Drastic changes of (p,t) analyzing powers for the four Ni isotopes in ground-state transitions were observed. The changes are not explained by direct one-step processes but are interpreted by including strong two-step (p,d) (d,t) processes. Interference between the two processes of comparable intensities is essential. Marked incident-energy dependence of the analyzing powers is interpreted similarly.

[NUCLEAR REACTIONS Vector analyzing power $A_y\left(\theta \right)$ and cross sections $\sigma \left(\theta \right)$ for g.s. (p,t) on ${}_{}{}^{58,60,62,64}{}_{}{}^{}\mathrm{Ni}$, $E_{\mathrm{p}}=22,20, \mathrm{and} 18$ MeV, first- and second-order DWBA. Strong, sequential, two-step (p,d) (d,t) processes.]

Measurements of the reaction cross sections for ∼70 MeV (laboratory kinetic energy) antiprotons on lead and carbon are presented. Although lacking great statistical authority, the large observed cross sections suggest that the low energy reaction cross sections increase rapidly at lower energies above the Coulomb barrier.

[NUCLEAR REACTIONS 72 ± 10 MeV $\overline{\mathrm{p}}$ annihilation cross section on C, Pb.]

Estimates are given for the cross section of producing pionic atoms of exotic nuclei in heavy-ion collisions. The production cross section for exotic nuclear fragments is determined by the abrasion-ablation model, while the number of pions and their momentum distributions are obtained from the fireball model. The radiative capture probability of the pion into the atomic orbits of the nuclear fragment is estimated and is found to be very small. Alternative capture mechanisms are suggested.

[NUCLEAR REACTIONS Exotic nuclear fragments and pions from heavy-ion collisions; radiative capture of pion.]

Sub-barrier fusion of heavy ions is studied in a model that uses an $l$-dependent nuclear potential to reproduce the experimentally observed enhancement of the fusion cross sections. The parameters of the potential are found to scale with the reduced radii of the systems investigated, which points to dynamic deformations and/or neck formation as being the possible cause of the enhancement.

[NUCLEAR REACTIONS Sub-barrier fusion, $l$-dependent nuclear potential.]

A comparison is made between the classical phenomenological surface friction model and a time-dependent Hartree-Fock study by Dhar for the system ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ + ${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$ at $E_{\mathrm{lab}}\left(\mathrm{P}\mathrm{b}\right)=1600\mathrm{}$ MeV. The general trends for energy loss, mean values for charge and mass, interaction times, and energy-angle correlations turn out to be fairly similar in both methods. However, contrary to Dhar, the events close to capture are interpreted as normal deep-inelastic, i.e., not as fast fission processes.

The use of mass relationships for extrapolative purposes is based on a randomness assumption which is globally fulfilled. According to this assumption, specific correlations are expected within the experimentally observed deviations from the relationships, when shifts in the $Z,N$ plane are performed. In reality, however, we find anomalous values of these correlations.

[NUCLEAR MASSES Mass relationships; calculation of correlations between shifted sets.]

We have measured distinguishable gamma rays for the transition to the ground state and to the first excited state following 27.7-keV $s$-wave neutron resonance capture by ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ with a good signal-to-noise ratio, using a 60-${\mathrm{cm}}^3$ pure Ge detector. Partial radiation widths have been obtained for both transitions. It has been found that those widths are not comprehensible in the valency capture model. The results suggest that there is some possibility of core excitation in $s$-wave neutron resonance capture by ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$.

[NUCLEAR REACTIONS ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}(\mathrm{n},\gamma ){}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$, $E=27.7\mathrm{}$ keV, $s$-wave resonance; partial radiation widths, valency capture model calculation, pure Ge detector.]

Measurements of ${\sigma }_{\gamma }$ for ${}_{}{}^3{}_{}{}^{}\mathrm{He}(\alpha ,\gamma ){}_{}{}^7{}_{}{}^{}\mathrm{Be}$, central to the solar $\nu$ problem, disagree. In a direct capture model, the normalization constants $N_{\frac{3}{2}}$ and $N_{\frac{1}{2}}$ of the $P_{\frac{3}{2}}$ and $P_{\frac{1}{2}}$ bound state wave functions of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ at large ${}_{}{}^3{}_{}{}^{}\mathrm{He}-\alpha$ separations determine ${\sigma }_{\gamma }$. $N_{\frac{3}{2}}$ and $N_{\frac{1}{2}}$ are given by (simpler) measurements of ${\sigma }_{\gamma }$ at a higher energy $E$, or, as here, by analytic continuation of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}-\alpha p_{\frac{3}{2}}$ and $p_{\frac{1}{2}}$ phase shifts, $\delta \mathrm{}\left(E\right)\mathrm{}$. The method has been successfully tested on calculations of Tang et al. Better measurements of $\delta \mathrm{}\left(E\right)\mathrm{}$ are called for.

