The level structure of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ has been studied by proton inelastic scattering using a 65-MeV polarized beam. Spin and parity assignments for the excited states below 8 MeV of excitation in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ were made by the distorted-wave Born approximation analysis. The distributions of the excitation strengths for the $2^{+}$, $3^{\mathrm{-}}$, and $4^{+}$ states were obtained. The energy-weighted sum rule fractions were found to be 7.12%, 9.35%, and 1.22% for the $2^{+}$, $3^{\mathrm{-}}$, and $4^{+}$ states, respectively. The distribution of the octupole excitation strengths in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ is compared with those in ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}$ and ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$. The excitation strength corresponding to the first $J^{\pi }$${=3\mathrm{}}^{\mathrm{-}}$ state in ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$ was found to be fragmented in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$, and this fragmentation was shown to be consistent with the prediction by a simple liquid drop model for deformed nuclei. The systematic behavior of the $3^{\mathrm{-}}$ states below 1ħω excitation in the Ti isotopes shows that the fine structure of the $3^{\mathrm{-}}$ excitation strength distribution is closely correlated to the quadrupole deformation of the ground state.

Neutron-diffraction patterns have been measured for isotopically enriched powder samples of calcite using both steady-state and pulsed-neutron techniques. Greatly enhanced precision over previous work has been achieved for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$, while the results for ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{43}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ represent new data. The coherent scattering lengths deduced from these measurements have been employed in a more definitive analysis of primary electric-dipole gamma rays from thermal-neutron capture. In three cases ${(}^{40}$Ca, ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$) the estimates from a spherical optical-model formulation of the direct-capture mechanism are in agreement with the experimental cross sections. In ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$ the theory overestimates the measured cross sections on average by about 60%; this divergence can be explained by considering the modifications to the theory due to collective vibrations of the ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$ core.

We have determined the ground-state photon decay probability and the branching ratios to a number of low-lying states as a function of excitation energy in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ up to ∼15 MeV. Results for the giant quadrupole resonance at 10.6 MeV include determination of a ground-state electromagnetic transition strength B(E2)↑=5800±1600 $e^2$${\mathrm{fm}}^4$ and observation of strong suppression of the E1 transition from the resonance to the $3^{\mathrm{-}}$ state at 2.6 MeV. These results confirm the common assumption of the predominately isoscalar character of the 10.6-MeV resonance. Ground-state gamma coincidences enable us to isolate the isovector giant dipole resonance, which is too weak to be seen in singles, and to test models for its excitation in heavy-ion scattering.

Experimental fission excitation functions for compound nuclei ${}_{}{}^{52}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{49}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{46}{}_{}{}^{}\mathrm{V}$, and ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems.

Differential cross sections for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{12}$C, ${}_{}{}^8{}_{}{}^{}\to 2\mathit{\alpha }$${)}^{16}$O reaction have been measured at eight incident energies in the 2.43≤$E_{\mathrm{c}.\mathrm{m}.\mathrm{}\mathrm{\le }5.24}$-MeV range, detecting α particles in 200-μm thick Makrofol polycarbonate foils, which were subsequently carefully etched and scanned under microscope for the ${}_{}{}^8{}_{}{}^{}$Be→2α group and the α groups from the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{12}$C, α${)}^{20}$Ne reaction. The ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$ channel cross section, ranging between 4×${10}^{\mathrm{-}4}$ μb and 280 μb, is smaller for $E_{\mathrm{c}.\mathrm{m}.\mathrm{}\ge 3.91}$ MeV, but larger for $E_{\mathrm{c}.\mathrm{m}.\mathrm{}\mathrm{\le }3.13}$ MeV than the ${\alpha }_0$${+}^{20}$${\mathrm{Ne}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ channel cross section. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{12}$C, ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$${)}^{16}$O cross section is well reproduced by the distorted-wave Born approximation calculation of a direct α-transfer reaction down to $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=3.91\mathrm{}}$ MeV. In the 3.13≥$E_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ ≥2.43-MeV range, however, the measurements exceed the distorted-wave Born approximation prediction by one to three orders of magnitude. It is suggested that the formation of ${}_{}{}^{12}{}_{}{}^{}\mathrm{-}_{}^{12}{}_{}{}^{}$C dinuclear states, favoring an α transfer, becomes a predominant process at incident energies $E_{\mathrm{c}.\mathrm{m}.\mathrm{}\mathrm{\le }3.13}$ MeV.

