Elastic scattering cross sections for ${\pi }^{\pm }$ scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ are presented for pion energies of 65 and 80 MeV and for scattering angles from 20° to 120°. Energy dependent isospin effects are observed. The cross sections were fit with the Kisslinger potential, and the potential strength parameters show an $\frac{\mathrm{}(N-Z)\mathrm{}}{A}$ dependence similar to that predicted by the impulse approximation at 65 MeV, but not at 80 MeV. Calculations using the Siciliano potential, which contains the explicit isospin dependence of the Lorentz-Lorenz-Ericson effect plus isoscalar, isovector, and isotensor terms, indicate the importance and energy dependence of absorption effects. Finally a "model independent" parametrization of the neutron density suggests a neutron excess at the surface of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ but not ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$.

NUCLEAR REACTIONS Elastic scattering of 65 and 80 MeV ${\pi }^{\pm }$ from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$. Angular distributions: $20°<{\theta }_{\mathrm{lab}}<120\mathrm{}°$. Isospin dependence of optical models.

We present a relativistic model of nucleon structure which places particular emphasis on translational invariance. An analysis of the field equations of the Friedberg-Lee soliton model is presented which avoids the static approximation. The matrix element of the quark-field operator between a nucleon state and a "diquark" state is written in terms of a quark wave function, and an equation which determines this wave function is given. We do not solve this equation here. Instead, we introduce a simple parametrization of the quark wave functions and proceed to calculate various nucleon observables. We present a calculation of nucleon electromagnetic form factors using a vector dominance model. We also calculate the axial current form factors and discuss the Goldberger-Treiman and partially-conserved axial vector current relations in our model. In our calculations the nucleon magnetic moment is given as the sum of three terms: a recoil moment, a confinement moment, and a mesonic term, the latter term contributing about 50 percent of the proton (or neutron) moment. We find that the recoil part of the proton moment is equal to $\left(\frac{3}{5}\right)g_A$, where $g_A$ is the ratio of the axial vector coupling constants, $g_A=\frac{G_A}{G_V}$. Other models of the nucleon moment usually stress only one aspect of the calculation. For example, in the (static-cavity) MIT bag models the moment is entirely a "confinement moment," the calculated moment being proportional to the confinement radius. In nonrelativistic quark models the quarks are assigned an anomalous magnetic moment and the entire nucleon moment is explained on that basis; in our calculations the analogous contribution to the magnetic moment, the "mesonic term," contributes only about 50 percent of the total moment, as noted above.

NUCLEAR STRUCTURE: Intermediate energy; analysis of the Friedberg-Lee soliton model; matrix elements of quark currents; nucleon electromagnetic form factors, magnetic moments and axial form factors.

It is shown that elastic $\pi \mathrm{d}$ differential cross sections from 47.5 MeV up to 116 MeV are quite well described by the impulse approximation theory in its form-factor formulation. This theory is used to derive a theoretical expression for the charge asymmetry $A$, valid for $T_{\pi }\lesssim 100$ MeV, which includes the effects of Coulomb distortion, $\Delta$- and target-baryon mass differences, and internal Coulomb corrections. The theoretically predicted $A$ is found to be in reasonable agreement with the only existing data for $A$ below 100 MeV at $T_{\pi }=65\mathrm{}$ MeV.

NUCLEAR REACTIONS ${}_{}{}^2{}_{}{}^{}\mathrm{H}({\pi }^{\pm }, {\pi }^{\pm })$, $T_{\pi }=65\mathrm{}$ MeV; impulse approximation theory; charge-asymmetry $A$; (${\Delta }^{++}, {\Delta }^{-}$) mass difference; Coulomb distortion; internal Coulomb correction.

We report first measurements of the spin correlation parameters, $A_{\mathrm{NN}}$ and $A_{\mathrm{LL}}$, for $\mathrm{pp}\to \mathrm{np}{\pi }^{+}$ above the $\Delta$-production threshold. Our results for this dominant inelastic channel are in good agreement with a theoretical model that does not include any dibaryon resonances.

Pion single charge-exchange reactions exciting giant electric isovector resonances are studied for a series of nuclei. The reaction mechanism is treated in the distorted-wave impulse approximation. Emphasis is put on the nuclear structure aspects probed in these reactions. Transition densities for charge-exchange excitations are calculated using the sum-rule method and microscopically, in the Hartree-Fock—random-phase-approximation framework. The resulting cross sections are sensitive to the nuclear structure input. Double differential cross sections as functions of the nuclear excitation energy are calculated.

