Excitation-energy distributions of transition strength to $1^{+}$ states excited via the (p,n) reaction at 134.4 MeV on targets of ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$, ${}_{}{}^{82}{}_{}{}^{}\mathrm{Se}$, ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$, and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ were measured for excitation energies up to 25 MeV. Structures observed in the neutron spectra with forward-peaked (ΔL=0) angular distributions were identified as $1^{+}$ states, except for the isobaric analog transitions. The total $1^{+}$ strength in these reactions was extracted by normalizing the intensity in the $1^{+}$ peaks to the Fermi transition strength observed in the isobaric analog state. The Gamow-Teller strength observed in $1^{+}$ peaks above a fitted polynomial background is typically 55% of the sum rule obtained by assuming that the strength of ${\beta }^{+}$ transitions is negligible. The portion of this strength found at excitation energies less than that of the Gamow-Teller giant resonance varied from 15% for ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$ to 38% for ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$. Experimental results are compared with predictions of a shell model that includes a pairing force and a long-range Gamow-Teller force in both parent and daughter nuclei. A comparison of the strength functions of the tellurium isotopes is made; this comparison is relevant in determining whether double-beta decay without neutrino emission (0ν decay) is observed in these isotopes.

Single-proton $g_{9/2}$ spectroscopic factors have been obtained from the ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$(α,t${)}^{52}$Cr reaction at 81 MeV for states identified by electron scattering as having $8^{\mathrm{-}}$ spins. If we interpret these as the simple ($f_{7/2}^{\mathrm{-}1}$$g_{9/2}$) stretched single-particle states, we find 45% of the expected total T=2 stripping strength to the $g_{9/2}$ shell, with this strength spread thinly throughout the spectrum, but 73% of the expected T=3 strength is concentrated into a single T=3 $8^{\mathrm{-}}$ state. These results are compared to electron scattering data and to the results of a shell-model calculation, as well as to comparable results for ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$. Previous stripping distorted-wave Born approximation results for ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$ were in error, and this is corrected in the present work.

Angular distributions of the ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$(p,n${)}^{54}$Co and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$(n,p${)}^{54}$Mn cross sections have been measured to test the Gamow-Teller sum rule [$S_{\mathrm{-}}$-$S_{+}$=3(N-Z)] in a case where the Gamow-Teller strength is large for both channels. The results for $S_{\mathrm{-}}$ and $S_{+}$ are compared to several models which have moderate success in describing the data. Large scale shell-model and quasiparticle random-phase-approximation calculations correctly predict the distribution of Gamow-Teller strength but overestimate the total strength. A model that approximates the nuclear surface to be a semi-infinite slab describes the cross sections well in the quasielastic scattering region if 2p-2h correlations are included.

We measured differential cross sections and vector analyzing powers for the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$(d,n${)}^{49}$Sc reaction at 79 MeV. An overall energy resolution of about 325 keV was achieved, and data were extracted for states up to 3.4 MeV of excitation. Both distorted-wave Born approximation and Johnson-Soper adiabatic approximation calculations were performed; in general, the Johnson-Soper adiabatic approximation calculations provide a better description of the data, and yield reasonable spectroscopic factors.

Levels of ${}_{}{}^{55}{}_{}{}^{}\mathrm{Co}$ between 7.3 and 8.9 MeV have been studied by resonant proton inelastic scattering and capture on ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ at beam energies from 2.1 to 3.9 MeV. In all, 163 resonances, some of which are doublets, were identified in this region. Spins of 100 of the resonances were found from their capture spectra and from angular distributions of the (p,p’γ) and (p,γ) reactions. On the basis of energy and spin, a number of new proposals are made for the ${}_{}{}^{55}{}_{}{}^{}\mathrm{Co}$ analogs of ${}_{}{}^{55}{}_{}{}^{}\mathrm{Fe}$ states up to 4 MeV.

Neutron elastic and inelastic scattering cross sections have been determined for neutrons incident on ${}_{}{}^{189}{}_{}{}^{}\mathrm{Os}$ at three very low energies. Cross sections for scattering to the ground state and 36.2-keV excited level have been measured for incident energies of 63.5 and 73.3 keV, and also to the 69.6-keV excited level at 97.5-keV incident energy. These measurements are combined with neutron scattering cross sections for ${}_{}{}^{187}{}_{}{}^{}\mathrm{Os}$, neutron capture cross sections, and other low-energy scattering observables to provide a basis for a single, consistent model of all data for both odd-A Os isotopes. The properly interpreted capture rates are important for the Re/Os nucleochronology and for s-process nucleosynthesis rates. The elastic and inelastic scattering cross sections provide a very-low-energy test of statistical model-flux distributions; model accuracy at very low energies is an important issue for reaction rates used in nucleosynthesis estimates.

