The excitation energy of the lowest $1^{+}$, $T=1\mathrm{}$ state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, which is important for parity nonconservation studies, has been determined in a photon scattering experiment to be 11 262.3 ± 1.9 keV. Values for the $\gamma$-ray branching of this level to the ground state and to the first $2^{+}$ level in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ are 84 ± 5% and 16 ± 5%, respectively.

NUCLEAR REACTIONS ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}(\gamma , \gamma )$, $E_{\gamma }<18\mathrm{}$ MeV, bremsstrahlung; measured $E_{\gamma }$, $\gamma$ branching. Ne natural targets.

Two different prescriptions for the spin dependent amplitudes in inelastic proton-nucleus scattering have been put forward in the literature. We compare their predictions. The correct one is essentially the eikonal approximation to the distorted-wave Born approximation. The other one gives radically different predictions for many spin observables.

NUCLEAR REACTIONS Spin observables in ($p, p^{\prime }$)reactions with a numerical illustration for 800 MeV proton-${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ scattering.

An analysis of the differential cross section for electron scattering at 180° from complex nuclei is made in the distorted-wave Born approximation to see the conditions in which charge multipoles may contribute to such cross sections, questioning the usual interpretation of the data in terms of pure transverse form factors.

NUCLEAR REACTIONS Electron scattering; complex nuclei. Charge multipole contributions to 180° ($e, e^{\prime }$) in DWBA.

High-lying states of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$ produced in α scattering are compared with the spectra corresponding to the two dynamical symmetries of the U(4) model. The ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ system prefers the O(4) limit, while in the other cases, where the experimental spectra are less complete, there are no such preferences.

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{24,26}{}_{}{}^{}\mathrm{Mg}(\alpha , {\alpha }^{\prime })$ resonances, application of the algebraic model.

Negative parity $\Delta J=1\mathrm{}$ bands were observed in ${}_{}{}^{118,120}{}_{}{}^{}\mathrm{Sb}$ with (${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, $3\mathrm{n}\gamma$) and (${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, $3\mathrm{n}\gamma$) reactions. Bandhead and level spacing properties are consistent with the $g_{\frac{9}{2}}$ proton-hole collectivity and a decoupled $h_{\frac{11}{2}}$ neutron. These bands decay to the low-lying $(\pi d_{\frac{5}{2}}, \nu h_{\frac{11}{2}})8^{-}$ isomers via several high-spin states, one of which, $7^{\mathrm{}(+)\mathrm{}}$ in ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sb}$, had a measured $t_{\frac{1}{2}}=22.4\mathrm{}\pm 0.5$ ns. Comparisons to $\pi {g_{\frac{9}{2}}}^{-1\mathrm{}}$ $\Delta J=1\mathrm{}$ bands in odd-mass Sb nuclides are made.

NUCLEAR REACTIONS ${}_{}{}^{114,116}{}_{}{}^{}\mathrm{Cd}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, 3n)${}_{}{}^{118,120}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$(${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, 3n)${}_{}{}^{118}{}_{}{}^{}\mathrm{Sb}$; measured $\gamma -\gamma -t$ coinc. ($E, \gamma , t$); deduced level schemes in ${}_{}{}^{118,120}{}_{}{}^{}\mathrm{Sb}$, $\gamma$ multipolarities, $J^{\pi }$, $T_{\frac{1}{2}}$. Enriched targets, Ge detectors.

We have performed a coincidence measurement of the angular distribution of fission fragments for the complete capture reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}({}_{}{}^{238}{}_{}{}^{}\mathrm{U}, f)$ and have discriminated against fission fragments from incomplete capture reactions. The angular distribution is consistent with a $\frac{1}{sin\theta }$ dependence, in contrast to expectations assuming statistical equilibrium and saddle shapes given by the rotating liquid drop model.

NUCLEAR REACTIONS ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}({}_{}{}^{238}{}_{}{}^{}\mathrm{U}, f)$, $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=291\mathrm{}$ MeV, $\sigma \left({\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right)$ ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=119\mathrm{}°-164\mathrm{}°$, angular distribution compared to RLDM.

Half-lives and delayed neutron emission probabilities have been measured for ${}_{}{}^{121-123}{}_{}{}^{}\mathrm{Ag}$. The new isotope ${}_{}{}^{124}{}_{}{}^{}\mathrm{Ag}$ has been identified by its delayed neutron decay. Its half-life is 0.54±0.08 s and its neutron emission probability is > 0.1%. From beta decay measurements, a half-life of 2.07±0.03 s was found at mass 123 and assigned to the previously unknown ${}_{}{}^{123}{}_{}{}^{}\mathrm{Cd}$. An improved half-life for ${}_{}{}^{124}{}_{}{}^{}\mathrm{Cd}$ of 1.2±0.1 s is reported.

