We have looked for the $J^P=0^{+}$ nuclear excitation of ${\mathrm{Zn}}^{68}$ in muonic atoms as suggested by Henley and Wilets. ${\mathrm{Zn}}^{68}$ was chosen because the energy of the $0^{+}$ excitation is close to the energy difference of the $2s-1s$ muonic levels, thus allowing a dynamic interaction between a muon in a $2s$ state and the nucleus in the ground state. We find that the $2s-1s$ level difference is 20 keV less than the nuclear excitation energy and, as a result, the dynamic interaction is too small for us to observe. We measure the ${\mathrm{Zn}}^{66}$-${\mathrm{Zn}}^{68}$ isotope shift to be $\frac{\delta R}{\delta R_{\mathrm{std}}}=0.47\mathrm{}\pm 0.11$.

A search for double $\gamma$ emission from the first excited ${\mathrm{O}}^{+}$ states in ${\mathrm{Ca}}^{40}$ and ${\mathrm{Zr}}^{90}$ has been carried out using a NaI(Tl) scintillation spectrometer and a sum-coincidence technique. No definite evidence for double $\gamma$ emission is found in either case. In the 3.35-MeV, ${\mathrm{O}}^{+}$-to-ground-state transition in ${\mathrm{Ca}}^{40}$, an upper limit of 4 × ${10}^{-4\mathrm{}}$ has been established for the branching ratio of double $\gamma$ emission with respect to internal pair emission. For the 1.75-MeV ${\mathrm{O}}^{+}$-to-ground-state transition in ${\mathrm{Zr}}^{90}$, an upper limit of 1.8 × ${10}^{-4\mathrm{}}$ has been obtained for the branching ratio of double $\gamma$ emission with respect to the sum of internal-conversion electrons and internal pairs. The significance of these results in the light of existing theories is discussed.

The analysis of inelastic scattering of 11-MeV protons from quadrupole and octupole collective levels of 14 even-even nuclei between ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ and ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$ is reported. The distorted-wave Born approximation is used to calculate the cross sections using the collective-model generalization of the optical model for inelastic scattering. The analysis is performed using both real and complex form factors for the model. A satisfactory description of all the data is obtained when a contribution due to compound-nucleus decay for most of the octupole levels and a few of the quadrupole levels is included.

Angular distributions have been measured for 15 levels observed in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^3{}_{}{}^{}\mathrm{He},d){}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ reaction at 40-MeV bombarding energy. Distorted-wave Born-approximation calculations for the proton unstable excited states quasibound by the Coulomb and centrifugal barrier were performed using a form factor corresponding to an unbound (resonance) level in a Woods-Saxon well. The resulting spectroscopic factors are found to be insensitive to the scattering phase shifts, and in agreement with those obtained by elastic scattering. Most of the available $1f_{\frac{7}{2}}$, $2p_{\frac{3}{2}}$, and $2p_{\frac{1}{2}}$ strength and a large portion of the $1f_{\frac{5}{2}}$ strength is observed below 6-MeV excitation. Little $1g_{\frac{9}{2}}$ or $2d_{\frac{5}{2}}$ strength is observed.

Total reaction cross sections for protons on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ have been measured at 15 energies between 10.3 and 21.6 MeV by the beam-attenuation method. The total reaction cross section for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ rises sharply at low energies, reaches a maximum value around 13 MeV, and reaches a minimum value around 16 MeV. The rise at the lower energies is a result of the Coulomb barrier. The dip at 16 MeV is probably associated with the ($p,n$) threshold for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$. A comparison is made between the present experimental values and preliminary optical-model predictions based on available elastic-scattering data and polarization data. The variation in the reaction cross section is also compared with the integrated partial cross sections for elastic scattering. Total reaction cross sections for protons on carbon have been measured at ten energies between 9.88 and 19.48 MeV. Resonances in the total reaction cross section are observed in the neighborhood of 10.4 and 13.8 MeV. Variations of 200 mb are seen in the cross sections with changes in energy of the incident protons of about 200 keV. A comparison is made of the present total reaction cross sections and the integrated partial cross sections for elastic scattering and inelastic scattering to the first excited state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$.

