The inelastic electron scattering form factor for the $0^{+}$ first excited state of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been calculated with wave functions from the recoil corrected continuum shell model. The use of a realistic interaction and proper boundary conditions lead to excellent agreement with experiment. These results demonstrate that this state can be understood as a superposition of simple 1p-1h excitations in the internal coordinates.

The radiative proton capture reaction on ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ was measured over the energy region $E_p$=20–90 MeV. Presented are experimental differential cross sections at ${\theta }_{\gamma }$=60° for captures populating the ground and various excited states of ${}_{}{}^{16}{}_{}{}^{}0$. Differential cross sections and analyzing-power angular distributions are presented at a proton energy of $E_p$=49.69 MeV. Calculations from a phenomenological direct-semidirect and a more detailed relativistic model describe cross sections well, but are less satisfactory in describing analyzing powers. Results of the energy-dependence measurements show that there are giant resonances built on all the excited states investigated.

We derive the differential cross section for the scattering of plane polarized photons by protons below pion threshold. The contributions from the charge, spin, and anomalous magnetic moment is calculated with no approximation in the photon energy, ω. The contribution from the proton structure is included only to lowest order [viz., O((ω/M${)}^2$) ], and comes from the electric and magnetic dipole polarizabilities.

Angular distributions of cross sections and analyzing powers were measured for the ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(p→,γ${)}^4$He reaction at incident proton energies of 2.0, 5.0, and 9.0 MeV. The 90° analyzing power was measured at 11 energies between 0.8 and 9.0 MeV. A transition matrix element analysis indicated that the inclusion of M1 strength gave better fits and eliminated the anomalously large ${}_{}{}^3{}_{}{}^{}\mathrm{D}_2^{}{}_{}{}^{}$ (E2) strength reported in earlier work. An E1-plus-E2 direct capture calculation was performed. It is shown that this calculation can be brought into agreement with the data if an M1 strength comparable to that found in the T-matrix element analysis (0.5–1.0% of the total capture cross section) is added.

The exclusive (e,e’p) reaction and the inclusive (p,p’) reaction for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at intermediate energy are studied in order to understand the reaction mechanism leading to multinucleon knockout in electron scattering. We focus on the effect of the final-state interaction in the missing-energy spectrum measured (under parallel kinematics) in a coincidence (e,e’p) experiment in the dip region, where the many-body process is the dominant channel. To disentangle complex many-body processes and understand the final-state interaction quantitatively, we first study the inclusive (p,p’) reaction at the corresponding proton energy, which represents the final-state interaction in the on-shell limit. We show that the single scattering process, which means that the incident proton interacts inelastically with the target nucleon only once before coming out, is dominant at small proton scattering angles and can be treated within the framework of distorted-wave impulse approximation by using the effective nucleon-nucleon (NN) interaction. This prescription is able to be applied to the (e,e’p) reaction, since the forward proton scattering in the final state is important under parallel kinematics. Based on the knowledge obtained from the study of the (p,p’) reaction, we examine the two-body type of final-state interaction in electron scattering within the above approach. We indicate limitations of the two-body process as a mechanism for understanding the (e,e’p) reaction. Furthermore, the presence of the many-body mechanism involving more than two nucleons is speculated from qualitative investigations, and some possible experiments which could provide important information on the many-body mechanism are suggested.

Kinematically complete breakup experiments for final-state interaction and collinear configurations have been analyzed by rigorous Faddeev calculations. The two-nucleon Paris potential and a one-boson-exchange parametrization of the new Bonn potential have been used. The treatment of charge-dependent forces in the Faddeev scheme is discussed and a simple (2/3-(1/3 rule is derived. In the collinear configuration a significant discrepancy is found between theoretical and experimental cross sections.

Elastic scattering cross sections have been measured for 8, 10, and 24 MeV neutrons incident on ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$. These measurements, together with other neutron elastic scattering and total cross section data available up to 29 MeV, are used in grid searches to obtain an optical model potential which contains a dispersion relation term. This potential is then extrapolated toward negative energies to predict bound single-particle state properties. An overall good description of the data at positive and negative energies is achieved.

