High-resolution γ-ray spectra from the interaction of neutrons in the energy range from 3 to 200 MeV with ${}_{}{}^{207,208}{}_{}{}^{}\mathrm{Pb}$ were measured with the white neutron source at the weapons neutron research (WNR) facility at Los Alamos National Laboratory. From these data, excitation functions for prominent γ transitions in ${}_{}{}^{200,202,204,206,207,208}{}_{}{}^{}\mathrm{Pb}$ were derived from threshold to 200 MeV incident neutron energy. These γ-production cross sections reflect the excitation cross sections for the respective residual nuclei. The results are compared with the predictions of nuclear reaction calculations based on the exciton model for precompound emission, the Hauser-Feshbach theory for compound nucleus decay, and coupled channels calculations to account for direct excitation of collective levels. Good agreement was obtained over the entire energy range covered in the experiment with reasonable model parameters. The results of this work clearly demonstrate that multiple preequilibrium emission has to be taken into account above about 40 MeV, and that the level density model of Ignatyuk, which accounts for the gradual disappearance of shell effects with increasing excitation energy, should be used instead of the Gilbert-Cameron and backshifted Fermi-gas models if excitation energies exceed about 30 MeV. No indication for a reduction of the nuclear moment of inertia below the rigid body value was found.

The crystal blocking technique has been used to measure nuclear time delays in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(135 MeV)${+}^{\mathrm{nat}}$Ni reaction. From the axial blocking patterns the time delays for the production of fragments with Z from 13 to 18 have been extracted. Times of the order of ${10}^{\mathrm{-}18}$ s for even Z and less than the sensitivity of the method for odd Z have been found. Two interpretations of these findings have been discussed. The first one seems to indicate that nucleus-nucleus dynamics has to be included in simple statistical models to understand the time scale of fusion-fission processes. In the second interpretation, an explicit model for dechanneling shows how the blocking technique can be extended to measure time delays in decay chains.

This article presents a new analysis of primary projectile-like fragments produced in peripheral and mid-peripheral collisions in the reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${+}^{\mathrm{nat}}$Cu at 35 MeV/nucleon. The data were obtained using the charged particle amphora array. The distributions of multiplicity, inclusive charge, and heaviest fragment charge of the deexcitation products as well as the moments characterizing the single event charge partitions are remarkably well reproduced by a statistical sequential binary decay model even up to excitation energies of more than 8 MeV/nucleon. The results produced by the sequential binary decay model and a simple bond percolation model are qualitatively very similar. However the sequential binary decay mechanism leads to charge fluctuations which are in better agreement with the data than those predicted by the percolation model.

Differential cross sections and analyzing powers have been measured for inelastic proton excitation of states in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ up to an excitation energy of 20 MeV. Angular distributions are reported for incoming proton energies of 200, 318, 398, 597, 698, and 800 MeV, typically over the momentum transfer range from 0.5 to 2 ${\mathrm{fm}}^{\mathrm{-}1}$; some of these data have been published previously. Reaction calculations in the distorted-wave impulse approximation have been carried out for most of the data. Agreement between theory and experiment for both the magnitudes and shapes of the cross-section data is generally good; the analyzing-power distributions are less well described.

Proton and α-particle spectral shapes and multiplicities have been measured in coincidence with evaporation residues from 145 to 220 MeV ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${+}^{165}$Ho and 115 and 140 MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{197}$Au${,}^{208}$Pb fusion reactions. Evaporation residues were separated using an electrostatic deflector and detected with large area surface barrier detectors. Light charged particles were detected at forward and backward angles with 14 single NaI detectors. In the context of the statistical model, the charged particle spectra provide information about the shapes and level densities of the emitting systems. Deformed emitters are inferred, and to a varying degree, an energy-dependent level density parameter is compatible with the data in each of the three cases. Implications for current fusion and fission dynamics studies are discussed.

Monoenergetic photons of 11.4 MeV, originating from the Ni(n,γ) reactions, were elastically scattered from three isotopically enriched lead targets, a ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ target, and a ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ target. Cross sections for the lead isotopes at θ=90° and 140° differ significantly from predictions based on known giant dipole resonance (GDR) parameters showing marked structures in this region of energy. The cross sections for ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$, and ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ are in agreement with a previous measurement. The ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ cross section is the only case where agreement is found with calculations based on known GDR parameters. New GDR parameters for ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ were deduced by combining the present elastic scattering with those from previous measurements, leading to ${\mathrm{\kappa }}_{\mathrm{GDR}}$=0.35±0.06.

