The effect of a neutron skin on the collective states of medium and heavy-mass nuclei is discussed. We consider two well-known collective modes which correspond to the motion of neutrons with respect to protons, namely, the M1 (scissors) and the isovector E1 (giant dipole) resonance. For nuclei with a sufficient excess of neutrons the behavior of the ‘‘pygmy resonance’’ is also discussed.

This work demonstrates that the model of a deep attractive NN potential (the Moscow NN potential) with a deep lying extra state may be interpreted as a potential in the N(1440)-N system. Under such an interpretation, the deep-lying level forbidden for the NN system describes the N(1440)-N component in deuteron. This conclusion is used to obtain the momentum distribution for the N(1440)-N component in deuteron.

The intermediate mass fragment production in the interaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$${+}^{208}$Pb at E/A=19.6 MeV was studied using a CR-39 plastic track detector. Exit channels with up to three intermediate mass fragments were observed. It seems that events having at least one intermediate mass fragment originate from central collisions. The relative velocity correlation functions were determined for these events and discussed.

The consistent Q formalism of the interacting boson model (IBA) is systematically confronted with data on deformed vibrational states and found to be empirically supported. Exploiting this, we test a central IBA prediction, which is in stark contrast with traditional models, of an inherent linkage between the properties of the β and γ vibrations, and find this linkage to be confirmed by the data.

We have measured the spin-transfer parameters ${\mathit{K}}_{\mathit{L}\mathit{L}}$, ${\mathit{K}}_{\mathit{S}\mathit{L}}$, ${\mathit{K}}_{\mathit{L}\mathit{S}}$, and ${\mathit{K}}_{\mathit{S}\mathit{S}}$ at 788 MeV from 47° to 177° c.m., and also uncovered a 10–16 % normalization discrepancy which affects all previous np elastic spin data from LAMPF. Results disagree significantly from previous phase-shift predictions. With the inclusion of these new data the NN phase shifts and amplitudes (isospin 0 and 1) become well determined for the first time near 800 MeV.

Measurements of the unpolarized triple differential cross section and the ${\mathit{A}}_{\mathit{y}\mathit{y}}$ tensor analyzing power for the ${}_{}{}^1{}_{}{}^{}\mathrm{H}$(d,pp)n reaction were made using a 94.5 MeV polarized deuteron beam at the Indiana University Cyclotron Facility. Scattering angles (θ and φ) and energy information were recorded for the two emerging protons using large-area wire chambers backed by stopping plastic scintillator detectors. Events were selected that were close to the symmetric constant relative energy geometry in order to enhance the sensitivity of the observables to off-shell and three-body effects. The measurements covered values of α, the center-of-mass angle between the incoming proton and the outgoing neutron, from 72° to 180°. Comparisons are made to Faddeev calculations that use either separable potentials or an exact treatment of the S-wave nucleon-nucleon interaction in conjunction with a perturbative treatment of higher partial waves. While none of these calculations, which use only two-nucleon interactions, is completely satisfactory, there remains too much variation among different theoretical treatments to demonstrate the need for including additional dynamical features in the three-body model.

We have studied the reaction p+p→p+p+${\mathrm{\pi }}^0$ from 320 to 500 MeV by detecting the γ rays from ${\mathrm{\pi }}^0$ decay in coincidence in two large NaI crystals. The obtained differential and total cross sections of the pions are in agreement with previous measurements but are of a higher precision. We have also measured the pion analyzing powers; the first measurement of this observable. Our results are compared with those for the reactions np→NN${\mathrm{\pi }}^{\pm }$ with confusing conclusions concerning the contribution of ${\mathrm{\sigma }}_{01}$, the zero isospin pion production channel.

A leading correction to the zero-range theory is considered for three-body systems. The correction is linear in the force range ${\mathit{r}}_0$. An explicit expression is obtained for this correction for the case of correlation between the three-body binding energy and the particle-pair scattering length, as well as for the practically interesting case of correlation between the triton binding energy and the neutron-deuteron doublet scattering length. The correction for the neutron-deuteron quartet scattering length is also found. Physics of the correction involves a modification of the effective long-range interaction 1/${\mathit{R}}^2$, which arises in the three-body systems under the conditions of the zero-range theory, by a singular correction ${\mathit{r}}_0$/${\mathit{R}}^3$.

