In order to obtain information about the role of multiphoton processes in recently reported laser-induced nuclear fusion, the cross section for simultaneous net absorption of $n$ photons by a system of two point charges has been calculated numerically for $e^{-}-p$ scattering in a ruby laser beam at an incident relative energy of 100 eV. The results show that at laser intensities involved in fusion experiments multiphoton processes apparently play an important role, partly contributing to the same order within certain $n$ intervals.

The Mössbauer effect has been observed in the decay of the ${\frac{5}{2}}^{-}$ 121.2-keV state of ${\mathrm{Sm}}^{147}$. Sources were ${\mathrm{Pm}}^{147}$ in a mixed Pm-Sm oxide matrix and ${\mathrm{Eu}}^{147}$ in ${\mathrm{Sm}}_2$${\mathrm{O}}_3$. Both types of sources gave single Lorentzian lines when used with an ${\mathrm{Sm}}_2$${\mathrm{O}}_3$ absorber. The ${\mathrm{Eu}}^{147}$ source was used with a samarium iron garnet absorber to obtain the excited-state nuclear moments. The magnetic dipole moment is found to be $-0.445\mathrm{}\pm 0.025{\mu }_N$. Using an atomic-beam measurement of the ground-state quadrupole splitting, an estimate of -0.31 ± 0.12 b is obtained for the excited-state quadrupole moment. Three light rare-earth odd-neutron nuclei have now been studied by the Mössbauer effect: ${\mathrm{Nd}}^{145}$, ${\mathrm{Sm}}^{147}$, and ${\mathrm{Sm}}^{149}$. The $g$ factors for the low-lying levels of these nuclei cluster about -0.22. The present theoretical models are not particularly successful in accounting for the magnetic moments.

We have carried out a search for neon and argon isotopes produced in ternary fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$, using high-sensitivity mass spectrometry. The following upper limits - expressed in atoms per binary fission - were obtained: ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ < 5.8 × ${10}^{-8\mathrm{}}$, ${}_{}{}^{21}{}_{}{}^{}\mathrm{Ne}$ < 3.4 × ${10}^{-10\mathrm{}}$, ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ < 5.9 × ${10}^{-9\mathrm{}}$, ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ < 2.4 × ${10}^{-9\mathrm{}}$, ${}_{}{}^{37}{}_{}{}^{}\mathrm{Ar}$ < 2.2 × ${10}^{-9\mathrm{}}$, ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$ < 2.0 × ${10}^{-9\mathrm{}}$, ${}_{}{}^{39}{}_{}{}^{}\mathrm{Ar}$ < 7.8 × ${10}^{-10\mathrm{}}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ < 6.9 × ${10}^{-7\mathrm{}}$, ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ar}$ < 2.2 × ${10}^{-9\mathrm{}}$. Except in the case of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, these limits are lower by 1 to 4 orders of magnitude than indicated from results of triple-coincidence experiments carried out by previous workers. Assuming unique formation of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, the upper limit for this nuclide is a factor of 5 lower than the triple-coincidence frequency.

$\alpha$-emitting high-spin isomeric states in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Ho}$ and ${}_{}{}^{154}{}_{}{}^{}\mathrm{Ho}$ were found by bombarding targets of ${}_{}{}^{142}{}_{}{}^{}\mathrm{Nd}$ and ${}_{}{}^{144}{}_{}{}^{}\mathrm{Nd}$ with nitrogen ions accelerated in the Oak Ridge isochronous cyclotron. In the experiments, recoil nuclei ejected from the thin targets were stopped in helium gas, swept through an orifice, and deposited on the surface of a wheel. After bombardment, the wheel was turned by remote control to place the collected activity in front of an $\alpha$-particle Si(Au) spectrometer for assay. The previously unreported high-spin isomer in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Ho}$ was found to have a half-life of 2.0 ± 0.1 min and an $\alpha$-decay energy of 3.91 ± 0.01 MeV. The $\beta$ decay of the 3.25-min ${}_{}{}^{154}{}_{}{}^{}\mathrm{Ho}$ high-spin isomer had been investigated earlier by Ward and Neiman. In the present study it was found that the isomer also emits $\alpha$ particles with an energy of 3.72 ± 0.01 MeV. The nuclidic assignments of these two new $\alpha$ emitters were based primarily on (1) a comparison of yield curves for their production with yield curves for the production of the known pairs of $\alpha$-emitting isomers in ${}_{}{}^{151}{}_{}{}^{}\mathrm{Ho}$ and ${}_{}{}^{152}{}_{}{}^{}\mathrm{Ho}$, and (2) cross bombardments which demonstrated that the $\alpha$ groups could not be due to decay from previously unknown isomers in dysprosium and terbium nuclei in the investigated mass region.

