An improved search for the $K$-capture branch in ${\mathrm{In}}^{113m}$ has established a new upper limit for this decay mode of 0.0036%, from which one may conclude $log\mathrm{ft}>\mathrm{}6.5\mathrm{}$ for this first-forbidden transition.

Computer calculations of Coulomb-distortion effects are presented for inelastic electron scattering inducing $M2\mathrm{}$ transitions in light nuclei. The distortion effect is presented over $1<Z<\mathrm{}20\mathrm{}$, $40 \mathrm{MeV}<E_0<140\mathrm{}$ MeV, $10<k<\mathrm{}19\mathrm{}$ MeV, and for two large angles of scatter. The dependence of the calculation on the assumed nuclear transition current is displayed.

Low-energy $\gamma$ rays following slow-neutron capture in thulium have been used to check the angular-momentum assignments of the neutron resonances. A previous discrepancy in the spin of the 17.5-eV resonance has been resolved. The correlation between reaction widths noted in previous work has been recalculated and found to be substantially unchanged. An isomeric state at 183.2 keV has been investigated by measuring the delay in the low-energy transitions involving this state, and a half-life of 3.2 ± 0.3 μsec is obtained, in fair agreement with previous work.

Previously reported helium recoil energy distributions produced by neutron elastic scattering from ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in a gaseous scintillator have been modified to provide cross-section data suitable for use in current phenomenological investigations of the nucleon-helium interaction.

The $R$ matrix of Wigner and Eisenbud is a function of a set of parameters (channel radii, boundary numbers, etc.) as well as of the energy of the incoming particle. Invariant imbedding techniques have been applied, which give the variation of the $R$ matrix with respect to changes of the parameters entering into the theory. A generalization of various formulas, derived originally by Wigner and Teichmann and Wigner, to the multichannel case has been obtained. Our general results apply also to deformations of the nucleus other than spherical. An application of the invariant imbedding technique is also shown concerning Robson's theory of the isobaric spin analogs.

The effects of central, spin-orbit, and tensor components of the Sussex interaction on various ground-state properties of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nuclei are studied. It is observed that a major contribution to the binding energy comes from the central part of the interaction alone. In the case of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, almost all of the $1p_{\frac{1}{2}}-1p_{\frac{3}{2}}$ splitting comes from the spin-orbit component. However, in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, the tensor part of the interaction also provides large splitting, but its contribution is of the wrong sign.

The experimental cross sections for production of the Li, Be, and B isotopes and their isotopic ratios have been determined for interactions produced by 70-MeV $\alpha$ particles with the carbon and nitrogen nuclei of a nuclear emulsion. The cross-section values as well as the isotopic ratios have been fitted with the help of Rudstam's formula; there is good agreement for the carbon target and poor agreement for the nitrogen target.

The new method of Truelove and Nicholls for obtaining reaction matrix elements for nuclear-structure calculations is discussed. In this method, the Bethe-Goldstone wave function is expanded in terms of eigenfunctions of two interacting nucleons bound in a common potential well. The Bethe-Goldstone equation, which is written in terms of an expansion over noninteracting two-particle states, is then solved iteratively. In practice, the method is most easily applied when a harmonic-oscillator basis is used; the Pauli operator $Q$ can then be treated exactly. The convergence of the Truelove-Nicholls iteration scheme and of the above two expansions is investigated. It is shown that the original method is incorrect for nucleon-nucleon potentials with an infinite hard core. A simple way of correcting the method is presented.

Slater determinants used in a standard Hartree-Fock calculation and built with parity-mixed single-particle orbitals do not have a definite parity; a parity projection after the variation is needed, in general. A different solution is investigated here, in which the projection is performed before the variation. Conditions are studied for the case where the solution is still a Slater determinant. The results of explicit calculations for both methods are compared in the case of a three-nucleon system. A larger binding energy is obtained in the case of projection before variation, and in the corresponding solution (which is not a Slater determinant) considerable parity mixing in single-particle wave functions is allowed.

