We have accurately measured the total-conversion coefficient for the 156.0-keV, $M4\mathrm{}$ transition in ${}_{}{}^{117}{}_{}{}^{}\mathrm{Sn}$ as ${\alpha }_T=46.40\mathrm{}\pm 0.25$. The Hager and Seltzer theoretical value is 47.8. A comparison between experimental and theoretical ${\alpha }_K$ and ${\alpha }_T$ values for 15 $E3\mathrm{}$ and $M4\mathrm{}$ transitions shows that the theoretical values are systematically 2-3% higher.

A systematic study of $\beta$-decay energies has been made for mass-separated activities of Kr gaseous fission products and their daughters at the TRISTAN on-line separator facility at the Ames Laboratory research reactor. A well-type plastic scintillator was used in coincidence with a Ge(Li) $\gamma$ detector to determine $\beta$-group end-point energies and deduce $Q$ values. The following $\beta$-decay energies have been determined: ${}_{}{}^{88}{}_{}{}^{}\mathrm{Kr}$, 2.93 ± 0.03 MeV; ${}_{}{}^{88}{}_{}{}^{}\mathrm{Rb}$, 5.30 ± 0.06 MeV; ${}_{}{}^{89}{}_{}{}^{}\mathrm{Kr}$, 4.93 ± 0.06 MeV; ${}_{}{}^{90}{}_{}{}^{}\mathrm{Kr}$, 4.35 ± 0.05 MeV; ${}_{}{}^{90}{}_{}{}^{}\mathrm{Rb}$, 6.32 ± 0.07 MeV; ${}_{}{}^{91}{}_{}{}^{}\mathrm{Kr}$, 6.12 ± 0.07 MeV; ${}_{}{}^{91}{}_{}{}^{}\mathrm{Rb}$, 5.68 ± 0.04 MeV; ${}_{}{}^{92}{}_{}{}^{}\mathrm{Kr}$, 5.97 ± 0.08 MeV; ${}_{}{}^{92}{}_{}{}^{}\mathrm{Rb}$, 7.58 ± 0.15 MeV; ${}_{}{}^{92}{}_{}{}^{}\mathrm{Sr}$, 1.93 ± 0.03 MeV; ${}_{}{}^{93}{}_{}{}^{}\mathrm{Kr}$, 8.3 ± 0.5 MeV; and ${}_{}{}^{93}{}_{}{}^{}\mathrm{Rb}$, 7.23 ± 0.10 MeV. The decay energies are compared with previous measurements, systematics predictions, and two currently accepted mass relations. The energies are used to predict the $\beta$-decay energies for 13 additional nuclei by means of systematics.

The $\alpha$ decay of ${}_{}{}^{235}{}_{}{}^{}\mathrm{Np}$ has been studied by quantitative $\alpha$ singles and $\alpha -\gamma$ coincidence techniques, and the $\beta$ decay of ${}_{}{}^{231}{}_{}{}^{}\mathrm{Th}$ by quantitative $\gamma$-ray singles and $\gamma -\gamma$ two-parameter coincidence measurements with semiconductor detectors. Rotational bandheads in ${}_{}{}^{231}{}_{}{}^{}\mathrm{Pa}$ at 102.30, 174.10, and 183.47 keV are given the Nilsson assignments $\left[\Omega \pi \right(N{n}_z\Lambda \left)\right] \frac{3}{2}+\left(651\right)\mathrm{}$, $\frac{5}{2}-\left(523\right)\mathrm{}$, and $\frac{5}{2}+\left(642\right)\mathrm{}$. Decay schemes for ${}_{}{}^{235}{}_{}{}^{}\mathrm{Np}$ and ${}_{}{}^{231}{}_{}{}^{}\mathrm{Th}$ are presented as well as a transition intensity balance for ${}_{}{}^{231}{}_{}{}^{}\mathrm{Th}$ which includes $\beta$ branchings. Energy level spacings and $\alpha$, $\beta$, and $\gamma$ transition probabilities are interpreted in terms of a strong Coriolis interaction among the even-parity rotational bands and admixtures in the wave functions are given for the observed levels.

