An optical-model analysis of the scattering of 64.3-MeV $\alpha$ particles from ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Fe}$, and of 50.2-MeV $\alpha$ particles from ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, has been performed using independent real- and imaginary-potential-geometry parameters. The scattering is found to be sensitive only to the potential form at radial distances beyond about 6 F. Real-potential-parameter ambiguities have been studied with particular reference to the quality of the analyzed data. The potentials found are compared with expectations based upon a simple folding of matter sizes and effective two-body forces.

The reaction ${}_{}{}^{49}{}_{}{}^{}\mathrm{Ti}({}_{}{}^3{}_{}{}^{}\mathrm{He},d){}_{}{}^{50}{}_{}{}^{}\mathrm{V}$ has been studied at 15-MeV incident energy with an over-all energy resolution better than 20 keV full width at half maximum. 54 states were observed in ${}_{}{}^{50}{}_{}{}^{}\mathrm{V}$ up to 6-MeV excitation, and corresponding deuteron angular distributions were measured in the angular interval 7 to 50°. Spectroscopic information has been extracted for 30 of the stronger or well-isolated transitions by means of a distorted-wave analysis of the differential cross sections. The results are compared with nuclear-model predictions.

The mean lifetime of the 2.94-MeV level in ${}_{}{}^{33}{}_{}{}^{}\mathrm{S}$ has been measured by the recoil distance method using the ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}(\alpha ,n){}_{}{}^{33}{}_{}{}^{}\mathrm{S}$ reaction. The lifetime was found to be 40.5±2.0 psec.

The energy levels of ${\mathrm{Au}}^{195}$ were studied by observation of conversion electrons following the ($p,2n$) reaction on ${\mathrm{Pt}}^{196}$, and by measurement of the energy spectrum and angular distribution of tritons from the ${\mathrm{Au}}^{197}\mathrm{}(p,t)\mathrm{}$ reaction. Many new energy levels are reported, and several new $I-\pi$ assignments are made by combining information from the two experiments.

The energy dependance of the 437-keV $\beta$—176-keV $\gamma$ directional correlation is measured with a conventional slow-fast scintillation assembly. The results are in good agreement with those of Dubard et al. The matrix-element parameters of this $\beta$ transition are determined using the present results and the allowed shape of the $\beta$ spectrum. The matrix-element parameters indicate that an algebraic cancellation among rank-1 matrix elements is responsible for the retardation of the 437-keV $\beta$ transition. The ratio of the matrix elements $\int \overrightarrow{\alpha }$ and $\int i\overrightarrow{\mathrm{r}}$ is not in agreement with the value predicted on the basis of conserved-vector-current theory.

The decay of ${}_{}{}^{231}{}_{}{}^{}\mathrm{Pa}$ was reinvestigated by means of Ge(Li) singles and coincidence techniques. Our best spectrometer showed a resolution (full width at half maximum) of 850 eV for the 300-keV $\gamma$ rays. 78 $\gamma$ rays were attributed to the decay of ${}_{}{}^{231}{}_{}{}^{}\mathrm{Pa}$. A level scheme for ${}_{}{}^{227}{}_{}{}^{}\mathrm{Ac}$ was proposed and interpreted in terms of rotation bands. Alternating terms in the $K=\frac{3}{2}$ bands were discussed in connection with Coriolis coupling to $K=\frac{1}{2}$ bands.

Thirty-six transitions from the excited levels of ${}_{}{}^{156}{}_{}{}^{}\mathrm{Gd}$ as fed by electron capture in ${}_{}{}^{156}{}_{}{}^{}\mathrm{Tb}$ have been studied. Level spins and parities, along with transition multipolarities, have been determined utilizing germanium solid-state detectors for the $\gamma$ rays and the Davis precision solenoidal $\beta$-ray spectrometer for the conversion electrons. The energies as measured by the spectrometer are determined to well within one part in 7000. A decay scheme is presented and the energy levels are discussed.