The level structure of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Bi}$ has been investigated using both stripping and pickup reactions. The ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}({}_{}{}^3{}_{}{}^{}\mathrm{He},d)$ and ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}(\alpha ,t)$ reactions permit the identification of a series of doublets arising from the coupling of a proton in the $h_{\frac{9}{2}}$, $f_{\frac{7}{2}}$, $i_{\frac{13}{2}}$, $f_{\frac{5}{2}}$, and $p_{\frac{3}{2}}$ single-particle states with a neutron hole in the $p_{\frac{1}{2}}$ shell. The ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}\mathrm{}(d,t)\mathrm{}$ and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha )$ reactions populate the multiplets arising from coupling of a neutron hole in the $p_{\frac{1}{2}}$, $f_{\frac{5}{2}}$, $p_{\frac{3}{2}}$, $i_{\frac{13}{2}}$, $f_{\frac{7}{2}}$, and $h_{\frac{9}{2}}$ states with a proton in the $h_{\frac{9}{2}}$ shell. A detailed analysis shows that the total strength in each multiplet is close to that for the corresponding single-particle or single-hole transition on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. In addition to the strong transitions leading to states of these multiplets, some relatively weak transitions are observed which provide a measure of the mixing of different configurations. The structure and purity of the particle-hole multiplets below about 3-MeV excitation is in good agreement with shell-model calculations.

A method of identifying the atomic number of $\gamma$-ray spectra of ${\mathrm{Cf}}^{252}$ fission products by means of $K$ x-ray and $\gamma$-ray coincidence techniques has been applied to Cs ($Z=55\mathrm{}$) and Ba ($Z=56\mathrm{}$) fission products. The separation of the $K\alpha$ x-ray peak centroids for this pair is only 1.2 keV, while the full width at half maximum of these peaks [using a Si(Li) detector] is 1.6 keV. It is shown that by using computer analysis, assignment of $\gamma$ lines to either Cs or Ba may still be achieved with a high degree of reliability. 22 $\gamma$ transitions have been analyzed in the energy range 125-300 keV. 12 of these have been tentatively assigned to Cs, and 10 to Ba.

The energy spectra of nuclear fragments produced by the interaction of 5.5-GeV protons with uranium have been determined at several laboratory angles by means of $\frac{\mathrm{dE}}{\mathrm{dx}}-E$ measurements with semiconductor-detector telescopes. Individual isotopes of the elements from hydrogen to carbon were resolved, and from nitrogen to argon the study was continued for the elements without isotopic separation. The evaporation-like energy spectra were integrated to obtain angular distributions and total cross sections for the isotopes of helium through carbon. Total cross sections for many rare isotopes were also estimated. The yield surface constructed from these cross sections has a ridge-like shape positioned one neutron in excess of the line of $\beta$ stability. The yields fall off more steeply on the neutron-deficient side and exhibit odd-even effects reflecting those of the mass surface. The energy spectra of the neutron-deficient isotopes differ from the others in that the high-energy parts of the spectra are more pronounced and flatter, and the angular distributions are more forward peaked.

