Resonant photon scattering from ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ has been measured from 5 to 10 MeV using Ge(Li) detectors and bremsstrahlung beams with end-point energies of 7.6 and 10.3 MeV. Energies and values of $g\frac{{\Gamma }_0^2}{\Gamma }$ were obtained for more than 40 levels, most of which have not been observed in previous photon experiments. Spins of 13 levels were determined from angular distribution measurements. In complementary lower-resolution ($\Delta E\sim 100$ keV) tagged photon measurements, average elastic and inelastic (to the first excited state) photon scattering cross sections were measured from 5.8 to 11.5 MeV (i.e., to above the neutron threshold). The combination of these measurements provides the most detailed account of bound-state dipole strength available in this mass region.

Measurements of the (${}_{}{}^3{}_{}{}^{}\mathrm{He}$, n) reaction have been carried out on a number of odd-$Z$ targets in the vicinity of the closed proton shell at $Z=50\mathrm{}$. For the targets ${}_{}{}^{107,109}{}_{}{}^{}\mathrm{Ag}$ and ${}_{}{}^{113,115}{}_{}{}^{}\mathrm{In}$ the results can be interpreted in terms of the coupling of proton particles or holes to the known pairing vibrational states in neighboring tin nuclei. For targets of ${}_{}{}^{121,123}{}_{}{}^{}\mathrm{Sb}$ the expected $L=0\mathrm{}$ transition strength is observed, but is found to be spread over several final states.

The energy and angular distribution of the $\alpha$ particles from the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}(\mathrm{n},\alpha )$ and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}(\mathrm{n},\alpha )$ reactions for 14.1 MeV incident neutron energy were measured by means of a multitelescope system. The results concerning the total He-production cross sections and the angle-integrated $\alpha$-emission cross sections $\frac{d\sigma }{d{E}_{\alpha }}$ are in fair agreement with previous measurements; for the angular distribution no detailed measurements have as yet been reported. The results are analyzed in the framework of the statistical model of nuclear reactions. Comparison of such calculations with the measured $\alpha$-emission cross sections allows one to extract nuclear level densities for ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$, the residual nuclei reached in the studied reactions in the energy region up to the neutron binding energy, and for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$, the residual nuclei reached by neutron emission for energies around 11 MeV. Within experimental error a purely exponential increase of the level density with excitation energy was found for both ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$. The spin cutoff parameters for ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ derived from the data indicate that there is no reduction of the effective moment of inertia below the rigid body value.

Elastic and inelastic proton scattering angular distributions of cross section and analyzing power were measured on three analog resonances at 10.30, 10.54, and 10.60 MeV in the ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$-plus-proton system. The data have been analyzed using a coupled-channels-plus-resonance formalism. Optical-model parameters required for the analysis were obtained from measurements at two off-resonance energies. Polarization measurements carried out on two of these resonances are consistent with values predicted from the analysis of the cross-section and analyzing-power data. The analysis yields improved values of the spectroscopic amplitudes for coupling of nucleons to the ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ $2_1^{+}$ core.

Transverse inelastic electron scattering cross sections for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ have been measured at 180° in the quasielastic region for 12 incident electron energies. From these data transverse response functions have been extracted at constant three-momentum transfers of 250, 290, 330, 370, 410, 450, 490, and 530 MeV/c. The results in the quasielastic region have been compared with two relativistic Fermi gas models: one employing a momentum-transfer-dependent effective mass $M^{*}$, the other employing the free-nucleon mass. The region beyond the quasielastic peak has been compared with model calculations incorporating meson-exchange currents and nucleon-nucleon correlations. Transverse response function $y$ scaling is also discussed.

Formulation is made of an exact finite-range distorted-wave Born approximation for the case in which the distorting potentials depend on the total angular momentum $J$. The general formula thus derived is then simplified for the cases in which the spins of the projectile, target, and ejectile are zero. This simplified form of the new exact finite-range distorted-wave Born approximation formula is applied to the analyses of the resonant structures seen in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$,${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$)${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$($4_1^{+}$) reaction, and it is found that good fits to data are obtained. It is also shown that the mechanism embodied in the band crossing model plays an essential role in achieving these good fits. A detailed discussion concerning the absolute magnitude of the distorted-wave Born approximation cross sections is also presented, based on recent calculations which use the cluster model.

