The branching ratio $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }$ for the electromagnetic decay of the 7.655 MeV second excited state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ has been measured by detecting the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(0.0 MeV) recoils in coincidence with $\alpha$ particles from the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}({}_{}{}^3{}_{}{}^{}\mathrm{He}, {\alpha }_2){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ (7.655 MeV) reaction at $E_{{}_{}{}^3{}_{}{}^{}\mathrm{He}}=4.00\mathrm{}$ MeV. Coincidence events were identified by means of time-of-flight, energy, and kinematic constraints. Thus, of all the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nuclei formed in the second excited state, only those decaying to the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ground state by either $\gamma$-ray or positron-electron pair emission were selected. Hence the experiment provides a direct measurement of $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }$, where ${\Gamma }_{\mathrm{rad}}={\Gamma }_{\gamma }+{\Gamma }_{e\pm }$, and gives $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }=(4.15\mathrm{}\pm 0.34)\times {10}^{-4\mathrm{}}$, which is in good agreement with other recent measurements, and suggests that the previously accepted value of $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }=(2.9\mathrm{}\pm 0.3)\times {10}^{-4\mathrm{}}$ may be too low. The significance of this result is discussed with respect to helium burning rates in stars.

NUCLEAR REACTIONS ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}({}_{}{}^3{}_{}{}^{}\mathrm{He}, \alpha )$, $E=4.0\mathrm{}$ MeV; measured $\alpha$-${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ coin. ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ level deduced $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }$. Enriched target.

Proton total reaction cross sections have been measured for the doubly magic nuclei ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ in the energy range 20-50 MeV. For the $p$+ ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ system, total reaction cross sections were measured in 400 keV steps over practically the entire energy range. The $p$+ ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and $p$+ ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ total reaction cross sections were measured at six and nine different energies, respectively. The experimental total reaction cross sections are compared with results based on optical model analyses in which preliminary data from the present experiment were included. An evaluation of the imaginary potential parameters is reported. Using the proton total reaction cross section information for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ available in the literature, general characteristics of these cross sections in the energy range 10-1000 MeV are shown. A comparison has been made between the measured total reaction cross sections and those predicted by global optical model parameter sets.

NUCLEAR REACTIONS Measured ${\sigma }_R$ for $p$+ ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, $p$+ ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, $p$+ ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$; $18<\mathrm{}{T}_p<48\mathrm{}$ MeV; compared with optical model predictions.

