Photoneutron resonances and their angular distributions have been studied in a high-resolution measurement of the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}(\gamma ,n){}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ reaction near threshold. The angular distributions observed for lower-energy photoneutron resonances tend to confirm the conclusions of earlier experiments which suggest the existence of a giant $M1\mathrm{}$ resonance in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$.

The contributions of compound-nuclear and direct processes to the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^6{}_{}{}^{}\mathrm{Li},d){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ 6.92- and 7.12-MeV levels at two c.m. energies are discussed.

A simple method is described for including the effect of bound-state breakup in the treatment of bound-state elastic scattering in terms of an effective two-body interaction. Applications to the four-body problem and to the treatment of deuteron-nucleus scattering are discussed.

The $T=1\mathrm{}$ isospin mixing in the 4.57-MeV ($T=0\mathrm{}$) state in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ is investigated via the $\alpha +d\to {}_{}{}^6{}_{}{}^{}\mathrm{Li}_{}^{*}{}_{}{}^{}\to \alpha +d^{*}$ reaction and found to be less than 1%.

Discrepancies between experimental results on nuclear Raman scattering in the giant-resonance region and theoretical predictions are discussed in the light of possible nonresonating contributions from direct transitions into the continuum. It is estimated that a 10-15% contribution may remove the existing differences.

The excitation function for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},\alpha ){}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ reaction leading to the $2^{+}$ state at 7.83 MeV possesses oscillations similar in width to those observed for the low-lying states. For the 7.83-MeV state, the oscillations are considerably damped in magnitude and are superimposed on a large underlying cross section that varies much more slowly with energy.

An extended derivation of the three-body cluster energy is given which clarifies the presentation in a previously published paper.

Sub-Coulomb stripping has been employed to study ${}_{}{}^{101}{}_{}{}^{}\mathrm{Mo}$ with 3.75-MeV deuterons. Proton groups assigned to states in ${}_{}{}^{101}{}_{}{}^{}\mathrm{Mo}$ at excitation energies of 0, 57, 239, 290, 349, 480, 540, 561, 812, 851, and 898 keV were observed. The states at 349, 561, and 851 keV have not been reported previously. The ground state and the excited state at 349 keV have been shown to be ${\frac{1}{2}}^{+}$ states with spectroscopic factors of 0.42 and 0.16. Tentative assignments of $l_n=2\mathrm{}$ have been made for the states at 57, 239, 290, and 480 keV. Assuming a ${\frac{3}{2}}^{+}$ nature for these states, the spectroscopic factors are 0.25, 0.09, 0.12, and 0.11, respectively. The sum of the spectroscopic factors for $l=0\mathrm{}$ and $l=2\mathrm{}$ transitions are shown to be consistent with previous results from stripping and pickup reactions on neighboring nuclei.

The relative intensities of $\gamma$ rays in ${\mathrm{Hf}}^{178}$, excited in the decay of 9.3-min ${\mathrm{Ta}}^{178}$, have been determined with a Ge (Li) spectrometer. It is proposed that the rates for decay of the 1276-keV ($2+,K=0$) state by $E2\mathrm{}$ transitions to the ground-state band are perturbed by an admixture of ($K=2\mathrm{}$) $\gamma$ vibration in the initial state.

Using the ${\mathrm{O}}^{16}$ beam from the University of Pittsburgh tandem Van de Graaff accelerator, the angular distribution of the ratio of scattered ions exciting the first $2^{+}$ state to elastically scattered ions has been measured. Values of the reduced transition probability $B(E2,0^{+}\to 2^{+})$ and the static quadrupole moment ${\mathrm{Q}}_{2^{+}}$ of the first $2^{+}$ state have been determined. The $B(E2,0^{+}\to 2^{+})$ values obtained are 0.672 ± 0.016, 0.418 ± 0.011, and 0.221 ± 0.009 ${\mathit{e}}^2$ ${\mathrm{b}}^2$ for ${\mathrm{Ba}}^{134,136,138}$, respectively. The spectroscopic quadrupole moments of the first $2^{+}$ state of these nuclei are found to be -0.64 ± 0.14, -0.19 ± 0.17, and -0.07 ± 0.15 e b, respectively. The results are compared with the predictions of various models.