[NUCLEAR REACTIONS ${}_{}{}^3{}_{}{}^{}\mathrm{He}(\alpha ,\gamma ){}_{}{}^7{}_{}{}^{}\mathrm{Be}$, $E<\mathrm{}300\mathrm{}$ keV, ${}_{}{}^3{}_{}{}^{}\mathrm{He}(\alpha ,\alpha ){}_{}{}^3{}_{}{}^{}\mathrm{He}$, $E<\mathrm{}4\mathrm{}$ MeV, effective range function, analytic continuation technique, bound state energies, and normalization.]

Differential cross sections for $\mathrm{d}+\mathrm{d}\to {}_{}{}^4{}_{}{}^{}\mathrm{He}+\gamma$ have been measured at ${\theta }_{\gamma }(\mathrm{c}.\mathrm{m}.)=73\mathrm{}° \mathrm{and} 91°$ for $T_{\mathrm{d}}=376\mathrm{}$ MeV. Our results are a factor of 60 smaller than the cross section measured at $T_{\mathrm{d}}=404\mathrm{}$ MeV by Akimov et al. The ratios of our results to those of Arends et al. for the inverse reaction, $\gamma {}_{}{}^4{}_{}{}^{}\mathrm{He}\to \mathrm{dd}$, are 2.0±0.9 at 73° and 1.7±0.9 at 91°. Considering the large uncertainties in both data sets, these ratios are consistent with time-reversal invariance in this isoscalar electromagnetic interaction of hadrons. Our data corroborate the reported deviation from the ${sin}^{2}2\theta$ angular distribution expected of this reaction.

[NUCLEAR REACTIONS ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\mathrm{d},\gamma ){}_{}{}^4{}_{}{}^{}\mathrm{He}$, $T_{\mathrm{d}}=376\mathrm{}$ MeV; measured $\sigma \left(\theta \right)$, $\theta \mathrm{}(\mathrm{c}.\mathrm{m}.\mathrm{})\mathrm{}=73\mathrm{}°,91\mathrm{}°$.]

A new supersymmetric scheme has been tested against two previously proposed schemes using data of six platinum isotopes. This new scheme is at least an order of magnitude better, in the least squares sense, than the previous schemes. In this new model, the lack of fit is due almost entirely to the lack of fit for the even isotopes. The fitted parameters show a smooth variation over the platinum isotopes studied.

It is shown that the interacting boson approximation naturally incorporates an effective dynamical axial asymmetry which stems from softness in the corresponding classical potential in the $\gamma$ direction. An explicit relationship is obtained between the effective $\gamma$ deformation variable and the one parameter, $\chi$, characterizing interacting boson approximation calculations in an SU(3) → O(6) region.

Elastic $\alpha$ scattering on the target nuclei ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ has been studied microscopically using the framework of the generator coordinate method. Combined with the results of previous microscopic investigations of elastic $\alpha$ scattering on the oxygen and calcium isotopes the present studies allow to set up some systematics which may lead to useful predictions concerning the general behavior of elastic $\alpha$ scattering on target nuclei in the mass range $A\simeq 14-48$. It is pointed out that the pure elastic phase shifts (correspondingly, the real part of the optical potential) cannot serve as an explanation for the different cross section behavior at backangles observed for elastic $\alpha$ scattering in this mass region. It is qualitatively shown that these differences are due to absorptive effects.

[NUCLEAR REACTIONS Generator coordinate method, study of $\alpha -{}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, $\alpha -{}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and $\alpha -{}_{}{}^{32}{}_{}{}^{}\mathrm{S}$, comparison of elastic $\alpha$ scattering on target nuclei in the mass region $A=14-48\mathrm{}$ at low energies, backangle anomaly, molecular resonances.]

Angular distributions of the cross section for the elastic and inelastic scattering of protons have been measured at four isobaric analog resonances of the ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$+p system and at two off-resonance energies. Spectroscopic information about the ${\frac{7}{2}}_1^{-},{\frac{3}{2}}_1^{-},{\frac{1}{2}}_1^{-}, \mathrm{and} {\frac{5}{2}}_1^{-}$ states of the parent nucleus ${}_{}{}^{145}{}_{}{}^{}\mathrm{Sm}$ is extracted, with the core ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ in the states $0_1^{+},2_1^{+},3_1^{-},4_1^{+}, \mathrm{and} 2_2^{+}$. The analysis includes direct and fluctuating nonresonant processes. The direct scattering amplitude is obtained from a coupled channel treatment. Different methods for the calculations of the single-particle widths have been employed. The experimental spectroscopic amplitudes were compared with nuclear structure calculations based on the particle-vibrator model. Both the liquid drop model and the quasi-particle random phase approximation were used to describe the vibrator. The calculations based on the latter model show good agreement with the experimental results.

