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 ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}(\alpha ,n){}_{}{}^{34}{}_{}{}^{}\mathrm{Cl}_{}^m{}_{}{}^{}$.

${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}\mathrm{}(d,p)\mathrm{}{}_{}{}^{89}{}_{}{}^{}\mathrm{Sr}$ excitation curves were measured at 90, 140, 160, and 170° for four states in ${}_{}{}^{89}{}_{}{}^{}\mathrm{Sr}$: the $d_{\frac{5}{2}}$ ground state, 1.03-MeV $s_{\frac{1}{2}}$ state, 2.00-MeV $d$ doublet, and 2.45-MeV $d_{\frac{3}{2}}$ state, at deuteron energies from 5.0 to 10.5 MeV. The excitation curves for ground state and 1.03-MeV $s_{\frac{1}{2}}$ state display cusps at the threshold of the charge-exchange-coupled channel, ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}\mathrm{}(d,n)\mathrm{}{}_{}{}^{89}{}_{}{}^{}\mathrm{Y}_{}^A{}_{}{}^{}$. The data are fit with coupled-channel Born-approximation calculations.

The ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha ){}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ reaction was studied by use of the 12-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ beam of the Argonne EN Tandem Van de Graaff and a broad-range magnetic spectrograph. Energy levels of ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ up to about 10-MeV excitation were observed, and spectra at 10 angles were taken. Relative spectroscopic factors were extracted with the aid of distorted-wave calculations. The results were compared with previous neutron-pickup reactions on ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$ and with theoretical predictions which were calculated within the framework of the rotational model.

Differential cross sections and polarizations for 39.6-MeV protons elastically scattered from the isotopes ${}_{}{}^{58,60,62,64}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{64,66,68}{}_{}{}^{}\mathrm{Zn}$ have been measured using the University of Minnesota linear accelerator. An atomic-beam-type polarized source was used for the polarization measurements. The data have been analyzed using both the standard optical model and a recent approach to the optical model developed by Greenlees, Pyle, and Tang, in which the real part of the central potential and the spin-orbit potential are obtained from the two-nucleon potential and the neutron, proton, and matter point-density distributions. Root-mean-square radii of the real central potentials are extracted from the data, but no systematic trend is evident for an isotopic sequence.

Bound states of ${\mathrm{P}}^{33}$ below 4.3-MeV excitation energy have been investigated via the ${\mathrm{P}}^{31}(t,p\gamma ){\mathrm{P}}^{33}$ reaction at triton bombarding energies of 2.45 and 3.10 MeV. Proton and $\gamma$-ray singles measurements, together with $p-\gamma$ coincidence measurements, have determined the principal $\gamma$-ray decay modes for the eight states previously reported below 4.3-MeV excitation energy in ${\mathrm{P}}^{33}$. Evidence is also obtained for the $\gamma$ decay of a previously unreported state at 4.19 MeV. Angular-correlation measurements, in conjunction with lifetime restrictions obtained from Ge(Li) studies of the $\gamma$-ray Doppler shifts, lead to the following determinations of spin parity for these levels [$\mathrm{MeV}\left(J^{\pi }\right)$] in ${\mathrm{P}}^{33}$: 0.0(${\mathrm{½}}^{+}$), $1.43\left({\frac{3}{2}}^{+}\right)$, $1.85\left({\frac{5}{2}}^{+}\right)$, $2.54\left({\frac{3}{2}}^{+}\right)$, $3.28(\frac{3}{2},\frac{5}{2})$, $3.49(\frac{3}{2} or \frac{1}{2})$, $3.63\left({\frac{7}{2}}^{+}\right)$, $4.05(\frac{3}{2},\frac{5}{2})$, $4.19(\frac{5}{2},\frac{7}{2})$, and $4.22\left({\frac{7}{2}}^{-}\right)$. These results serve in part to confirm the previously published assignments for the ground state and first three excited states, and establish new information for the higher-lying states. Restrictions on multipole mixing in the deexcitation transitions are summarized and compared with previous results. Finally, the experimental spectrum of ${\mathrm{P}}^{33}$ levels thus obtained is compared with applicable shell-model calculations for these low-lying levels.