The structure and properties of the high angular momentum states in ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}$ up to 5605 keV of excitation have been investigated via measurements of excitation functions of singles $\gamma$ rays and of $\gamma \gamma$ coincidences following the ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}(\alpha , 2n){}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}_{}^{*}{}_{}{}^{}\left(\gamma \right)$ reaction with $\alpha$ particle energies between 17-30 MeV. From these experiments and from high-resolution singles energy, angular-distribution, and Doppler-shift attenuation measurements, the position and the decay properties of many high angular momentum states in ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}$ have been determined. Levels at 626.82 (${\frac{5}{2}}_1^{+}$), 882.16 (${\frac{13}{2}}_2^{+}$), 927.78 (${\frac{3}{2}}_1^{+}$), 957.07 (${\frac{11}{2}}_1^{+}$), 1084.95 (${\frac{5}{2}}_2^{+}, {\frac{7}{2}}^{+}$), 1178.60 (${\frac{7}{2}}_2^{+}$), 1214.53 (${\frac{9}{2}}_1^{-}$), 1307.19 (${\frac{11}{2}}_2^{+}$), 1514.8 (${\frac{17}{2}}_1^{+}$), 1549.4 (${\frac{15}{2}}_1^{+}$), and 1702.1 (${\frac{13}{2}}_1^{-}$) with the $J^{\pi }$ values in parentheses are confirmed. New levels at 2119.4 (${\frac{15}{2}}_2^{+}$), 2183.2 (${\frac{19}{2}}_1^{+}$), 2231.1 (${\frac{17}{2}}_2^{+}$), 2546.4 (${\frac{21}{2}}_1^{+}$), 2846.7 (${\frac{21}{2}}_2^{+}$ or ${\frac{21}{2}}_1^{-}$), 2905.8 (${\frac{19}{2}}_2^{+}$), 3038.8 (${\frac{19}{2}}_3^{+}, {\frac{17}{2}}^{+}$), 3515.2 (${\frac{25}{2}}_1^{+}$), 3657.7 (${\frac{25}{2}}_2^{+}$ or ${\frac{25}{2}}_1^{-}$), 3917.5 (${\frac{29}{2}}_1^{+}$), 4292.2 (${\frac{27}{2}}_1^{+}$), 4455.4 (${\frac{29}{2}}_2^{+}$ or ${\frac{29}{2}}_1^{-}$), 4761.0 ($\frac{29}{2}, \frac{33}{2}$), and 5604.9 ($\frac{33}{2}, \frac{31}{2}$) with the $J^{\pi }$ values in parentheses are proposed. Possible levels at 2474.2, 3064.9, and 3209.2 (${\frac{21}{2}}_3^{+}$) keV are also suggested. The measured angular distributions provided (i) branching ratios, (ii) $J^{\pi }$ assignments corroborated by deduced angular-distribution attenuation coefficients, level excitation functions, and side-feeding yields, and (iii) multipole mixing ratios $\delta \left(\frac{E2\mathrm{}}{M1\mathrm{}}\right)$. Lifetimes for nine high-spin levels and limits for four additional ones were obtained by the Doppler-shift attenuation method from measurements with the ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}(\alpha , 2n){}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}_{}^{*}{}_{}{}^{}\left(\gamma \right)$ reaction at 18.5, 20.6, 23.6, and 26.7 MeV. The lifetimes were extracted from singles spectra taken in the presence of standards at 7, 4, 7, and 8 angles, respectively, between 0° and 90° for the four bombardment energies by examining the dependence on $E_{\alpha }$ of the effective level lifetime. For many transitions $B\left(E2\mathrm{}\right)\mathrm{}$ and $B\left(M1\mathrm{}\right)\mathrm{}$ values were obtained. The present results are compared with calculations based on the coupling of three-quasiparticle ${\left(g_{\frac{9}{2}}\right)}^3$ configurations to the quadrupole vibrations of the core and remarkable agreement is observed for states up to only ${\frac{19}{2}}_1^{+}$. This model fails to explain the properties of the higher-spin states with $J^{\pi }>~{\frac{21}{2}}^{+}$.

NUCLEAR REACTIONS ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}(\alpha , 2n){}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}_{}^{*}{}_{}{}^{}\left(\gamma \right)$, $E=17-30\mathrm{}$ MeV, monoisotopic targets. Measured $E_{\gamma }$, $I_{\gamma }$, $I_{\gamma }\left(\theta \right)$, $\sigma \mathrm{}\left(E\right)\mathrm{}$, $\Delta {\overline{E}}_{\gamma }(E, \tau )$, $\gamma -\gamma$ coin, deduced ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}$ levels, $J$, $\pi$, branching ratios, $\tau$, $\delta \left(\frac{E2\mathrm{}}{E1\mathrm{}}\right)$, $B\left(E2\mathrm{}\right)\mathrm{}$, and $B\left(M1\mathrm{}\right)\mathrm{}$ values; Ge(Li) detectors, Ge(Li)-NaI(Tl) anti-Compton spectrometer, 1.9 keV at 1332 keV.

The differences between the isovector and isoscalar parts of the collective deformation parameter $\beta$ are obtained from the results of microscopic effective-charge theory. For single-closed-shell nuclei, differences, due to the isovector parts, of up to about 20% between ${\beta }_{n{n}^{\prime }}$ and ${\beta }_{p{p}^{\prime }}$ are predicted, ${\beta }_{n{n}^{\prime }}$ being much closer to ${\beta }_{\mathrm{em}}$ than to ${\beta }_{p{p}^{\prime }}$. Data on single-closed-shell nuclei are tabulated and their general trend supports our predictions.

NUCLEAR REACTIONS $0^{+}$ → $2^{+}$ transitions; estimate of ${\beta }_2$ deformation parameter—differences for different transition mechanisms; comparison with data.

