The ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ spontaneous-fission decay constant has been determined with solid-state track recorders of preetched mica. Measurements have been carried out with electroplated ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ sources. Consistent spontaneousfission-rate measurements have been obtained for a large range of fission track densities over more than a 3-yr period. Systematic error due to source impurities has been established as insignificant relative to statistical error. The present experimental result for the ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ spontaneous-fission decay constant is ${\lambda }_f=(6.04\mathrm{}\pm 0.13)\times {10}^{-15\mathrm{}}$ ${\mathrm{yr}}^{-1\mathrm{}}$.

Contrary to the conclusions reached in a recent paper, we find that for the usual combination of long-range and pairing force that is used for calculations in heavy nuclei, the Belyaev-Inglis formula for moment of inertia is adequate and gives values close to those obtained from projection methods.

It is shown that the work of Varma et al., entitled "Comments on a Recent Paper on Moments of Inertia in Heavy Nuclei," is based on a misconception about our previous work and contains a basic error.

We have investigated the decays of 58-min ${}_{}{}^{69g}{}_{}{}^{}\mathrm{Zn}$ and 14-h ${}_{}{}^{69m}{}_{}{}^{}\mathrm{Zn}$ with a 30-${\mathrm{cm}}^3$ Ge(Li) detector. In addition to the 438.6-keV isomeric transition in ${}_{}{}^{69}{}_{}{}^{}\mathrm{Zn}$, $\gamma$ rays of energies 318.6, 574.3, and 872.5 keV were observed. These $\gamma$ rays have been incorporated into the known level scheme of ${}_{}{}^{69}{}_{}{}^{}\mathrm{Ga}$. Our studies show that the ${\beta }^{-}$ feeding to the 872-keV level in ${}_{}{}^{69}{}_{}{}^{}\mathrm{Ga}$ is from the ${\mathrm{½}}^{-}$, ${}_{}{}^{69}{}_{}{}^{}\mathrm{Zn}$ ground state and not from the ${\frac{9}{2}}^{+}$, ${}_{}{}^{69}{}_{}{}^{}\mathrm{Zn}$ metastable state as has been reported. The present results are consistent with a ${\frac{3}{2}}^{-}$ assignment for the 872-keV level.

It is shown that the yield of even-$Z$ x rays is relatively greater, over all, in the $\alpha$-particle-accompanied ternary than in the binary fission of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$. A possible reason for this difference is suggested.

An example is given for the use of single-particle resonant-state wave functions in describing nuclear-resonance phenomena. The resonant-state functions are generated by solving numerically the one-body Schrödinger equation with pure outgoing asymptotics. The Lane-model Hamiltonian of the target+nucleon system is diagonalized on a basis consisting of bound-neutron and resonant-proton wave functions. The agreement with the result obtained by the exact integration of the coupled Lane equations is good.

Both a static and a momentum-dependent potential are derived from one-meson-exchange Born amplitudes, and are adjusted to fit (i) the deuteron binding energy and quadrupole moment, (ii) $S$, $P$, and $D$ partial waves from 25 to 310 MeV, and (iii) the binding energy and saturation property of nuclear matter. This is possible through a different form of the central and tensor potentials which has not been used previously to calculate problems (i), (ii), and (iii) above. We find the $\sigma$ meson unsuitable to describe the two-pion-exchange region in that a potential with meson parameters common to all partial waves is not achieved.

The variational bounds on scattering parameters are reformulated without the explicit use of multichannel projection operators, thus avoiding completely the difficulty of nonorthogonality in rearrangement and exchange collisions. Resonance-energy calculations can be carried out using the operator which is effectively projected on the closed channels.

The differential cross section for the ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}(p, {\gamma }_0){}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ reaction has been measured at 90° for $0.6\le E_p\le 6.3$ MeV. Compound resonances in ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ have been located at (12.17±0.04)-, 12.55±0.03-, 12.91±0.02-, 14.33±0.02-, and 15.3±0.1-MeV excitation energy. The last four are probably analogs to the lowest four levels in ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$. Total widths and ground-state $\gamma$-ray widths of these levels are presented. The spins of the 12.55- and 14.33-MeV levels are shown to be ${\frac{1}{2}}^{+}\left({\frac{3}{2}}^{+}\right)$ and ${\frac{5}{2}}^{\mathrm{}(+)\mathrm{}}\left({\frac{3}{2}}^{-}\right)$, respectively.