The mean life of the 275-keV second excited state of ${\mathrm{Ne}}^{19}$ was measured to be 61.4 ± 3.0 psec. The ${\mathrm{He}}^3({\mathrm{Ne}}^{20},\alpha ){\mathrm{Ne}}^{19}$ reaction and the gas-target recoil-distance technique were used. The 275-keV state decays by $E1\mathrm{}$ emission to the ground state. The strength of this $E1\mathrm{}$ transition is equal within errors to that of the mirror transition in ${\mathrm{F}}^{19}$. This result is discussed.

We apply the unitary pole approximation (UPA) to a number of spin-dependent local potentials and use the separable potentials obtained to calculate the three-nucleon binding energy and scattering lengths. Excellent agreement is found between the binding energies obtained with the separable potentials and those calculated by Malfliet and Tjon using the local potentials. Simple analytic approximations are given for the UPA form factors, and comparisons are made between the local and the UPA two-body phase shifts.

New measurements of the nuclear spin-lattice relaxation times of ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ implanted in Au, Pd, and Pt have established lower limits of 60, 185, and 270 sec °K, respectively, of $T_{1}T$ for ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ in these metals. In conjunction with prior measurements of the effective moment of ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ in these metals, these $T_{1}T$ values show that the Knight shift of ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ in Au is positive, while in Pd and Pt it is negative. Using a common enhancement factor in these metals, one finds the value of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ magnetic dipole moment to be $\mu =(+{1.00285}_{-0.000\mathrm{}14}^{+0.000\mathrm{}15}){\mu }_N$.

The ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ electric quadrupole moment has been measured for the first time using the asymmetry of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ resonance lines in Be foil under magnetic-field reversal and the estimated field gradient at ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ lattice positions. The result is $Q\left({}_{}{}^{12}{}_{}{}^{}\mathrm{B}\right)=(+0.030\mathrm{}\pm 0.008)\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$.

Pion-deuteron elastic scattering is calculated via the impulse approximation (including double scattering) at intermediate energies. Good agreement is found with experiment at 87-, 142-, and 180-$\frac{\mathrm{MeV}}{c^2}$ incident pion energy. Thus the impulse approximation seems to give reliable results even in the region of a large resonance.

A flexible microscopic model is introduced in an attempt to illuminate problems associated with the calculation of single-nucleon-transfer form factors. The model employs a truncated shell-model basis augmented by a set of single-nucleon channels. It can be used even when the residual nucleus is unbound, but ignores contributions from many-particle breakup channels. The model wave function is fully antisymmetric, and it is shown that all quantities which appear in the model are calculable. An approximate single-channel calculation of form factors for the reactions ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}\mathrm{}(d,p)\mathrm{}{}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}\left(2.01\mathrm{} \mathrm{MeV}\right)$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^3{}_{}{}^{}\mathrm{He},d){}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}\left(2.10\mathrm{} \mathrm{MeV}\right)$ is used to illustrate some of the features of the model.

Levels of ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ below an excitation energy of 7 MeV have been investigated using the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha ){}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ reaction at a bombarding energy of 15 MeV. Previously unreported states of ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ were observed at excitation energies of 4.200, 4.625, 4.783, 5.351, 5.426, 5.463, 5.545, 5.831, 6.012, 6.089, 6.149, 6.290, 6.433, 6.744, 6.866, and 7.064 MeV. Angular distributions of strongly excited states are compared with distorted-wave Born-approximation calculations. The ground state and a state at 5.351 MeV have angular distributions characteristic of $l=0\mathrm{}$ neutron pickup whereas states at 0.273, 1.615, 4.551, 6.012, and 6.744 MeV correspond to $l=1\mathrm{}$ neutron pickup, and states at 0.238, 1.54, and 4.036 MeV correspond to $l=2\mathrm{}$ neutron pickup. The following new spin and parity assignments are made: 1.51, (${\frac{5}{2}}^{-}$); 1.54, ${\left(\frac{3}{2}\right)}^{+}$; 1.615, ${\left(\frac{3}{2}\right)}^{-}$; 4.036, ${\frac{3}{2}}^{+}$, (${\frac{5}{2}}^{+}$); 4.551, ${\frac{1}{2}}^{-}$, ${\frac{3}{2}}^{-}$; 5.351, ${\frac{1}{2}}^{+}$; 6.012, ${\frac{3}{2}}^{-}$, (${\frac{1}{2}}^{-}$); 6.744, ${\frac{3}{2}}^{-}$, (${\frac{1}{2}}^{-}$); energies in MeV. Relative spectroscopic factors are extracted and are compared with predicted configurations of negative-parity states in mass-19 nuclei and with the predicted ground-state neutron configuration of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$. Analog states in the mirror nucleus, ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$, are discussed.