The Doppler-shift attenuation method has been applied to measure the mean lives of levels in ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$. States were populated using the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}(d, p){}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ reaction at $E_d=3\mathrm{}$ MeV and protons emerging from the reaction were detected near 180° relative to the beam. $\gamma$ rays were detected in coincidence with the protons using a 65 ${\mathrm{cm}}^3$ Ge(Li) detector placed successively at angles of 53°, 90°, and 140°. Values or limits were obtained for the lifetimes of 39 levels in ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$. There is a serious disagreement between some of the lifetime values measured in the present experiment and those reported in a previous work. Accurate excitation energies and the decay scheme were also determined. Information from the lifetimes and decay scheme has been used to make spin assignments or restrictions to a number of levels in ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$. The electromagnetic transition strengths determined from the present lifetime measurements and a previous measurement of $\gamma$-ray angular correlations have been compared to the predictions of two models of the negative parity spectrum of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$. In addition, an interpretation of part of the positive parity spectrum has been developed using the strong-coupling model. This calculation includes the effects of the Coriolis term in the Hamiltonian which mixes rotational bands, and the calculated excitation energies, transition rates, and pickup spectroscopic factors have been compared with experiment.

NUCLEAR REACTIONS ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}(d, p\gamma )$, $E_d=3\mathrm{}$ MeV, measured Doppler-shift attenuation. ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ deduced levels, $\tau$, $J$, $\pi$, $B\left(\Lambda \right)$, branching ratios.

Energy spectra of inelastically scattered 16-MeV deuterons were measured at angles of 90° and 125° using enriched targets of ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$, and ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$. In each nucleus the ground state band is observed up to and including the $J^{\pi }=8^{+}$ level. The $\beta$ vibration $J^{\pi }=0^{+}$ level is identified in ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$, and in this and the remaining three nuclei evidence for the $\gamma$ vibration is discussed. At least three octupole bands are observed in each nucleus and $K$, $J^{\pi }$ assignments are made in a number of cases. $B\left(E2\mathrm{}\right)\mathrm{}$ and $B\left(E3\mathrm{}\right)\mathrm{}$ values are extracted for selected levels.

NUCLEAR REACTIONS ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}(d, d^{\prime })$, $E=16\mathrm{}$ MeV, measured $\sigma (E_{d^{\prime }}, \theta =90\mathrm{}°, 125°)$. ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ deduced levels, $J$, $K$, $\pi$, $B\left(E2\mathrm{}\right)\mathrm{}$, $B\left(E3\mathrm{}\right)\mathrm{}$; enriched targets.

A model for the calculation of the cross section for complete fusion in heavy ion reactions is suggested. The model does not explicitly depend on the sharp cutoff approximation. On the contrary, it allows for a gradual transition between compound and direct process when the bombarding energy is sufficiently high above the Coulomb barrier. The energy below which the reaction cross section is exhausted by compound processes is also estimated. Comparison with experimental results supports the validity of the model.

NUCLEAR REACTIONS Phenomenological model for complete fusion cross section in heavy ion reactions.

The $g$ factors of the $9^{-}$ state (2.236 MeV, $\tau =694\mathrm{}$ nsec) and the ${12}^{+}$ state (∼3.1 MeV, $\tau =228\mathrm{}$ nsec) in ${}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$ have been measured as $g\left(9^{-}\right)=-0.030\mathrm{}\left(3\right)\mathrm{}$ and $g\left({12}^{+}\right)=-0.157\mathrm{}\left(6\right)\mathrm{}$ by a time-differential perturbed-angular-distribution technique. The states were populated by ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}({}_{}{}^7{}_{}{}^{}\mathrm{Li}, 4n){}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}\left(9^{-}\right)$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}({}_{}{}^7{}_{}{}^{}\mathrm{Li}, 3n){}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}\left({12}^{+}\right)$ reactions with pulsed lithium beams. An in-beam superconducting magnet supplied a field of ∼60 kG. The $9^{-}$ state $g$ factor is in agreement with the additivity value obtained from empirical single-particle $g$ factors for a $({i_{\frac{13}{2}}}^{-1\mathrm{}}, {f_{\frac{5}{2}}}^{-1\mathrm{}})9^{-}$ configuration and consistent with a small anomalous orbital contribution $\delta g_l$ for the neutron. The $g$ factor for the ${12}^{+}$ state in ${}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$ is in surprisingly good agreement with those for the ${\left(i_{\frac{13}{2}}\right)}^{-2\mathrm{}}{12}^{+}$ state in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ and the ${i_{\frac{13}{2}}}^{-1\mathrm{}}$ state in ${}_{}{}^{205}{}_{}{}^{}\mathrm{Pb}$, in view of the possible existence of number-dependent effects.