The left-unitary operators that introduce the correlations of the hard core in an uncorrelated bound-state wave function of a finite number $A$ of particles are explicitly determined up to a unitary transformation. Left unitarity is required in order to keep orthonormality. Using a shell-model basis, transformed according to the correlation operator, it is possible to diagonalize the Hamiltonian in a subspace of the full Hilbert space with the technique of Bloch and Horowitz. Ground as well as excited states are treated on the same footing. In practice, the diagonalization is accomplished using the original single-particle basis and transforming back the Hamiltonian. This results in an $A$-body operator for which a cluster expansion is possible. In this cluster expansion, there are three- and four-body terms easy to evaluate, because they factorize. A particularly interesting application can be made to few-body systems, evaluating the integrals numerically. The unique approximation is then connected with the cut of the basis. The method developed seems comparatively simple and is free of the mathematical problems of the hard core.

Using a complex square-well distorting potential, the quasifree inelastic scattering of protons has been calculated in the impulse approximation. Calculations were performed for the nucleus ${\mathrm{C}}^{12}$ at both 160 and 1014 MeV to compare with experiment. The calculation was done with parameters determined from other data and was therefore essentially parameter-free. The agreement with experiment is quite satisfactory and relatively independent of the parameters. While the magnitude of the cross section is well determined, the location of the quasifree peak is in disagreement with experiment and only slightly shifted from the no-distortion case.

Using a theory previously developed for the ${\mathrm{O}}^{16}$ nucleus, the energy levels of ${\mathrm{He}}^4$ were calculated using the nuclear shell model and the random-phase approximation (RPA). Though no attempt was made to optimize the parameters of the calculation, the predicted energies of the excited states compare favorably with those determined from experimental analyses. Qualitative agreement with experiment is obtained for the calculated electron inelastic-scattering form factor to the first $0^{+}$ excited state and for the integrated photoabsorption cross section. However, the prediction of the majority of the $E1\mathrm{}$ strength in the higher of the 1—, $T=1\mathrm{}$ levels does not conform to most experiments which indicate the lower level to have the stronger ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ component. The RPA produces some improvement over an ordinary shell-model calculation by decreasing the energies of the lower excited states by several hundred keV and by increasing the relative $E1\mathrm{}$ strength of the lower 1—, $T=1\mathrm{}$ level.

Elastic and inelastic excitation functions and differential cross sections of $\alpha$ particles scattered from ${\mathrm{C}}^{12}$ have been measured. Excitation functions were taken from 18.90 to 30.06 MeV in 20-keV steps. Differential cross sections were measured at the energies of anomalies in the excitation functions. Optical-model and phase-shift fits to the elastic angular distributions were attempted without success. A statistical analysis of the excitation function indicates that the reaction is proceeding mainly through the compound nucleus with a coherence width $\Gamma$ of 360 keV (c.m.).

We show that the ${\mathrm{He}}^3$ and ${\mathrm{H}}^3$ photodisintegration reactions are to a large extent independent of the detailed properties of the three-nucleon ground state, but depend crucially on the nuclear interaction in the final continuum states. The bound-state properties considered are the analytic form of the principal $S$ state, the asymptotic behavior, the $S^{\prime }$ state, and the two-nucleon short-range repulsion. Since the rms radius of the bound state determines the over-all magnitude of the cross section, predictions of different wave functions with the same radius are compared. The final states are described by the Faddeev equations in the separable approximation. If the final-state interactions are correctly included, then the low-energy cross sections for the ${\mathrm{He}}^3(\gamma , p)d$ reaction are enhanced by 20-25%, and the cross sections for ${\mathrm{He}}^3(\gamma , n)2p$ are reduced by approximately 100%. A simultaneous but rough agreement is possible for the total two- and three-body breakup cross sections and the charge form factors of the three-particle nuclei; but, within the theoretical framework adopted, the two-body differential cross sections at 90° and the charge-form-factor data cannot be reconciled.

