A procedure is developed to calculate the chemical potential of a system of fermions at high temperatures in the independent particle model. This is then used to investigate the occurrence of liquid-gas phase transitions in finite nuclei employing various zero-range nuclear effective interactions. Finite size effects and the Coulomb force are found to lead to a sizeable reduction (∼8 MeV) in the "critical" temperature as compared to the case of infinite nuclear matter.

Differential cross section analyzing power angular distributions have been measured for transitions to low-lying bound states and the giant resonance region in ${}_{}{}^{92}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, through inelastic scattering of 104 MeV polarized protons. Collective model calculations employing a complex transition potential with spin-orbit coupling reproduce the data for the low-lying states very well. The cross section and the analyzing power angular distribution data for the giant quadrupole region are better fitted if a small admixture of the $L=4\mathrm{}$ component is added to the $L=2\mathrm{}$ multipole. Because of lack of knowledge about the absolute strength of the isovector potential, the magnitude of the calculated cross section for the giant dipole resonance is uncertain. This has limited the accuracy with which we could determine the contribution of the giant monopole resonance which is located in the same region of excitation as the dipole resonance.

The ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}(\alpha ,\mathrm{d}){}_{}{}^{208}{}_{}{}^{}\mathrm{Bi}$ reaction was investigated at 48.2 MeV with about 25 keV resolution. Angular distributions were obtained for 48 levels at excitation energies up to 5 MeV. Many previously unknown levels were seen and most seem to have two-particle—two-hole structure and spins above 6; however, the relatively structureless angular distributions permit only approximate $L$ assignments. Transitions to six low-lying one-particle—one-hole states were analyzed in detail. Distorted-wave Born approximation predictions agreed with the observed angular distributions, but the absolute cross sections computed from published ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Bi}$ wave functions are generally larger than observed, particularly those for the $J_{max}$ states. Contributions of the dominant two-step sequential stripping channels to the one-step results were investigated. They were important and gave varying amounts of enhancement for all six levels. The observed quenching of the $J_{max}$ cross sections was not reproduced.

Coulomb form factors for the $0^{+}\to 2^{+}$ transitions in some doubly even Ti, Cr, and Fe isotopes are studied in terms of the projected Hartree-Fock-Bogoliubov wave functions in the $2p-1f$ shell resulting from a slightly modified version of the Kuo-Brown effective interaction. The quadrupole moments of the first excited states as well as the reduced transition probabilities for $E2\mathrm{}$ transitions are also discussed in connection with the $C2\mathrm{}$ form factors. The overall agreement between the calculated and the experimental results is quite good.

We have used a 100-MeV electron linac and neutron time-of-flight facility to measure precise neutron total cross sections in the mass-140 region for incident neutron energies of 3-60 MeV. We measured the absolute neutron total cross section of ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ and the total cross section differences of ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$, and ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$. These cross section differences oscillate with energy. Optical model calculations have been performed which fit the ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ total cross section well over the 3-60 MeV energy region. The ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ difference data were satisfactorily fit by small changes in the geometrical parameters of the potential. The ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ data could not be fit by small changes in the geometry of the potential and we found that the changes required to achieve a satisfactory fit suggest that ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$ is either nonspherical or more easily deformed than ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$. Using our final optical model parameters we calculated $\delta \left(r^2\right)={}_{}{}^A{}_{}{}^{}〈r^2〉-{}_{}{}^{140}{}_{}{}^{}〈r^2〉$ for the real part of the potential. The ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ optical model values of $\delta \left(r^2\right)$ were in agreement with corresponding $\delta {\left(r^2\right)}_q$ values calculated using muonic x-ray data. The value for ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$-${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ was not.