NUCLEAR REACTIONS ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}({}_{}{}^7{}_{}{}^{}\mathrm{Li}, 4n){}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}\left(9^{-}\right)$, ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}({}_{}{}^6{}_{}{}^{}\mathrm{Li}, 3n){}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}\left({12}^{+}\right)$ $E_{\mathrm{Li}}=34\mathrm{}$ MeV, pulsed beam, measured spin rotation in $B=60\mathrm{}$ kG, deduced $g$.

States in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ were populated with the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}({}_{}{}^{16}{}_{}{}^{}\mathrm{O}, \alpha )$ reaction. Energy-averaged differential cross sections were measured in the energy range $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=16.9-18.5\mathrm{}$ MeV for 29 excited states in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ from 0 to 15 MeV of excitation, and for the laboratory angles of 7, 15, 25, and 150°. Single energy differential cross sections were measured for laboratory angles of 40, 55, and 70° at a bombarding energy of 43.2 MeV. The experimental angular distributions were compared with Hauser-Feshbach calculations, and good agreement was found for the states of known spin values in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$. Candidates for high-spin states in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ were selected for the groundstate rotational band, and for the $K={\frac{1}{2}}^{+}$ and $K={\frac{1}{2}}^{-}$ bands. The reliability of using Hauser-Feshbach calculations for spin assignments is discussed, and a comparison of the suggested excitation energies for highspin states with shell-model calculations is presented.

NUCLEAR REACTION ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}({}_{}{}^{16}{}_{}{}^{}\mathrm{O}, \alpha )$, $E_{{}_{}{}^{16}{}_{}{}^{}\mathrm{O}}=41.6\mathrm{} \mathrm{to} 45.4$ MeV, measured $\sigma \mathrm{}\left(E\right)\mathrm{}$ for ${\theta }_{\mathrm{lab}}=7, 15, 25, \mathrm{and} 150°$; $E_{{}_{}{}^{16}{}_{}{}^{}\mathrm{O}}=43.2\mathrm{}$ MeV, measured $\sigma \left(\theta \right)$; ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ deduced levels. Hauser-Feshbach calculations and suggested $J$ values. Enriched targets.

The use of Gaussian expansions for the bound-state functions in distorted-wave—Born-approximation calculations is discussed. The use of these expansions leads to an analytic expression for the form factor which can be used to simplify the numerical evaluation of the matrix element. In addition, the Gaussian functions are useful when studying the structure of the form factor. In particular, the validity of the "no-recoil" approximation is discussed and a semiclassical interpretation is presented. A computer program (Gauss) using the Gaussian expansions has been developed and used to evaluate the cross sections of some previously studied reactions. Comparisons of the results with those of other programs are given.

NUCLEAR REACTIONS Full-recoil DWBA, Gaussian expansions.

The elastic scattering of 1-GeV protons by ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ is analyzed using the first-order optical potential including the spin-orbit term. These potentials are generated using realistic nucleon-nucleon scattering amplitudes and nuclear densities with full isospin dependence maintained. The sensitivity of the differential cross sections and polarizations to the spin-orbit potentials and nuclear densities is investigated.

NUCLEAR REACTIONS $p$ + ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, $p$ + ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ elastic scattering, $E_{\mathrm{lab}}=1\mathrm{}$ GeV; optical potential theory; spin, isospin, density distribution, nucleon-nucleon amplitude effects.

The formalism for calculating the radiative pion capture cross section has been developed for shell model calculations in the impulse approximation. It includes the momentum dependent terms of the effective transition operator for any angular momentum of the pion. The giant dipole and giant quadrupole resonances are discussed. The quasifree background is calculated within the framework of the distorted wave impulse approximation. Realistic shell model calculations for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ yield good agreement with experiment.

NUCLEAR REACTIONS Theory of ${\pi }^{-}$ capture. Shell model, impulse approximation. Giant dipole and quadrupole states of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. Quasifree background.