The average number and average energy of $\gamma$ rays emitted within ∼5 nsec after fission have been determined as functions of fragment mass and as functions of fragment mass and total kinetic energy in two-dimensional representations. In a four-parameter experiment, energies of coincident pairs of fission fragments were measured with surface-barrier detectors and $\gamma$-ray energies were measured with a large NaI(Tl) detector, which was located 89 cm from a thin ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ target and positioned coaxially with the fragment detectors. The time difference between detection of a fission fragment and a $\gamma$ ray was measured to allow time-of-flight discrimination against fission neutrons. The $\gamma$-ray data were analyzed with a "weighting method" proposed by Maier-Leibnitz to deduce average numbers and energies of $\gamma$ rays from measured pulse heights. The Doppler shift in the laboratory angular distribution of $\gamma$ emission was utilized to obtain the number and energy of $\gamma$ rays as functions of single fragment mass. The results, for both average number and average energy as functions of single fragment mass, are characterized by a sawtooth behavior similar to that which is well known for neutron emission. The over-all average number and energy of $\gamma$ rays emitted per fission were found to be 6.51 ± 0.3 and 6.43 ± 0.3 MeV, respectively, giving an average photon energy of 0.99 ± 0.07 MeV.

The locations of 70 energy levels in ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ were deduced from Compton-suppressed $\gamma$-ray singles, three-crystal $\gamma$-ray pair, conversion-electron, and Ge(Li)-Ge(Li) $\gamma -\gamma$ coincidence measurements on the electron-capture-${\beta }^{+}$ decay of ${}_{}{}^{170}{}_{}{}^{}\mathrm{Lu}$. Both chemically separated and isotopically separated sources of ${}_{}{}^{170}{}_{}{}^{}\mathrm{Lu}$ were used in collecting the data. A total of 550 $\gamma$-ray transitions have been observed in the ${}_{}{}^{170}{}_{}{}^{}\mathrm{Lu}$ decay spectrum, 220 of which are definitely assigned to the ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ level scheme from 112 coincidence spectra. These definitive transitions account for 93% of the total observed $\gamma$-ray intensity. An additional 118 $\gamma$-ray transitions were placed on the basis of excited-state energy differences. Eight $E0\mathrm{}$ transitions were observed in the conversion-electron data. Each of four excited $0^{+}$ states identified has less than 1% $\beta$ decay feeding from the $0^{+}$ parent. Spin and parity assignments are proposed for 46 levels in addition to the ground-state rotational band members. The ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ level structure is compared with available theoretical calculations, and a preliminary interpretation of several features of the decay scheme is presented.

The $0^{+}$ level structure of ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ce}$ as revealed by the ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}(p,t)$ and ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}(p,t)$ reactions is reported. Comparisons are made to a model which mixes the anharmonic pair vibration with "two multipole-phonon" $0^{+}$ excitations and "one-phonon" $0^{+}$ proton configurations. The 5.57-MeV $0^{+}$ level in ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ may be a pair analog to the weak $0^{+}$ level in ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ce}$ at 2.32 MeV.

Cross sections have been measured for the ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(\alpha ,3n){}_{}{}^{236}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(\alpha ,t){}_{}{}^{236}{}_{}{}^{}\mathrm{Np}$, and ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(\alpha ,f)$ reactions at several α-particle bombarding energies between 24.5 and 28.0 MeV.

Excitation functions for the population of shape isomers in americium nuclei have been studied by triton and proton bombardment of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{242}{}_{}{}^{}\mathrm{Pu}$, and ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$ with triton energies ranging from 10 to 16 MeV and proton energies from 9 to 16 MeV. The reactions studied are ($t, 2n$), ($t, 3n$), and ($p, 2n$) leading to final nuclei ${}_{}{}^{241,243,245}{}_{}{}^{}\mathrm{Am}$, ${}_{}{}^{240,242,244}{}_{}{}^{}\mathrm{Am}$, and ${}_{}{}^{238,239,241,243}{}_{}{}^{}\mathrm{Am}$, respectively. In two cases half-lives were obtained, namely, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}(p, 2n){}_{}{}^{239m}{}_{}{}^{}\mathrm{Am}$, $T_{\frac{1}{2}}=163\mathrm{}\pm 12$ nsec and ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}(t, 2n){}_{}{}^{245m}{}_{}{}^{}\mathrm{Am}$, $T_{\frac{1}{2}}=390\mathrm{}\pm 70$ nsec.