The ($p, t$) reaction has been used to study the ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ nucleus which is expected to show the characteristics of a shape-transitional nucleus. A search has been made for a rotational band built upon the $0^{+}$ state at 737 keV. The incident energy was 19 MeV. Cross sections were measured to many states and a number of spins and parities were assigned from the ($p, t$) angular distribution. The results show no positive evidence for an axially symmetric rotational band built upon the 737-keV ($0^{+}$) state. The levels observed agree with those predicted from an axially asymmetric rotor in the model of Gneuss and Greiner. The present spin and parity assignments agree with the previous work for most of the states. However, a few discrepancies have been found.

With the use of the helium-gas-jet technique and a high-resolution Ge(Li) detector $\alpha$-decay branching ratios were measured for ${}_{}{}^{150}{}_{}{}^{}\mathrm{Dy}$, ${}_{}{}^{151}{}_{}{}^{}\mathrm{Dy}$, and ${}_{}{}^{149}{}_{}{}^{}\mathrm{Tb}_{}^m{}_{}{}^{}$. Sources containing these activities were produced by bombarding ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$ with ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions. They were then assayed for both $\alpha$-particle and x-ray radioactivity. The branching ratios deduced are as follows: 0.32 ± 0.05 for ${}_{}{}^{150}{}_{}{}^{}\mathrm{Dy}$, 0.055 ± 0.008 for ${}_{}{}^{151}{}_{}{}^{}\mathrm{Dy}$, and (2.0 ± 0.4) × ${10}^{-4\mathrm{}}$ for ${}_{}{}^{149}{}_{}{}^{}\mathrm{Tb}_{}^m{}_{}{}^{}$. The ${}_{}{}^{151}{}_{}{}^{}\mathrm{Dy}$ and ${}_{}{}^{149}{}_{}{}^{}\mathrm{Tb}_{}^m{}_{}{}^{}$ ratios were found to be in good agreement with previous measurements. While the ratio deduced for ${}_{}{}^{150}{}_{}{}^{}\mathrm{Dy}$ is almost midway in value between two earlier determinations, it appears to be in real disagreement with the more precise of the two previous measurements. Consequences of this discrepancy are discussed with respect to published cross-section data and $\alpha$-decay reduced widths for 84-neutron even-even nuclei. In the course of the investigation the half-life of ${}_{}{}^{149}{}_{}{}^{}\mathrm{Dy}$ was determined to be 4.6 ± 0.4 min from x-ray decay-curve analyses and 5.1 ± 0.9 min from the initial growth period observed in the decay of the 4.1-h, ${}_{}{}^{149}{}_{}{}^{}\mathrm{Tb}$ 3.967-MeV $\alpha$ group.

Mean lifetimes for four levels in ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ have been measured by the Doppler-shift attenuation method. $\gamma$-ray angular distributions have been measured for the $\gamma$ decay of excited levels in ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ up to 1127 keV in excitation. The levels were excited by the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(\alpha , p\gamma ){}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ reaction at a bombarding energy of 14.77 MeV. Spectra of $\gamma$ rays in coincidence with protons were obtained with a 55-${\mathrm{cm}}^3$ Ge(Li) detector. Spin assignments obtained from the present results for the low-lying positive-parity levels in ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ are in agreement with previous assignments. A $J^{\pi }$ of ${\frac{3}{2}}^{-}$ has been assigned to a level at 685 keV in excitation and a $J^{\pi }$ of ${\frac{5}{2}}^{-}\left({\frac{3}{2}}^{-}\right)$ has been assigned to an 809-keV negative-parity level. $\gamma$-ray mixing ratios measured for the $\gamma$ decay of excited low-lying levels in ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ have been combined with lifetime measurements to calculate the electromagnetic transition strengths. The experimental $E2\mathrm{}$ transition strengths are shown to be consistent with those predicted by a weak-coupling model.

NUCLEAR REACTIONS ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(\alpha , \mathrm{p}\gamma )$, $E=14.77\mathrm{}$ MeV; measured $\tau$, $E_{\gamma }$, $\mathrm{p}\gamma$ coin, $I_{\gamma }\left(\theta \right)$, $\delta$. ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ deduced levels $J$, $\pi$, $\Gamma$.