[NUCLEAR REACTIONS ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$(p,p′), $E=8.5-14\mathrm{}$ MeV, enriched targets, measured $\sigma (E_{\mathrm{p}},\theta )$; experimental and theoretical ${}_{}{}^{145}{}_{}{}^{}\mathrm{Sm}$ spectroscopic amplitudes.]

Angular distributions for elastic and inelastic scattering have been measured on six analog resonances in the ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$+p system and at two off resonance energies. Partial widths are deduced from the angular distributions. Formulae for the spectroscopic amplitudes within the framework of the quasiparticle random phase approximation are presented. The experimental results are compared with the theoretical predictions.

[NUCLEAR REACTIONS ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$(p,p′), $E=7.5-14\mathrm{}$ MeV; enriched targets, measured $\sigma (E_{\mathrm{p}},\theta )$; deduced spectroscopic amplitudes; ${}_{}{}^{131}{}_{}{}^{}\mathrm{Te}$ calculated and spectroscopic amplitudes predicted.]

A comprehensive model is introduced for alpha particle induced nuclear reactions. Five different mechanisms are examined and discussed. These include inelastic scattering of the incident alpha particle, nucleon pickup, binary fragmentation, dissolution of the alpha in the nuclear field, and preequilibrium processes initiated by alpha-nucleon collisions. A series of experiments was performed to measure the excitation functions of many nuclides produced from the irradiation of ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ by 40-140 MeV alpha particles. Together with alpha particle and proton spectra measured by other authors, these data form the basis of a test of the model introduced. A detailed analysis of the comparison between the calculated and experimental results, with particular emphasis on the interpretation of breakup processes, leads to the conclusion that breakup to four nucleons is preferred to the more commonly assumed binary fragmentation in that a much broader range of experimental data may be reproduced.

[NUCLEAR REACTIONS ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}(\alpha ,x\mathrm{n})$, $x=1-5\mathrm{}$; $(\alpha ,\mathrm{p}6\mathrm{n}),(\alpha ,2\mathrm{}\mathrm{p}x\mathrm{n}),x=1,5-7\mathrm{}$; $(\alpha ,3\mathrm{}\mathrm{p}x\mathrm{n}),x=5-8,10\mathrm{}$; $(\alpha ,4\mathrm{}\mathrm{p}x\mathrm{n}),x=5-7,9\mathrm{}$; $(\alpha ,5\mathrm{}\mathrm{p}9\mathrm{n}),(\alpha ,6\mathrm{}\mathrm{p}7\mathrm{n})$; ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, p spectrum; ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, p, and $\alpha$ spectra; $E=40-140\mathrm{}$ MeV; introduced model; calculated: $\frac{d\sigma }{d{E}_{\mathrm{p}}},\frac{d\sigma }{d{E}_{\alpha }},\sigma \left(E_{\alpha }\right)$ for all measured excitation functions.]

Small-angle inelastic $\alpha$-scattering measurements have been made at $E_{\alpha }=129\mathrm{}$ MeV on ${}_{}{}^{144,148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{142,146,150}{}_{}{}^{}\mathrm{Nd}$ to investigate the giant monopole resonance in transitional and deformed nuclei. The experimental data reveal a mixing of $L=0\mathrm{}$ and $L=2\mathrm{}$ modes in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ resulting in almost identical angular distributions for the two components of the giant resonance peaks in the angular range 2°—6°. A "splitting" of the giant monopole resonance is observed in ${}_{}{}^{150}{}_{}{}^{}\mathrm{Nd}$; the extent of this splitting is smaller than that reported for ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$. Comparison is made with the predictions of various theoretical models.

[NUCLEAR REACTIONS ${}_{}{}^{144,148}{}_{}{}^{}\mathrm{Sm}$, ${}_{}{}^{142,146,150}{}_{}{}^{}\mathrm{Nd}(\alpha ,{\alpha }^{\prime })$, $E_{\alpha }=129\mathrm{}$ MeV. Measured $E_x$, $\sigma \left(\theta \right)$, giant resonances; deduced $L$, mixing of modes.]

Electron scattering cross sections for ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ have been measured with a resolution of less than 40 keV in a momentum transfer range between $0.4<q<\mathrm{}3.1\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$ both at forward angles and at 160°, which allows a separation of longitudinal and transverse form factors. The analysis of the positive-parity states (including previous data for some of the states) results in transition densities. Most densities are compared to various model calculations. The density of the $8^{+}$ level is used to determine the radius of the $g_{\frac{9}{2}}$ proton orbit as $R \left(g_{\frac{9}{2}}\right)=5.035\mathrm{}\pm 0.045$ fm.