An isobar-doorway model is presented for $\pi$-nucleus scattering in the (3, 3) energy region. The connection between this model and multiple-scattering and optical-model approaches is demonstrated through various approximations used in evaluating the doorway amplitude. Effective scattering amplitudes, differing from the free $\pi -N$ amplitudes as the result of nuclear effects, are suggested for use in multiple-scattering expansions. The importance of a factor ${\Gamma }^{\downarrow }$ in these amplitudes is marked. (This factor seems associated with a phenomenon analogous to collision broadening for atomic collisions.) An extension of the formalism to (${\pi }^{+}, {\pi }^0$) charge exchange between analog states is given.

NUCLEAR REACTIONS Scattering theory for $\pi$-nucleus near (3, 3) resonance; isobar-doorway model compared with multiple-scattering techniques.

A multiple-diffraction expansion for heavy-ion reactions is constructed in which the leading term is Glauber's phenomenological multiple-diffraction amplitude. This is achieved with the help of a pseudopotential between elementary particles in ions which in the Glauber approximation gives the empirical elementary scattering amplitude. The leading corrections to Glauber's phenomenological amplitude include (i) a wave-spreading term of Wallace, (ii) an internal-excitation term of Hahn, (iii) a pseudopotential term which contains effects of wave spreading and zero-point motion of bound particles in ions, and (iv) a Pauli term for antisymmetrizing two clusters of identical fermions. Explicit expressions for these corrections are given in the impact-parameter representation. The nature of these corrections is briefly discussed.

NUCLEAR REACTIONS Multiple-diffraction expansion formalism for intermediate-energy reactions.

The half-life of the long-lived isomer of ${}_{}{}^{150}{}_{}{}^{}\mathrm{Eu}$ has been measured to be 35.8±1.0 yr. Two methods were used for the measurements. In the first, the ${}_{}{}^{150}{}_{}{}^{}\mathrm{Eu}$ half-life was measured relative to that of ${}_{}{}^{147}{}_{}{}^{}\mathrm{Eu}$, ${}_{}{}^{148}{}_{}{}^{}\mathrm{Eu}$, ${}_{}{}^{149}{}_{}{}^{}\mathrm{Eu}$, and ${}_{}{}^{152}{}_{}{}^{}\mathrm{Eu}$ by measuring the atom ratios and disintegration-rate ratios in a mixed tracer solution using mass-spectrometric and Ge(Li) counting techniques. The second method involved studying the $\gamma$ spectrum of three mass-separated ${}_{}{}^{150}{}_{}{}^{}\mathrm{Eu}$ sources over periods of up to 6.1 yr with several NaI(Tl) detectors. No evidence was found for the 6.2 yr half-life which has been previously reported for ${}_{}{}^{150}{}_{}{}^{}\mathrm{Eu}$.

RADIOACTIVITY ${}_{}{}^{150}{}_{}{}^{}\mathrm{Eu}_{}^m{}_{}{}^{}$; measured $T_{\frac{1}{2}}$, no evidence for 6.2 yr $T_{\frac{1}{2}}$.

The level structure of ${}_{}{}^{137}{}_{}{}^{}\mathrm{La}$ populated by the $\beta$ decay of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Ce}_{}^{m+g}{}_{}{}^{}$ was studied by $\gamma$-ray and conversion-electron spectroscopy using mass-separated sources, large-volume and Compton-suppressed Ge(Li) detectors, and a Si(Li) detector. Nine previously unreported transitions were observed and two more levels were established in ${}_{}{}^{137}{}_{}{}^{}\mathrm{La}$. The ${}_{}{}^{137}{}_{}{}^{}\mathrm{La}$ level structure is discussed in terms of the weak-coupling model.

RADIOACTIVITY ${}_{}{}^{137}{}_{}{}^{}\mathrm{Ce}_{}^{m+g}{}_{}{}^{}$ [from ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ce}(n, \gamma )$ and $\mathrm{Ba}(\alpha , \mathrm{Xn}\gamma )$]; measured $E_{\gamma }$, $I_{\gamma }$, $I_{\mathrm{ce}}$; deduced $log\mathrm{ft}$. ${}_{}{}^{137}{}_{}{}^{}\mathrm{La}$ deduced ICC, levels, $J$, $\pi$. Mass separation, Ge(Li) and Si(Li) detectors, Compton suppression spectrometer.