The use of the elements of the mass quadrupole tensor as generalized, nonredundant variables to describe nuclear collective motions is developed. The Hamiltonian for a group of $n$ identical particles in an oscillator well, which interact with each other by way of quadrupole two-body interactions, is rewritten in terms of the eigenvalues of the mass quadrupole tensor and angular momentum operators. The total angular momentum is separated into a part associated with rotations of the mass quadrupole tensor, and an intrinsic part. A semiclassical argument shows that the energies of states are approximately described by an expression in some respects indistinguishable from that of the empirical variable-moment-of-inertia model, which has been found adequate to represent the energies of the levels of a wide range of even nuclei.

Multiple-step processes (core excitation) are evaluated for the ($p,t$) reaction at a typical energy (30 MeV) and for a typical moderately collective spherical nucleus (nickel). Our model nucleus has three kinds of states; the ground and collective $2^{+}$, which have a strong direct transition, other typical noncollective states which also can be produced in a single step, and a two-phonon triplet, which can be produced only through multiple-step processes. We find that these latter are produced as strongly as the other noncollective states and that the angular distributions and polarizations are characterized by the multipolarity of the over-all transition and not by the multiplicity of the reaction mechanism. Comparison is made with the distorted-wave Born approximation. We find that it underestimates the ($p,t$) cross sections to all three types of states, and that even relative cross sections are in error by up to a factor 2, and absolute cross sections by as much as a factor 5.

The ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}(\alpha ,d){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reaction has been investigated up to an excitation energy of 20 MeV using a 40-MeV $\alpha$-particle beam from the Berkeley 88-in. cyclotron. Angular distributions were obtained for the three strongest levels at 14.40 ± 0.03, 14.82 ± 0.03, and 16.24 ± 0.04 MeV. Widths for these states, with the experimental resolution subtracted in quadrature, are 30 ± 30, 69 ± 30, and 125 ± 50 keV, respectively. Evidence for the probable [${}_{}{}^{14}{}_{}{}^{}\mathrm{N}\left(1^{+}\right)+\left(d_{\frac{5}{2}}\right)_{}^2{}_{5^{+}}{}^{}$] configuration of the three states is discussed.

The complex angular momentum technique is applied to the study of nucleon-nucleus elastic scattering. Regge-type representations are developed for the scattering amplitude, taking the spin of the incident nucleon into account. The pole parameters are determined using the optical-potential parameters as input. With these pole parameters, the differential cross sections for elastic nucleon-nucleus scattering are calculated using an appropriate Regge-type representation for the partial-wave amplitudes. These studies give insight into the applicability of complex angular momentum methods to the optical model of elastic scattering of nucleons from nuclei.

Measurements of neutron spectra from the reaction ${\mathrm{O}}^{16}(\mathrm{Ni},xn)$ and ${\mathrm{O}}^{16}(\mathrm{Ag},xn)$ with 160-MeV ${\mathrm{O}}^{16}$ ions and natural targets were made. Neutrons were detected at 15° intervals from 15 to 165°. Detection was accomplished with nuclear emulsions, using the internal-radiator method. The most striking feature of the spectra is the pronounced backward peaking in the c.m. system with ratios of $\frac{\sigma \left({180}^{\circ }\right)}{\sigma \left(0^{\circ }\right)}$ as high as 2.0. We interpret this peaking to be caused by transfer reactions. Following the transfer reaction, a part of the incoming ion travels forward with its initial velocity, while the remaining partially fused system is traveling backward in the c.m. system. Evaporated particles from the partially fused system are thus backward peaked in the c.m. system. The charged-particle spectra for these same reactions, as measured by other investigators, are also analyzed in terms of transfer reactions. Qualitative agreement with some unusual aspects of the measured spectra is obtained.