${}_{}{}^{106}{}_{}{}^{}\mathrm{In}$ has been studied via the reaction ${}_{}{}^{106}{}_{}{}^{}\mathrm{Cd}(\mathrm{p},\mathrm{n}\gamma ){}_{}{}^{106}{}_{}{}^{}\mathrm{In}$ in the energy range $E_{\mathrm{p}}=7-9\mathrm{}$ MeV. Inbeam $\gamma$-ray excitation functions, $\gamma -\gamma$ coincidence measurements, and ${\beta }^{+}$-delayed $\gamma$-ray excitation functions have been used to identify thirteen levels in ${}_{}{}^{106}{}_{}{}^{}\mathrm{In}$. From this new level scheme the energy separation of the high-spin ground state and the low-spin isomer has been determined to be 28.6±0.5 keV. The threshold energy of the strongest low-lying $\gamma$-ray transition yields a mass excess for ${}_{}{}^{106}{}_{}{}^{}\mathrm{In}$ of -80601±15 keV. Spins for some states are suggested by comparing the excitation functions to Hauser-Feshbach calculations. In-beam $\gamma$-ray excitation functions for the ${}_{}{}^{108}{}_{}{}^{}\mathrm{Cd}(\mathrm{p},\mathrm{n}\gamma ){}_{}{}^{108}{}_{}{}^{}\mathrm{In}$ reaction give a mass excess for the $3^{+}$ ${\beta }^{+}$-decaying state in ${}_{}{}^{108}{}_{}{}^{}\mathrm{In}$ of -84018±12 keV. The systematics of odd-odd In nuclei are discussed in a $j-j$ coupling model.

High resolution neutron transmission measurements have been performed on ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$ in the energy interval $E=0.4-105\mathrm{}$ keV. The transmission data were analyzed using a multilevel $R$-matrix code to deduce resonance parameters. Previously obtained neutron capture data were reanalyzed in the interval 2.6-86 keV. Values of $\frac{G{\Gamma }_{\mathrm{n}}{\Gamma }_{\gamma }}{\Gamma }$ were determined from the capture data. For those resonances where ${\Gamma }_{\mathrm{n}}$ could be determined from the transmission data, the capture data were analyzed to extract ${\Gamma }_{\gamma }$. Our results yield an average capture for a stellar temperature $kT=30\mathrm{}$ keV of 89.5±4.5 mb. The $s$-wave level density for ${}_{}{}^{205}{}_{}{}^{}\mathrm{Pb}$ corresponding to the neutron energy range investigated (i.e., $E\sim 105$ keV) relative to that for ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ (which has about the same neutron separation energy) is greater by about a factor of 10. The average $s$-wave strength function in this energy region is determined as $S_0=0.93\mathrm{}\times {10}^{-4\mathrm{}}$. This is an order of magnitude greater than that for a similar energy region in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ + n where a doorway is observed at $E\sim 500$ keV. However, the strength function in the initial $E=0-100\mathrm{}$ keV in ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$ + n is almost identical to the average value of that for ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ + n when the averaging interval for the latter is taken as $E_{\mathrm{n}}\approx 0-1000$ keV (i.e., over the doorway state). This suggests that the $s$-wave doorway state observed in the higher mass lead isotopes is completely mixed with "background" states in ${}_{}{}^{205}{}_{}{}^{}\mathrm{Pb}$, and most likely no intermediate structure will be observed in the $s$-wave strength function for the ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$ + n reaction.

Nonlocal spin-dependent couplings in the effective nucleon-nucleon interaction are shown to probe current $\otimes$ spin correlations in inelastic nuclear excitations. Together, these couplings and correlations provide an important dynamical source of polarization-analyzing-power differences observed in inelastic proton scattering. This is illustrated explicitly by schematic calculations for $0^{+}\to 1^{+}$ and $0^{+}\to 0^{-}$ transitions. More realistic distorted-wave impulse approximation calculations have been made for the $0^{+}\to 1^{+}$ transition in ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ at $E_x=8.9\mathrm{}$ MeV which support the more transparent schematic considerations. Distorted-wave impulse approximation calculations are also compared with experimental (p,p') data for the two lowest $1^{+}$ excitations in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. For isovector $0^{+}\to 1^{+}$ transitions these nuclear structure spin $\otimes$ current correlations also enter $\beta$ decay through the "induced tensor" couplings, and this relationship is used to help identify the nonlocality in the nucleon-nucleon effective interaction.