The ${}_{}{}^{13}{}_{}{}^{}$C${+}^{16}$O reaction has been studied by the kinematic coincidence technique in the $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ range between 19 and 30 MeV. Angular distributions and excitation functions were compared with results from ${}_{}{}^{12}{}_{}{}^{}$C${+}^{17}$O over the same energy range. Notable differences were found between the elastic angular distributions for the two reactions. Optical-model fits were performed to determine which parameters were sensitive to these differences. Broad structures, like shape resonances, were most apparent in the ${}_{}{}^{13}{}_{}{}^{}$C${+}^{16}$O reaction, particularly for the excitation of collective states. Transfer reactions involving single-particle states show a more complex energy dependence.

Lorentz-invariant cross sections for the production of ${\pi }^0$, ${\pi }^{+}$, and ${\pi }^{\mathrm{-}}$ have been investigated, for the pion c.m. momentum range 0–0.5 GeV/c at angles 0°–90°, by Monte Carlo methods for grazing nuclear collisions of ${}_{}{}^{207}{}_{}{}^{}$Pb${+}^{207}$Pb at 0.4 GeV/nucleon. Pions are considered to be produced isotropically at the center of mass at closest approach at random from a Gaussian momentum distribution. The pion equations of motion are solved including the electromagnetic effects due to the projectile and target ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ nuclei. The trajectory calculations differ from some earlier theoretical work in that pions are considered to scatter from the surface of, and propagate within, a spectator fragment. After surface scattering, the trajectory calculations continue but are weighted by the pion reflectivity. For that purpose, a model developed by Mehrem et al., for the relativistic oblique incidence of pions on nuclear matter represented by a uniform complex nuclear potential, has been used to evaluate the pion reflectivity for the three types of pions.

We have measured cross sections for inclusive reactions in which 1.7 GeV/N ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, 1.46 GeV/N ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$, 1.28 GeV/N ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$, and 0.8 GeV/N ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ increased in charge by one unit. Combining these results with data on charge pickup by ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ projectiles, we find that the cross section for charge pickup by ∼GeV/nucleon projectiles is generally given to within a factor of 2 by the expression ${\sigma }_{\Delta Z=+1\mathrm{}}$=1.7×${10}^{\mathrm{-}4}$ ${\gamma }_{\mathrm{PT}}$$A_P^2$ (in mb), where ${\gamma }_{\mathrm{PT}}$=$A_P^{1/3}$ +$A_T^{1/3}$-1.0. This expression, with roles of projectile and target interchanged, equally well fits cross sections for (p,xn) reactions at GeV energies when summed over x. The factor ${\gamma }_{\mathrm{PT}}$ implies peripheral collisions; the dependence on $A_P^2$ is the steepest ever reported for a nuclear process.

High-spin states in ${}_{}{}^{81}{}_{}{}^{}\mathrm{Rb}$ were investigated with the ${}_{}{}^{55}{}_{}{}^{}\mathrm{Mn}$${(}^{29}$Si, 2pn${)}^{81}$Rb reaction using a 95.2 MeV ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ beam. γ-γ coincidences were measured with three detectors at 23° and ±100°. The yrast and near-yrast rotational bands in ${}_{}{}^{81}{}_{}{}^{}\mathrm{Rb}$ have been extended well above the first band crossings, with spin assignments based on the directional correlations of oriented nuclei. The mean lifetimes of many higher levels were measured using the Doppler shift attenuation method. They imply moderate deformations with average transition moments of 2–2.5 eb, except at the sharp band crossing in the negative parity band, where they dip by a factor of 2. The data have been analyzed in terms of the Woods-Saxon cranking model. The crossing observed in the positive-parity band is attributed to the alignment of a $g_{9/2}$ neutron pair. Two negative-parity bands observed above I=(15/2 are suggested to contain ($g_{9/2}$${)}^2$ neutron and proton pairs, respectively.

Energy spectra and angular distributions were measured for high-energy gamma rays ($E_{\gamma }$>25 MeV) from the reactions ${}_{}{}^7{}_{}{}^{}$Li+Li, ${}_{}{}^7{}_{}{}^{}$Li+Pb, ${}_{}{}^{20}{}_{}{}^{}$Ne+Mg, ${}_{}{}^{40}{}_{}{}^{}$Ar+Ca, and ${}_{}{}^{40}{}_{}{}^{}$Ar+Pb at incident beam energies of E/A=30 MeV. The gamma-ray energy spectra for $E_{\gamma }$>25 MeV are roughly exponential and were observable to $E_{\gamma }$∼100 MeV. The angular distributions of the gamma rays are slightly forward peaked in the laboratory frame and are consistent with emission from a single source traveling at the nucleon-nucleon center-of-mass velocity. The angular distribution in the nucleon-nucleon frame shows a substantial dipole component. The gamma-ray production cross section is roughly proportional to ($A_{\mathrm{proj}{A}_{\mathrm{target}{)}^{2/3}}}$ or to the calculated mean number of first neutron-proton collisions.