Some of the energy spectra were fitted with calculated curves based on the isotropic evaporation of fragments from a system moving along the beam axis. The apparent Coulomb barriers obtained from this analysis were about one half the nominal Coulomb barriers, and the apparent nuclear temperatures fell in the 10- to 13-MeV range. For the highest-energy fragments observed at 90° the apparent temperatures rose to 20 MeV. From the forward-backward shifts in energy it was deduced that the average velocity of the moving system is about $0.006c$ and that there is a positive correlation between this velocity and the velocity of the fragments in the moving system. However, all of the data are more peaked forward in intensity than can be explained by this simple two-step model.

Radiochemical cross sections are also presented for the production of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ from uranium, silver, and aluminum, and for ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ from aluminum.

Proton elastic scattering data are analyzed in the framework of a single-particle theory to obtain energies, partial widths, total widths, and spectroscopic factors for 14 isobaric analog resonances in ${}_{}{}^{131}{}_{}{}^{}\mathrm{I}$. Excitation functions and fits are presented and the results are compared with those of similar analyses as well as with those of ($d,p$) investigations. A total of 42 excited states in ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ were identified from the inelastic spectra at the various resonances. Groups of states at the $d_{\frac{3}{2}}$, $f_{\frac{7}{2}}$, and $p_{\frac{3}{2}}$ resonances were analyzed as neutron particle-neutron hole states, and fits to the angular-distribution data for these states are presented. The analysis provides proton partial widths, spectroscopic factors, and assignment of possible spins and parities for these states. The ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ inelastic results are compared with those of other nuclei in the $N=82\mathrm{}$ mass region.

We examine the binding energy of nuclear matter for exactly phase-shift-equivalent potentials. We generate these potentials by applying a short-range unitary transformation to the Reid soft-core potential. All potentials have a one-pion-exchange tail. We find that, for the potentials studied, variations of up to 9.5 MeV in the binding energy and 0.33 ${\mathrm{F}}^{-1\mathrm{}}$ in the saturation density occur. The variations in binding energy are linearly correlated with the wound integral $\kappa$ for those potentials that give nearly the same deuteron electric form factor. An increase in $\kappa$ leads to less binding in nuclear matter. The sensitivity of the binding energy is somewhat greater to the ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}+{}_{}{}^3{}_{}{}^{}D_1^{}{}_{}{}^{}$ contribution to $\kappa$ than to the ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ contribution to $\kappa$. We give a theoretical explanation, based on the modified Moszkowski-Scott separation approximation, to account for the sensitivity of the binding energy to the ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}+{}_{}{}^3{}_{}{}^{}D_1^{}{}_{}{}^{}$ contributions to $\kappa$. We also discuss the relation of $\kappa$ and the binding energy of nuclear matter to the off-shell elements of the $T$ matrix. We discover that far-off-shell elements ($q\gtrsim 6$ ${\mathrm{F}}^{-1\mathrm{}}$) play a significant role in nuclear matter.

The excited levels of ${\mathrm{Cd}}^{109}$ have been investigated from the decay of ${\mathrm{In}}^{109}$ with high-resolution Ge(Li) and Si(Li) detectors as well as with standard scintillation counters. ${\mathrm{In}}^{109}$ was produced by the ($\alpha ,n$) reaction on enriched ${\mathrm{Cd}}^{106}$. This reaction produced ${\mathrm{Sn}}^{109}$, which decays with a short half-life to ${\mathrm{In}}^{109}$. Levels of the following energies (in keV) have been established in ${\mathrm{Cd}}^{109}$: 59.5, 203.3, 347.4, 426.2, 623.8, 673.7, 721.5, 822.5, 997.5, 1352.2, 1475.6, 1539.8, 1622.5, and 1772.6. The use of two Ge(Li) detectors in connection with the PDP-8/I and a program for two-dimensional analysis with a 4096-dual analog-to-digital converter revealed the presence of several previously unreported transitions in ${\mathrm{In}}^{109}$. Based on the $\gamma -\gamma$ and $\beta -\gamma$ coincidence results, a consistent level scheme for ${\mathrm{Cd}}^{109}$ is given. The spin and parity assignments of levels of ${\mathrm{Cd}}^{109}$ are discussed.