The influence of the interaction between the magnetic moment of a neutron and the Coulomb field of a target proton is investigated. For this interaction, channel spin is not conserved. A formalism is developed which includes the resulting singlet-triplet mixing. The scattering amplitude, or $M$ matrix, is presented, and its elements are related to the coefficients of the most general form of the $M$ matrix. Expressions for the nine most common nucleon-nucleon-scattering observables are obtained, including the effects of the singlet-triplet mixing. Coupled radial wave equations are derived and solved to reveal the phase-shift modifications. Calculations are performed over an energy range from 25 to 210 MeV using nuclear phase shifts previously determined from best ${\chi }^2$ fits to the scattering data. Our calculations indicate that all nine of the scattering observables considered are significantly influenced by the Mott-Schwinger interaction, but only for very small (<5°) scattering angles.

The $\beta$ decay of ${\mathrm{F}}^{21}$ has been investigated, utilizing the ${\mathrm{F}}^{19}(t, p){\mathrm{F}}^{21}$ reaction to form the ${\mathrm{F}}^{21}$ activity and a 1.3-MeV mechanically-chopped beam. The existence of previously reported $\beta$ branches to the ground and first two excited states of ${\mathrm{Ne}}^{21}$ has been confirmed, and an upper limit for decay to the third excited state of ${\mathrm{Ne}}^{21}$ has been established by detecting $\beta -\gamma$ coincidences and $\beta$-ray singles with NaI(Tl) and plastic scintillation detectors. The ${\mathrm{Ne}}^{21}$ levels in keV, ${\mathrm{F}}^{21}$ $\beta$ branches populating these levels in percent, and corresponding $log\mathrm{ft}$ values are 0.0, 29±6, 5.23±0.10; 350, 63±6, 4.76±0.05; 1746, 7.6±1.0, 5.07±0.07. The $log\mathrm{ft}$ values measured in the present work differ markedly from those previously reported. Measurements of the excitation energies of the first two excited states of ${\mathrm{Ne}}^{21}$ yielded (in keV) 350.5±0.3 and 1745.6±0.4, respectively. The upper limit on the percent branch to the third excited state is 0.15%, corresponding to a limit on the $log\mathrm{ft}$ of 6.0.

The lowest $T=2\mathrm{}$ states of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$, and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ have been formed using the ($p, t$) reaction. The isospin-forbidden proton ($\Delta T=1\mathrm{} or 2$) and $\alpha$-particle ($\Delta T=2\mathrm{}$) decay modes of these states have been determined by counting triton-proton and triton-$\alpha$ coincidence events. The major decay modes of the states are ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}({\alpha }_1+{\alpha }_2, {\alpha }_3+{\alpha }_4)$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}\left(p_0\right)$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}\left({\alpha }_0\right)$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}\left(p_0\right)$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}\left({\alpha }_0\right)$. Simple Coulomb calculations were performed for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$; these assumed pure shell-model configurations and considered isospin mixing in only the ($1d, 1f$) shells. They did not predict the relatively large $\Delta T=2\mathrm{}$ isospin impurities necessary to explain the observed $\alpha$-particle decay.

Cross sections for the production of ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$, ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$, and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$ have been determined from the separated isotopes of magnesium, silicon, and sulfur, using 300- and 400-MeV protons. These values, together with previous measurements, provide data for targets of each mass number of 23 to 34 inclusive for ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ and ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ and from 25 to 34 inclusive for ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$. The main feature of the results is that the cross section is highest for those targets having the $\frac{N}{Z}$ closest to that of the products. Thus, events involving the loss of about the same number of neutrons as protons have the highest probability. Cascade-evaporation calculations were performed for 400-MeV protons on each of these nuclides. The calculations reproduce the experimental trends.