The ground-state mass difference between ${}_{}{}^{81}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$ was determined by a $Q$-value comparison of the ${}_{}{}^{82}{}_{}{}^{}\mathrm{Kr}$(d, t)${}_{}{}^{81}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{82}{}_{}{}^{}\mathrm{Kr}$(d, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$)${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$ reactions. Energy resolution was optimized by using an ion-implanted target. Implications for calibration of the proposed bromine solar neutrino detector are presented.

Differential cross sections and analyzing powers for $0^{-}$ states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been measured in inelastic scattering of 65 MeV polarized protons. This is the first observation of both isovector and isoscalar $0^{+}$${\to 0}^{-}$ transitions in proton scattering on a particular isotope. Microscopic distorted-wave Born approximation and distorted-wave impulse approximation calculations do not describe very well either experimental cross sections or analyzing powers. It is suggested that more complicated reaction mechanisms and wave functions may be needed to describe these transitions.

Final state interaction in the expanding fireball of a heavy ion reaction may allow the depletion of excited states of nuclei through hadronic reactions. Such depletion would result in a cooler apparent temperature as measured by excited state population distributions than what is found by fitting inclusive cross sections. This idea is applied to the recently measured lithium and beryllium distributions in the $35A$ MeV ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$+Ag reaction, and the temperature predicted to be associated with the excited state populations is shown to be in the range observed experimentally.

Magnetic excitations in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been measured by inelastic electron scattering at backward scattering angles for momentum transfers between $q=0.5\mathrm{} \mathrm{and} 3.3$ ${\mathrm{fm}}^{-1\mathrm{}}$. Data for $M1\mathrm{}$, $M2\mathrm{}$, $M3\mathrm{}$, and $M4\mathrm{}$ transitions are compared to shell model calculations. In general, the excitation energies are reasonably predicted, as are the momentum transfer dependences of the form factors. However, the form factor magnitudes often exceed measurements by factors of more than 2. Candidates for $2^{-}$ states are seen at excitation energies of 18.2 and 22.7 MeV. It is shown how structure effects may reduce estimates of isospin mixing matrix elements from ($\pi$,${\pi }^{\prime }$) ratios.

Inclusive data from fragmentation reactions of the type $A_P+A_T\to Z+X$ are analyzed and a reaction mechanism is proposed. A projectile $A_P (\mathrm{p}, \mathrm{He}, \alpha , or \mathrm{Ne})$ collides with a target nucleus $A_T$ (Au) and one fragment with charge $Z$ and energy $E$ is observed at a solid angle $\Omega$. Projectile energies vary between $84A$ MeV and several $A$ GeV. We propose a parametrization for the triple differential cross section $\frac{d^3\sigma }{d\Omega }\mathrm{dE}\mathrm{dZ}$ with six free parameters. The parametrization generalizes the two-vector model which is often used to describe spallation products in proton-nucleus collisions. By fitting data from various experiments we establish a systematics of the six parameters. The experimental values of the parameters can be quantitatively understood in a model where the target nucleus breaks into several fragments similar to the shattering of glass.

Characteristics of intermediate mass fragment emission data advanced as experimental evidence of a hadronic gas to liquid phase transition are reviewed. Ambiguities in the interpretation of these characteristics are presented. The necessity of large $Z$ fragments to tunnel through a large Coulomb barrier is shown to make extraction of a phase transition signature difficult.

Quasielastic yields have been measured for the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$+${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ reaction at $E_{\mathrm{lab}}\left({}_{}{}^{28}{}_{}{}^{}\mathrm{Si}\right)=225\mathrm{}$ MeV. The inelastic scattering is dominated by excitation of the first $2^{+}$ level in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. The angular distribution for this state is found to contain insufficient information to determine accurately the quadrupole deformation parameter once the possibility of hexadecapole deformation is admitted. The ambiguity is resolved by requiring a simultaneous fit to the angular distribution of the first $4^{+}$ state in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. A large fraction of the total reaction cross section is found to be contained in quasielastic neutron transfer, and transfer of a single proton. It is shown that these large quasielastic yields are consistent with the expectations from distorted-wave Born approximation calculations.

Excitation functions for the yields of residual nuclei from the ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$+${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$+${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ reactions have been measured for ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ laboratory bombarding energies of 12 to 34 MeV and 15 to 63 MeV, respectively. Beginning at Coulomb barrier energies, we find that the total fusion cross section diverges from the total reaction cross section obtained from optical model fits to elastic scattering data. This indicates that the process responsible for fusion cross section limitations in this mass region begins near the Coulomb barrier and becomes progressively more important as the bombarding energy is increased. Comparison of the critical angular momenta deduced from the total fusion cross sections for these and two previously investigated entrance channels which form the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ compound nucleus, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$+${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$+${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, rules out a compound nucleus limitation at these energies. A systematic study of fusion cross sections in this mass and energy region, together with the results of a previous study of the light particles produced in the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$+${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$+${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ reactions, suggests that competition for entrance channel flux by reactions producing light particles with projectilelike velocities is primarily responsible for the fusion cross section limitations.