The observation of different temperatures obtained in heavy-ion reactions by measuring kinetic energy distributions (kinetic temperatures) or abundances of different species (chemical temperatures) is addressed by means of a computer simulation based on the quasiparticle dynamics model. The simulations qualitatively agree with experiment: For both ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ nuclei emitted in intermediate-energy heavy-ion reactions, the chemical temperature is found to be in the 3±1 MeV range, much lower than the kinetic temperature. Further, we do not find a strong variation of the chemical temperatures over the laboratory bombarding energy range of 35A to 100A MeV. The difference in the two temperatures is found to be established after a fairly short time scale roughly corresponding to the breakup time of the reaction region.

High-spin states in ${}_{}{}^{185}{}_{}{}^{}\mathrm{Pt}$ have been studied with the ${}_{}{}^{173}{}_{}{}^{}\mathrm{Yb}$${(}^{16}$O,4n${)}^{185}$Pt reaction at 90 MeV using a multidetector array consisting of five Ge detectors and a multiplicity filter of six NaI counters. Rotational bands built on the Nilsson configurations ${(9/2\mathrm{}}^{+}$[624], ${(7/2\mathrm{}}^{\mathrm{-}}$[503], and ${(1/2\mathrm{}}^{\mathrm{-}}$[521] have been identified and interpreted within the framework of the cranked shell model. Additional band structures built on levels at 3.131 and 3.294 MeV are observed which arise from more complex configurations. Experimental values of B(M1;I→I-1)/B(E2;I→I-2) ratios have been extracted and compared to predictions of the semiclassical Dönau and Frauendorf approach.

Four rotational band sequences have been established in the doubly odd ${}_{}{}^{128}{}_{}{}^{}\mathrm{Cs}$ nucleus via the ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$${(}^{11}$B,3nγ) reaction. One band shows the characteristic features for the π$h_{11/2}$⊗ν$h_{11/2}$ configuration which has systematically been observed in doubly odd nuclei throughout the A∼130 mass region. Triaxial cranked shell-model calculations have been performed to assist in the assignment of quasiparticle configurations to the other bands.

The dissipative excitation functions of the ${}_{}{}^{19}{}_{}{}^{}$F${+}^{63}$Cu reaction have been measured in the energy range $E_{\mathrm{lab}=100\mathrm{}}$ to 108 MeV in 250 keV energy steps at angles ${\theta }_{\mathrm{lab}=10\mathrm{}}$°,20°,30°,40°,50°. The energy-coherence width of the cross section has been determined by means of the spectral-density method. The results concerning the ${}_{}{}^{19}{}_{}{}^{}$F${+}^{63}$Cu and ${}_{}{}^{28}{}_{}{}^{}$Si${+}^{48}$Ti reactions are compared to evidence the angular momentum effects on the cross-section autocorrelation function. The probability distribution of the cross section is considered in discussing the possible selective excitation of intermediate-system doorway states.

We propose a detailed model, combining the concepts from a partition temperature model and wounded nucleon model, to describe high-energy nucleus-nucleus collisions. One partition temperature is associated with collisions at a fixed wounded nucleon number. The (pseudo-) rapidity distributions are calculated and compared with experimental data. Predictions at higher energy are also presented.

$K^{+}$ meson production by 2.1-GeV/nucleon Ne, d, and p projectiles on NaF and Pb targets has been measured. The cross sections depend exponentially upon the kaon energy in the nucleon-nucleon c.m. frame, with an inverse slope $T_0$ larger than the values obtained from comparable proton and ${\pi }^{\mathrm{-}}$ spectra. The angular distribution in this frame is approximately isotropic. The A dependence of the kaon yield has been determined. Data are compared with theoretical predictions.

We examine a variety of methods for determining both the impact parameter and the direction of the impact vector in symmetric nuclear collisions at intermediate energies. Two quantities, the particle multiplicity and the midrapidity charge, retain their dependence on the impact parameter after filtering through the acceptance of a typical 4π detector. By gating on these quantities we can select four ranges of impact parameters. There is some overlap of these ranges. It is noted that this is dependent on the model used to simulate the collisions. The midrapidity charge has the advantage that it integrates over the final fragments and should be less sensitive to how the collision zone disassembles. The angle of the impact vector is well reproduced with the method developed by Danielewicz and Odyniec. The difference between known and determined reaction plane has a half-width at half-maximum of less than 70°. Some comparisons are made to experimental data.