NUCLEAR REACTIONS Pion single charge exchange exciting giant isovector resonances.

A semirelativistic model based on an approximate solution of the Bethe-Salpeter equation used previously to construct a conserved electromagnetic current with arbitrary interaction is generalized to arbitrary processes and extended to many body targets. Although the technique appears valid and useful for introducing kinematic corrections in processes off few body targets, a paradoxical result emerges for large nuclei in that the relevant form factors, which must be evaluated far off-shell, can be dramatically different from that for free nucleons, contrary to the usual picture of the nucleus as composed of nearly free nucleons.

NUCLEAR REACTIONS Bethe-Salpeter equation, off-shell kinematics, impulse approximation, paradox for large nuclei.

The $\gamma$- and $\beta$-ray radiation following the decay of ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ba}$ to ${}_{}{}^{142}{}_{}{}^{}\mathrm{La}$ were measured in experiments in which $\beta$ end-point energies, $\beta \gamma$ coincidences, $\gamma$-ray singles, $\gamma \gamma t$ coincidence, and $\gamma \gamma t\left(\theta \right)$ angular correlation data were collected. The ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ba}$ activity was produced by on-line mass separation from the ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}({\mathrm{n}}_{\mathrm{th}}, f)$ reaction. A level scheme for odd-odd ${}_{}{}^{142}{}_{}{}^{}\mathrm{La}$ was deduced from coincidence information that includes 90 $\gamma$ rays which are placed among 23 levels. A 0.87±0.17 μs isomeric state was established at 145 keV. The $Q_{\beta }$ value of 2200±25 keV was determined from $\beta -\gamma$ coincidence data. Beta-ray intensities and $log\mathrm{ft}$ values have been evaluated, and along with internal conversion and angular correlation measurements, yielded spin-parity assignments for a number of levels. The low-lying levels were compared with level schemes projected from $\pi \nu$ multiplet parabolas computed using parameters extracted from parabolic fits in ${}_{}{}^{140}{}_{}{}^{}\mathrm{La}$ and ${}_{}{}^{142}{}_{}{}^{}\mathrm{Pr}$.

RADIOACTIVITY ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ba}$ [from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}({\mathrm{n}}_{\mathrm{th}}, f)$] measured $E_{\gamma }$, $I_{\gamma }$, $E_{\beta }$, ${\alpha }_k$, $\gamma \gamma t$ coincidence, $\gamma \gamma t\left(\theta \right)$ angular correlation, $\beta \gamma$ coincidence; HPGe $\beta$ and $\gamma$ detectors; ${}_{}{}^{142}{}_{}{}^{}\mathrm{L}$A deduced levels $J^{\pi }$, $I_{\beta }$, $\delta$, $log\mathrm{ft}$, level lifetime, and $Q_{\beta }$. Mass separated ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ba}$ activity.

A new technique has been developed in the measurement of the $K$-shell fluorescence yield of cesium from the analysis of the sum peaks observed with a high resolution intrinsic Ge detector. The value found is ${\omega }_k\left(\mathrm{Cs}\right)=0.896\mathrm{}\left(16\right)\mathrm{}$, which is in good agreement with the fitted value of Bambynek et al.

RADIOACTIVITY ${}_{}{}^{133}{}_{}{}^{}\mathrm{Ba}$: measured $I_{\gamma }$, $I_{\mathrm{Kx}}$, sum peak area, deduced ${\omega }_K$.

Gamma ray spectroscopic studies of the $\beta$ decay of ${}_{}{}^{160}{}_{}{}^{}\mathrm{Tm}$ have led to the identification of a new 74.5 s isomer in the ${}_{}{}^{160}{}_{}{}^{}\mathrm{Tm}$ nucleus. This isomer is found to emit seven new $\gamma$ rays of 375.8, 738.7, 840.8, 926.7, 1104.1, 1115.8, and 1186.1 keV which populate six new levels in ${}_{}{}^{160}{}_{}{}^{}\mathrm{Er}$ at 765.7, 1128.6, 1230.3, 1316.6, 1505.7, and 1576.0 keV. The 765.7 keV level is the $6^{+}$ member of the ground-state band known from in-beam $\gamma$-ray studies, whereas the 1128.6-, 1316.6-, and 1505.7-keV levels are tentatively assigned as the $4^{+}$, $5^{+}$, and $6^{+}$ members of the $\gamma$ band, respectively. The 1230.3-keV level is proposed as the $4^{+}$ member of the $\beta$ band.

