Various features of the mass yield in heavy-ion collisions are studied. Simple pictures are first developed from an exactly soluble canonical ensemble model which has its basis in a statistical view of the collision. Several different high energy proton-nucleus data may be understood in terms of a geometric property and a recursive feature of the distribution of fragments. The geometric property is discussed in terms of the concept of self-similarity and scaling laws associated with generalized Renyi entropies. The recursive feature is discussed in terms of iterative one-dimensional maps. Nuclear cobwebbing, attractors of the dynamics, Lyapunov exponents, correlation lengths, and dimensions associated with scaling relations are investigated. Fourier transforms of the mass yield are used to obtain power spectra which are then used to investigate a possible power-law behavior 1/${\mathit{f}}^{\mathrm{\beta }}$ behavior) with frequency f.

The final-state interactions of quasielastically photoproduced charmonium have been computed in a quantum-mechanical QCD-inspired model for a range of photon energies and nuclear targets. In this model, charmonium in its rest frame interacts with an array of nucleon flux tubes via its color dipole moment as color electric fields ‘‘flash’’ on and off around it. The photoproduction amplitude is modeled as the narrowest superposition of open charmonium channels available at a given photon energy. A complete calculation of the final-state interactions has been performed; this involves retaining all the charmonium states present in the initial amplitude and produced upon interactions with the medium, and allowing them to scatter into each other upon further medium interactions. This work permits the computation of ${\mathit{A}}^{\mathit{e}\mathit{f}\mathit{f}}$/A with and without ‘‘transparency’’; the results support the utility of a study of the energy dependence of ${\mathit{A}}^{\mathit{e}\mathit{f}\mathit{f}}$/A in elucidating transparency in the exclusive process considered. Moreover, a comparison of the underlying J/ψ-nucleon cross section with that deduced from a Glauber analysis of the computed A dependence shows the Glauber analysis to be misleading.

The cloudy quark bag model is applied to the coupled (K¯N,Σπ,Λπ) system for S-D partial waves. Energy-dependent separable potentials are derived, as are new numerical algorithms for solving the coupled Lippmann-Schwinger equations. The parameters of the model are fit to ${\mathit{K}}^{\mathrm{-}}$p scattering and reaction cross sections, branching ratios, and mass spectra from ${\mathit{K}}^{\mathrm{-}}$p→Σπππ,Λπππ. Within the constraints of the model, the branching ratio and Σπ mass spectrum data are in conflict. The ${\mathrm{\Sigma }}_{\mathit{p}13}$(1385) and ${\mathrm{\Lambda }}_{\mathit{D}03}$(1520) resonances are found to be predominately elementary bag states with considerable dressing for the ${\mathrm{\Sigma }}_{\mathit{P}13}$. The ${\mathrm{\Lambda }}_{\mathit{S}01}$ (1405) appears as a complicated composite systems arising from two poles. The model with certain parameter sets does predict two sign changes in the real part of the K¯N scattering amplitude near threshold, but they are not quite at the correct energies to produce agreement with the sign of the strong interaction shift of kaonic hydrogen.

We report a measurement of the β asymmetry of the first-forbidden transition from the 1/$2^{+}$ ground state of ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ to the 1/$2^{\mathrm{-}}$ level at 110 keV in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$. Using atomic beam methods to prepare a 100% polarized source of ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$, we identify the 1/$2^{+}$→1/$2^{\mathrm{-}}$ decays by the detection of the subsequent 110 keV gamma emitted in coincidence with a beta. The average β asymmetry of the first-forbidden transition is measured to be 〈A〉=17±12 %. We simultaneously make an improved measurement of the branching ratio of the same transition and find Γ=(1.13±0.09)×${10}^{\mathrm{-}4}$ in good agreement with previous results. Our measurement is used to obtain an improved calibration of the isovector parity-mixing matrix element between the 1/$2^{+}$ ground state of ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and the 1/$2^{\mathrm{-}}$ level at 110 keV.