The slopes of the energy spectra of p, d, t, and α particles emitted from ${}_{}{}^{59}{}_{}{}^{}\mathrm{Cu}$ nuclei formed in the reaction of ${}_{}{}^{32}{}_{}{}^{}$S${+}^{27}$Al at a bombarding energy of 150 MeV are described by statistical-model calculations in which the deformation is frozen during the first two steps of the deexcitation chain. The resultant fits to the high-energy portions of the spectra are comparable to those previously obtained by modifying the spin dependence of the level density, suggesting that dynamic effects may be important in evaporation from light nuclei.

The shapes of α-particle spectra from hot, high-spin compound nuclei produced in energetic heavy-ion fusion reactions are analyzed within the framework of a statistical model. Contrary to claims made in the literature, good agreement is obtained between calculated and experimental spectra when the evaporation barrier of each nuclide in the complex cascade is assumed equal to its respective absorption channel barrier. The dependence of the shape of α-particle spectra on nuclear deformation is discussed both in terms of the transmission coefficients and the spin-dependent level density of deformed nuclei. For deformations of the magnitude given by the rotating liquid drop model, α-particle spectra and effective barriers are insensitive to whether deformed or spherical nucleus transmission coefficients are used. It is important, however, to include the deformation dependence in the nuclear level density. Model calculations indicate that the shape of α-particle spectra may be quite insensitive to large deformations.

The excitation functions of the reactions ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$${(}^{16}$O${,}^{20}$Ne${)}^{20}$Ne and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$${(}^{16}$O${,}^{12}$C${)}^{28}$Si were measured at ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}=90\mathrm{}}$° and 70°, respectively, in the energy interval of 25 to 34 MeV in steps of 240 keV. They display strong structures with widths of 1 to 2 MeV and are compared to calculations including the coupling to higher orders between elastic and α-transfer channels, through the dynamic α-transfer polarization potential.

A simple parametrization has been developed for the proton-neutron bremsstrahlung amplitude which reproduces the results of a meson exchange potential model including the convection, magnetization, and the two-body current contributions. Our parametrization maintains the important role of exchange contributions at high photon energies. We apply the model to the description of energetic photon production in heavy ion induced reactions.

Neutron time-of-flight spectra have been measured for emission from products of reactions between ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$ at a bombarding energy of 930 MeV. Neutrons were detected in coincidence with projectilelike fragments from strongly damped reactions using a heavy ion ΔE-E telescope which permitted the total kinetic energy loss to be extracted for each event. The neutron spectra were separated into 25-MeV-wide total kinetic energy loss bins over the total kinetic energy loss range from 0 to 450 MeV. Moving source fits were made to the neutron spectra to determine emission temperatures, multiplicities, velocities, and angles for the projectilelike fragment, targetlike fragment, and nonequilibrium emission sources as a function of the total kinetic energy loss. The extracted temperature of the projectlike fragment is found to be larger than that of the targetlike fragment source at all total kinetic energy losses, approaching that of the targetlike fragment only at the largest total kinetic energy losses. The results suggest an equal division of the available excitation energy at small total kinetic energy loss with a thermal energy division occurring only at the largest total kinetic energy losses. The velocity of the nonequilibrium source is found to remain constant at approximately one-half of the beam velocity independent of the final projectlike fragment velocity. This result supports models of nonequilibrium emission in which nucleon emission is isotropic in the nucleon-nucleon center-of-mass system as opposed to models in which the nonequilibrium emission occurs isotropically from the heavy fragments along their reaction trajectories.

We discuss the time-dependent Hartree-Fock equations which maintain independent nucleon spin degrees of freedom, and which include spin-orbit interactions. The complex numerical task of including the spin-orbit force in reaction studies is described in detail.

We calculate the energy spectra of high energy photons and pions produced in heavy ion collisions at intermediate energies of around 75 MeV/nucleon. We use a unified approach based on the Boltzmann-Uehling-Uhlenbeck theory and the assumption that both pions and high energy gamma rays are produced in individual nucleon-nucleon collisions during the course of the heavy ion reaction. A comparison to existing data for energy spectra of neutral pions and high energy photons shows good agreement.