A study of isobaric-analog states (IAS) excited in the ($p,d$) and ($d,t$) reactions on ${}_{}{}^{92,94,96}{}_{}{}^{}\mathrm{Mo}$, the (${}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha$) reaction on ${}_{}{}^{92,96}{}_{}{}^{}\mathrm{Mo}$, and the ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}\mathrm{}(p,d)\mathrm{}{}_{}{}^{97}{}_{}{}^{}\mathrm{Mo}$ reaction is reported. Coulomb energies and angular distributions were measured for analogs of all parent states observed in a ($d,{}_{}{}^3{}_{}{}^{}\mathrm{He}$) study on Mo targets, and some additional nuclear structure information was obtained. Distorted-wave Born-approximation calculations were performed, and the resulting spectroscopic factors reveal a pronounced decrease in $l=1\mathrm{}$ hole strength with increasing mass number as well as fluctuations in the ratios $\frac{C^2{S}_n\mathrm{}(p,d)\mathrm{}}{C^2{S}_n\mathrm{}(d,t)\mathrm{}}$. The first effect is discussed in terms of mixing with the dense spectrum of $T_{<}$ levels in the IAS region.

The nuclei ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$, ${}_{}{}^{183,184}{}_{}{}^{}\mathrm{W}$ were studied with the ($n,\gamma$) reaction for neutrons of several resonant energies. High- and low-energy $\gamma$ radiation following resonant capture was observed with Ge(Li) detectors. Level schemes were constructed from these data in conjunction with previous information from charged-particle reactions and decay studies. Some discrepancies among previous studies were clarified and a large number of spin assignments suggested. From these and data from the ($d,p$) reaction an analysis is made of the fractionation and distribution of the single-particle Nilsson strength in the energy region 1.3-2.3 MeV. It is found that the Nilsson model breaks down rather suddenly above the vibrational energy: A much larger than expected number of rotational bands are observed and the ($d,p$) strength is severely fragmented. This mixing appears to be larger in ${}_{}{}^{183}{}_{}{}^{}\mathrm{W}$ than in ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$ and still larger in ${}_{}{}^{184}{}_{}{}^{}\mathrm{W}$. The data for $2^{+}$ and $1^{+}$ states in ${}_{}{}^{184}{}_{}{}^{}\mathrm{W}$ are compared with recent random-phase-approximation calculations: Again, much more configuration mixing is observed than is calculated and significant ($d,p$) strength occurs lower than predicted in the spectrum.

Processes involving two vertices are analyzed in nuclear physics. By means of an appropriate isospin analysis, corrections to the usual single-particle Hamiltonian arising from nuclear correlations are explicitely given for Compton scattering and muon and pion radiative capture. In particular the $\Delta T=2\mathrm{}$ channel is seen to play a fundamental role in radiative muon capture for medium and heavy nuclei where its contribution to the rate amounts to ∼10% for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and affects sensitively the estimates of $g_p$.

The ${}_{}{}^{94}{}_{}{}^{}\mathrm{Zr}({}_{}{}^3{}_{}{}^{}\mathrm{He},d){}_{}{}^{95}{}_{}{}^{}\mathrm{Nb}$ reaction was studied with 35.6-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ particles from the Argonne cyclotron. Experimental angular distributions are compared with distorted-wave Born-approximation calculations to determine $l$ values and spectroscopic factors. The results are compared with the previous data on (${}_{}{}^3{}_{}{}^{}\mathrm{He},d$) and ($d,{}_{}{}^3{}_{}{}^{}\mathrm{He}$) reactions and $\beta$ decay. The proton configurations of ${}_{}{}^{95}{}_{}{}^{}\mathrm{Nb}$ are discussed in terms of this data and recent theoretical results.

Levels of ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ have been studied with the ${}_{}{}^{96}{}_{}{}^{}\mathrm{Mo}(p,\alpha )$ reaction at 15-MeV incident energy. Angular distributions for transitions to a dozen prominent levels below 2 MeV have been measured with 30- to 40-keV experimental resolution over ${15}^{\circ }\le {\theta }_L\le {150}^{\circ }$, and they have been compared with distorted-wave Born-approximation (DWBA) calculations. Angular distributions for $p-{}_{}{}^{96}{}_{}{}^{}\mathrm{Mo}$ and $\alpha -{}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ elastic scattering have also been measured, and proton and $\alpha$-optical-model potential parameter sets have been determined by a search procedure. Of the three sets of $\alpha$-potential parameters, the one which best reproduced the measured ($p,\alpha$) angular distributions of known low-lying levels in ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ was chosen as the standard set for the rest of the ($p,\alpha$) calculations. The conventional triton-cluster form factor was used exclusively for the ($p,\alpha$) DWBA calculations which lead to $J^{\pi }$ assignments. A semimicroscopic form factor was used in a few test cases in order to check the sensitivity of calculations to the choice of form factor. Reliable $J^{\pi }$ assignments have been made for levels below 1.5 MeV based on the $j$ dependence for $l=1(p,\alpha )$ transfers, as well as for higher angular momentum transfers observed in the present work; and they are in excellent agreement with those determined from recent Coulomb-excitation and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(\alpha ,p\gamma )$ works. Dominant three-nucleon shell-model configurations to which the levels of interest belong have been proposed.