Differential cross sections for neutrino- (and antineutrino-) induced nucleon knockout are calculated for neutral-current reactions from nuclei. A relativistic Fermi gas model with binding energy corrections is used. We examine the accuracy with which strange quark axial and vector current parameters can be extracted from both existing and (possible) future experiments. Both high (above 1 GeV) and low (near 150 MeV) neutrino energies and the knockout of neutrons and protons are considered.

Intense ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ radioactive ion beams have been produced by the two-accelerator method. They have been used to investigate the ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$(p,γ${)}^{14}$O reaction, in particular to measure directly its cross section in the energy region of interest in nuclear astrophysics. The results of a complete set of experiments thereby carried out on this reaction allowed the determining of the stellar conditions under which the cold and hot CNO cycles, for the nuclear ‘‘burning’’ of hydrogen and its transformation into helium, dominate.

The rp process provides a mechanism whereby energy is generated and proton-rich nuclei are synthesized in various astrophysical environments. Understanding this process requires knowledge of the half-lives, binding energies, and reaction cross sections for the nuclei along its path, which for A≳60 lies near the proton-drip line. Using the A1200 radioactive-beam facility at the National Superconducting Cyclotron Laboratory, we have performed an experiment to measure the β-decay half-lives of several ${\mathit{T}}_{\mathit{z}}$=-1/2 nuclei in this mass region by identification and implantation of projectile fragments followed by a rapid beam cutoff and observation of the β decay. Using this technique, the half-lives of ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ga}$, ${}_{}{}^{63}{}_{}{}^{}\mathrm{Ge}$, and ${}_{}{}^{65}{}_{}{}^{}\mathrm{As}$ (0.15±0.03 s, ${95}_{\mathrm{-}20}^{+23\mathrm{}}$ ms, and 0.${19}_{\mathrm{-}0.07}^{+0.11\mathrm{}}$ s, respectively) have been measured and are found to be consistent with expectations from β-decay theory for decay between mirror states with ${\mathit{Q}}_{\mathrm{\beta }}$∼9 MeV. In addition, the proton-rich nucleus ${}_{}{}^{66}{}_{}{}^{}\mathrm{Se}$ has been observed for the first time. The experimental method used for this measurement and the implications of these results for the rp process are discussed.

We measured thick-target yields of ${}_{}{}^{126,128,130}{}_{}{}^{}\mathrm{I}$ from bombardments of natural Te targets with 15-, 30-, 45-, and 50-MeV protons, together with iodine production cross sections for 1.85- and 5.0-GeV protons. Using these data, we have estimated the relative cosmic-ray induced production of ${}_{}{}^{126}{}_{}{}^{}\mathrm{Xe}$, ${}_{}{}^{128}{}_{}{}^{}\mathrm{Xe}$, and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$ in Te ores. These quantities are significantly different from those used previously in a determination of the ratio of the double-β decay half-lives of ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ and ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$, and as a result the cosmic-ray correction is smaller than previously assumed. A revised correction of cosmic-ray produced xenon can change the half-life ratio by about 6%. This quantity is of importance because it can be used to set a limit on the 0-ν double-β decay mode.

We have performed a search for the ${\mathrm{\beta }}^{+}$ decay of ${}_{}{}^{54}{}_{}{}^{}\mathrm{Mn}$ by looking for back-to-back 511-keV γ rays in two high-purity Ge detectors. No excess of events above background was observed, and a limit of 5.7×${10}^{\mathrm{-}7}$% has been established for the ${\mathrm{\beta }}^{+}$ branch. The significance of this result for the use of ${}_{}{}^{54}{}_{}{}^{}\mathrm{Mn}$ as a cosmic ray chronometer is discussed.