The isotopes ${\mathrm{K}}^{47}$, ${\mathrm{Ca}}^{50}$, and ${\mathrm{Sc}}^{50}$ were formed by the bombardment of ${\mathrm{Ca}}^{48}$ with 3.3-MeV tritons. Half-lives of 18.1 ± 1.0, 13.9 ± 0.6, and 102.5 ± 0.5 sec, respectively, were measured by following the decay of the $\gamma$ rays emitted by these nuclides. The $\gamma$ rays were observed with a Ge(Li) detector, and $\gamma$-ray energies and relative intensities were obtained. ${\mathrm{K}}^{47}$ decays to the second and third excited states of ${\mathrm{Ca}}^{47}$; ${\mathrm{Ca}}^{50}$ to the fourth excited state of ${\mathrm{Sc}}^{50}$; and ${\mathrm{Sc}}^{50}$ to the second and third excited states of ${\mathrm{Ti}}^{50}$. The results for ${\mathrm{K}}^{47}$, together with previous results, establish the spin-parity of the 2578- and 2599-keV levels of ${\mathrm{Ca}}^{47}$ as ${\frac{3}{2}}^{+}$ and ${\mathrm{½}}^{+}$, respectively. The results for ${\mathrm{Sc}}^{50}$ and ${\mathrm{Ca}}^{50}$ are consistent with previous work, but are more accurate.

The ${\mathrm{Zn}}^{64}$ compound nucleus was formed at an excitation energy of 33.3 MeV using tow different target-projectile systems: 26.0-MeV protons on ${\mathrm{Cu}}^{63}$ and 31.3-MeV $\alpha$ particles on ${\mathrm{Ni}}^{60}$. Neutrons were detected with nuclear emulsions using the internal-radiator method. Exposures were made simultaneously at the following angles: 18, 33, 90, 147, and 162°. The c.m. energy spectra (2-15 MeV) of the two systems are very nearly the same. For both systems symmetry about 90° in the c.m. angular distributions is seen up to about 6 MeV followed by a forward peaking at higher energies. The symmetric (compound-nuclear) parts of the angular distributions differ significantly in anisotropy. For the $p+{\mathrm{Cu}}^{63}$ system the distribution is essentially isotropic while for the $\alpha +{\mathrm{Ni}}^{60}$ system we have an average anisotropy of about 1.4. We also observe for the $\alpha +{\mathrm{Ni}}^{60}$ system a slight but significant increase in anisotropy with energy of the emitted neutron (1.290 ± 0.047 at 2 MeV to 1.649 ± 0.119 at 6 MeV). The changes in average anisotropy, as we change target-projectile systems, are basically consistent with multiple-emission calculations using a rigid-sphere moment of inertia ($r_0=1.22\mathrm{}$ F). The change in anisotropy with emission energy is not seen in the calculations. It is estimated that, for the $p+{\mathrm{Cu}}^{63}$ and $\alpha +{\mathrm{Ni}}^{60}$ systems, direct-reaction neutrons constitute 5 and 3% of the total observed neutron spectra.

The neutron pick-up reactions ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}\mathrm{}(p,d)\mathrm{}{}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}\mathrm{}(p,d)\mathrm{}{}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ have been studied at a bombarding proton energy of 27.3 MeV. Several angular distributions were analyzed with the distortedwave Born approximation and the resulting spectroscopic factors and sum rule are given. The results indicate that the neutron configuration of the silicon isotopes contains $1d_{\frac{5}{2}}$, $2s_{\frac{1}{2}}$, and $1d_{\frac{3}{2}}$ components. A small $f$-wave neutron component has been found in ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$. Strong $d_{\frac{5}{2}}$ transitions have been observed to the unresolved doublet ($J^{\pi }=3^{+},2^{+}$; $T=1\mathrm{}$) at 9.32 MeV in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and to the ($J^{\pi }={\frac{5}{2}}^{+}$; $T=\frac{3}{2}$) level at 8.32 MeV in ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$. These states are the isobaric analogs to the states of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ (0 and 0.031 MeV) and to the ground state of ${}_{}{}^{29}{}_{}{}^{}\mathrm{Al}$, respectively. The $J^{\pi }=4^{+}$ state at 4.61 MeV in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ was excited in the ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}\mathrm{}(p,d)\mathrm{}{}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ reaction, indicating target excitation effects in single-nucleon-transfer reactions.