Differential cross sections for neutron elastic scattering and inelastic scattering to the first $2^{+}$ and $3^{\mathrm{-}}$ excited states have been measured at 10, 14, and 17 MeV for ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$ and at 10 and 14 MeV for ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$. Analyzing powers have also been measured at 10 and 14 MeV for elastic scattering from both isotopes and at 10 MeV for inelastic scattering from ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$. These data have been analyzed in the framework of the coupled-channels formalism for vibrational nuclei. Previously reported neutron scattering measurements performed below 25 MeV, along with total cross-section measurements from 10 keV to 100 MeV, and s- and p-wave strength functions were also considered in the analysis in order to place additional constraints on the optical potential parameters. Neutron scattering deformations have been deduced for the quadrupole and octupole vibrations. These deformations have been compared with those derived from earlier (n,n’) and (p,p’) scattering measurements which were reanalyzed in the present work.

The neutron${\mathrm{-}}^{86}$Kr mean field is formulated in terms of a dispersive optical model potential in which the real part contains dispersive contributions derived from the imaginary part by the dispersion relation. The dispersive contribution is added to the Hartree-Fock potential, which is assumed to have a Woods-Saxon shape and a depth that decreases linearly with increasing energy. The shape parameters for all components of the potential are assumed to be independent of energy. The model is formulated in terms of the energy relative to the Fermi energy, and the imaginary potential is assumed to be symmetric about the Fermi energy, which is set equal to -7.7 MeV on the basis of the empirical level structure for n${\mathrm{-}}^{86}$Kr. All other parameters are taken from earlier analyses of other nuclei, particularly of ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$. The model is shown to give good overall predictions for the n${\mathrm{-}}^{86}$Kr mean field by comparison to the following three sets of empirical data: (i) the observed energies of the occupied and unoccupied valence levels, (ii) the energy-averaged total cross section for neutron energies up to 25 MeV, and (iii) the averaged scattering functions for s-, p-, and d-wave neutrons in the resolved resonance region from 0.015 to 0.96 MeV. The latter comparison is the unique feature of this work; the partial-wave-scattering functions that are available for s, p, and d waves in the resonance region for ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$ make possible detailed comparisons to the scattering functions from the model.

The neutron total and neutron capture cross sections of ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$ have been measured using the neutron time-of-flight technique at a pulsed electron linear accelerator. Data analyses have been performed in the energy ranges 1 to 500 keV and 1 keV to 1 MeV, respectively, for capture and transmission, with R-matrix multilevel multichannel codes and with resonance shape fitting procedures, to determine the resonance parameters $E_0$, g${\Gamma }_n$, g${\Gamma }_Y$, J, and l. Subsequent values for the average resonance parameters for s-wave and p-wave neutron resonances are $D_0$=(43.4±4.7) keV and $S_0$=(2.85±0.25)×${10}^{\mathrm{-}4}$ up to 1 MeV, and $D_1$=14.7 keV and $S_1$=(0.30±0.05)×${10}^{\mathrm{-}4}$ up to 200 keV. The following nonstatistical effects are indicated in the resonance parameter set: two gaps are observed in the s-wave level distribution, where at least two resonances for each gap are missing; a strong discontinuity in the level spacing is observed for p-wave resonances whereby three energy ranges, up to 500 keV, with different level spacings may be distinguished. This energy-dependent behavior of the p-wave level density shows that the level density parameter (a) strongly depends on the excitation energy and causes parity dependence of nuclear states in the neutron energy range (200–500) keV. These deviations of the resonance parameters from statistical behavior may be explained by doorway structures with a small energy spread of states, as has been observed for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ which, like ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$, have a multiple of four nucleons in the target nucleus.