Inelastic electron scattering from high-lying $6^{+}$ states in the Ni isotopes has been measured. These states are interpreted as core-excited states.

Buss and Smither recently studied levels in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ by investigating the thermal-capture reaction ${}_{}{}^{147}{}_{}{}^{}\mathrm{Sm}(n,\gamma )$. Of the 32 levels that they considered (many of these were proposed as new states) only 18 have been observed in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Eu}$ decay. Our investigation of the ${}_{}{}^{148}{}_{}{}^{}\mathrm{Eu}$ decay scheme has produced strong corroborative evidence for the existence of seven additional states proposed by Buss and Smither. Their energies (in keV) and spin assignments are as follows: 1454.6, $2^{+}$; 1664.2, $2^{+}$; 1903.8, $3^{+}$ or $4^{+}$; 2173.2, $2^{+}$; 2339.4, $2^{+}$ or $3^{-}$; 2390.0, $3^{+}$; and 2570.5, $2^{+}$. The 1454.6-keV level is apparently the second $2^{+}$ level expected from energy-level systematics to be at ∼1.4 MeV, but for which no conclusive evidence has been available.

Conflicting data on ${}_{}{}^{20}{}_{}{}^{}\mathrm{Na}$ ${\beta }^{+}$ decay are discussed. Estimates show that the process ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}\mathrm{}(p,2n)\mathrm{}{}_{}{}^{23}{}_{}{}^{}\mathrm{Al}\left({\beta }^{+}\right){}_{}{}^{23}{}_{}{}^{}\mathrm{Mg}\left(0.0\mathrm{} \mathrm{MeV}\right)$ (of indistinguishable half-life and end-point energy) interfered with early measurements of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}(p,\alpha n){}_{}{}^{20}{}_{}{}^{}\mathrm{Na}\left({\beta }^{+}\right){}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}\left(1.63\mathrm{} \mathrm{MeV}\right)$.

We have performed partial-wave calculations using the Klein-Gordon and the Dirac equations for the 1-GeV proton scattering experiments of Palevsky et al. Without the explicit introduction of spin in the optical potential, the two equations give closely similar results. Compared with the eikonal approximation the differential cross sections of the partial-wave analysis show considerable filling in of the diffraction minima. We compare the simple Watson theoretical optical-potential predictions with phenomenological fits to the data, and reach substantially the same conclusions as Palevsky et al. The optical potentials used in this work are either the fourth component of a four-vector or a scalar potential.

The ratio $\frac{B(E2;4\mathrm{}\to 2)}{B(E2;2\mathrm{}\to 0)}$ has been calculated for even-even rotational ($152\le A\le 188$) nuclei from lifetime and Coulomb excitation data. Better agreement with theory is achieved when modern data, free from hyperfine interaction effects, are being considered.

The isospin-forbidden proton and $\alpha$-particle decay modes of the lowest $T=2\mathrm{}$ state in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$-($E_{\mathrm{exc}}=22.717\mathrm{}$ MeV) have been measured, using the reaction ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}\mathrm{}(p,t)\mathrm{}{}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ at $E_p=43\mathrm{}$ MeV. Decay protons and $\alpha$ particles to states in ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, respectively, were detected in coincidence with outgoing tritons. Proton branching ratios of (25 ± 6)%, and (22 ± 5)%, and (15 ± 5)% to the ground state, 5.27 + 5.30, and 6.32-MeV states were obtained. The total $\alpha$-particle branching ratio to the ground state and 4.44-MeV state in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ is zero within the experimental uncertainties. These results thus indicate that a branch of about 37% is unaccounted for by proton and $\alpha$-particle decay to the low-lying states of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$.

The highly selective reactions ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$)${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}({}_{}{}^{16}{}_{}{}^{}\mathrm{Li},t){}_{}{}^{17}{}_{}{}^{}\mathrm{F}$ have been used to populate mirror states below 7 MeV in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$. Negative-parity states are populated much more strongly than positive-parity states. The strongest state observed in ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$ is a new state at $E_x=5.220\mathrm{}\pm 0.01$ MeV, which is identified as the mirror of the 5.217-MeV state in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$.