Differential cross sections and tensor polarizations of elastic neutron-deuteron scattering (n-d) are calculated at $E_{\mathrm{lab}}^{\mathrm{n}}<15\mathrm{}$ MeV with different nuclear potentials. The pole extrapolation of these model data reproduces the $S$-state normalization within 1% and misses the $D$- to $S$-state ratio $\eta$ by about 5%. Approximate Coulomb distortion corrections to n-d tensor polarization calculations that improve the agreement with proton-deuteron (p-d) data yield smaller contributions to $\eta$ than found previously within a distorted-wave Born approximation. Extrapolation of recent n-d differential cross section data and Coulomb corrected p-d tensor polarization leads to deuteron asymptotic normalizations compatible with current experimental values.

Excitation functions and detailed differential recoil range distributions for radioisotope products of the reactions of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ on ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$, together with inclusive proton and $\alpha$ particle spectra, have been measured at energies up to 157 MeV. The range distributions clearly show three separable components, which are attributed to complete fusion of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, incomplete fusion of ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$, and incomplete fusion of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, respectively, with the target. Detailed Monte Carlo modeling of the shapes of the recoil range distributions for these processes, using information on the breakup process derived from the measured $\alpha$ particle spectra, has enabled the separate contribution of each fusion process to the formation of each product studied to be deduced as a function of energy up to 100 MeV. The partitioning amongst the observed products is consistent with statistical model predictions for the subsequent evaporation; this allows the total cross section for each process to be estimated as a function of energy. For projectile energies up to 100 MeV, the observed yield of "breakup" $\alpha$ particles is exhausted by incomplete fusion. The results suggest that incomplete fusion is occurring principally for partial waves near or even outside the hard grazing value, and that the total cross section for the various fusion processes exceeds the hard-grazing cross section.

A high resolution study of the breakup of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ has been made at 9 MeV per nucleon. The experimental configuration preferentially detects sequential breakup events. The dominant source of $\alpha$-${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and $\alpha$-${}_{}{}^{16}{}_{}{}^{}\mathrm{C}$ coincidence events is the decay of excited states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, respectively. The experimental technique and the reaction mechanism leading to sequential breakup are discussed.

The $g$ factors of the $I^{\pi }={11}^{-}$ isomer in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Er}$ and $I^{\pi }={\frac{13}{2}}^{+}$ isomers in ${}_{}{}^{155}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Yb}$ were measured using the technique of time-dependent perturbed angular distributions. The value obtained for ${}_{}{}^{154}{}_{}{}^{}\mathrm{Er}$, $g=+0.0154\mathrm{}\left(12\right)\mathrm{}$, indicates a predominant configuration of $\nu {[i_{\frac{13}{2}},h_{\frac{9}{2}}]}_{{10}^{-},{11}^{-}}$ for the isomeric state. The results for ${}_{}{}^{155}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Yb}$, $g=-0.085\mathrm{}\left(5\right)\mathrm{}$ and $g=-0.116\mathrm{}\left(12\right)\mathrm{}$, respectively, are explained in terms of Pauli blocking of the $3^{-}$ core excitation component in the wave function of the ${\frac{13}{2}}^{+}$ state.

Sub-barrier fusion cross sections for 12 systems involving $p$-shell nuclei are analyzed in an attempt to determine directly the universal form of the internucleus potential. We use a previously developed inversion procedure based on the Wentzel-Kramers-Brillouin approximation, which new model calculations presented here show to be highly accurate. The scaling implied by the proximity formulation is found to be roughly consistent with the data, with the structure of the colliding nuclei having little effect. The proximity function $\Phi$ determined from the data is consistent with the original function of Blocki et al. at intermediate separations, subject to the use of a different formula for the nuclear radii. Data for selected systems involving $\mathrm{sd}$-shell nuclei lead to a more attractive potential than that found for the $p$-shell systems, while data for systems involving Ca isotopes exhibit "reentrant" barriers characteristic of a breakdown of the basic assumptions of the inversion procedure.

The effects of virtual Coulomb excitation of giant multipole resonances as well as of relativity on sub-barrier elastic scattering of heavy ions are investigated. Closed expressions for the effect of giant quadrupole and octopole excitation from the adiabatic polarization potential, on the elastic scattering differential cross section, are derived. Comparison with optical model and coupled channels calculations is reported. The effect of special relativity on the Rutherford cross section is also described in a closed form.