A separable approximation $T^{\left(S\right)}$ to the two-body T matrix of the form 〈${\mathit{kT}}^{\mathrm{}\left(\mathrm{S}\right)\mathrm{}}$(E)k’〉=〈kVk’〉+${\mathrm{\Sigma }}_{\mathit{s}=1\mathrm{}}^{\mathrm{S}}$ 〈kV${\mathrm{\Gamma }}_{\mathit{s}}$(E)〉(1-${\gamma }_{\mathit{s}}$${)}^{\mathrm{-}1}$ 〈${\mathrm{\Gamma }}_{\mathit{s}}$(E)Vk’〉 is examined, where V is the Reid soft core potential, ${\Gamma }_s$ are the Weinberg eigenstates of the operator $G_0$(E)V for positive energy E, and ${\gamma }_s$(E) are the corresponding discrete complex eigenvalues. General projection techniques which improve the convergence of the sum above are considered. For the triplet state a nonlocal potential U is defined which in the l=0 channel represents the effect of the tensor coupling to the l=2 channel. It is found that the presence of U in the triplet state is responsible for the increased number of terms needed in the separable representation of T, as compared to the representation in the singlet state, where U is absent. The effect of U is largest for momenta less than 1 or 2 ${\mathrm{fm}}^{\mathrm{-}1}$. .AE

The reactions ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{208}{}_{}{}^{}(\mathit{p}$,xn) have been measured with 80.5 MeV protons in the neutron continuum $E_n$>20 MeV and the angular range 0°≤θ≤145°. Whereas the angle-integrated spectrum can be explained by semiclassical preequilibrium models, this nucleon-nucleon scattering approach fails at far backward angles. In contrast, the quantum statistical multistep calculations give good agreement. They are indicative of a decrease of the effective nucleon-nucleon interaction with increasing nucleon energy.

The momentum distributions of projectile and target residues from spallation reactions induced by relativistic projectiles already in the literature are transformed into consistent quantities and compared. The momentum imparted to the residual nucleus is presented in terms of a longitudinal velocity, 〈${\beta }_{?}$〉, and a root-mean-squared momentum, $P_{\mathrm{rms}}$. These parameters from all spallation products from many disparate systems display the same systematic dependence on observed mass loss. The rms momentum is shown to depend on the square root of the observed mass loss due to momentum conservation in either of three competing processes with no dependence on the initial reaction. The longitudinal momentum is shown to depend on the observed mass loss and therefore on the excitation energy with only a kinematical factor from the entrance channel. Thus, the longitudinal momenta depend on the velocity but not the mass of the reaction partner.

Several rotational bands have been populated in ${}_{}{}^{131}{}_{}{}^{}\mathrm{La}$ via the ${}_{}{}^{116}{}_{}{}^{}\mathrm{Cd}$${(}^{19}$F, 4nγ) fusion-evaporation reaction. Bands built on low-lying $h_{11/2}$, $g_{7/2}$, and $d_{5/2}$ proton states have been identified. At higher spins, both proton and neutron [$h_{11/2}$${]}^2$ alignments have been observed. While the proton alignment from low-Ω orbitals maintains a prolate nuclear shape, the alignment of high-Ω neutrons drives the nucleus to a collectively rotating oblate shape (γ∼-60°). The results are interpreted in the framework of the cranked shell model. In addition, B(M1;I→I-1)/B(E2;I→I-2) ratios have been extracted for several of the bands and the results compared to a semiclassical model to identify the detailed structure.

Particle-particle coincidence measurements have been made between light charged particles ${(}^1$,2,3H and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$) produced in the reaction (8.5 MeV/nucleon) ${}_{}{}^{56}{}_{}{}^{}$Fe${+}^{\mathrm{nat}}$Ag. This coincidence requirement emphasizes central collisions leading to evaporation residues. Average multiplicities are found to be approximately three alphas and approximately four protons per evaporation residue; these values imply that approximately (1/2 the initial excitation energy of about 211 MeV is evacuated from the evaporation residues by these particles. This fractional energy evacuation by charged particles is considerably larger than that found for the similar reaction (8.5 MeV/nucleon) ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ag}$. In both reactions the effective emission barriers for ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ (as deduced from the energy spectra) are found to be significantly lower than corresponding empirical fusion barriers between cold nuclei. This is particularly surprising for emitter nuclei that survive fission.

For the reactions of 30 MeV/nucleon ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ with Ag, singles and coincidence measurements have been made for heavy residues, fragments (3≤z≤14), and light charged particles (z≤2). Mass-velocity correlations for the residues and fragment-residue coincidences indicate that increasing residue velocities do correspond to increasing excitation energy. Excitation energies as high as 90% of those which would result from complete fusion are reached. The spectra of light particles detected in coincidence with residue groups having different average velocities are analyzed with a moving source fit. When recoil effects are properly taken into account, excellent fits to the data are obtained. From the energy spectra and multiplicities of particles emitted from a fusion-like source the initial temperatures of the primary composite nuclei are determined. The results suggest that a plateau temperature near 6.5 MeV is reached above excitation energies of 3 MeV/nucleon. The temperatures are compared to those resulting from various model calculations.