Two main goals are pursued in this work. The first one is concerned with the relativistic effects in high energy nuclear collisions, when noninvariance of simultaneity is taken into account. It is shown that the time ordering of nucleon-nucleon collisions is quite different for different observers, giving in some cases noninvariant final results for intranuclear cascade calculations. In particular, we have shown an example of such a case, in which the intranuclear cascade simulation, depending on the reference frame, presents a kind of density instability caused by a specific time ordering of collision events. The second one is to propose a new intranuclear cascade calculation, using a causality preserving scheme, which minimizes this kind of relativistic effect. It is verified that the causality preserving intranuclear cascade prescription essentially recovers the relativistic invariance.

The level structure of the four-valence-proton $N=82\mathrm{}$ nucleus ${}_{}{}^{150}{}_{}{}^{}\mathrm{Er}$ has been studied by $\gamma$-ray spectroscopy following reactions of 225-255 MeV ${}_{}{}^{58,60}{}_{}{}^{}\mathrm{Ni}$ beams on ${}_{}{}^{92,94,95}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ targets. Yrast levels in ${}_{}{}^{150}{}_{}{}^{}\mathrm{Er}$ are established up to 9.5 MeV excitation energy; they include isomeric levels at 2797, 7372, and 9509 keV. The observed levels up to 5222 keV are interpreted in terms of shell model configurations involving the four valence protons outside the ${}_{}{}^{146}{}_{}{}^{}\mathrm{Gd}$ core. They include states with dominant seniority two and four configurations ${\pi h}_{\frac{11}{2}}^4$, ${\pi h}_{\frac{11}{2}}^3{s}_{\frac{1}{2}}$, and ${\pi h}_{\frac{11}{2}}^3{d}_{\frac{3}{2}}$, and octupole excitations. The levels above 5222 keV must involve excitation of the ${}_{}{}^{146}{}_{}{}^{}\mathrm{Gd}$ core, and they are not interpreted in detail. The energies of the ${\pi h}_{\frac{11}{2}}^4$ levels are found to agree reasonably with predictions based on empirical two-body interactions taken from the ${\pi h}_{\frac{11}{2}}^2$ spectrum of ${}_{}{}^{148}{}_{}{}^{}\mathrm{Dy}$. Even better agreement is obtained by taking account also of the known ${\pi h}_{\frac{11}{2}}^3$ energies in ${}_{}{}^{149}{}_{}{}^{}\mathrm{Ho}$. The dependence of $E2\mathrm{}$ transition probabilities in $N=82\mathrm{}$ nuclei on the ${\pi h}_{\frac{11}{2}}$ subshell occupation number is discussed.