RADIOACTIVITY ${}_{}{}^{160}{}_{}{}^{}\mathrm{Tm}$ [from ${}_{}{}^{164}{}_{}{}^{}\mathrm{Er}$(p,5n)]; measured $T_{\frac{1}{2}}$, $E_{\gamma }$, $I_{\gamma }$, $\gamma -\gamma$ coin; deduced ${}_{}{}^{160}{}_{}{}^{}\mathrm{Er}$ levels. Enriched ${}_{}{}^{164}{}_{}{}^{}\mathrm{Er}$ target, intrinsic Ge detectors.

The nuclear matrix elements entering the double $\beta$ decays of the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$-${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$-${}_{}{}^{58}{}_{}{}^{}\mathrm{Fe}$ systems have been calculated using a realistic two nucleon interaction and realistic shell model spaces. Effective transition operators corresponding to a variety of gauge theory models have been considered. The stability of such matrix elements against variations of the nuclear parameters is examined. Appropriate lepton violating parameters are extracted from the $A=48\mathrm{}$ data and predictions are made for the lifetimes of the positron decays of the $A=58\mathrm{}$ system.

RADIOACTIVITY Double $\beta$ decay. Gauge theories. Lepton nonconservation. Neutrino mass. Shell model calculations.

An oil vapor helium-jet transfer system was used to study the ${\beta }^{+}$ decay of ${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ produced in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$,2pn)${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ reaction at 110-130 MeV. Singles and coincidence measurements established the decay to four levels in ${}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ and allowed measurements of $T_{\frac{1}{2}}=0.9\mathrm{}\pm 0.2$ sec for the decay halflife and $Q_{\mathrm{EC}}=6986\mathrm{}\pm 227$ keV for the total decay energy. In-beam studies of the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}, 3\mathrm{p}\gamma ){}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ reaction were made at 117 MeV. Two distinct bands were observed in ${}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ and probable spin and parity assignments were made. These data favor $J^{\pi }={\frac{5}{2}}^{+}$ for the ${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ ground state. The ${}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ bands are compared to neighboring odd-$A$ nuclei and to recent calculations.

RADIOACTIVITY ${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ [from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$,2pn)], $E=110-130\mathrm{}$ MeV. Measured $T_{\frac{1}{2}}$, $\sigma \mathrm{}\left(E\right)\mathrm{}$, $E_{\gamma }$, $E_{\beta }$, $I_{\beta }$, $\gamma -\gamma$, $x-\gamma$, and $\beta -\gamma$ coincidences, deduced levels, $Q_{\mathrm{EC}}$, $log\mathrm{ft}$. He jet, Ge(Li), Ge, and plastic detectors.

NUCLEAR REACTIONS ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}, 3\mathrm{p}\gamma ){}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$, $E=117\mathrm{}$ MeV. Measured $E_{\gamma }$, $I_{\gamma }$, $\sigma \left(\theta \right)$, $p-\gamma$, and $\gamma -\gamma$ coincidences. Deduced levels, branching ratios, $J^{\pi }$, $\delta$. Ge(Li) detectors. Enriched target. Comparison with systematic trends and calculations.

The multiphonon method—i.e., exact diagonalization in the restricted space of collective phonons of different types—is tested in a simple model allowing an exact solution for a many body system of fermions interacting via pairing plus quadrupole and octupole forces. It appears satisfactory for the description of the anharmonicities of the lowest-lying vibrational states with $K^{\pi }=0^{+} \mathrm{and} 0^{-}$ in deformed nuclei. In particular, it allows electromagnetic transitions between the different one phonon states which cannot be described in any harmonic treatments such as the Tamm-Dancoff or random-phase approximations.

NUCLEAR STRUCTURE Multiphonons $K=0^{+}$ and $K=0^{-}$ states of deformed nuclei discussed in a simple model.

We propose a modification of the standard Faddeev equations which takes into account the effects of a three-body force in first order perturbation theory on the triton wave function and its binding energy. Furthermore, we report our results for the energy expectation value caused by the two-pion-exchange three-nucleon force.

NUCLEAR STRUCTURE Faddeev equations, energy expectation value of the two-pion-exchange three-nucleon force.