RADIOACTIVITY ${}_{}{}^{121-124}{}_{}{}^{}\mathrm{Ag}$, ${}_{}{}^{122-124}{}_{}{}^{}\mathrm{Cd}$ [from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(n, f)$]; measured $t_{\frac{1}{2}}$, $P_n$, on-line mass separation, $n$, $\beta$ multiscaling.

$Z=1-7\mathrm{}$ particles were observed in coincidence with energetic protons that resulted from bombardment of ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$ with 191-MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions. The multiplicities of the coincident particles and their dependence on the angle of the gating energetic protons are consistent with the existence of two principal reaction processes of comparable magnitude yielding energetic protons: (1) disintegration of the projectile and (2) preequilibrium emission with the remaining projectile mass fusing with the target usually at low excitation energy.

NUCLEAR REACTIONS ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, \mathrm{p}X)$, $E=191\mathrm{}$ MeV; measured $\sigma$ of $Z=1-7\mathrm{}$ particles in coincidence with energetic protons.

We have measured excitation functions of the $\gamma$ rays resulting from the bombardment of ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ by polarized and unpolarized protons in the energy range $E_p=2.5-9.5\mathrm{}$ MeV with emphasis on identifying dipole decays to the first ($0^{+}$) and second ($3^{-}$) excited states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. Resonances in ${\gamma }_{12}$ are observed at $E_x=16.21, 16.45, 16.82, 17.12, 18.03, 18.98, 19.90, \mathrm{and} 20.41$ MeV. The 16.21 and 17.12 MeV resonances in ${\gamma }_{12}$ are identified as $M1\mathrm{}$ decays of the $1^{+}$ $T=1\mathrm{}$ states to the 6.05 MeV $0^{+}$ state in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. The measured ratio of reduced strengths $\frac{B(M1, {\gamma }_1)}{B(M1, {\gamma }_0)}$ is 0.48±0.03 for decays from the 16.21 MeV state and 0.55±0.04 for decays from the 17.12 MeV state. The 18.03 MeV resonance is due to a $3^{-}$ $T=1\mathrm{}$ state in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with a strength $\frac{{\Gamma }_p{\Gamma }_{{\gamma }_2}}{\Gamma }=(1.96\mathrm{}\pm 0.27)$ eV and the 18.98 MeV resonance is due to the $4^{-}$ $T=1\mathrm{}$ stretched particle-hole state with a strength of (0.85±0.10) eV. We determine absolute particle and $\gamma$ widths for these states. The $M1\mathrm{}$ ${\gamma }_2$ width of the 18.98 MeV state, (7.1±3.1) eV, is in agreement with a shell-model calculation. Resonances in ${\gamma }_3$ are observed at 16.82 and 17.27 MeV and in ${\gamma }_4$ at 17.88 MeV. The excitation energies and widths of these levels as well as the strengths of the $\gamma$ transitions suggest a $T=1\mathrm{}$ character for all of the resonances for which capture $\gamma$ rays are observed. Correspondences of our resonances to levels in ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ are given. Strong ${\alpha }_1$ branches for many of these states indicate isospin impurities. We compare $\gamma$ widths, including ground-state $M1\mathrm{}$ decays, and allowed $\beta$ transition rates in $A=16\mathrm{}$ nuclei with shell model calculations and obtain rough agreement with the experimental results. Additional shell model calculations for $M1\mathrm{}$ and Gamow-Teller decays in the $A=14, 15, 17, \mathrm{and} 18$ nuclei are presented, which indicate that Gamow-Teller matrix elements are quenched by ∼20% relative to shell model predictions and also relative to the spin part of the $M1\mathrm{}$ matrix elements.

NUCLEAR REACTIONS ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}(p, \gamma ){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}(p, p^{\prime }\gamma ){}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}(p, {\alpha }_1\gamma ){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, $E=2.5-9.5\mathrm{}$ MeV, measured capture $\gamma$ rays to $E_x=6.05, 6.13, 6.92, \mathrm{and} 7.12$ MeV final states. Measured $\sigma \left(90\mathrm{}°\right)$, $A_y\left(90\mathrm{}°\right)$, $\sigma \left(\theta \right)$. Deduced $M1\mathrm{}$ and $E1\mathrm{}$ resonance strengths. Performed shell model calculations and compared with these and other $M1\mathrm{}$ and Gamow-Teller strengths in nuclei near $A=16\mathrm{}$. Deduced average inhibition of GT matrix elements relative to shell model and to the spin part of $M1\mathrm{}$ matrix elements.