Fractional independent yields of ${}_{}{}^{133}{}_{}{}^{}\mathrm{Xe}_{}^m{}_{}{}^{}$, ${}_{}{}^{133}{}_{}{}^{}\mathrm{Xe}_{}^g{}_{}{}^{}$, ${}_{}{}^{135}{}_{}{}^{}\mathrm{Xe}_{}^m{}_{}{}^{}$, and ${}_{}{}^{135}{}_{}{}^{}\mathrm{Xe}_{}^g{}_{}{}^{}$ have been measured for fission of ${}_{}{}^{233}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$, and ${}_{}{}^{242}{}_{}{}^{}\mathrm{Am}_{}^m{}_{}{}^{}$ induced by thermal neutrons and for fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, and ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$ induced by 14-MeV neutrons. The same yields have been measured for fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ induced by degraded fission spectrum neutrons from a bare critical assembly. Some upper limits and ratios of yields of these same isomers have been obtained for the fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ and ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$ by the degraded fission spectrum neutrons. The average angular momentum of these independently formed fission products has been derived from the measured isomer ratios. A method that is particularly well adapted to use with computers for solving the differential equations of radioactive decay and growth is described.

Angular distributions of cross section were measured for the ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\mathrm{p}, \gamma ){}_{}{}^3{}_{}{}^{}\mathrm{He}$ reaction at $E_x=9.83, 10.83, 12.78, 15.47, \mathrm{and} 16.12$ MeV and of analyzing power at $E_x=10.83\mathrm{} \mathrm{and} 16.12$ MeV. The data were fitted by expansions of Legendre and, where appropriate, associated Legendre polynomials. The coefficients of those fits are reported. The data at $E_x=10.83\mathrm{} \mathrm{and} 16.12$ MeV were also analyzed under simplifying assumptions to extract the $s=\frac{1}{2}\left(E1\right)$, $s=\frac{1}{2}\left(E2\right)$, and $s=\frac{3}{2}\left(E1\right)$ transition matrix elements, where $s$ represents the incident channel spin. The results indicate that the data are consistent with a 2(3)% $E2\mathrm{}$ and a 3(5)% $s=\frac{3}{2}\left(E1\right)$ admixture at $E_x=10.83\mathrm{}\left(16.12\right)\mathrm{}$ MeV. These results are discussed in light of other recent experiments and calculations.

Analysis of recent high resolution measurements of fission and capture cross sections of (${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$+n) between 2 and 32 keV has been done to extract the energy dependence of the average $s$-wave fission width and neutron strength function. A correlation analysis of the data indicates that the large fluctuations in $\alpha$, the capture-to-fission ratio, are due to intermediate structure in the average fission width. The structure can be simulated by using a double-humped barrier model that takes into account coupling of class I and class II states in exactly the same way that has been used successfully to describe structure in subthreshold fission. These results suggest that the presence of intermediate structure is a general phenomenon in suprathreshold fission as well, and that, to describe such structure in the unresolved resonance region, one must include the coupling between class I and class II states.

The energy and mass distributions and their correlations have been studied for the spontaneous fission of ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$ and the thermal neutron induced fission of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$. A comparison of the ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$(sf) and the ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}({\mathrm{n}}_{\mathrm{th}},f)$ results shows a narrower mass distribution, a much higher peak yield, a much lower symmetric fission yield, and a more pronounced fine structure for the spontaneous fission than for the neutron induced fission. The average total kinetic energy is 1.3 MeV higher for ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$(sf) than for ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}({\mathrm{n}}_{\mathrm{th}},f)$, and also the energy-mass correlations behave differently in both cases. All these results are discussed and interpreted in the framework of the scission point model of Wilkins et al. Finally, the damping of the ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$ fission mode below the barrier is demonstrated.

The relative importance of the diagrams contributing to the $\pi \mathrm{N}\to \pi \pi \mathrm{N}$ reaction in the framework of the Weinberg effective Lagrangian theory is investigated. Total production cross sections, pion-pion angular correlations, and the energy spectrum of the outgoing nucleon given by various approximate schemes proposed in the literature are found to be very different from those predicted by the Weinberg theory. We indicate the inadequacies of these approximate schemes and discuss their implications to the predicted ($\pi$,$2\pi$) total cross sections on complex nuclei. The relevance of our findings to microscopic models for pion-nucleus double charge exchange reactions is also discussed.

The sensitivities to input parameters of the (p,${\pi }^{+}$) observables calculated using a relativistic one-nucleon distorted-wave Born approximation model are discussed. We investigate the effects of variations in bound state geometry and of ambiguities in the pion optical potential, as well as finite range effects in the production vertex.