The 29-day isomer ${}_{}{}^{179m_2}{}_{}{}^{}\mathrm{Hf}$ has been found to decay via 21.03- and 257.32-keV transitions to the ${\frac{21}{2}}^{+}$ and ${\frac{19}{2}}^{+}$ members of the ground-state rotational band of ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$. From conversion-electron studies, $M2\mathrm{}$ and $E3\mathrm{}$ multipolarities were deduced, respectively, for the 21.03- and 257.32-keV isomeric transitions. The spin and parity ${\frac{25}{2}}^{-}$ is assigned to the isomeric state.

The $\gamma$ rays emitted from 3 to 2000 nsec after spontaneous fission of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ have been studied in detail. Both fission fragments were stopped on Si detectors; a Ge detector was used to detect $\gamma$ rays from the fragments on one Si detector. A time-to-amplitude converter was started on the fission-fragment signal and stopped on the $\gamma$-ray signal. For each event the two fission-fragment kinetic energies, the $\gamma$-ray energy, and the time delay were recorded. The data were then analyzed to obtain the energy, half-life, and intensity of each $\gamma$ ray as well as the mass of the emitting fission fragment. Some 144 $\gamma$ rays were so analyzed, corresponding to more than 80 isomeric states.

$\gamma$ rays were observed from practically all masses. However, the intensity was concentrated in the mass regions near 96, 108, 134, and 146. The energy spectrum consisted of a group of $\gamma$ rays below 500 keV and a group near 1300 keV. The high-energy group associated with masses 134 and 136 dominates the energy intensity after 50 nsec. A strong cascade from a 162-nsec isomeric state is assigned to ${}_{ 52}{}^{134}{}_{}{}^{}\mathrm{Te}_{82}^{}{}_{}{}^{}$, and a 3000-nsec isomeric state to ${}_{ 54}{}^{136}{}_{}{}^{}\mathrm{Xe}_{82}^{}{}_{}{}^{}$. Rotational cascades were not observed, in contradiction with earlier low-resolution work. The observed energies and half-lives can be accounted for by $E1\mathrm{}$, $M1\mathrm{}$, or $E2\mathrm{}$ transitions, either allowed or $K$ forbidden by a few units. The interpretation of these results is that the initially high spins of the fragments have less effect on the delayed $\gamma$ rays than was previously thought.

Fragment kinetic energy distributions were obtained for fissions leading to the emission of a particular $\gamma$ ray. The $\gamma$ ray serves to restrict the events to those having a definite final isotope for one fragment. The average kinetic energy of such events is found to be slightly greater than the average for all fissions yielding the same mass.

The static quadrupole moments of the 511.7-keV $2^{+}$ state in ${\mathrm{Pd}}^{106}$ and the 373.8-keV $2^{+}$ state in ${\mathrm{Pd}}^{110}$ have been determined by employing Coulomb-excitation techniques. Foils (∼175 μg/${\mathrm{cm}}^2$) of separated Pd isotopes were bombarded with 25- and 30-MeV ${\mathrm{O}}^{16}$ ions and 55- and 56-MeV ${\mathrm{S}}^{32}$ ions from the Purdue University and Argonne National Laboratory tandem accelerators. The angular distributions of the inelastically scattered ions were measured in coincidence with the deexcitation $\gamma$ rays to determine the relative excitation probabilities. The experimental data were fitted using the Winther-de Boer multiple-Coulomb-excitation program so that the sign and magnitude of the static quadrupole moment could be extracted. The effect of higher excited states on the excitation probability of the $2^{+}$ state has been calculated using the matrix elements determined by Robinson et al. and the Winther-de Boer program. Self-consistency of the oxygen and sulfur data suggests that the excitation via the second $2^{+}$ state interferes constructively so as to increase the excitation probability. With this choice for the interference via the second $2^{+}$ state, the values of the static quadrupole moments are $Q_{22}=-0.458\mathrm{}\pm 0.059$ b for ${\mathrm{Pd}}^{106}$ and $Q_{22}=-0.483\mathrm{}\pm 0.049$ b for ${\mathrm{Pd}}^{110}$. If the excitation via the second $2^{+}$ state interferes destructively, the values of the static quadrupole moments are $Q_{22}=-0.282\mathrm{}\pm 0.059$ b for ${\mathrm{Pd}}^{106}$ and $Q_{22}=-0.266\mathrm{}\pm 0.049$ b for ${\mathrm{Pd}}^{110}$.