The $\beta$ decay of 17.6-h ${}_{}{}^{135}{}_{}{}^{}\mathrm{Ce}$ to levels in ${}_{}{}^{135}{}_{}{}^{}\mathrm{La}$ was studied by $\gamma$-ray and conversion-electron spectroscopy, and by extensive $\gamma -\gamma$-coincidence experiments. The use of mass-separated sources, a Compton-suppressed spectrometer, and the megachannel analyzer system for coincidence studies has enabled substantial extension of the experimental knowledge of ${}_{}{}^{135}{}_{}{}^{}\mathrm{La}$. Seventy-three previously unreported transitions were observed in the singles and coincidence data. Six levels not proposed in earlier works are firmly established here, and two other levels are tentatively proposed. The level structure of ${}_{}{}^{135}{}_{}{}^{}\mathrm{La}$ is compared to the systematics of related nuclei and to qualitative interpretations of nuclear models that attempt to describe this nucleus.

RADIOACTIVITY ${}_{}{}^{135}{}_{}{}^{}\mathrm{Ce}$ [from ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ce}(\gamma , n)$ and $\mathrm{Ba}(\alpha , Xn)$]; measured $E_{\gamma }$, $I_{\gamma }$, $I_{\mathrm{ce}}$, $\gamma -\gamma$ coin; deduced $log\mathrm{ft}$ ${}_{}{}^{135}{}_{}{}^{}\mathrm{La}$ deduced levels, $J$, $\pi$, ICC. Enriched targets, mass separation, Ge(Li) and Si(Li) detectors.

The hyperfine structure of the $6s{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}-6p{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ line of Ta V at 1708 Å has been resolved using a 150 A sliding spark discharge. The $6p-8s$ multiplet was identified and the ionization energy was redetermined. With these new data a value for the nuclear dipole moment of ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ of $(2.36\mathrm{}\pm 0.02){\mu }_N$ is derived. New wavelengths are given for all previously classified lines.

NUCLEAR MOMENTS Spectrum, tantalum, ionization energy.

Hartree-Fock-Bogoliubov calculations have been performed for self-conjugate even-even nuclei in the $2p-1f$ shell using the central Yukawa interaction and Kuo-Brown reaction matrix elements for the Hamada-Johnston potential. The possibility of generalized pairing correlations is studied by considering $T=0\mathrm{}$, $T=1\mathrm{}$, and $T=0+T=1\mathrm{}$ correlations and comparing the ground-state properties for axial and triaxial shapes. It is found that for nuclei studied neither the correlations $T=0\mathrm{}$ nor $T=1\mathrm{}$ play any important role in the ground state. In general $T=0+T=1\mathrm{}$ pairing yields results which are identical with those obtained with either $T=0\mathrm{}$ or $T=1\mathrm{}$. In the excited states, however, the $T=0\mathrm{}$ correlations are found to be more important than the $T=1\mathrm{}$ correlations.

NUCLEAR STRUCTURE ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{60}{}_{}{}^{}\mathrm{Zn}$; calculated binding energies, quadrupole moments, pickup strengths. Hartree-Fock-Bogoliubov method with generalized pairing.

The polarization function is derived for a virtual photon propagating in uncorrelated nuclear matter. The modification of the photon propagator and the induced charge distribution in the presence of the external field source are expressed in terms of a finite effective photon mass which is dependent on the Fermi momentum. The application is made to a finite nucleus by subtracting the local field due to the surrounding infinite matter distribution. It is found that the correction to the potential due to the scattering of exchanged virtual photons by the nucleus results in a short range repulsive force on the orbiting muon in muonic atoms. The estimated energy shifts are -560 eV for the $2p_{\frac{1}{2}}\to 1s_{\frac{1}{2}}$ transition, and -291 eV for the $3d_{\frac{5}{2}}\to 2p_{\frac{3}{2}}$ transition in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$; and -58 eV and -2.5 eV, respectively, in ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$. The effects are negligible for higher orbits.

NUCLEAR STRUCTURE ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$; calculated induced charge density in muonic atoms. Nucleon Compton scattering effect on photon propagator.