Coincidences between $L$ x rays and $K\alpha$ x rays, emitted during the filling of $K$ and $L$ vacancies in Hg in the decay of ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{204}{}_{}{}^{}\mathrm{Tl}$, are measured with high-resolution Si(Li) and Ge(Li) x-ray spectrometers in a fast-coincidence arrangement. The following $L$-subshell fluorescence and Coster-Kronig yields are measured: ${\omega }_2=0.316\mathrm{}\pm 0.010$, ${\omega }_3=0.300\mathrm{}\pm 0.010$, and $f_{23}=0.190\mathrm{}\pm 0.010$.

Angular distributions, average projected ranges, and cross sections for the production of ${}_{}{}^{137m}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{137g}{}_{}{}^{}\mathrm{Ce}$ from the ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}({}_{}{}^4{}_{}{}^{}\mathrm{He},3n)$ and ${}_{}{}^{137}{}_{}{}^{}\mathrm{Ba}({}_{}{}^3{}_{}{}^{}\mathrm{He},3n)$ reactions have been measured over the energy intervals 27-44 and 14-33 MeV, respectively. The average ranges were found to be consistent with a compound-nuclear process over the entire energy interval for both reactions. The isomer ratios are in good agreement with a calculation based on the spin-dependent statistical theory. Comparison is made with previous cross-section and isomer-ratio measurements, and various discrepancies are discussed. The angular distributions were analyzed to give the average total kinetic energy of the neutrons and photons emitted in the reactions. Comparison of these quantities at the same excitation energy and angular momentum of the compound nuclei shows that they are equal within the limits of error and thereby confirms the independence hypothesis. The observed differences in the average photon energies for reactions leading to ${}_{}{}^{137m}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{137g}{}_{}{}^{}\mathrm{Ce}$ are quantitatively related to the difference in the average angular momentum of compound nuclei leading to each isomer.

Using a ${\mathrm{He}}^3$-${\mathrm{He}}^4$ dilution refrigerator coupled with adiabatic demagnetization, ${\mathrm{Au}}^{198}$ has been polarized in a magnetized Fe foil at 5 mK. By measuring the directional distribution of the $\gamma$ rays emitted following the $2^{-}$→$2^{+}$ first-forbidden $\beta$ decays to ${\mathrm{Hg}}^{198}$, the $\beta$ dealignment parameters $U_2$ and $U_4$ have been determined. For the 0.96-MeV transition, we find $U_2=0.795\mathrm{}\pm 0.007$ and $U_4=0.347\mathrm{}\pm 0.03$. This implies that about 60% of the total decays carry off no angular momentum, about 39% carry off one unit of angular momentum, while 1% ±1% carry off two units of angular momentum. For the 0.29-MeV transition, we find $U_2=1.047\mathrm{}\pm 0.054$, implying that less than 1% of the decays carry off one or two units of angular momentum.

The symmetry of neutron-induced fission in ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ has been measured at a large number of epithermal levels with a time-of-flight energy-resolved beam from an underground nuclear explosion. The energy resolution was improved over previous similar "wheel" experiments. The symmetry of fission, as measured radiochemically by the ratio of ${}_{}{}^{115}{}_{}{}^{}\mathrm{Cd}$ to ${}_{}{}^{99}{}_{}{}^{}\mathrm{Mo}$, shows a bimodal distribution. If the results are averaged separately for the two apparent groups, the first group (I) has an average ${}_{}{}^{115}{}_{}{}^{}\mathrm{Cd}$/${}_{}{}^{99}{}_{}{}^{}\mathrm{Mo}$ ratio which is 0.593 times the thermal value; the second-group (II) average is 1.11 times the thermal value. The average fission width in I is one-half the average fission width in II. The numbers of levels assigned to I and II are 24 and 14, respectively. The energies of levels assigned to I are 19.30, 21.07, 22.94, 23.63, 26.44, 27.81, 30.91, 32.10, 33.55, 34.85, 40.51, 41.91, 43.41, 44.04, 45.79, 46.93, 48.06, 48.82, 51.37, 56.58, 57.83, 58.15, 60.25, and 61.10 eV; assignments to II are at 24.23, 25.65, 28.35, 34.39, 35.21, 35.75, 36.64, 38.42, 39.44, 44.75, 49.51, 52.27, 53.56, and 58.68 eV. From analogy with conclusions based on a similar set of observations in the fission of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$ and on arguments derived from fission-channel theory, it is hypothesized that $J=4\mathrm{}$ in I and 3 in II.