The photoproton and photoneutron cross sections for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are evaluated in the light of several recent measurements, and are found to be substantially different in the energy region below 30 MeV. Because these cross sections are dominated by $\Delta S=0\mathrm{}$, $\Delta T=1\mathrm{}$ $E1\mathrm{}$ transitions, this result implies strong isospin mixing in the four-nucleon system. Furthermore, since available continuum shell-model calculations including Coulomb effects predict only small differences in the photoproton and photoneutron cross sections except near threshold, this result suggests that a nonzero charge asymmetry is present in the nuclear force.

NUCLEAR REACTIONS ${}_{}{}^4{}_{}{}^{}\mathrm{He}(\gamma , p){}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}(\gamma , n){}_{}{}^3{}_{}{}^{}\mathrm{He}$, evaluated cross sections, cross-section ratio; isospin mixing, charge asymmetry.

Inclusive energy spectra of light charged particles from the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ + ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$+$p$, and ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ + ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ reactions have been measured using beams of 30 to 75 MeV. The continuum parts have been studied in the framework of phase space calculations. The influence of other reaction mechanisms, such as final state interactions, sequential processes, and quasifree reactions is evaluated. We deduce the nontrivial angular dependence of the various phase spaces.

NUCLEAR REACTIONS ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ + ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at $E_{\mathrm{lab}}=40\mathrm{}$ MeV; ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$+$p$ at $E_{\mathrm{lab}}=45\mathrm{}$ MeV; ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ + ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, $E_{\mathrm{lab}}=30, 50, 75$ MeV; measured charged light particle spectra $1\le Z\le 4$, $1\le A\le 9$; interpretation of inclusive spectra with phase space model; comparison with other models; deduced angular dependence of various exit channels.

The levels of the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ nucleus were studied via the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(p, \alpha )$ reaction at incident proton energies of 30 and 50 MeV. Accurate excitation energies as well as some of the corresponding widths are extracted for the first few levels known. Marked differences with accepted values were found. The existence of higher excited states in the region $E_{\mathrm{exc}}=8-12\mathrm{}$ MeV cannot be ruled out. The aim is not to study reaction mechanisms leading to ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ excited states but rather to establish their excitation energies and widths and to compare them to the published values. The importance of understanding the continuum in the particle spectra is stressed as far as it influences the position and width of the excited states.

NUCLEAR REACTIONS ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(p, \alpha ){}_{}{}^6{}_{}{}^{}\mathrm{Li}$, $E_{\mathrm{lab}}=30, 50$ MeV. Measured alpha particle spectra; continuous spectra; phase space model; deduced excitation energies and widths; comparison with previous values.

It is shown that the position and width of resonant levels, as deduced from experimental spectra, are dependent upon their structure. The corresponding corrections to get true positions and widths may be considerable for light nuclei.

NUCLEAR REACTIONS Phase space model; resonances; level parameters and breakup; continuous spectra; application to the $A=6\mathrm{}$ isomultiplet.

The energy dependence and analytic structure of the effective interaction for elastic scattering of composite particles are investigated using Feshbach's projection technique. A generalized Levinson theorem is established for complex, nonlocal, and energy-dependent interactions. The analytical results are illustrated by means of Argand diagrams for a solvable model and the effect of energy averaging is discussed.

NUCLEAR REACTIONS Scattering theory, $S$ matrix for absorptive, energy-dependent potentials, Levinson theorem.

The elastic scattering neutron cross section at low energy displays many narrow resonances. By definition, the optical-model scattering function is equal to a suitable energy average of the actual scattering function. This average should be independent of the particular representation chosen for parametrizing the actual scattering function and also fairly independent of the averaging weight function. In particular, it should be fairly independent of the width of the weight function, even though a sparsity of resonances might require the width to be comparable to the energy range of the measurements. It is shown by direct numerical calculations of the average that this holds in the example of the scattering of $p_{\frac{3}{2}}$ neutrons by ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$. Attention is drawn to pitfalls which exist when this average is evaluated analytically from parametrized forms of the scattering function. Several ways of graphically representing or of parametrizing the average scattering function are illustrated and discussed.

NUCLEAR REACTIONS High resolution $R$-matrix scattering function, average scattering function, and optical model scattering function; application to ${}_{}{}^{32}{}_{}{}^{}S+n$ for $p_{\frac{3}{2}}$ neutrons.