Data for the elastic and inelastic scattering of 60 MeV polarized ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ by ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ have been analyzed using coupled-channels (CC) techniques. The diagonal and off-diagonal interaction potentials used in the analysis were derived from empirical α${+}^{26}$Mg and d${+}^{26}$Mg optical model potentials by means of the cluster-folding method. The effects of projectile excitation to the three low-lying T=0 resonant states, as well as to nonresonant continuum states ranging from 2.1 MeV to 11.5 MeV excitation energy relative to the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ ground state, have also been studied. A good description of the data has been achieved without renormalization of the interaction potentials.

The 4π multidetector AMPHORA has been used to measure yield distributions and energy spectra for products of the collisions in the reactions of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ with ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at 35 MeV/nucleon. Events of high multiplicity (≥10) for which ≥85% of the total entrance channel atomic number is detected have been isolated and found to result from the most violent collisions which lead to excitation energies near 6 MeV/nucleon. A large fraction of these collisions lead to multifragment final states. A detailed comparison of the experimental data with results of various models indicates that statistical models which allow for expansion of the system or treat the multifragmentation process as a simultaneous disassembly are more successful than normal sequential binary models at reproducing the yield data and the event complexity inherent in the multifragment events. Quantum molecular dynamic (QMD) calculations are found to provide generally good agreement with the data but overestimate the proton and neutron emission. The agreement is significantly improved if an appropriate afterburner is used to deexcite the separated primary QMD fragments. The sensitivity of such hybrid calculations to the assumed matching time between the dynamical calculation and the afterburner has been explored. The experimentally filtered QMD calculations which provide good agreement with the experimental observables suggest that the most complex events observed in this work come not from the most central collisions, which decay more by light particle emission, but from a region of impact parameter b/${\mathit{b}}_{\max }$=0.5. This suggests that angular momentum effects play an important role in the multifragment decay modes. A comparison of the present results with those for projectile fragmentation in intermediate impact parameter collisions of 600 MeV/nucleon ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ with Cu indicates that a similar multifragmenting system is produced in the two very different reaction systems.

The inclusive and exclusive cross sections of the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^3$He,d) and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^3$He,dp) reactions have been measured at incident energy ${\mathit{E}}^3$He=240 MeV for an excitation energy of the residual nucleus ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ up to ∼16 MeV. The measured data are analyzed by means of the breakup-fusion theory. A formulation of the theory is developed for calculation of both exclusive and inclusive cross sections. Elastic breakup, breakup-fusion, and breakup-fusion followed by subsequent decay are taken into account in our theoretical description of the inclusive and exclusive data. The respective roles of the different processes are discussed. It is shown that the calculations reproduce very well the main features of the observed cross sections.

Using thick-target, thick-catcher recoil range techniques, target residues from the interaction of copper with 40 MeV/nucleon ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, 35 MeV/nucleon ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, and 25 MeV/nucleon ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ have been studied. Isobaric and mass yield distributions as well as longitudinal momentum transfer information have been determined from measured cross section, average forward range, and forward-to-backward ratios. Comparisons with previously reported reactions involving copper and lighter ions have been made. Comparisons of the data with the interaction-evaporation model Boltzmann-Vehling-Uhlenbeck-pace are presented.

Exact calculations of the Glauber amplitude for α${\mathrm{-}}^{12}$C scattering at 1.37 GeV are carried out by expanding it into multiple scattering sequences and by classifying them into equivalent kinds. A comparison has been made with those based on various approximation schemes. The convergence of the expansion is investigated.

A possible mechanism of the production of light nuclei in fusion reactions is considered. It is shown that the decay of the dinuclear system during its evolution to a compound nucleus yields a substantial rate for the production of light nuclei. The cross section of this process is calculated for the reaction ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${+}^{58}$Ni. The coupling of other modes of motion causes an increase of the asymmetric decay of the dinuclear system.

Angular distributions for elastic and inelastic scattering of the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}_{}^{+}{}_{}{}^{}$ ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ system leading to the 1/$2^{+}$ (g.s.), 5/$2^{+}$ (0.197 MeV), 3/$2^{+}$ (1.554 MeV), and 9/$2^{+}$ (2.780 MeV) states in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ were calculated with a coupled channels (CC) method using cluster folding (CF) interactions based on a ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+t${+}^{12}$C three-body model at ${\mathit{E}}_{\mathit{L}}$${(}^{12}$C)=30–60 MeV. The calculations reproduce well the experimental angular distributions for the elastic and inelastic scattering to the 5/$2^{+}$ and 3/$2^{+}$ states at all energies, although for the inelastic scattering to the 5/$2^{+}$ and 3/$2^{+}$ states the phases of the calculated angular distributions seem to be shifted slightly backward from the experimental ones. The calculations are compared with the CC calculations using Woods-Saxon interaction in order to investigate the effect of the shape of the interaction.