Resonant energies, widths, strengths, spins, and parities are deduced for a total of 56 compound nuclear levels in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne} \left(16.4\mathrm{}\le E_x\le 21.1 \mathrm{MeV}\right)$ using $\alpha +{}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ elastic and inelastic scattering data. Writing the reaction amplitude for spinless positive-parity particles as a nonresonant term plus a sum over resonant partial waves permitted fitting the data at up to 20 angles. The procedure works effectively on regions at least up to 1.4 MeV wide and containing up to 15 resonances. Forty-one levels appear in the elastic scattering channel, while 11 are visible in the inelastic scattering to the first excited state in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O} (E_x=6.05\mathrm{} \mathrm{MeV})$. Four levels appear in both channels. Sixteen of these levels have not been reported previously.

The high neutron resolution capability of the Oak Ridge Electron Linear Accelerator has been used to investigate the unbound region of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ via neutron resonance spectroscopy studies of the ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$+n system. The total cross section of ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ was measured over the neutron energy range from 90 to 1500 keV, and the capture cross section was measured over the range from 30 to 1100 keV. Analysis of the data yielded spectroscopic factors for the $s$ states in the unbound region for excitation energies from 7 to 8 MeV. Continuum shell model calculations of the $s$ and $d$ states were also performed for both the bound and the unbound regions of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$. In general, the measured and calculated neutron strengths for $s$ waves in the unbound region are in reasonable agreement, although the fragmentation of single-particle strength seen experimentally is somewhat higher than that predicted. Core-particle calculations for the $p$ states in the unbound region of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ were also performed, and, on the basis of all these results, plus those of others, we have summarized our understanding of the distributions of single-particle neutron strengths in the $s$, $p$, and $d$ states of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ for excitation energies up to 8.5 MeV.

The $s$- and $p$-wave neutron scattering functions obtained previously by $R$-matrix analyses of high resolution transmission data for 0-1.4 MeV neutrons on ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ have been averaged by means of a simple analytic approximation to obtain experimental optical model scattering functions. To describe these with a spherical optical model potential requires the real well depth to be about 20% deeper for $p$ waves than for $s$ waves. This result agrees with an earlier analysis for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ and suggests that deformation effects must be included for all three nuclei.

Recent analysis of ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ neutron scattering data in the low energy resonance region has resulted in optical potential parameters having different $s$- and $p$-wave well depths. We show that a proper inclusion of the collective excitations of the target nucleus reduces this difference to well within the limits of experimental error and confirms the ability of the neutron resonance reaction to act as a meaningful probe of the bulk properties of target nuclei.

Neutron capture by enriched ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ and by natural Cl was measured as a function of neutron time-of-flight over a 40 m path. Resonance peaks were fitted by least squares to Breit-Wigner parameters. The energy range covered was 4 to 225 keV for 54 ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$ resonances and 8 to 151 keV for 12 ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ resonances. Corresponding average capture in stellar environments at $kT=30\mathrm{}$ keV was calculated as (10.0±0.3) mb for ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$ and (2.15±0.08) mb for ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$.

Differential cross sections for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(p,p)${}_{}{}^3{}_{}{}^{}\mathrm{He}$ elastic scattering have been measured at 11 energies in the laboratory energy range 19.5 to 47.5 MeV. The most forward c.m. angle for the angular distributions varies from 10.1° to 13.4°, and the most backward angle varies from 163.2° to 173.4°. The relative errors in the data are usually less than 2%, and the scale error is 1.5%. The present data, together with analyzing power and total reaction cross section data of others, have been subjected to an energy-dependent phase shift analysis. The extracted phase shifts and the differential cross sections are compared with the results of a simple resonating-group calculation.

Analyzing power data $A_y\left(\theta \right)$ have been obtained for $\overrightarrow{\mathrm{p}}+{}_{}{}^3{}_{}{}^{}\mathrm{He}$ elastic scattering at 11 energies between 21.4 and 49.6 MeV for laboratory angles between 20° and 160°. Errors typically are less than 0.01. These data are compared with fits obtained in a single energy phase-shift analysis and $R$-matrix predictions.

Angular distributions have been measured for the reaction ${}_{}{}^{25}{}_{}{}^{}\mathrm{Mg}$(d,p)${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$, at a bombarding energy of 12.0 MeV, for states up to 6 MeV excitation in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$. Distorted-wave analysis has allowed extraction of $l$-value admixtures and spectroscopic strengths. Comparison is made with shell-model calculations.

Angular distributions for the ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}(\alpha ,\mathrm{t}){}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}(\alpha ,\mathrm{h}){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ one-nucleon transfer reactions have been measured for an incident energy of 80 MeV. Finite-range distorted-wave Born-approximation calculations, using new $\mathrm{sd}$-shell model wave functions, were found to be in reasonable agreement with the data corresponding to exciting positive-parity final states. Transitions to negative-parity $4^{-}$, $5^{-}$, and $6^{-}$ $T=0\mathrm{} \mathrm{and} 1$ states display shapes characteristic of an $l=3\mathrm{}$ orbital angular momentum transfer, consistent with a dominant ($0f_{\frac{7}{2}}0d_{\frac{5}{2}}^{-1\mathrm{}}$) model configuration. Extracted strengths are in generally fair agreement with previous results, except for those corresponding to the unbound $5^{-}$ and $6^{-}$ $T=1\mathrm{}$ ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ states which are about 50% more fragmented than previously observed.