Simple graphical techniques are employed to obtain a new (simultaneous) derivation of a large class of connected-kernel scattering equations. This class includes the Rosenberg, Bencze-Redish-Sloan, and connected-kernel multiple scattering equations as well as a host of generalizations of these and other equations. The basic result is the application of graphical methods to the derivation of interaction-set equations. This yields a new, simplified form for some members of the class and elucidates the general structural features of the entire class.

NUCLEAR REACTIONS Graphical techniques and connected-kernel equations. Rosenberg, Bencze-Redish-Sloan, and interaction-set equations.

We have measured differential cross section and analyzing powers $A_y^p$, $i{T}_{11}$, $T_{20}$, $T_{21}$, and $T_{22}$ for proton-deuteron elastic scattering near 20 MeV deuteron energy. The total error of the differential cross section was 1% or less. Each deuteron analyzing power was measured independently with the maximum efficiency. The total error of the analyzing power was less than 0.007. Faddeev calculations have been performed for three cases of nucleon-nucleon interaction. None of them gives an overall quantitative fit to the measured values. The effect of the Coulomb interaction is discussed.

NUCLEAR REACTIONS ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\overrightarrow{p}, p){}_{}{}^2{}_{}{}^{}\mathrm{H}$, $E_p=11.1\mathrm{}$ MeV; measured ${\sigma }_0\left(\theta \right)$, $A_y^p\left(\theta \right)$; ${}_{}{}^1{}_{}{}^{}\mathrm{H}(\overrightarrow{d}, d){}_{}{}^1{}_{}{}^{}\mathrm{H}$, $E_d=17.0, 20.0, 22.2$ MeV; measured $i{T}_{11}\left(\theta \right)$, $T_{20}\left(\theta \right)$, $T_{21}\left(\theta \right)$, $T_{22}\left(\theta \right)$. Faddeev calculations.

Negative-parity states of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ are studied by high-resolution inelastic electron scattering. The form factors of the $1^{-}$ (8.904), $5^{-}$ (9.702), $1^{-}$, $2^{-}$ (9.929), $3_2^{-}$ (10.180), and $4^{-}$ $T=1\mathrm{}$ (12.664) states are determined for the first time, for momentum transfers between 0.9 and 2.4 ${\mathrm{fm}}^{-1\mathrm{}}$. The $3_1^{-}$ (6.879) state is studied by subtracting off the theoretical contribution of the nearby $4^{+}$ (6.889) state. An upper limit for the $5^{-}$ $T=1\mathrm{}$ (13.248) is established. The $3^{-}$ $T=\frac{0}{6^{-}}$ $T=0\mathrm{}$ complex (11.58) remains unresolved. We present evidence for oblate-prolate deformation changes in the $3^{-}$ $T=0\mathrm{}$ states. The experimental data are compared with predictions of the open-shell random phase approximation of Rowe and Wong. In ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, the open-shell random phase approximation is demonstrated to be extremely sensitive to the ground state wave function used, and other possible limitations of the open-shell random phase approximation are discussed.

NUCLEAR REACTIONS ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ ($e, e^{\prime }$), $E=96-279\mathrm{}$ MeV, $\theta =90\mathrm{}°, 160°$, negative parity states; measured $\frac{d\sigma }{d\Omega }(E, \theta )$; deduced electromagnetic form factors, Tassie model parameters, $B\left(\mathit{\lambda }\right)$ values. Open-shell random phase approximation calculations.

A high resolution measurement of the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\gamma , p)$ cross section is presented from threshold to 28 MeV. In combination with the known ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\gamma , n)$ cross section an estimate of the total absorption cross section is obtained and compared with current theoretical predictions. An estimate of the distribution of the isospin components in the giant dipole resonance shows that isospin splitting and the relative $T_{<}$ and $T_{>}$ strengths are in agreement with predictions.

NUCLEAR REACTIONS ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\gamma , p)$, $E_{\gamma }=17.5-28.0\mathrm{}$ MeV; measured beta activation yield with bremsstrahlung, deduced cross section, integrated cross section, comparison with theory, isospin GDR components deduced.

Using a multiple scattering framework we construct a variant of the usual distorted-wave Born approximation transition matrix for stripping and pickup reactions. An alternative to the local energy approximation is derived which in the appropriate limit gives the commonly used zero range approximation for ($p, d$) and ($d, p$) reactions. Model calculations are developed in an eikonal framework and an examination of the sensitivity and energy dependence of the nuclear response function is made, using the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, d){}_{}{}^{11}{}_{}{}^{}\mathrm{C}({\frac{3}{2}}^{-}, \mathrm{g}.\mathrm{s}.\mathrm{})$ process.

NUCLEAR REACTIONS ($p, d$), ($d, p$), intermediate energy, multiple scattering formalism with direct treatment of realistic nucleon-nucleon potential.