Calculated ($\alpha ,x\mathrm{n}$) excitation functions ($x=1\mathrm{} \mathrm{to} 4$) for ${}_{}{}^{233,234,235}{}_{}{}^{}\mathrm{U}$ and ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$ targets, for incident ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ energies to 45 MeV, have been compared with experimental results. Calculations used experimental fission barriers with single particle ratios which were deduced by fitting experimentally deduced fission probabilities at excitations up to 12 MeV. Standard precompound parameters used for fitting spectra of nucleon-induced reactions were used, changing only the initial exciton number to four, appropriate for $\alpha$-induced reactions. Agreement with experimental results was good to excellent, without the need of multiple precompound decay, nor of variation of precompound decay parameters from those required for nonfissile systems.

The Coulomb excitation of ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$ by 135 MeV ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ ions was studied using the particle-gamma coincidence technique. Scattered projectiles were detected within an angular range of ${30}^{\circ }\le \Theta \le {172}^{\circ }$, and the impact-parameter dependence of the gamma-ray intensities was measured. Excitation of the ground-state rotational band was observed up to the ${10}^{+}$ state, while the $\beta$- and $\gamma$-vibrational bands were seen up to the $4^{+}$ and $8^{+}$ states, respectively. Levels belonging to the $K^{\pi }=0^{-} \mathrm{and} 1^{-}$ octupole vibrational bands were also identified. From the scattering-angle dependent gamma-ray intensities $E2\mathrm{}$ transition matrix elements within the ground band and interband matrix elements connecting levels of the $\gamma$ band with the ground band are deduced. Gamma-ray branching ratios for transitions from the $\gamma$- and octupole-vibrational bands to ground-band levels are also determined. Both transition matrix elements and branching ratios are compared with nuclear-model predictions.

The $\gamma$-ray decay of the $J^{\pi }=0^{+}$ shape isomer at 2557.6 keV of excitation in ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ has been reinvestigated using the ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}\mathrm{}(\mathrm{d},\mathrm{p}\mathrm{n})\mathrm{}{}_{}{}^{238}{}_{}{}^{}\mathrm{U}_{}^m{}_{}{}^{}$ reaction with a new two-detector technique. A line at 2512.7±0.5 and another possible one at 1877.6 keV are attributed to decay of the isomer. The cross section for production of the 2512.7-keV $\gamma$ ray by 18-MeV deuteron bombardment of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ is 42±12 μb, consistent with our earlier conversion-electron work on ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}_{}^m{}_{}{}^{}$. The isomer decay is about 5% by fission and 95% by $\gamma$ rays and conversion electrons.

We have measured the $A$ dependence of absolute Ge(t,p) cross sections using a natural Ge target and an enriched ${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$ target of known composition.

Differential cross sections and analyzing powers were measured for the inelastic scattering of 160-MeV polarized protons over the angular range $6^{\circ }\le \theta \le {49.5}^{\circ }$. The spectra covered excitation energies up to about 11 MeV in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$. Angular distributions and analyzing powers were determined for 28 separate peaks. The data are compared to distorted-wave impulse approximation calculations and spin assignments are suggested for many of the states. The resulting level diagram is compared to three different shell model calculations of the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ spectrum.

(p,p), (p,n), and (n,n) scattering on ${}_{}{}^{116,118,120,122,124}{}_{}{}^{}\mathrm{Sn}$ have been analyzed employing the Lane coupled equations. The (p,n) measurements were made at $E_{\mathrm{p}}=24.5\mathrm{}$ MeV, the appropriate energy at which to complement existing (p,p) measurements at 24.5 MeV and (n,n) measurements at 11 MeV. A search routine on the Lane coupled equations code yielded the complex isovector and isoscalar strengths from the simultaneous fitting of (p,p) and (p,n) data. These strengths have provided excellent fits to the (n,n) data on all five tin isotopes. The near constancy of the real and imaginary isovector strengths with $A$ implies that the effects of channel coupling to the first $2^{+}$ and $3^{-}$ states are either small or fairly uniform over the isotopic sequence. The implications of the Lane coupled equations with regard to the Coulomb correction on the imaginary optical potential are discussed.

High spin states in ${}_{}{}^{86}{}_{}{}^{}\mathrm{Y}$ were studied through the ${}_{}{}^{85}{}_{}{}^{}\mathrm{Rb}(\alpha ,3\mathrm{}\mathrm{n})$ reaction at energies between 30 and 55 MeV, using techniques of in-beam $\gamma$-ray spectroscopy. Eight levels were observed on top of the $J^{\pi }=8^{+}$ (218.3 keV) metastable state which are connected by $\gamma$ rays in cascade and five levels decaying to the $J^{\pi }=5^{-}$ (208.1 keV) excited state. The former were interpreted in terms of the weak coupling of the proton $\pi \left(1\mathrm{}{g}_{\frac{9}{2}}\right)$ and the neutron hole $v^{-1\mathrm{}}\left(1\mathrm{}{g}_{\frac{9}{2}}\right)$ coupled to the ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$ excited states on the basis of the shell model.