A general model for the fragmentation of a two-component or bipartite system (e.g., protons and neutrons) is proposed and solved exactly. The extension of this model to any number of components is also shown to be exactly solvable. A connection between this model and the permutation group is discussed and used to obtain closed-form solutions. The notion of isotopic equivalence is defined in order to evaluate the equivalence of these models to earlier one-component models. All the one-component models considered in earlier papers are shown to be equivalent to a particular subclass of two-component models. A simplified model applicable to the case of nuclear fragmentation is introduced and analyzed. Modifications to this model to include effects such as pairing and Coulomb interactions are discussed.

The quantum statistical model (QSM) is used to calculate nuclear fragment distributions in chemical equilibrium. Several observable isotopic effects are predicted for intermediate energy heavy ion collisions. It is demonstrated that particle ratios for different systems do not depend on the breakup density—the only free parameter in our model. The importance of entropy measurements is discussed. Specific particle ratios for the system Au+Au are predicted, which can be used to determine the chemical potentials of the hot midrapidity fragment source in nearly central heavy ion collisions.

One-nucleon transfer processes between heavy ions at intermediate energies are studied in the framework of the eikonal distorted-wave Born approximation. Optical phase shifts describing core-core relative motion are microscopically described in the Glauber model, starting from experimental nuclear densities and nucleon-nucleon scattering amplitudes at the corresponding energies. The interaction responsible for the nucleon transfer is a complex energy-dependent potential obtained by the Abel transform of the nucleon-core phase shift. Applications to one-proton and one-neutron transfer reactions on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ induced by ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ projectiles are discussed for both angular distributions and normalization factors.

Coulomb dissociation of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ into the ${}_{}{}^7{}_{}{}^{}\mathit{p}$ low energy continuum is studied theoretically in first- and second-order perturbation theories and in the sudden approximation. The summation over all intermediate continuum states in the second-order amplitude is achieved by closure, using an expansion which is valid for low excitation energies. In view of the importance of the ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$(p,γ${)}^8$B reaction for the ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ solar neutrino problem we investigate especially the optimal conditions for possible experiments. Double as well as triple differential cross sections are calculated for 5 MeV/A, 46.5 MeV/A and 200 MeV/A beam energy as a function of the ${}_{}{}^8{}_{}{}^{}\mathrm{B}_{}^{\mathrm{*}}{}_{}{}^{}$ scattering angle, the ${}_{}{}^7{}_{}{}^{}\mathit{p}$ relative energy, and momentum.

In the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$(t,p${)}^{22}$Ne reaction at a bombarding energy of 15 MeV, excitation energies have been measured for 81 levels up to ${\mathit{E}}_{\mathit{x}}$=13.4 MeV. Thirteen new levels were identified. Distorted-wave Born-approximation (DWBA) calculations with spherical and deformed potentials were used to analyze the angular distributions. Two-step processes were found to make important contributions to the reaction. For most low-lying positive-parity levels, results are analyzed with two-particle transfer amplitudes from a realistic shell-model calculation. We have assigned spin-parities to 42 levels above 6.6 MeV based on the success of the DWBA analysis.

A systematic calculation for energy deposition in intermediate energy heavy-ion collisions, concerning the effects of both entrance channel dynamics and intrinsic properties of nuclei, has been carried out by means of the Boltzmann-Uehling-Uhlenbeck (BUU) simulation. The limitation on excitation energy is essentially related to the dynamics of the entrance channel, while the contribution from the mean field may also be quite large and cannot be neglected.

Effects of the nonlocality of factorizable potentials are taken into account in the calculation of nucleus-nucleus fusion cross section through an effective mass approach. This cross section makes use of the tunneling factor calculated for the nonlocal barrier, without the explicit introduction of any result coming from coupled channel calculation, besides the approximations of Hill-Wheeler and Wong. Its new expression embodies the nonlocal effects in a factor which redefines the local potential barrier curvature. Applications to different systems, namely, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{59}$Co, ${}_{}{}^{16,18}{}_{}{}^{}\mathrm{O}$${+}^{58,60,64}$Ni, and ${}_{}{}^{16,18}{}_{}{}^{}\mathrm{O}$${+}^{63,65}$Cu are presented, where the nonlocal range is treated as a free parameter.