Quasielastic yields are reported for the ${}_{}{}^{30}{}_{}{}^{}\mathrm{Pb}$ reaction at $E_{\mathrm{lab}{(}^{30}}$Si)=222 MeV. Coupled-channels analysis of the elastic and inelastic scattering results in an excellent description of the experimental data. The static quadrupole moments of the first two $2^{+}$ states in ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$ are measured to be -9±4 e${\mathrm{fm}}^2$ and -4±9 e ${\mathrm{fm}}^2$, respectively. The sign of the interference term for the transition between these two states is unambiguously determined to be negative, corresponding to destructive interference. Few-nucleon-transfer reaction data are also presented. Quasielastic processes account for 25% of the total reaction cross section.

The angles of all charged secondaries have been measured in central collisions of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with AgBr at 14.6, 60, and 200 GeV per nucleon. The pseudorapidity distributions are approximately Gaussian in shape. The widths increase monotonically with beam energy, but are essentially independent of multiplicity at a fixed beam energy. Quantitatively, the widths are consistent with Landau’s hydrodynamical model and inconsistent with a spherical fireball model and with Bjorken’s hydrodynamical scaling model. There are no statistically significant correlations in the azimuthal angle of the observed charged secondaries. Analysis of the two-particle pseudorapidity correlation functions and of the pseudorapidity gap distributions provide no evidence of significant cluster production. The data are consistent with a Monte Carlo simulation based on independent emission of the secondary particles, although intrinsic few-particle correlations could be hidden by the high multiplicities in these events.

Differential cross-section angular distributions have been measured for single-nucleon transfer reactions induced by E/A=50 MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ on targets of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. Finite-range distorted-wave Born-approximation calculations reproduce the shape of the angular distributions for all targets. Although the cross-section magnitudes are sensitive to the choice of distorting potentials, reasonable potentials are found that yield spectroscopic factors within 50% of light-ion results for all targets.

The quantum molecular dynamic method is used to study multifragmentation and fragment flow and their dependence on in-medium cross sections, momentum dependent interactions, and the nuclear equation of state, for collisions of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$${+}^{197}$Au and ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$${+}^{93}$Nb in the bombarding energy regime from 100 to 800A MeV. Time and impact parameter dependence of the fragment formation and their implications for the conjectured liquid-vapor phase transition are investigated. We find that the inclusive fragment mass distribution is independent of the equation of state and exhibits a power-law behavior Y(A)∼$A^{\mathrm{-}\tau }$ with an exponent τ≊-2.3. True multifragmentation events are found in central collisions for energies $E_{\mathrm{lab}\mathrm{\sim }30–200}$ MeV/nucleon. The associated light fragment (d,t,α) to proton ratios increase with the multiplicity of charged particles and decrease with energy, in agreement with recent experiments. The calculated absolute charged particle multiplicities, the multiplicities of intermediate mass (A>4) fragments, and their respective rapidity distributions do compare well with recent 4π data, but are quite insensitive to the equation of state.

On the other hand, these quantities depend sensitively on the nucleon-nucleon scattering cross section, and can be used to determine σ experimentally. The transverse momentum flow of the complex fragments increases with the stiffness of the equation of state. Reduced (in-medium) n-n scattering cross sections reduce the fragment flow. Momentum dependent interactions increase the fragment flow. It is shown that the measured fragment flow at 200A MeV can be reproduced in the model. We find that also the increase of the $p_x$/A values with the fragment mass is in agreement with experiments. The calculated fragment flow is too small as compared to the plastic ball data, if a soft equation of state with in-medium corrections (momentum dependent interactions plus reduced cross sections) is employed. An alternative, most intriguing resolution of the puzzle about the stiffness of the equation of state could be an increase of the scattering cross sections due to precritical scattering in the vicinity of a phase transition.