The variable-moment-of-inertia model of Mariscotti et al. is extended to high spins.

${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ excitation energies were measured by means of the ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}(p, p^{\prime })$ reaction. Approximately 40 levels below 6 MeV not previously identified in inelastic scattering studies were seen. Over-all experimental resolution was 8 keV. The existence of several close-lying doublets previously postulated to explain apparent conflicts in ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}(t, p){}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(p, t){}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ spin assignments was confirmed. A number of new levels are pointed out as candidates for unnatural parity states.

The existence of a 62±5-sec isomer of ${}_{}{}^{222}{}_{}{}^{}\mathrm{Ac}$ is confirmed. Its production cross section in thorium bombarded with 600-MeV protons is 8.8±1.4 mb.

The neutron capture cross section of ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}(n, \gamma )$ has been measured with high resolution at the Oak Ridge electron linear accelerator. The capture results show that the reported $s_{\frac{1}{2}}$ doorway in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ is not observed in the photon channel.

Previous measurements of the internal bremsstrahlung associated with the $K$-capture decay of ${}_{}{}^{204}{}_{}{}^{}\mathrm{Tl}$ have ignored the contribution to the spectrum due to double internal bremsstrahlung from the $\beta$ decay of ${}_{}{}^{204}{}_{}{}^{}\mathrm{Tl}$. We have measured the internal bremsstrahlung spectrum, using a two-parameter analysis to subtract this contribution. A fit to the data using the theory of Glauber and Martin and a relativistic correction factor $R_{1s}=0.29\mathrm{}$ yields a transition energy of 385±20 keV. The ratio of the theoretical to the experimental intensity is 3.6.

Excitation functions for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^6{}_{}{}^{}\mathrm{Li}, t)$ reaction at 7.5° have been measured in 100-keV steps from 22.0 to 24.6-MeV incident energy. Data for the 0.0-, 0.24+0.27-, 1.51+1.54+1.62-, and 2.79-MeV states exhibit no prominent structure over the energy range studied and are suggestive of a predominantly direct reaction mechanism.

Existing data for the charge form factors of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and some assumptions are employed to construct a model of the triton wave function. Given this wave function, the Schrödinger equation may be trivially solved for the effective local potential. The discrepancy between this potential and those predicted by typical pair-interaction models in the domain where all three particles are close together appears to provide evidence for a strong attractive three-body force.

Differential elastic cross sections for neutrons scattered by carbon were measured for 7.20-, 7.35-, 7.73-, 8.20-, and 9.00-MeV incident neutron energies using the Aerospace Research Laboratory neutron time-of-flight facility. The inelastic differential cross sections for neutrons leaving the residual ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nucleus in the 4.43-MeV excited state were also measured for 7.73-, 8.20-, and 9.00-MeV incident neutrons. These data have uncertainties relative to the normalizations of 1.5 to 8% for the elastic cross sections and 4 to 18% for the inelastic cross sections. The normalization uncertainty is 4%. The elastic angular distributions are compared to optical-model calculations using the Rosen potential. Neither this potential nor any other with reasonable geometry fits the data. The angle-integrated cross sections combined with previously reported ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(n, \alpha ){}_{}{}^9{}_{}{}^{}\mathrm{Be}$ cross sections are compared to the total neutron cross sections at 7.73, 8.20, and 9.00 MeV. Because of the several strongly over-lapping resonances in the 7-9-MeV energy region, a unique phase-shift analysis of the data is not possible.

The $\mathrm{D}(\alpha , pd)\mathrm{T}$ and $\mathrm{D}(\alpha , dt)\mathrm{H}$ sequential reactions through ${}_{}{}^4{}_{}{}^{}\mathrm{H}$* and ${}_{}{}^5{}_{}{}^{}\mathrm{He}$* are investigated in a kinematically complete experiment with $E_{\alpha }=70\mathrm{}$ MeV, particle identification, and online computer coincidence electronics. Data analysis of various $p-d$ and $d-t$ coincidence spectra are presented. Sequential decay through the 20.1-, 21.4-, and 22.4-MeV states of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and the 16.7-MeV states of ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ are observed. The results are in good agreement with previous work on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$* and spectral structure due to ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ excited states is suggestive of narrow states at 18.6, 18.8, and 19.2 MeV of excitation.

