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.

The generator-coordinate method is applied to the rotational spectra of the ground state of even nuclei. The trial functions are generated from the Nilsson well, taking into account pairing correlations for fixed values of the deformation parameter $\delta$. This wave function is projected onto eigenstates of angular momentum and is used to evaluate the expectation value of the Hamiltonian, which consists of the kinetic energy and the interactions between nucleons. A Gaussian form with Rosenfeld mixture is assumed for the nucleon-nucleon potential. Numerical calculations are performed for isotopes of Hf. Without changing the values of parameters, characteristic features of the energy spectra are reproduced and agreement with experiment is good. The quadrupole moments of various rotational states, as well as $E2\mathrm{}$ transition matrix elements, are also calculated. To make more extensive comparisons, the kernels used in the above calculations are expressed in terms of parameters, which are selected to give agreement with experimental spectra up to the second excited states for each isotope. Then energy spectra are calculated using these adjusted parameters for all rotational nuclei with mass number greater than 100. Good agreement with experimental data is obtained.

An approximate $K$-matrix calculation of elastic nucleon-deuteron scattering is carried out including the effects of two-nucleon tensor forces. The results of these computations, which are carried out in the energy range from 11 to 40 MeV, are in reasonable agreement with the experimental nucleon polarizations and differential cross sections.

Data from the inelastic scattering of 40-MeV protons by ${\mathrm{Ni}}^{58}$ and ${\mathrm{Ni}}^{60}$ are presented and analyzed in terms of a coupled-channel approach. Previous discrepancies between the experimental and theoretical distributions of the first excited $2^{+}$ states are removed. The nature of coupled-channel calculations at this energy is discussed, with reference to absorptive strengths and form factors. $4^{+}$ states around 2.5-MeV excitation are shown to require one-phonon mixing in order to explain the observed cross sections. Spin-parity assignments are given for states at 3.2-, 5.1-, and 6.1-MeV excitation in ${\mathrm{Ni}}^{60}$.

Evidence for the existence of a ground-state rotational band in the nucleus ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ has been rounded out by a lifetime measurement of the 8543-keV $6^{+}$ level. Using the 2203-keV resonance in the ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}(p,\gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ reaction, and the Doppler-shift attenuation technique, 18 ± 6 fsec is found for the mean life of the $6^{+}$ state. It follows that the strength of the $6^{+}$ → $4^{+}$ 3926-keV transition is 9.4 ± 3.0 Weisskopf units (W.u.), in good agreement with theoretical predictions. This measurement removes objections that arose from an earlier result of 2.9 W.u. for the $6^{+}$ → $4^{+}$ transition strength.

The $\gamma$-ray decay properties of the $J^{\pi }$, $T={\frac{7}{2}}^{-},\frac{5}{2}$ analog of the ground state of ${\mathrm{S}}^{37}$, observed previously at $E_p=1887\mathrm{}$ keV in the ${\mathrm{S}}^{36}(p,\gamma ){\mathrm{Cl}}^{37}$ reaction, have been reexamined. Transitions to previously unobserved levels in ${\mathrm{Cl}}^{37}$ at $E_x=4.811\mathrm{} \mathrm{and} 5.574$ MeV were found in addition to the known strong $M1\mathrm{}$ transition to the $J^{\pi }$, $T={\frac{7}{2}}^{-},\frac{3}{2}$ antianalog state at $E_x=3.105\mathrm{}$ MeV. Other weak transitions suggest the presence of levels at $E_x=3.911\mathrm{} \mathrm{and} 6.482$ MeV. The data are consistent with a hypothesis that the 4.811- and 5.574-MeV levels, and possibly the other two suggested levels, are members of the group of ${\frac{7}{2}}^{-}$, $T=\frac{3}{2}$ configuration states expected from fragmentation of the antianalog state by spin and isospin recoupling of the ${d_{\frac{3}{2}}}^4$ nucleon group in $A=37\mathrm{}$. Detailed analysis of the strengths of the analog $M1\mathrm{}$ and Gamow-Teller $\beta$ decays to the 3.105-MeV level, and of the $M1\mathrm{}-E2\mathrm{}$ and $M2\mathrm{}-E3\mathrm{}$ mixing ratios, yields information on the wave function of the antianalog state and a prediction of the mean life of this level. A similar analysis of the ${\frac{7}{2}}^{-}$ parent, analog, and antianalog system in $A=35\mathrm{}$ is performed and the results are presented. In both the $A=35\mathrm{} \mathrm{and} 37$ systems, recoupling in the ${d_{\frac{3}{2}}}^n$ nucleon group appears necessary to explain the data. Additional information on ${\mathrm{Cl}}^{37}$ levels obtained from measurements at the analog resonance, and at the $E_p=1147\mathrm{}$-keV resonance, include the more accurate value $Q=8384.5\mathrm{}\pm 1.5$ keV for the ${\mathrm{S}}^{36}(p,\gamma ){\mathrm{Cl}}^{37}$ reaction, the energies 1.723 ± 0.002 and 3.1048 ± 0.0005 MeV for the first and third excited states, and the mean life ${\tau }_m={0.17}_{-0.05\mathrm{}}^{+0.09\mathrm{}} \mathrm{and} >~1.0$ psec for the 1.723- and 3.105-MeV levels, respectively. The results of angular-correlation measurements at the 1147-keV resonance are consistent with earlier assignments of $J=\frac{1}{2}$ for the 1.723-MeV level. The results are compared with recent shell-model calculations involving ${d_{\frac{3}{2}}}^n{f}_{\frac{7}{2}}$ and ${d_{\frac{3}{2}}}^n{p}_{\frac{3}{2}}$ configurations. The observed $M2\mathrm{}$ transition rates are successfully explained using bare-nucleon $g$ factors when recoupling of the ${d_{\frac{3}{2}}}^n$ group is considered.