The fission induced in heavy nuclei ($Z^2$/A>30) by photons, pions, and protons of intermediate energy was studied. The fissilities were deduced from measured fission cross sections using the total reaction cross sections specific for each probe. The energies of the projectiles were chosen in such a way to produce similar configurations of the residual compound nuclei: to this end an intranuclear-cascade model was employed. With this choice, the obtained fissilities, plotted as a function of the 〈$Z_{\mathrm{cn}{}^2\mathrm{〉}/\mathrm{〈}{A}_{\mathrm{cn}\mathrm{〉}}}$ of the compound nuclei formed, are found in nice agreement irrespective of the probe used, and also in agreement with the fissilities calculated with the cascade-evaporation model based on the two-step picture of the process.

The electromagnetic longitudinal and transverse inclusive responses for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ are analyzed using the concept of y scaling. The longitudinal, $F_L$, and transverse, $F_T$, scaling functions are defined, and their experimental values are obtained and compared with the predictions of two theoretical approaches. The first one, based upon the impulse approximation, Hartree-Fock-type wave functions for finite nuclei, and final state interaction treated by complex optical potentials, yields a reasonable interpretation of $F_L$ but cannot predict the experimental splitting between $F_L$ and $F_T$. The second approach, based on an infinite nuclear matter model, quantitatively reproduces the experimental splitting when the spin and isospin dependence of the effective particle-hole interaction is properly taken into account. The effects of ρ-meson exchange and Δ-hole intermediate states on the scaling functions are also analyzed.

We explore the cross section for π° production by virtual photons from electron scattering, interacting with the Coulomb field of heavy nuclei. The same process with real photons, generally known as the Primakoff effect, has been used in the past to investigate the π° lifetime. In the present work, virtual photons bring into focus the electromagnetic structure of the γγπ° vertex.

Nuclear spin longitudinal and transverse response functions in the isovector channel are calculated by the continuum random-phase approximation with the orthogonality condition. This method treats the nucleus as of finite size and with a continuum single-particle spectrum. It can include an imaginary potential for the particle states. The corresponding longitudinal and transverse cross sections for ${}_{}{}^{40}{}_{}{}^{}(\mathit{p}$,p’) at $E_p$=500 MeV are calculated by distorted-wave impulse approximation fully quantum mechanically which is beyond the previous analyses by the Glauber approximation. The results are compared with the longitudinal-transverse response ratio extracted from the polarization transfer observables of the Los Alamos experiment. Large effects of the finiteness of the nucleus are seen especially in the longitudinal response. Effects of the distortion diminish the softening and hardening due to nuclear correlation, but the enhancement and quenching still remain. These effects cooperatively reduce the ratio.

We perform a global analysis of intermediate energy nucleon plus ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ scattering data using the Dirac phenomenology. Proton elastic differential cross sections, analyzing powers, spin rotation functions, and total reaction cross sections, together with neutron total cross sections, spanning an incident energy range of 80–800 MeV, are used in the determination of a Dirac scalar-vector global potential. Two of six energy dependencies studied are selected to construct best-fit nucleon-nucleus potentials for the reduced incident-energy interval of 95–300 MeV. These potentials reproduce the experimental data uniformly within the reduced energy interval. Explicit values for the isovector strengths of the nucleon-nucleus potential are given. The correlations and ambiguities among the parameters of the potentials are studied. Predictions are made for the elastic differential cross section and spin observables for neutron plus ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ scattering.

In an effort to better understand the dynamics of nucleon-nucleon bremsstrahlung in producing energetic photons, we have investigated the contribution of each part of the current associated with the different terms in the nuclear Hamiltonian to the neutron-proton bremsstrahlung cross sections. In the range of photon energy investigated here, we find meson-exchange currents to be the dominant source of high-energy photons (ω≳50 MeV). Although the one-body current contribution is small for such energetic photons, its interference with the two-body current is important and enhances the cross section. At low photon energy the convection current dominates. We find that the bremsstrahlung cross section is very sensitive to the ${}_{}{}^3{}_{}{}^{}$(SD${)}_1$ states and offers a potential means of investigating short-range correlation effects. Off-energy-shell effects are estimated to have only a small influence on the neutron-proton bremsstrahlung inclusive cross section. In connection with the neutron-proton bremsstrahlung process, the nucleon-nucleon collisional mechanism in producing high-energy photons in proton-induced reactions has been also investigated within the nuclear matter approximation. Nuclear medium effects in intermediate states are shown to have a minor influence on the photon cross section; therefore, the use of a free nucleon-nucleon T matrix instead of a G matrix seems to be well justified. However, the results are found to be very sensitive to medium effects in the initial and final states.