Neutron—neutron-hole configurations of states in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ were studied by proton scattering through the $d_{\frac{5}{2}}$ isobaric analog resonance in ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$. Angular distributions for the scattered protons were taken from 60 to 173° for the states in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ which have excitation energies between 4.69 and 6.30 MeV. The on-resonance—to—off-resonance ratio for these states was at most 15:1. The resolution in all spectra was 18 keV or better. The data were analyzed to obtain total proton inelastic scattering cross sections. With this information and the proton single-particle widths extracted from elastic scattering data, total inelastic proton partial widths were calculated. Final-state spins were specified by fitting the observed angular distributions with an appropriate expression for the differential cross section and by comparing those results to information derived from other experiments.

A search for the parity-nonconserving contribution to the $\gamma$ decay of ${}_{}{}^{159}{}_{}{}^{}\mathrm{Tb}$ has been made. A complete description of the experimental technique is presented. The angular distribution of the 363-keV line of ${}_{}{}^{159}{}_{}{}^{}\mathrm{Tb}$ was measured with a pair of Ge(Li) detectors. The ${}_{}{}^{159}{}_{}{}^{}\mathrm{Gd}$ parent atoms were located in the +453-kG hyperfine field of Gd${\mathrm{Fe}}_2$ held at 28 mK by a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ dilution refrigerator. The resulting 7% polarization of the ${}_{}{}^{159}{}_{}{}^{}\mathrm{Gd}$ led to a $P_1\left(cos\Theta \right)$ term of +(2.7 ± 1.8) × ${10}^{-4\mathrm{}}$ in the $\gamma$-ray angular distribution, where $\Theta$ is measured with respect to the nuclear polarization. Thus, for full Tb polarization, the asymmetry would be +(4.5 ± 3.0) × ${10}^{-3\mathrm{}}$ $P_1\left(cos\Theta \right)$, peaked in the direction of Tb nuclear spin alignment. This sign of the $P_1\left(cos\Theta \right)$ term is based on an assumed negative moment of the ${}_{}{}^{159}{}_{}{}^{}\mathrm{Gd}$ parent. We measure the magnitude of this moment to be $(0.22\mathrm{}\pm 0.05){\mu }_N$.

The 637- and 723-keV states in ${\mathrm{Xe}}^{131}$ have been investigated by employing the technique of nuclear resonance fluorecence. The angular distribution of the resonantly scattered radiation from the 637-keV level is consistent with the assignment of either spin and parity ${\frac{5}{2}}^{+}$, decaying to the ground state predominantly by an $M1\mathrm{}$ transition, or a spin and parity of ${\frac{7}{2}}^{+}$ with the decay to the ground state being pure $E2\mathrm{}$. Considering the results of other investigators, a ${\frac{7}{2}}^{+}$ assignment appears to be the correct choice. Assuming a spin of $\frac{7}{2}$, the mean life of the 637-keV level is found to be 1.8 ± 0.8 psec. The fact that resonant scattering from the 723-keV level was observed with a source of gaseous ${\mathrm{II}}^{131}$ is attributed to Coulomb fragmentation of the ${\left({\mathrm{IXe}}^{131}\right)}^{+}$ molecular ion formed following the $\beta$ decay of ${\mathrm{I}}^{131}$. The angular distribution of the resonantly scattered 723-keV $\gamma$ rays is consistent with a spin and parity assignment of ${\frac{5}{2}}^{+}$ to this level, and a pure $M1\mathrm{}$ decay to the ground state. Our results indicate that the mean life of the 723-keV level is greater than 1.5 psec.

The average-resonance-neutron-capture spectra of ${}_{}{}^{147}{}_{}{}^{}\mathrm{Sm}(n,\gamma ){}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{149}{}_{}{}^{}\mathrm{Sm}(n,\gamma ){}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ obtained with the Argonne in-pile ($n,\gamma$) facility are used to develop and extend the level schemes of ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$. In particular, the experiment gives information about the spin and parity assignments of 33 levels with excitation energies from 0 to 2.7 MeV in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and 47 levels from 0 to 2.5 MeV in ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$. Unique spin and parity assignments are given for almost all the states below 2.2 MeV in both isotopes. In many cases in which previous experiments gave conflicting indications, the new data led to definite spin assignments. The neutron binding energies in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ were found to be 8140.6±1.8 and 7986.4±1.8 keV, respectively, after correction for the energy spectrum of the captured neutrons.