Analysis of data from the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^6{}_{}{}^{}\mathrm{Li},t){}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ reaction shows that the tentative new 4.59-MeV state in ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ is indeed present. As a result, a state is missing in the corresponding region of excitation in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$. Possible mirror correspondences are discussed.

In this paper, we include off-shell two-body $T$ matrices in both the unary and binary terms of the optical potential derived from Watson's multiple-scattering theory. We take a wholly momentum-space-oriented approach: All calculations are performed in terms of momentum variables and spatial coordinates do not appear. We conclude that it is not possible at present to obtain definitive information on the off-shell nucleon-nucleon $T$ matrix from intermediate-energy elastic nucleon-nucleus scattering. On the other hand, the size of the off-shell effect is sufficiently large that it is not possible to unambiguously select a model for the pair-correlation function without a definite model for the off-shell nucleon-nucleon scattering amplitude.

The binding energy problem of ${}_{\Lambda }{}^3{}_{}{}^{}\mathrm{H}$ in the ground state and in a possible excited state has been investigated in the light of the recent experimental and theoretical results available for the low-energy parameters of $\Lambda$-nucleon interaction. The calculations are performed in Faddeev's formalism with two-body nonlocal separable potentials between pairs of particles, two of which are of unequal masses. For each of the sets of $\Lambda -N$ potentials, the binding energy of the $\Lambda$ particle within the hypertriton has been evaluated. One of our results for the binding energy of the hypertriton in an excited state ($J=\frac{3}{2}$) is in reasonably good agreement with that of Toepfer and Schick. We have also discussed the possible qualitative effects of charge-symmetry breaking in the $\Lambda -N$ interaction in relation to the quantitative comparisons of the $\Lambda$ binding energies.

We calculate the triton binding energy and charge form factor for a set of phase-shift-equivalent, $S$-wave, spin-independent potentials. The Faddeev equations are solved by the method of Padé approximants. We present a partial wave expansion for the triton form factor for a $J=0\mathrm{}$ spatially symmetric wave function. A 6-MeV variation in triton binding energy results occurs for the potentials studied. All but 1 MeV of this off-shell variation is attributable to changes in the deuteron wave function. The relation between the triton binding energy and deuteron wave function is discussed. We find that the triton binding energy is sensitive to the relative amount of scale distortion in the momentum-space deuteron wave function. For the potentials studied, less binding in the triton is associated with deuteron wave functions that are more "compressed," i.e., fall off more rapidly in momentum space for $k<\mathrm{}2\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$. We also find that potentials that yield less binding in the triton (in worse agreement with experiment) yield a diffraction minimum in the form factor at smaller momentum transfer (in better agreement with experiment). The disparity between the binding-energy results and form-factor results with respect to experiment may indicate a role for three-body forces in the three-nucleon system.

A nonlinear integrodifferential equation for the correlation function between two nucleons in nuclear matter is obtained. This equation results by writing the (trial) expression of the energy per particle in nuclear matter in a suitable form and applying subsequently the variational principle. The investigation of the behavior of the equation for large internucleon distances $r_{12}$ leads to a new integral constraint on the correlation function.

The cross section for neutrino-induced nuclear reactions is presented in the form of a multipole expansion, appropriate for the excitation of nuclear levels of a definite spin and parity. The theory is then applied to the $T=1\mathrm{}$ levels of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, knowledge of their excitation cross sections being required for both low-energy $E_{\nu }\le 53$ MeV, with neutrinos from stopped muons) and high-energy ($E_{\nu }\sim \mathrm{GeV}$) neutrino experiments that use counters containing carbon. We take a phenomenological approach, determining the needed transition densities from fits to the measured form factors of these levels for the closely related electroexcitation process. While the low-energy cross section is dominated by the excitation of the $1^{+}$ ground state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$, the high-energy cross sections receive their largest contributions from both positive-parity spin-flip states and especially from the $1^{-}$ giant-resonance levels, with additional strength from $3^{+}$ and $2^{-}$, $4^{-}$ levels.

We have compared the usual impulse-approximation and the elementary-particle treatments of nuclear processes using nuclear $\beta$ decays as examples. Both treatments are shown to lead to essentially equivalent results for allowed transitions and for natural-parity forbidden transition of the types $\Delta J^{P_i{P}_f}=1^{-} \mathrm{and}\mathrm{possibly} 2^{+},3^{-},\dots$. There exist, however, some differences in detailed structures in small correction terms. In the case of unnatural-parity forbidden transitions, in particular, $J_i^{P_i}\left(0^{-}\right)\to J_f^{P_f}\left(0^{+}\right)+e^{-}+{\overline{\nu }}_e$, there exist some discrepancies between the two approaches, suggesting an important role of meson-exchange corrections in the impulse approximation.