The fusion cross sections for the ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ systems are compared for bombarding energies up to 18 MeV/nucleon. The energy spectra, angular distributions, and relative yields of the evaporation residues are analyzed in terms of simple kinematic considerations and Hauser-Feshbach calculations. Simultaneous determinations of mass, charge, and energy and two particle coincidence measurements at $E_{{14}_{\mathrm{N}}}=13\mathrm{}$ MeV/nucleon support the identification of evaporation residues based on inclusive measurements of $Z$ and $E$ alone. The gross characteristics of the residues are consistent with the main process being complete fusion followed by equilibrium decay. The excitation functions of the ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ systems show significant differences which cannot be explained in terms of simple macroscopic models. At the highest bombarding energies the fusion cross sections decrease as $\frac{1}{E_{\mathrm{c}.\mathrm{m}.\mathrm{}}}$ for both systems and are consistent with a maximum angular momentum limit of $\sim 27\hslash$.

The entropy of hot matter produced in medium energy nuclear collisions is inferred from recent data on light fragment cross sections. A previously suggested model is used to fit the abundances of both the deuterons, and the deuteronlike pairings contained in higher mass clusters, with a single parameter. The model takes into account finite density effects in six-dimensional phase space. The entropy rises monotonically with energy, as expected, but remains rather high even at the lower energies. Surprisingly the measured entropy always lies above the theoretically expected value (about 3.3) at the critical point of the liquid-gas phase transition which, it is argued, depends only upon the gross features of the nuclear matter equation of state.

The entropy of hot nuclear systems is deduced from the mass distribution of fragments emitted from high energy proton- and nucleus-induced reactions via a quantum statistical model. It is found that the entropy per baryon, $\frac{S}{A}$, of intermediate rapidity ("participant") fragments is higher than the entropy of target rapidity ("spectator") fragments. The spectator fragments exhibit $\frac{S}{A}$ values of ≅ 1.8 independent of the projectile energy from 30 MeV/nucleon up to 350 GeV. This value of the entropy coincides with the entropy at which nuclear matter becomes unbound.

We formulate a three-dimensional quantum-mechanical model for the study of nucleon transfer in heavy ion collisions. This model describes the independent particle motion of nucleons initially separated in two adjacent cubic boxes and brought into contact through a window created in the separating wall. We calculate the one-sided flux and the spread of the mass distribution and compare them with results derived from other models.

We further analyze the validity of the density matrix expansion applied to the complex heavy ion optical potential by separately treating the direct and exchange contributions. We show that the discrepancies found previously when comparing the density matrix expansion optical potential with the exact one are mainly to be ascribed to the direct contribution. For the exchange part the density matrix expansion is nearly exact in the tail region and remains very good down to zero separation distance. The Campi-Bouyssy prescription for accelerating the density matrix expansion convergence is also examined.

Results are presented for the reaction ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,p)${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$, at $E\left({}_{}{}^7{}_{}{}^{}\mathrm{Li}\right)=16.0\mathrm{}$ MeV, leading to states up to 6.61 MeV excitation.

States populated in the ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$,d)${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ reaction at 22 MeV are compared with those in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$,d)${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ at the same energy. Cross section ratios are in good agreement with a weak-coupling model, in contrast to previous observations via the (${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,t) reaction. Two strong transitions are observed to states at $E_x=8.288\mathrm{} \mathrm{and} 8.957$ MeV in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$. The measured angular-distribution shapes and alpha-transfer strengths for these states are consistent with their being, respectively, the ${\frac{13}{2}}^{-}$ and ${\frac{11}{2}}^{-}$ members of the $K^{\pi }={\frac{1}{2}}^{-}$ band in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$. A comparison between the measured alpha-particle widths for these states and the single-particle alpha widths calculated in a Woods-Saxon well supports the above assignments.

Angle integrated excitation functions for elastic scattering and reactions of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$+${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been measured in 100 keV steps over the energy range $E_{\mathrm{lab}}=105-121\mathrm{}$ MeV. Narrow fluctuations are observed in all channels as well as in the angle-integrated cross section summed over all channels. These data have been subjected to a detailed statistical analysis. The probability densities of the summed deviation and cross-correlation functions have been derived from the assumptions of the statistical model and compared with the experimental results. These statistical tests show that the observed narrow structures are of nonstatistical character and correspond to long lived states of the composite system with high angular momenta and excitation energy.