The Mössbauer isomer shift for the 93.2-keV transition in ${\mathrm{Hf}}^{178}$ has been studied in Hf metal, Hf${\mathrm{O}}_2$, HfC, and cyclopentadinyl hafnium dichloride, Hf${\mathrm{}\left(\mathrm{Cp}\right)\mathrm{}}_2$${\mathrm{Cl}}_2$. One can qualitatively understand the shifts in terms of shielding of $s$ electrons by valence $5d$ electrons. An unambiguous isomer shift of +0.19 ± 0.06 mm/sec has been observed between Hf${\mathrm{}\left(\mathrm{Cp}\right)\mathrm{}}_2$${\mathrm{Cl}}_2$ and Hf metal. This is interpreted as evidence of a shrinking of the nuclear charge radius of ${\mathrm{Hf}}^{178}$ in the first rotational state. We estimate the change in the $s$ electron density between Hf${\mathrm{}\left(\mathrm{Cp}\right)\mathrm{}}_2$${\mathrm{Cl}}_2$ and Hf metal by correlating it to the observed isomer shifts between Os${\mathrm{}\left(\mathrm{Cp}\right)\mathrm{}}_2$ and Os metal and calculate

$\delta 〈r^2〉\left({\mathrm{Hf}}^{178}\right)=-0.37\mathrm{}\times {10}^{-3\mathrm{}}{\mathrm{fm}}^2,$

$\frac{\delta 〈r^2〉}{〈r^2〉\left({\mathrm{Hf}}^{178}\right)}=-0.13\mathrm{}\times {10}^{-4\mathrm{}}.$

The lifetimes of the first and second excited states were determined in ${}_{}{}^{194,196}{}_{}{}^{}\mathrm{Pt}$ with delayed coincidence techniques: ${}_{}{}^{194}{}_{}{}^{}\mathrm{Pt}$ $\tau \left(2^{+}\right)=50\mathrm{}\pm 5$ psec, $\tau \left(2^{+\prime }\right)=51\mathrm{}\pm 6$ psec, ${}_{}{}^{196}{}_{}{}^{}\mathrm{Pt}$ $\tau \left(2^{+}\right)=43.6\mathrm{}\pm 3.0$ psec, $\tau \left(2^{+\prime }\right)=52\mathrm{}\pm 5$ psec. For this latter level the crossover/stopover intensity ratio is ≤6.${10}^{-5\mathrm{}}$. Deduced $B\left(E2\mathrm{}\right)\mathrm{}$ transition probabilities show a simultaneously diminishing trend for $2^{+}$′ → $0^{+}$ and $2^{+}$′ → $2^{+}$ versus atomic mass number. New lifetimes are used to reevalute nuclear $g$ factors, which all lie around $g_{2^{+}}\approx 0.3$. Phenomenological anharmonic vibration-model calculations reproduce well the measured quadrupole transition probabilities and nuclear $g$ factors.

Previous measurements of the asymmetry in the elastic scattering by ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ of partially polarized 2-4-MeV neutrons from the $\mathrm{D}\mathrm{}(d,n)\mathrm{}{}_{}{}^3{}_{}{}^{}\mathrm{He}$ reaction are compared with recent data of others for the polarization in the reactions ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}\mathrm{}(n,n)\mathrm{}{}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and $\mathrm{D}\mathrm{}(d,n)\mathrm{}{}_{}{}^3{}_{}{}^{}\mathrm{He}$. The consistency of various sets of data which are linked by the above measurement is discussed.

Estimates for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}(\alpha ,{\alpha }^{\prime })$ cross sections at 65 MeV show strong preference for high angular momentum transfers and, if the maximum allowable collective strength is invoked, yield absolute cross sections comparable to those recently measured in the 10-25-MeV excitation region of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$.

Proton-proton bremsstrahlung cross sections are calculated for the Bryan-Scott III and the Hamada-Johnston potentials and compared with a recent experiment at 156 MeV with forward coplanar asymmetric geometry. The cross section for unequal angles involves a simple extension of earlier results. The calculations include rescattering but do not include Coulomb effects. Also presented is a $\mathrm{pp}\gamma$ calculation at 65 MeV (25, 35°) in comparison with experiment and other calculations. At 156 MeV there is some experimental agreement, but the trend with increasing inclusive angle between the outgoing protons is in the wrong direction. The results at 65 MeV are consistent with experiment.