The energy and angular distribution of $\alpha$ particles inelastically scattered from Al have been measured from 30 to 170° for 20.0- and 27.5-MeV bombarding energies. Angular distributions of the inelastic $\alpha$ particles corresponding to residual nuclei excited to the continuum are found to be symmetric around 90°. For a number of angular distributions, the magnitude of the anisotropy is large; i.e., the ratio of differential cross sections at 170 to 90° is greater than 2.5. In the interpretation of the experimental results, the nuclear-level-density parameter and the spin cutoff parameter are derived by application of the semiclassical compound-nucleus theory of Ericson and Strutinski. This cutoff parameter is consistent with the rigid-rotor model of the nucleus. In order to obtain agreement between the magnitudes of the calculated and the experimentally measured cross sections, it was necessary to incorporate nuclear shell effects into the statistical-theory calculations.

Experimental energies, spectroscopic factors, and electromagnetic data associated with the low-lying levels of ${\mathrm{Cr}}^{53}$ are fitted by means of a model in which the basis states are taken to be single-particle orbits vector-coupled to states of the ${\mathrm{Cr}}^{52}$ core. Unknown properties of the core states are treated as parameters. A least-squares minimization procedure is used to determine optimum fits to the data. Although most of the low-energy data can be fitted quite successfully, the spectroscopic factors and quadrupole moment are not well reproduced. The observed levels appear to be more highly mixed than is suggested by the model. It is also found to be necessary to introduce an effective charge in order to reproduce the $B\left(E2\mathrm{}\right)\mathrm{}$ data.

Levels are calculated for the $N=29\mathrm{}$ and $Z=29\mathrm{}$ nuclei, ${\mathrm{Ti}}^{51}$, ${\mathrm{Cr}}^{53}$, ${\mathrm{Fe}}^{55}$, ${\mathrm{Cu}}^{61,63,65}$. The model used is the intermediate-coupling model with quasivibrational core, as developed by True and Thankappan. A pattern search routine is used to fit the five parameters to the levels and stripping strengths. Except for the case of ${\mathrm{Cr}}^{53}$, levels and strengths are fitted fairly well. In particular, in ${\mathrm{Fe}}^{55}$ we identify the states at 1.917 and 2.051 MeV as ${\frac{3}{2}}^{-}$ and ${\mathrm{½}}^{-}$ states, respectively. $B\left(E2\mathrm{}\right)\mathrm{}$ values for transitions to the ground state are calculated, and the comparison with data for ${\mathrm{Cu}}^{63}$ and ${\mathrm{Cu}}^{65}$ shows good agreement. However, there are no experimental $B\left(E2\mathrm{}\right)\mathrm{}$ data available for the other nuclei.

The even selenium isotopes ${}_{}{}^{72}{}_{}{}^{}\mathrm{Se}$, ${}_{}{}^{74}{}_{}{}^{}\mathrm{Se}$, ${}_{}{}^{76}{}_{}{}^{}\mathrm{Se}$, and ${}_{}{}^{78}{}_{}{}^{}\mathrm{Se}$ have been investigated by means of the $\mathrm{Ge}(\alpha ,2n\gamma )\mathrm{Se}$ and $\mathrm{Ge}(\alpha ,4n\gamma )\mathrm{Se}$ reactions. The $\gamma$ radiation from these nuclei was studied during the irradiation using techniques of in-beam spectroscopy. The energies of the $\gamma$ rays, their relative intensities, their angular distributions, and their time distributions relative to the 2-nsec beam bunch have been measured. Quasirotational ground-state bands were observed up to 10+ for ${}_{}{}^{76}{}_{}{}^{}\mathrm{Se}$, up to 8+ for ${}_{}{}^{74}{}_{}{}^{}\mathrm{Se}$ and ${}_{}{}^{78}{}_{}{}^{}\mathrm{Se}$, and up to 6+ for ${}_{}{}^{72}{}_{}{}^{}\mathrm{Se}$. The level energies are compared to a semiempirical formula.

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.