With barium isotopes of mass 130, 132, 134, 136, and 138 as targets, proton elastic scattering excitation functions have been obtained at several angles. In the proton energy range 7.0-12.0 MeV, we observed several resonances which correspond to isobaric analogs of the low-lying states of the target-plus-neutron systems. The resonance data have been analyzed to extract proton elastic widths, total widths, and resonance energies. Spectroscopic factors have been extracted by comparing the measured proton elastic widths with the single-particle widths calculated on the basis of a shell-model description of the analog state. The spectroscopic factors so determined are compared with those from the $\mathrm{Ba}\mathrm{}(d,p)\mathrm{}$ reaction to the parent analog states. The variation of single-particle width with the parameters of the bound-state neutron well has been investigated. From the analog resonance energies and the $Q$ values for the parent states in $\mathrm{Ba}\mathrm{}(d,p)\mathrm{}$ reactions, the Coulomb shifts of the principal resonances have been found.

An experiment has been performed on the thermal-neutron-induced fission of ${\mathrm{U}}^{235}$, in which the energies of complementary fission fragments and the time of flight of one fragment were measured. Fragment masses after neutron emission were obtained directly from this information. Pre-neutron masses and kinetic energies were deduced by means of a reflection method which simulates a double-time-of-flight experiment. Subtraction of post-neutron from primary fragment masses then gave the number of neutrons emitted by single fragments in each event. Among the results presented are the distributions of the numbers of neutrons emitted by single fragments of fixed mass. This information is very difficult to obtain from other types of experiments, and there has been no previous publication of such results for any fissioning nucleus. The results also include the average number of neutrons emitted as a function of mass and total kinetic energy, as well as mass distributions in fixed kinetic energy intervals, and total kinetic energy distributions at fixed fragment masses.

The Doppler-shift attenuation method was used to obtain the mean lives of the first two excited states in ${}_{}{}^{29}{}_{}{}^{}\mathrm{P}$: $\tau \left(1.38\mathrm{} \mathrm{MeV}\right)=(2.1\mathrm{}\pm 0.6)\times {10}^{-13\mathrm{}}$ sec and $\tau \left(1.95\mathrm{} \mathrm{MeV}\right)=\left({3.2}_{-1.1\mathrm{}}^{+1.5\mathrm{}}\right)\times {10}^{-13\mathrm{}}$ sec. The excited states were populated by the reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}\mathrm{}(d,n)\mathrm{}{}_{}{}^{29}{}_{}{}^{}\mathrm{P}$ using deuteron energies ranging from 2.93 to 3.50 MeV. Pulse-shape discrimination was employed for the neutron-$\gamma$-ray coincidence measurements. The results are compared with those in ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ and with the predictions of the strong-coupling rotational model.

The bootstrap theory is applied to the case of pairing vibrations; an approximation used by Dang and Klein in their treatment of pairing is shown to be consistent with the bootstrap theory. A modified Tamm-Dancoff approximation is described. The numerical results for ${\mathrm{Ni}}^{58,60,62}$ are compared with the exact solutions and with the results of Dang and Klein.

Some recent calculations based on the statistical model have employed the adiabatic assumption inconsistently. In particular, the high central repulsive core in ion-ion collisions is due to a trial density function which leads to unphysically large densities in the close-in region.

States in ${}_{}{}^{57}{}_{}{}^{}\mathrm{Ni}$ have been observed at excitations of 2.45 ± 0.01 and 3.00 ± 0.01 MeV using the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha ){}_{}{}^{57}{}_{}{}^{}\mathrm{Ni}$ reaction, confirming previous indications of their existence from ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}(\alpha ,n\gamma ){}_{}{}^{57}{}_{}{}^{}\mathrm{Ni}$ studies.