Channel-coupling effects on the properties of the n + ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ system are studied. The channels included are n + ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, n + ${}_{}{}^6{}_{}{}^{}\mathrm{Li}_{}^{*}{}_{}{}^{}$, and ${}_{}{}^3{}_{}{}^{}\mathrm{H}+\alpha$ channels. The calculation shows that there exist $S=\frac{1}{2}$, $L=0\mathrm{} \mathrm{and} 1$ resonance states in the n + ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ continuum, in agreement with the result of a recent $R$-matrix study. In addition, it is found that the ${}_{}{}^3{}_{}{}^{}\mathrm{H}+\alpha$ channel has a substantial influence, indicating that the energetically most-favored cluster configuration must always be considered in a resonating-group investigation. The coupling between n + ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and n + ${}_{}{}^6{}_{}{}^{}\mathrm{Li}_{}^{*}{}_{}{}^{}$ channels turns out generally to be fairly weak, although it does become somewhat enhanced when the ${}_{}{}^3{}_{}{}^{}\mathrm{H}+\alpha$ channel is included in the calculation.

We have measured the cross section for the important fusion-energy reaction ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\mathrm{t},\alpha )\mathrm{n}$ at 17 energies over the triton bombarding energy range of 12.5-117 keV. This corresponds to an equivalent deuteron bombarding energy range of 8.3-78.1 keV and to a plasma temperature ($\mathrm{kT}$) range of 0.7-18.8 keV. The cross section is accurate to 1.4% over most of the energy range, with the error rising to 4.8% at the lowest energy. These data are considerably more accurate than the previous d + t measurements in this energy range. We compare our data with those of other measurements and with an existing $R$-matrix analysis of the mass-5 system. We have also performed a single-level $R$-matrix analysis of a restricted data base that contains our data and have used that analysis to compute Maxwellian reactivities up to a plasma temperature of 20 keV. In addition, for calibration purposes, we measured to better than 1% absolute error the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(p,p)${}_{}{}^2{}_{}{}^{}\mathrm{H}$ elastic differential cross section at six laboratory angles at a proton bombarding energy of 10.04 MeV.

Absolute ($\gamma ,{\mathrm{p}}_0$) and ($\gamma ,{\mathrm{p}}_1$) differential cross sections for ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ have been measured at seven angles in the energy interval between 13.4 and 25.8 MeV. A sum of Legendre polynomials was fitted to the angular distributions to deduce the angular distribution coefficients. The ($\gamma ,{\mathrm{p}}_0$) and ($\gamma ,{\mathrm{p}}_1$) cross sections have a similar magnitude and represent a minor fraction of the total photoproton channel. The global difference between the two cross sections is attributed to configurational splitting effects. From the ($\gamma ,{\mathrm{p}}_0$) angular distribution coefficients, an $E2\mathrm{}$ cross section was estimated, contributing about 37% to the total $E2\mathrm{}$ energy-weighted sum rule.

We construct and examine the properties of the energy-independent potential $\overline{U}$ which is wave function equivalent to the usual optical potential $U\left(E\right)\mathrm{}$. A simple procedure is presented for constructing $\overline{U}$ in the uniform medium, and physical examples are discussed. The general result for the finite system, a recursive expansion in powers of $U\left(E\right)\mathrm{}$, is used to investigate the multiple scattering expansion of $\overline{U}$ The energy-independent potential is found to have serious shortcomings for direct microscopic construction or phenomenological parametrization. The microscopic theory, as exemplified here by the multiple scattering approach, does not lead to a reliable approximation scheme. Phenomenological approaches to $\overline{U}$ are unattractive because the physics does not guide the parametrization effectively: the structure of the nonlocality is not tied directly to the dynamics; Im $\overline{U}$ changes sign; different elements of the physics, separate in $U\left(E\right)\mathrm{}$, are completely entangled in $\overline{U}$.

The absolute ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(\gamma ,{\mathrm{p}}_0){}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ cross section was measured in the energy region of the giant dipole resonance. The magnitude of our 90° differential cross section, which has an absolute uncertainty of about 12%, is in disagreement with the one obtained by detailed balance from a recent ($\mathrm{p},{\gamma }_0$) measurement, but is in reasonable correspondence with the combined data from the Argonne and Stanford groups.