$\alpha$-active isotopes in the rare-earth region were investigated by bombarding ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$ and ${}_{}{}^{162}{}_{}{}^{}\mathrm{Er}$ targets with ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ 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 catcher foils. After each bombardment the activity collected on the catchers was assayed with an $\alpha$-particle Si(Au) spectrometer. In the case of the ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$ target relative yields were obtained as a function of bombarding energy for known erbium, holmium, and dysprosium nuclides. Excitation functions determined from statistical-model calculations were found to be in reasonable agreement with the shapes of the experimental (${}_{}{}^3{}_{}{}^{}\mathrm{He},xn$) and (${}_{}{}^3{}_{}{}^{}\mathrm{He},pxn$) curves but not with those of the (${}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha \mathrm{xn}$) curves. Experimentally, the yields for (${}_{}{}^3{}_{}{}^{}\mathrm{He},pxn$) and (${}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha \mathrm{xn}$) products were found to be ∼3 to 5 times greater than those for (${}_{}{}^3{}_{}{}^{}\mathrm{He},xn$) products. The statistical-model calculations, contrastingly, indicated the (${}_{}{}^3{}_{}{}^{}\mathrm{He},xn$) and (${}_{}{}^3{}_{}{}^{}\mathrm{He},pxn$) cross sections to be comparable and ∼5 times greater than those for (${}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha \mathrm{xn}$) products. Similar yields were measured for nuclides observed in bombardments of the ${}_{}{}^{162}{}_{}{}^{}\mathrm{Er}$ target and were used in the assignment of two new $\alpha$-emitting isotopes to ${}_{}{}^{156}{}_{}{}^{}\mathrm{Yb}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Yb}$. Their half-lives and $\alpha$-decay energies were measured to be: (1) ${}_{}{}^{156}{}_{}{}^{}\mathrm{Yb}$, 24 ± 1 sec, 4.80 ± 0.01 MeV, and (2) ${}_{}{}^{157}{}_{}{}^{}\mathrm{Yb}$, 34 ± 3 sec, 4.50 ± 0.01 MeV. The assignment of the 4.80-MeV $\alpha$ group to ${}_{}{}^{156}{}_{}{}^{}\mathrm{Yb}$ was clearly established by noting a generic relationship between it and its known $\alpha$-decay daughter, ${}_{}{}^{152}{}_{}{}^{}\mathrm{Er}$. A similar clear-cut confirmation, based on a generic relationship, was not possible for ${}_{}{}^{157}{}_{}{}^{}\mathrm{Yb}$. The previously unknown nuclide, ${}_{}{}^{151}{}_{}{}^{}\mathrm{Er}$, was found in the ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$ bombardments by noting an initial growth period in the 4.60-MeV $\alpha$-particle group known to follow the decay of its daughter, ${}_{}{}^{151m}{}_{}{}^{}\mathrm{Ho}$. From this growth the half-life of ${}_{}{}^{151}{}_{}{}^{}\mathrm{Er}$ was found to be 23 ± 2 sec. The existence of 5.3-min ${}_{}{}^{155}{}_{}{}^{}\mathrm{Er}$, previously observed by us in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ bombardments of ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$, was confirmed. Its $\alpha$-decay energy was measured to be 4.01 ± 0.01 MeV, in agreement with the value reported earlier.