We propose here a new method, called a term-by-term bosonization method, to be used to construct the boson expansion theory. It is trivial to justify it mathematically. Its use makes the whole procedure of the bosonization very easy and transparent.

NUCLEAR STRUCTURE Boson expansion theories, Marumori-Yamamura-Tokunaga method, term-by-term bosonization method, fermion system, norm matrix, reduction to irreducible tensors, truncation to collective space.

Low $Q$ value weak nuclear decays are considered which have two-body final states (electron captures and bound-state beta decays). This opens the possibility for the observation of a process analogous to the Mössbauer effect, where the emitted (anti)neutrinos would be resonantly absorbed by atoms in a suitable absorber. Candidates for such a process are examined. Linewidths as small as the narrowest observed in Mössbauer spectroscopy may conceivably allow a new class of $\nu$ (disappearance) oscillation experiments.

NUCLEAR REACTIONS Discuss recoilless resonant neutrino absorption by nuclei.

Cross sections for pion elastic and inelastic scattering to the ground state and the 0.122 MeV $2^{+}$ state of ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$ are presented. Coupled channel and distorted-wave impulse approximation analysis of the data indicate that the neutron quadrupole deformation parameter ${\beta }_2\left(\mathrm{n}\right)$ is nearly equal to the proton quadrupole deformation parameter ${\beta }_2\left(\mathrm{p}\right)$.

NUCLEAR REACTIONS ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}({\pi }^{\pm }, {\pi }^{\pm }){}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}(\mathrm{g}.\mathrm{s}.\mathrm{}, {2_1}^{+})$, $T_{\pi }=180\mathrm{}$ MeV, $\sigma \left(\theta \right)$, $\theta =17\mathrm{}°-50\mathrm{}°$; DWIA, coupled channels, transition strengths.

The isotope ${}_{}{}^{75}{}_{}{}^{}\mathrm{Rb}$ was produced via the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$(${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, p2n) reaction and mass separated with an on-line isotope separator. Its half-life was determined to be 21.4 ± 1.0 sec. Twenty-one $\gamma$ rays were placed in a partial decay scheme with levels in ${}_{}{}^{75}{}_{}{}^{}\mathrm{Kr}$ up to 1042.4 keV in excitation. The data are consistent with the existence of previously proposed ${\frac{5}{2}}^{+}$ ground-state and ${\frac{3}{2}}^{-}$ first-excited-state rotational bands in ${}_{}{}^{75}{}_{}{}^{}\mathrm{Kr}$, and with a ${\frac{3}{2}}^{-}$ or ${\frac{5}{2}}^{-}$ assignment for the ground state of ${}_{}{}^{75}{}_{}{}^{}\mathrm{Rb}$.

RADIOACTIVITY ${}_{}{}^{75}{}_{}{}^{}\mathrm{Rb}$ [from ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$(${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, p2n)] measured $T_{\frac{1}{2}}$, $E_{\gamma }$, $I_{\gamma }$, $\gamma \gamma$ coin; ${}_{}{}^{75}{}_{}{}^{}\mathrm{Kr}$ deduced levels, $J^{\pi }$. Mass-separated samples.

We derive a resolution of unity over real Slater determinants using simple symmetry arguments. The resulting simplification of the measure with respect to the previous representations makes it a good candidate for stochastic evaluations.

Continuous spectra of light particles from heavy ion induced reactions with velocities extending to values above the beam velocity are analyzed in terms of the generalized exciton model. Data are found to be reproduced by model calculations with only one individually adjustable model parameter: the number of initial degrees of freedom $n_0$. This quantity is energy dependent in contrast to light ion induced reactions.

NUCLEAR REACTIONS ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^6{}_{}{}^{}\mathrm{Li}, c)X$, $c=p-\alpha$, $E=156\mathrm{}$ MeV, ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$(${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, $n$+evaporation residues), $E=220, 290, 400$ MeV; calculated spectra for different angles.

We discuss the pion nucleon partial wave mixing due to the Pauli projection operator in $\pi$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ scattering. In a previous numerical investigation we found that this partial wave mixing generates only small corrections in the cross sections. In the present study we demonstrate that the coupling between partial waves vanishes in the limit $\frac{m_{\pi }}{m_{\mathrm{N}}}\to 0$, thereby explaining these numerical findings.

NUCLEAR REACTIONS $\pi$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ scattering, optical potential, Pauli principle corrections.