We obtain the leading off-shell correction to the high-energy optical potential: $v=v_0\times [1-(\frac{\gamma }{2k^2}\left)v_0\right]$, where $\gamma =k{\left[\right(\frac{\partial }{\partial q}\left)\ln f\right(q;k\left)\right]}_{q=k}$ for $f(q;k)=f(\overrightarrow{\mathrm{q}}, \overrightarrow{\mathrm{q}};k)$ the off-shell projectile-nucleon scattering amplitude. A slow energy variation of the amplitude at very high energy gives $\gamma =k\left(\frac{\partial }{\partial k}\right)\ln f_k\mathrm{}\left(0\right)\mathrm{}$, where $f_k\mathrm{}\left(0\right)\mathrm{}$ is the on-shell amplitude, and the correction is small. In the region of projectile-nucleon resonances, we describe the two-body interaction by a separable potential and relate $\gamma$ to the scattering phase shifts. The leading off-shell correction is substantial for an absorptive resonance but "anomalously" small at an elastic resonance.

The Ali-Bodmer $\alpha \alpha$ potential is used to calculate the properties of the $3\alpha$ system. A generator-coordinate method is used to solve the three-body problem. Results are compared with the known properties of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$.

Neutron time-of-flight radiative capture data taken at the Oak Ridge electron linear accelerator have been analyzed for single-level resonance parameters. Eleven resonances were found, with parameters as indicated, listing $E_0$ (keV), $J$ value assumed, and ${\Gamma }_{\gamma }$ (eV) in order: 27.07 (2) 1.4 ± 0.3, 48.7 (1) 1.7 ± 0.4, 97.0 (1) ≤6.0 ± 1.8, 269 (2) 3.5 ± 0.8, 270 (1) ≤ 4.4, 386 (1) ≥ 7±2, 490.5 (0) ≥ 10±3, 595 (2) ≥ 7 ± 2, 1460 (1) ≥ 11±3. Values of total width were also found for these resonances. Two resonances are very narrow and their capture areas yield estimates of $g{\Gamma }_n$. At 43.5 keV, $g{\Gamma }_n=0.086\mathrm{}\pm 0.02$ eV if $J\ge 1$ or ${\Gamma }_n=0.42\mathrm{}\pm 0.1$ eV if $J=a$, and, at 173.5 keV, $g{\Gamma }_n=0.35\mathrm{}\pm 0.10$ eV. The increase of nearly an order of magnitude in radiative width with increasing energy up to 600 keV is notable. Twelve large resonances between 1600 and 5000 keV were not analyzed for capture because of detector sensitivity to the inelastic scattering channels which open in that energy region.

The width of the first excited state of ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ has been determined from the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(d, n){}_{}{}^{13}{}_{}{}^{}\mathrm{N}_{}^{*}{}_{}{}^{}$ reaction to be $\Gamma =36.15\mathrm{}\pm 0.54$ keV. This result is compared with those of previous determinations from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, \gamma ){}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, p){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ experiments. These previous measurements are reviewed and it is shown that they imply a width of $\Gamma =32.5\mathrm{}\pm 0.55$ keV. This discrepancy is discussed and some possible sources of the differences are examined.

We examine the convergence rate of the sum over intermediate-particle states in the second-order core-polarization diagram of the effective shell-model interaction. For a $G$ matrix resulting from the Reid soft-core interaction, convergence is achieved in an oscillator basis only after the intermediate particle is summed over five or six major-shell excitations ($10\hslash \Omega$ to $12\hslash \Omega$ excitations). The total effect of this diagram on the shell-model spectra of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ is markedly altered from the results of Kuo and Brown and others who only include oscillator excitations of one major shell ($2\hslash \Omega$) in the second-order diagram. We further demonstrate that slow convergence is attributed to strong components of the effective tensor force in the $G$ matrix.