The independent isomeric yield ratios for ${}_{}{}^{129}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{130}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{131}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{133}{}_{}{}^{}\mathrm{Te}$, and ${}_{}{}^{136}{}_{}{}^{}\mathrm{I}$ for the photofission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ with 12-30-MeV bremsstrahlung and for ${}_{}{}^{126}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{129}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{130}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{131}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{133}{}_{}{}^{}\mathrm{Te}$, and ${}_{}{}^{136}{}_{}{}^{}\mathrm{I}$ for the photofission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ have been determined using radiochemical techniques and gamma spectrometry of fission product catcher foils and irradiated uranium samples. The root-mean-square values of the primary angular momenta of the corresponding fission fragments, $J_{\mathrm{rms}}$, were calculated with the statistical procedure of Huizenga and Vandenbosch and with the more elaborate deexcitation model of Min and Martinot. Both procedures gave, except for ${}_{}{}^{130}{}_{}{}^{}\mathrm{Sb}$, almost the same $J_{\mathrm{rms}}$ values. Our experimental results show a near independency of $J_{\mathrm{rms}}$ on the spin and excitation energy of the compound nucleus. An increase of the $J_{\mathrm{rms}}$ values with the excitation energy of the fragments is observed. In addition, a significant proton odd-even effect on the $J_{\mathrm{rms}}$ values is present for the photofission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ as well as ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. Our experimental photofission results show a qualitative agreement with the theoretical calculations of Dietrich and Zielinska-Pfabé.

Recently it has been shown that the standard nonrelativistic theory of the nuclear optical potential is unable to explain the spin-dependent observables for proton-nucleus scattering for projectile energies from about 400 MeV to 1 GeV if one uses the impulse approximation to calculate the potential. On the other hand, a relativistic impulse approximation leads to a (relativistic) optical potential for use in the Dirac equation; the relativistic model is able to provide good fits to the spin observables in the energy range noted above. We discuss the relationship between the nonrelativistic and relativistic models of the optical potential and show that the nonrelativistic potential may, to a first approximation, be identified with one of two terms in an expression for the relativistic optical potential. This identification is not precise since the density matrices of the target are different in the relativistic and nonrelativistic theories. The second term in our expression for the relativistic optical potential is associated with projectile propagation in negative-energy states. It may be seen that this term and the corrections arising from the use of a relativistic density matrix for the target are responsible for the success of the relativistic model.

The fourth-order noniterative diagrams of $\pi \rho$ exchange involving nucleon-isobar intermediate states are evaluated in momentum space in the framework of noncovariant perturbation theory. It is shown that the sum of all time orderings (iterative plus noniterative) can be reasonably well approximated by twice the isoscalar piece of the iterative ones (which are much simpler to evaluate). The same approximation is used in order to describe the sum of all time orderings for the corresponding diagrams involving double-isobar intermediate states. The role of these contributions is studied in NN scattering. Especially, it is investigated whether such contributions can quantitatively replace part of the $\omega$-exchange contribution used in one-boson-exchange models.

We investigate the spectrum of antinucleon-nucleon resonances, using an optical potential we derived recently. An effective method to compute the $S$-matrix poles is presented. The corresponding phase shifts do not behave as ordinary resonances in the Argand diagram. We show, however, that the poles can be located by extrapolating the phase shifts with the aid of polynomial fits. The annihilation part of our potential is state and energy dependent and of short range. It yields a richer spectrum than that given by a longer ranged annihilation model.

Energy spectra and angular distributions have been measured for 46 isotopically separated Li through Mg fragments produced in reactions of 480 MeV protons with Ag. This silicon solid state detectors have been used with time-of-flight techniques to extend measured fragment energies as low as 1 MeV per nucleon, well below the most probable fragment energies. Reasonable fits to the relatively small evaporative components of the spectra are obtained using a self-consistent calculation previously developed. An analysis of the remaining nonevaporative components using contours of relativistically invariant cross section in the plane of rapidity and perpendicular momentum indicates that these components can be described in terms of isotropic emission from moving sources if the source velocity is allowed to be a function of the fragment's radial velocity in the source frame. The relationship between these velocities is essentially independent of fragment $Z$ and $A$. Coupled with the evaporation calculation, this relationship allows all spectra to be reasonably fit at all angles by use of a simple (four parameters per fragment) phenomenological form for the isotropic nonevaporative component in the moving source frame. While such a form might suggest a statistical origin for the nonevaporative components, detailed consideration of the parameters required suggests difficulties with such an interpretation. Implications of these data for other models are discussed. Energy integrated and total cross sections are calculated.