Monte Carlo calculations have been made of electron-photon cascades in thick tungsten targets bombarded by electrons with energies up to 60 MeV. The following information has been obtained: (1) the bremsstrahlung efficiency, (2) the angular distribution of the emitted bremsstrahlung intensity, (3) the spectra of the bremsstrahlung emitted in various directions, (4) the transmission of primary and secondary electrons through the target, (5) energy deposition as function of the depth in the target, (6) the differential photon track length distribution inside the target, and (7) the yield of photoneutrons. The paper also includes various comparisons with experimental data.

We have developed a semiempirical description of the ground-state band of even quasirotational nuclei, based on the picture of anharmonic vibrations, which agrees surprisingly well with experiment. Comparison with previous empirical and semiempirical formulas is presented.

The ($p,n$) reaction cross sections were measured to ±4% for 3- to 5.5-MeV protons on ${}_{}{}^{117,119,120,122,124}{}_{}{}^{}\mathrm{Sn}$ and on natural Sn and In. Analyses with a conventional optical-model potential were made in the energy regions where the ($p,n$) cross sections are nearly equal to the total absorption cross sections. These analyses show that the energv dependence in the real well is about three times greater for 5- to 10-MeV protons than it is for 10- to 61-MeV protons. The best-fit potential for 3- to 5.5-MeV protons on the Sn isotopes has a surface absorptive layer about half as thick as at 10 MeV. The In strength functions are fitted by increasing both the width and depth of the imaginary part of this potential by about 25%. The $Q$ value for ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}\mathrm{}(p,n)\mathrm{}{}_{}{}^{120}{}_{}{}^{}\mathrm{Sb}$ was found to be -3465 ± 7 keV.

Levels in ${}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$ have been studied through the reactions ${}_{}{}^{168}{}_{}{}^{}\mathrm{Er}\mathrm{}(d,p)\mathrm{}{}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{170}{}_{}{}^{}\mathrm{Er}\mathrm{}(d,t)\mathrm{}{}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$, using 12-MeV deuterons, and via thermal-neutron capture in ${}_{}{}^{168}{}_{}{}^{}\mathrm{Er}$. Over 40 states below 1.5 MeV are populated in the charged-particle reactions. These data, coupled with the $\approx 150$ capture $\gamma$ rays observed, lead to a level scheme that includes the following spectroscopic assignments (rotational band-head energy in keV, followed by the Nilsson single-particle state believed to be dominant): 0.0, ${\mathrm{½}}^{-}$[521], with associated rotational band to spin ${\frac{11}{2}}^{-}$, 92.2, ${\frac{5}{2}}^{-}\mathrm{}\left[512\right]\mathrm{}$, with band to ${\frac{11}{2}}^{-}$; 243.7, ${\frac{7}{2}}^{+}\mathrm{}\left[633\right]\mathrm{}$, with band to ${\frac{13}{2}}^{+}$; 562.1, ${\mathrm{½}}^{-}$[510], with band to ${\frac{7}{2}}^{-}$; 714.5, ${\frac{3}{2}}^{-}\mathrm{}\left[521\right]\mathrm{}$, with band to ${\frac{11}{2}}^{-}$; 823, ${\frac{7}{2}}^{-}$ [514], with band to ${\frac{9}{2}}^{-}$; 850, ${\frac{5}{2}}^{-}\mathrm{}\left[523\right]\mathrm{}$, with band to ${\frac{11}{2}}^{-}$; and 1081.8, ${\frac{3}{2}}^{-}\mathrm{}\left[512\right]\mathrm{}$, with band to ${\frac{7}{2}}^{-}$. In addition, a level at 860.2 keV is assigned as the head of a $K^{\pi }={\frac{3}{2}}^{+}$ band that is mainly the ($K-2\mathrm{}$) $\gamma$-vibrational state associated with ${\frac{7}{2}}^{+}\mathrm{}\left[633\right]\mathrm{}$. The data suggest that the 562.1-, 714.5-, and 1081.8-keV bands also have significant vibrational admixtures. Several features of the level scheme, including certain $\gamma$-ray branching ratios, are interpreted in terms of Coriolis mixing. The neutron separation energy for ${}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$ is determined as 6003.1 ± 0.3 keV, and the $Q$ value for the ${}_{}{}^{170}{}_{}{}^{}\mathrm{Er}\mathrm{}(d,t)\mathrm{}{}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$ reaction is found to be -950 ± 30 keV.