Fusion cross sections have been measured for ${}_{}{}^{16}{}_{}{}^{}$O${+}^{147}$,149Sm at bombarding energies in the range 61 MeV ≤$E_{\mathrm{lab}{(}^{16}\mathrm{O})\mathit{\le }75}$ MeV by off-line observation of x rays emitted in the radioactive decay of Yb isotopes and their daughters. The fusion excitation functions are similar to those of the adjacent even Sm isotopes. It appears, therefore, that the odd valence neutrons do not have any unusual influence on the subbarrier enhancement of ${\sigma }_{\mathrm{fus}}$ in these systems. The x-n distributions of the evaporation residues were also determined. The nuclear deformation parameters ${\beta }_2$ deduced for the odd and even Sm isotopes using Wong’s model establish a smooth systematic behavior of ${\beta }_2$ with target collectivity. Fusion cross sections for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with all the stable Sm isotopes are tabulated.

Electromagnetic dissociation of ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ target nuclei and their subsequent deexcitation by two-neutron emission was observed. Beams of relativistic ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, and ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$ ions were used. The measured electromagnetic dissociation cross sections become large for high-Z targets and projectiles, reaching 335 mb for the ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$${(}^{139}$La,X${)}^{195}$Au reaction with 1.26 GeV/nucleon ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$ projectiles. The experimental cross sections in excess of the estimated nuclear contributions are in reasonable agreement with a calculation of the electromagnetic dissociation contribution using the Weizsäcker-Williams method for estimating the virtual photon spectrum.

States have been established in the neutron-deficient ${}_{}{}^{139}{}_{}{}^{}\mathrm{Gd}$ nucleus for the first time via the ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$${(}^{50}$Cr,2pnγ) reaction. Both γ-γ and γ-n coincidence techniques were employed. The yrast band, built on the ν$h_{11/2}$${\left[514\right](9/2\mathrm{}}^{\mathrm{-}}$ orbital, shows a signature splitting of ∼100 keV implying a significant triaxial shape. At a rotational frequency ħω∼0.29 MeV a pair of $h_{11/2}$ quasiprotons align. Associated with this alignment are a decrease in the signature splitting, indicating a near-prolate nuclear shape, and an enhancement of the interband M1 transitions relative to the E2 crossovers, which is consistent with a mixed neutron-proton configuration. In addition, a tentative decoupled band showing the characteristics of a band theoretically expected for the β-driving ν$i_{13/2}$ orbital was observed.

Differential cross sections for the elastic scattering of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ ions have been measured at a bombarding energy of 210 MeV. Angular distributions for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ (3.6°–45.9°), ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ (4.6°–43.5°), and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ (4.0°–43.6°) extend sufficiently into the rainbow region to enable the extraction of unique ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ potentials. For the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ target (3.1°–36.0°), Coulomb scattering dominates with only a slight evidence of nuclear diffraction at the largest angles. The data were analyzed in terms of a six-parameter phenomenological optical-model potential with Woods-Saxon form factors. The unique potentials obtained show a weak target-mass dependence, which allowed the prediction of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ potential parameters. Using the present results and lower energy analyses, an energy dependence for the ${}_{}{}^6{}_{}{}^{}\mathrm{nucleus}$ potentials was derived. For all targets, the volume integral per nucleon pair of the real potential seems to satisfy a logarithmic energy dependence of the form ${\mathit{J}}_{\mathit{R}}$/6A=${\mathit{J}}_{\mathit{R}}^0$/6A-β ln ${\mathit{E}}_{\mathrm{lab}}$ with $J_R^0$/6A=830±30 MeV ${\mathrm{fm}}^3$ and β=105±5 MeV ${\mathrm{fm}}^3$. This result is consistent with elastic scattering of other light ions. By truncating the angular distributions for the lighter targets up to the rainbow angle, several discrete potentials, corresponding to the different families found at lower energies, were obtained.