An approximate version of the Hartree-Fock method is proposed. This approximate version involves the solution of a set of linear equations. An application to a solvable model with a nontrivial Hartree-Fock solution yields good results.

A recently proposed definition of the average scattering amplitude is evaluated numerically for a variety of resonance models. The results differ from both the predicted and the physically required values.

A method, described earlier, which has been shown to help resolve the question of phase-equivalent discrete ambiguities in the optical-model-potential description of heavy-ion scattering is applied to the case of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ elastic scattering.

An extension of the intermediate-coupling model of Thankappan and True that would include incoherent 2p-1h modes of excitation is suggested.

The present results are compared with those of ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}(n,\gamma ){}_{}{}^{141}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}\mathrm{}(p,p)\mathrm{}{}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ analog experiments. The ($n,\gamma$) and ($d,p$) results do not yield consistent spin assignments for six states between 1809- and 2523-keV excitation in ${}_{}{}^{141}{}_{}{}^{}\mathrm{Ce}$. The use of conventional distorted-wave Born-approximation theory in the analysis of the ($d,p$) data is questioned. The available ($p,p$) analog data does not support either the ($n,\gamma$) or ($d,p$) spin assignments.

An expression is proposed for the transition quadrupole moment in terms of the mass number and the moments of inertia of the initial and final states as obtained from the variable-moment-of-inertia model. The expression is shown to give reasonable results for $0+\leftrightarrow 2+$, $2+\leftrightarrow 4+$, and $4+\leftrightarrow 6+$ transitions. For $6+\leftrightarrow 8+$ transitions the calculated values appear to be a little higher than the experimental ones.

High-resolution singles and 4096×2048 Ge(Li)-Ge(Li) coincidence-spectrum measurements have been made to clarify the properties of the $\beta$ and $\gamma$ vibrational bands in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$. A $2_{\gamma }\to 2_{\beta }$ transition is placed from coincidence experiments and $\frac{B (E2;2_{\gamma }\to 2_{\beta })}{B (E2;2_{\gamma }\to 2_g)}=1.3\mathrm{}\pm 0.4$. The $\frac{B (E2;3_{\gamma }\to 2_{\beta })}{B (E2;3_{\gamma }\to 2_g)}<0.6\mathrm{}$. Of the six transitions out of the $2_{\gamma }$ and $2_{\beta }$ levels, the intensities of four were revised from coincidence measurements and new branching ratios obtained. The $2_{\gamma }\to 4_g$ transition intensity is shown to be too low to allow a one-parameter fit to the $\gamma$-band branching ratios.

A Projected Hartree-Fock calculation of the properties of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ is used as the basis for a core-quasiparticle coupling treatment of ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{29}{}_{}{}^{}\mathrm{P}$, and ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$. Very good agreement with the known properties of these nuclei is achieved in this calculation with a variation of essentially one parameter, the coupling strength.

The elastic scattering of nucleons by carbon, at incident energies of 142, 210, and 330 MeV, is calculated from an optical potential retaining all terms to second order in the $N-N$ amplitudes. The amplitudes are calculated using recent $N-N$ phase-parameter sets obtained by the Yale, Livermore, and Michigan State Groups. Nuclear correlation functions of both the Fermi and Brueckner-Gammel types are used to represent nuclear structure. Comparison with experiment is made in order to distinguish among different $N-N$ phase-parameter sets, and among different types of nuclear correlation functions.

Targets of Pr, Ce, Nd, Ir, Au, and Pb have been bombarded with heavy ions in order to produce fission isomers with nanosecond lifetimes. In all cases, limits for detection were set which were much lower than the cross sections previously reported for these systems. It is concluded that fission isomerism was not observed in the previously reported experiments.