Additional data on neutron-proton bremsstrahlung measurements at 208-MeV neutron energy are presented. These are at $({\theta }_n,{\theta }_p)=({40}^{\circ },{30}^{\circ })$ and (45°, 30°). Also, the analysis of the symmetric-angle data reported earlier has been improved resulting in small changes in the cross sections.

The excitation function for all neutron groups leading to the formation of the 6.38-sec first excited state of ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ was measured for incident proton energies from 5.2 to 8.0 MeV by detecting the residual radioactivity. Resonances were observed corresponding to 19 levels in ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ ranging in excitation energy from 13.43 to 16.10 MeV. For the first four resonances, which are due to the $n_1$ group alone, neutron angular distributions were measured. $R$-matrix calculations produced fits to the excitation curve and angular distributions which permit spin and parity assignments of ${\frac{1}{2}}^{+}$, ${\frac{3}{2}}^{+}$, ${\frac{3}{2}}^{-}$, and ${\frac{5}{2}}^{+}$ to the levels of excitation energies 13.433, 13.703, 13.867, and 13.998 ± 0.015 MeV, respectively. Possible correspondence to isobaric analog states in ${}_{}{}^{27}{}_{}{}^{}\mathrm{Mg}$ is discussed.

In this paper we evaluate the radiative photon spectrum and the branching ratio $R$ of radiative-to-ordinary muon capture rate in ${\mathrm{Ca}}^{40}$, taking into account the nucleon-nucleon residual interaction by means of Migdal's quasiparticle model.

The most important effect of the residual interaction is to reduce both the ordinary and radiative rate about 40% lower than that obtained in the closure-harmonic-oscillator model. This result differs from that obtained by Fearing using the giant-dipole-resonance model, while it confirms the prediction of Rood and Tolhoek (RT) that the branching ratio $R$ would be nearly independent of the nuclear model. We also evaluate the circular polarization of the photons, $P_{\gamma }$. We find that our values of $P_{\gamma }$ are greater than the RT values by about 15% in the high-energy range. In the low-energy range, our values of $P_{\gamma }$ are in close agreement with those of RT. For the maximum energy of the photon spectrum, we obtain the average value $k_{max}=90.5\mathrm{}$ MeV, which is very close to the RT value.

Comparing our results with the experimental data of Conversi, Diebold, and Di Lella, we find that our calculation requires $g_P=(12.4\mathrm{}\pm 2.8)g_A$ to fit the experimental values, where $g_P$ is the induced pseudoscalar coupling constant and $g_A$ the axial-vector coupling constant.

Finally, we think that the disagreement between our result and the more currently accepted value of $g_P$ is not so great as to call into question the theoretical mechanism of the radiative capture, if one takes into account the large experimental uncertainties.

The levels of ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$ up to an excitation energy of 7 MeV have been investigated by the ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}\mathrm{}(t,p)\mathrm{}$ reaction with 15-MeV tritons. Proton spectra were measured by a $\Delta E-E$ counter telescope system with an over-all resolution of 35 keV, and close-lying peaks were resolved by additional measurements with a magnetic spectrograph. Angular distributions were measured from 12.5 to 90°, and comparisons with zero-range distorted-wave Born-approximation calculations permitted spin assignments of 32 of the 45 levels observed. Four excited $0^{+}$ states were observed. From a comparison of their cross sections with the ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}\mathrm{}(t,p)\mathrm{}{}_{}{}^{90}{}_{}{}^{}\mathrm{Sr}$ groundstate cross section, no one of them could be identified as the pairing vibration state; the strength of the latter appears to be fragmented. The data are compared with previous information on the ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$ level structure.

The energies, spins, decay modes, and lifetimes of the first three excited states of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ have been determined. The results are: 3.832 MeV ($2^{+}$), 0.053 ± 0.024 psec; 4.284 MeV ($0^{+}$), 322 ± 16 psec; and 4.507 MeV ($3^{-}$), ${8.8}_{-2.8\mathrm{}}^{+5.5\mathrm{}}$ psec.