The isospin-nonconserving reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}(d,{\alpha }_1){}_{}{}^{26}{}_{}{}^{}\mathrm{Al}(0.23, T=1)$ has been investigated at deuteron energies between 12 and 17 MeV. This experiment was prompted by Noble's recent proposal that the direct-nuclear part of the cross section in the isospin-violating ($d,\alpha$) reaction may proceed via an isospin-mixed $2^{+}$ doublet in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$. In the present study we find no evidence for this mechanism; but even at the high bombarding energies, the largest fraction of the isospin-forbidden cross section is due to compound-nucleus processes. This was determined from the strong fluctuations in the excitation functions.

Lifetimes were measured for ${\mathrm{K}}^{39}$, ${\mathrm{Ca}}^{41}$, and ${\mathrm{Ca}}^{43}$ states formed by promoting a particle from the $d_{\frac{3}{2}}$ shell to the $f_{\frac{7}{2}}$ shell. In ${\mathrm{Ca}}^{43}$, this state occurs at 990-keV excitation and has a mean life of 0.12 ± 0.04 nsec. By taking account of the branching ratio we find that the partial mean life for the transition ${\frac{3}{2}}^{+}\to {\frac{7}{2}}^{-}$ is 45 ± 16 nsec. which represents an inhibition of 120 relative to the single-particle estimate. In ${\mathrm{Ca}}^{41}$, the hole state occurs at 2010 keV and has a lifetime of 0.8 ± 0.2 nsec. No other branch is observed, so this is the mean life for the ${\frac{3}{2}}^{+}\to {\frac{7}{2}}^{-}$ transition. It is inhibited by a factor 62 relative to the single-particle estimate. In ${\mathrm{K}}^{39}$ the state occurs at 2820 keV and the mean life for this ${\frac{7}{2}}^{-}\to {\frac{3}{2}}^{+}$ transition is less than 0.08 nsec; the inhibition here is less than 18. All of the above rates are consistent with the theoretical model of Kurath and Lawson. From additional data on ${\mathrm{Ca}}^{43}$, we find that the partial mean life for the 612-keV ${\frac{3}{2}}^{+}\to {\frac{5}{2}}^{-}$ transition is 1.4 nsec. This is 0.06 times the single-particle value and is not explainable in the scheme of Kurath and Lawson.

Previously reported evidence for photofission of iron is investigated by a more extensive study. Thin foils of iron were bombarded with beams of 1.5-, 3-, 5-, and 16-GeV electrons. $\gamma$-ray spectroscopy and radiochemical measurements were used to measure yields of radionuclides produced in the targets. The yields of 25 nuclides were measured for the bombarded iron foils; these include eight nuclides in the mass region $22<~A<~35$. A thin aluminum target was bombarded with 16-GeV electrons, and the yields of seven radionuclides were measured. The yield of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$ in a thick iron target was measured as a function of target thickness and compared with that of radionuclides produced by cascade-evaporation reactions. The experimental evidence obtained in this series of experiments indicates that nuclides of mass <35 produced in the iron targets are the result of a fissionlike process. For cascade-evaporation reaction products, there is a decrease in the variation of yield with $\Delta Z$ as the bremsstrahlung energy is increased.

Excitation curves for ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}\mathrm{}(p,n)\mathrm{}{}_{}{}^{34}{}_{}{}^{}\mathrm{Cl}$ and ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}(\alpha ,n){}_{}{}^{34}{}_{}{}^{}\mathrm{Cl}$ were measured from the observed thresholds at 6438 ± 10 and 6360 ± 10 keV, respectively, to 1.6 MeV above threshold by detecting the residual radioactivity. Two prominent resonant structures were found in both reactions at the same excitation energies, 12.9 and 13.9 MeV, in the compound nucleus ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$. Excitation curves for ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}(\alpha ,{\alpha }_0)$ were also measured in the region of these resonances, but no similar prominent resonances were found. Arguments are presented that indicate a $T=\frac{3}{2}$ assignment for these resonances. Absolute values of the total cross section were determined for the above ($p,n$) and ($\alpha ,n$) reactions and also for ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}\mathrm{}(p,n)\mathrm{}{}_{}{}^{34}{}_{}{}^{}\mathrm{Cl}_{}^m{}_{}{}^{}$ and ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}(\alpha ,n){}_{}{}^{34}{}_{}{}^{}\mathrm{Cl}_{}^m{}_{}{}^{}$.