Production of neutron-rich Bi isotopes was investigated by irradiating Hg, Tl, and Pb targets with ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ ions in the 5-10 MeV/nucleon range. Following irradiation, bismuth was chemically separated and the yields of ${}_{}{}^{211-213}{}_{}{}^{}\mathrm{Bi}$ isotopes were determined via $\alpha$-emitting Po daughters. Effective residual transfers of ${}_{}{}^{3-5}{}_{}{}^{}\mathrm{H}$ to ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{7,8}{}_{}{}^{}\mathrm{He}$ to ${}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$, and ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ to ${}_{}{}^{204}{}_{}{}^{}\mathrm{Hg}$ were observed. Cross sections generally peaked in the 7-8 MeV/nucleon region and ranged from a high of ∼2 mb for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ absorption to ∼0.6 nb for ${}_{}{}^8{}_{}{}^{}\mathrm{He}$ absorption. Total $\alpha$- and $\beta$-decay branches of the $J^{\pi }=9^{-},25\mathrm{}$ min isomer of ${}_{}{}^{212}{}_{}{}^{}\mathrm{Bi}$ were measured to be 67% and 33%, respectively, (3.2±0.2)% of the decays being associated with $\beta$-delayed $\alpha$-particle emission. Production yields for the $J^{\pi }=1^{-}$ ground state and $9^{-}$ and ${15}^{-}$ isomeric levels for ${}_{}{}^{212}{}_{}{}^{}\mathrm{Bi}$ were extracted. The ratio of isomeric states to the ground state increased by more than two orders of magnitude over the energy range studied. However, the maximum value of the cross section ratio $\frac{\sigma (J^{\pi }={15}^{-})}{\sigma (J^{\pi }=9^{-})}$ was only 0.04, implying a low angular momentum transfer. The reactions were analyzed using the Wilczyński "sum rule," which gave a rather poor fit to the results with respect to both the yield and the implied angular momentum transfer. The observed relatively high cross sections, modest angular momentum transfer, and broad excitation functions indicate that transfer processes provide a viable method for reaching neutron-rich nuclides in the heavy element region.

The isospin-averaged cross section for the reaction $\mathrm{N}Y\to \mathrm{NN}\overline{\mathrm{K}}$ is calculated in the one-pion exchange model. This reaction is relevant to the production of antikaons in heavy-ion collisions at subthreshold energies. Using a simplified kinetic model in which antikaons are produced from the interaction of hyperons with the thermalized participant hadrons, it is estimated that the contribution to antikaon productions from the reaction $\mathrm{N}Y\to \mathrm{NN}\overline{\mathrm{K}}$ is only a few percent of that from the reaction $\pi Y\to \mathrm{N}\overline{\mathrm{K}}$.

An application of intensity interferometry to relativistic heavy ion collisions is reported. The correlation between two like-charged pions is used to study the reactions $\mathrm{A}\mathrm{r}+\mathrm{K}\mathrm{C}\mathrm{l}\to {2\pi }^{\pm }+X$ and $\mathrm{N}\mathrm{e}+\mathrm{N}\mathrm{a}\mathrm{F}\to {2\pi }^{-}+X$, both at an incident beam energy of $1.8A$ GeV. Source sizes and lifetimes are measured and compared to the predictions of simple geometric models and of Monte Carlo cascade calculations. There appears to be a substantial coherent component of the pion source, although measurement is complicated by the presence of final state interactions. A detailed discussion of the techniques of intensity interferometry is also presented. The generation of uncorrelated background events is discussed, along with the influence of the correlation on the background and the prescription for its removal. The statistical errors in the background spectrum are examined and found to have nontrivial implications for the analysis. The effect of the mutual Coulomb repulsion of the two pions, and of the pion-nuclear Coulomb interaction, on the two-pion correlation function is analyzed. The impact parameter bias resulting from a two-pion trigger is calculated and found to be substantial. Finally, a simple model for the interpretation of Gaussian source parameters is presented and compared to the predictions of Monte Carlo cascade calculations.

The neutron-induced fission cross section of ${}_{}{}^{242}{}_{}{}^{}\mathrm{Am}_{}^m{}_{}{}^{}$ has been measured over the energy region from ${10}^{-3\mathrm{}}$ eV to ∼20 MeV in a series of experiments utilizing a linac-produced "white" neutron source and a monoenergetic source of 14.1 MeV neutrons. The cross section was measured relative to that of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ in the thermal (0.001 to ∼3 eV) and high energy (1 keV to ∼20 MeV) regions and normalized to the ENDF/B-V ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(\mathrm{n},f)$ evaluated cross section. In the resonance energy region (0.5 eV to 10 keV) the neutron flux was measured using thin lithium glass scintillators and the relative cross section thus obtained was normalized to the thermal energy measurement. This procedure allowed a consistency check between the thermal and high energy data. The cross section data have a statistical accuracy of ∼0.5% at thermal energies and in the 1-MeV energy region, and a systematic uncertainty of ∼5%. We confirmed that ${}_{}{}^{242}{}_{}{}^{}\mathrm{Am}_{}^m{}_{}{}^{}$ has the largest thermal fission cross section known with a 2200 m/sec value of 6328 b. Results of a Breit-Wigner sum-of-single-levels analysis of 48 fission resonances up to 20 eV are presented and the connection of these resonance properties to the large thermal cross section is discussed. Our measurements are compared with previously reported results.