Beams of 185–204 MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ ions have been used to bombard ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$, ${}_{}{}^{96}{}_{}{}^{}\mathrm{Ru}$, ${}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$, and ${}_{}{}^{106}{}_{}{}^{}\mathrm{Cd}$ targets in order to produce the proton-decay candidate nuclei ${}_{}{}^{128}{}_{}{}^{}\mathrm{Pm}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Eu}$, ${}_{}{}^{138}{}_{}{}^{}\mathrm{Tb}$, and ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ho}$ via the 1p3n fusion evaporation channel. In each case no evidence for proton radioactivity was found. On the basis of mass model systematics it was concluded that the odd proton is not sufficiently unbound in these nuclei for proton emission to compete successfully with β decay.

Excitation functions were measured by the stacked-foil technique for ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,α${)}^{58}$${\mathrm{Co}}^{\mathit{m}}$ and ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,α${)}^{58}$${\mathrm{Co}}^{\mathit{m}+\mathit{g}}$ reactions using 88.84% enriched ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$ from threshold up to 18.6 MeV. Thin samples of ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$ were prepared by electrodeposition on gold foils. The radioactivity of the activation products was determined via high resolution x- and γ-ray spectrometry. From the measured experimental data isomeric cross-section ratios [${\mathrm{\sigma }}_{\mathit{m}}$/${\mathrm{\sigma }}_{\mathit{m}+\mathit{g}}$] were deduced. Statistical model calculations taking into account precompound effects were performed for the strong ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,xn) channels as well as for the weak ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,α) process. The experimental ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,xn) and ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,α) excitation functions are described well by the calculation over the whole investigated energy range. The isomeric cross-section ratio for the isomeric pair ${}_{}{}^{58}{}_{}{}^{}\mathrm{Co}_{}^{\mathit{m},}{}_{}{}^{}$g formed in the ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$(p,α) process is also reproduced well by the model calculation, provided the input level scheme and the spin distribution are properly taken into account.

Two new resonances in the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(α,n) reaction, at ${\mathit{E}}_{\mathrm{\alpha }}$=656 and 802 keV, have been observed and the resonance strengths have been measured. Limits on the (α,γ) strengths have been determined. Strengths for previously known (α,n) resonances at 1053 and 1586 keV are also reported.

Proton elastic scattering on Li isotopes ${}_{}{}^{6,7,9,11}{}_{}{}^{}\mathrm{Li}$ at ${\mathit{E}}_{\mathit{p}}$∼60 MeV is described by a nonlocal optical model potential which is constructed by folding a microscopic density-dependent effective interaction with Hartree-Fock single-particle wave functions of the target nuclei. Experimental data are well-described systematically from ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ to ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ by our model calculation, implying that the underlying microscopic theory is applicable even at the extreme circumstance of the neutron drip line limit.

We calculate the phase variation parameter γ in terms of an effective NN potential which is consistent with the small angle NN scattering data at 1.75 GeV/c. It is found that γ is positive and is of much smaller magnitude than required to reproduce the α elastic scattering data on light nuclei at the corresponding energy. However, our estimate is in accord with the value of γ as obtained from the pp phase shifts.

It is customary to extract deformation lengths from inelastic scattering data by using a deformed optical potential. It is then assumed that this deformation length also characterizes the deformation of the underlying density distribution of the excited nucleus. This equivalence is exact for a dipole deformation, but this corresponds simply to a spurious excitation mode, namely a shift of the center of mass of the system. We show that, even when the potential is obtained by folding an effective interaction over the density distribution, the deformed potential model is not exact for other multipoles, except in the limit that the interaction has a zero range. The errors made when the interaction has a realistic finite range can be large.

A semiclassical approach to study pure Coulomb excitation of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ giant dipole isovector resonance is examined. We consider medium energy projectiles and assume the target excitation to be described by a simple Goldhaber-Teller model. It is shown that the main features concerning the angular distribution are obtained in the angular range described by the model and an estimate is made of the pure Coulomb dipole contribution to the measured cross sections.

A difficulty in the derivation of the cross section for statistical multistep direct reactions is resolved.

Heavy-ion collisions between asymmetric systems are studied in the framework of the Boltzmann-Uehling-Uhlenbeck approach. For central collisions, it is found that different values of the incompressibility of nuclear matter lead to different exotic density shapes after the most violent stages of the reaction.