}_{30}^{61}\mathrm{Zn}$ have been extended with the results of gamma-gamma coincidences and directional correlation from oriented state measurements used to determine the level excitation energies, spins, and parities of a number of near yrast states. The decay schemes deduced are compared with previous work and interpreted in terms of shell model calculations, with a restricted basis of the $f_{5/2},$ $p_{3/2},$ $p_{1/2}$ orbitals outside a ${}_{28}^{56}\mathrm{Ni}$ core, and either the $g_{9/2}$ orbital with a closed core, or $f_{7/2}$ excitations from the core.

Quite a few superdeformed bands in the mass regions of 150 as well as 190, having different trends in the dynamic moments of inertia with increasing angular momentum, are studied in a simple version of the particle-rotor model. Transition energies, dynamic, and kinematic moments of inertia have been calculated. A reasonably good agreement with the experimental data justifies the application of this version of the model in the new regime of nuclear structure. Electromagnetic moments calculated within the same model also agree with the experimental results. The role of high-$j$ intruder orbitals in the structure of the superdeformed bands in both the regions has been reinvestigated.

The isovector $M1\mathrm{}$ transitions between low-lying $T=1\mathrm{}$ and $T=0\mathrm{}$ states in odd-odd $N=Z$ nuclei are analyzed. Simple analytical expressions for $M1\mathrm{}$ transition strengths are derived within a single-$j$-shell approximation for both the $j=l+1/2\mathrm{}$ and $j=l-1/2$ cases. The large $B\left(M1\mathrm{}\right)\mathrm{}$ values for the $j=l+1/2\mathrm{}$ case are attributed to quasideuteron configurations. The $B\left(M1\mathrm{}\right)\mathrm{}$ values for the $j=l-1/2$ case are found to be small due to partial cancellation of spin and orbital parts of the $M1\mathrm{}$ matrix element.

A semiclassical distorted wave (SCDW) model with realistic single particle wave functions in a finite range single particle potential is presented for multistep direct processes in nucleon inelastic scattering and charge exchange reactions to the continuum, making use of the Wigner transform of a one-body density matrix. The higher momentum components of target nucleons are properly taken into account in comparison with the previous SCDW model with a local density Fermi gas model. The new SCDW model still gives a simple closed-form expression for the cross section with no free adjustable parameter which allows a simple intuitive interpretation, just as in the previous SCDW model. This model is applied to the analyses of multistep direct processes of ${}^{90}\mathrm{Zr}{(p,p}^{\prime }x)$ reactions at incident energies of 80 and 160 MeV. The calculated double differential cross sections including up to three-step processes are compared with experimental data. The calculated cross sections at backward angles are larger than those given by the previous calculations, and the agreement with experimental data is much improved. Discussions on the mechanism of this improvement are given in terms of the momentum distribution of target nucleons.

The properties of the remnant resulting from the emission of prompt particles in the interaction of $1A\mathrm{GeV}\mathrm{}{}^{197}\mathrm{A}\mathrm{u}+\mathrm{C}$ interactions have been compared with intranuclear cascade and Boltzmann-Uehling-Uhlenback transport calculations. The number of first-stage particles and the energy spectra of first-stage protons are also compared. Both models can fit the general but not the detailed features of the data.