Thin targets of U, Bi, Pb, Au, W, Ho, and Ag were bombarded with 7-GeV protons in order to measure the fission and spallation cross sections. Muscovite mica, Makrofol-$N$, Makrofol-$E$, and Daicel track detectors were employed in $4\pi$ and $2\pi$ geometry arrangements. The binary- and ternary-fission cross sections (${\sigma }_b$ and ${\sigma }_t$) and the value of fissility ($\frac{{\sigma }_{\mathrm{fission}}}{{\sigma }_{\mathrm{inelastic}}}$) increase with increasing value of $\frac{Z^2}{A}$ of the target. The spallation cross section (${\sigma }_{\mathrm{spall}}$) shows an increase with increasing mass number of the target. However, $\frac{{\sigma }_t}{{\sigma }_b}$ and $\frac{F}{B}$ (forward to backward) ratios decrease with increasing value of $\frac{Z^2}{A}$.

The vector analyzing power $i{T}_{11}$ has been measured for the $\pi \overrightarrow{\mathrm{d}}$ elastic scattering reaction at 12 incident pion energies between 117 and 325 MeV, using a vector polarized deuteron target. The results cover an average of 14 angles per incident pion energy. A detailed comparison with existing Faddeev calculations is made. The effect of including dibaryon resonances with one of these predictions is investigated.

The free propagator for the spin $\frac{3}{2}$, isospin $\frac{3}{2}$ (delta) particle is discussed, comparing the Rarita-Schwinger formalism and another of Hayward. Its use in the calculation of resonant graphs in pion-nucleon scattering, photon-nucleon scattering, and pion photoproduction from nucleons is exemplified using explicit formulae and numerical results. Predictions using the two formalisms are shown to be in significant disagreement.

The properties of deep inelastic electron scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ are analyzed in the context of relativistic $y$ scaling. A large enhancement of the transverse response relative to the longitudinal response is observed in the quasielastic region which is in contradiction to impulse approximation predictions assuming a free one-body current. Scaling behavior is recovered when a relativistic effective mass is included in the nucleon current operator. The first two moments of the longitudinal scaling function are also evaluated.

The effective forward, perpendicular, and backward ranges of ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ produced in the interaction of 90-350 MeV ${\pi }^{\pm }$ with carbon have been measured using conventional thick-target thick-catcher activation techniques. With increasing pion energy, the forward ranges decrease, the backward ranges increase, and the perpendicular ranges remain essentially unchanged. However, these trends are much more pronounced for ${\pi }^{-}$ than for ${\pi }^{+}$. The results have been compared with an intranuclear cascade code. The ratios of calculated effective ranges for ${\pi }^{-}$ and ${\pi }^{+}$ bombardment show the same energy dependence as observed experimentally.

We formulate inelastic electron scattering using Dirac single-particle wave functions to describe the nuclear states. The lower components of these wave functions are much larger than those obtained assuming a free space relation with the upper component taken to be a Schrödinger single-particle wave function. We note that the impulse approximation to the nuclear current operator is ambiguous in the present case. However, one of the two possible forms yields an explicitly conserved current in the single particle limit. We identify an inelastic amplitude which is linear in the lower components and is therefore very sensitive to the "relativity" of the bound nucleons. This amplitude is found to be dominant for transverse isoscalar transitions.