The $\gamma -\gamma$ perturbed angular correlation of the 236-50-keV cascade in ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ has been investigated, yielding $g({\frac{3}{2}}^{-},50\mathrm{} \mathrm{keV})=+0.28\mathrm{}\pm 0.04$. The magnetic hyperfine fields experienced by Ra nuclei embedded in Ni, Co, and Fe lattices were found to be -30 ± 10, -80 ± 16, and -105 ± 20 kOe, respectively.

A study of the neutron-capture reaction mechanism for radiative capture of resonant-energy neutrons has been made for ${}_{}{}^{175}{}_{}{}^{}\mathrm{Lu}(n,\gamma ){}_{}{}^{176}{}_{}{}^{}\mathrm{Lu}$. The statistical distribution of the partial radiation widths over 11 neutron resonances is inconsistent with a ${\chi }^2$ distribution with one degree of freedom. No correlations are observed between the $\gamma$-ray partial widths and the reduced neutron widths of either the capturing or final states. Neither is there any significant correlation among the individual $\gamma$-ray widths. Such facts indicate that neither channel capture nor doorway states contribute strongly to the neutron-capture process in the region above the neutron binding energy. However, there is a small but significant departure from a purely statistical compound-nuclear process. Final states unreported in previous experiments are observed. In addition, the spins of 11 resonances, as well as limitations on the spins of the low-lying final states are determined.

Photon scattering cross sections were measured with 70-keV resolution from 6 to 9 MeV in Sn, and from 8.5 to 12.5 MeV in Zr. A new method of analysis is used to infer relatively reliable total photon interaction cross sections. Both the elastic scattering and the total interaction cross sections vary more rapidly with energy than had been anticipated; the best identified localization of transition strength is between 11.4 and 11.8 MeV in Zr. The average total interaction cross sections are qualitatively similar to, but about 50% larger than, an extrapolation of the electric dipole giant resonance. The cross sections are large enough to imply that electric dipole interaction dominates at most energies. The relative probability of photon scattering and photoproton emission is very sensitive to correlations between proton widths and ground-state $\gamma$-ray widths. There is no evidence for width correlations associated with the additional strength concentrated near 11.5 MeV in ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$.

We have calculated the effect of nuclear deformability on the cross section for interaction of heavy ions with uranium. Static calculations indicate that these effects should be large; dynamic calculations with liquid-drop parameters indicate that they should be smaller, but measurable with currently available heavy ions (argon incident on uranium). Dynamic calculations with parameters derived from spectroscopic measurements indicate that the effects should be quite small, in agreement with experiment. We have done both classical and quantum-mechanical calculations; the two methods give the same results. The quantum-mechanical calculations also give the probability of Coulomb excitation to the vibrational states of the target nucleus. We discuss the value of several approximations used to estimate total reaction cross sections.

The $\beta -\gamma$ angular correlation of the $(536\mathrm{}-\mathrm{K}\mathrm{e}\mathrm{V}-\beta )-(604\mathrm{}-\mathrm{k}\mathrm{e}\mathrm{V}-\gamma +612\mathrm{}-\mathrm{k}\mathrm{e}\mathrm{V}-\gamma )$ transition in ${\mathrm{Ir}}^{192}$ was measured and found to be zero. The $\gamma$-conversion-$e^{-}$ correlation of the 604-keV-316-keV transitions in ${\mathrm{Pt}}^{192}$ was used to estimate the $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratio of the 605-keV $\gamma$ ray, giving $\delta =3\mathrm{}$.