We investigate the reason behind the fact that the Δ isobar effectively behaves as a stable particle. We first obtain model-independent conditions for this behavior that depend only on the imaginary part of the delta propagator. We then consider a toy model in which the NΔ system is decoupled from the NN system and check that the approximate behavior of the Δ as a stable particle is not in effect controlled by the coupling to NN channels nor due to the narrow width of the Δ resonance. Finally, we describe the NΔ amplitude in the isospin T=2 channels within a meson-exchange model. Experimental NΔ T=2 phase shifts would be welcome.

Modified Faddeev equations that allow the inclusion of irreducible three-body forces in addition to two-body interactions are formulated and the technical apparatus for their solution in momentum space is described. Results for the triton binding energy are obtained with realistic two-nucleon interactions and the Tucson-Melbourne two-pion exchange three-nucleon force and compared with previous calculations. Excellent agreement with the results of other groups is found confirming that the accuracy of present-day techniques for handling three-nucleon forces is very high indeed.

The cross section for inclusive electron scattering by nuclear matter is calculated at high momentum transfers using a microscopic spectral function, and compared with that extrapolated from data on laboratory nuclei. It is found that the cross section obtained with the plane-wave impulse approximation is close to the observed data at large values of the energy loss, but too small at low values. In this regime final-state interactions are important; after including their effects theory and data are in fair agreement. It is necessary to treat nucleon-nucleon correlations consistently in estimating the final-state interactions. The effects of possible time dependence of the nucleon-nucleon cross section, giving rise to nuclear transparency, are also investigated. The y scaling of the response function is discussed to further elucidate the role of final-state interactions.

A modification of the resonating-group method (RGM) is proposed which includes the multiquark shell-model configurations in the nucleon overlap region. The instanton, gluon, and π,σ exchange is taken into account, the interaction constants being consistent with the baryon spectrum. This enables one to cover a wide interval of NN scattering energies up to ${\mathit{E}}_{\mathrm{lab}}$=2 GeV. The projection of the six-quark wave function onto the NN and other baryon channels is discussed in detail in our approach and in other RGM versions as well, and in this context the problem of repulsive core in the NN forces is discussed.

The reactions ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${+}^{14}$N at ${\mathit{E}}_{\mathrm{N}}$=40 MeV and ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$${+}^{27}$Al at ${\mathit{E}}_{\mathrm{Al}}$=90 MeV are used to populate high-spin levels in a number of ${\mathit{f}}_{7/2}$ nuclei, from ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$ to ${}_{}{}^{52}{}_{}{}^{}\mathrm{Fe}$. In ${}_{}{}^{51}{}_{}{}^{}\mathrm{Cr}$, the ${\mathit{f}}_{7/2}$ band-terminating state at ${\mathit{J}}^{\mathrm{\pi }}$=23/$2^{\mathrm{-}}$ is identified at 5.711 MeV, and further transitions, from the pf band, are found. Similar evidence for interband transitions in ${}_{}{}^{51}{}_{}{}^{}\mathrm{Mn}$ is sought without success. In ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$, new transitions are found within the positive-parity band and between the negative- and positive-parity bands.

We have used the Michigan State University National Superconducting Cylcotron Laboratory A1200 radioactive beam facility and a newly designed neutron detector array to measure the first β-delayed neutron spectrosopy of ${}_{}{}^{15}{}_{}{}^{}\mathrm{B}$ and the ${}_{}{}^{15}{}_{}{}^{}\mathrm{B}$ β-decay branch to ${}_{}{}^{15}{}_{}{}^{}\mathrm{C}$ bound states. The ${}_{}{}^{15}{}_{}{}^{}\mathrm{B}$ ions were produced as projectile fragments in the interaction of an E/A=80 MeV ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ beam with a thick beryllium target. From these measurements, we deduce the ${}_{}{}^{15}{}_{}{}^{}\mathrm{B}$ β-decay branching ratios. The results are compared with shell-model predictions carried out in the psd model space.

The photon-decay modes of the giant dipole resonance (gdr) in the nuclei ${}_{}{}^{142,146,148,150}{}_{}{}^{}\mathrm{Nd}$ were investigated via elastic and inelastic photon scattering. Considerable inelastic scattering was seen into the first excited state of each nucleus. In ${}_{}{}^{148}{}_{}{}^{}\mathrm{Nd}$ and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Nd}$, scattering into several higher levels was also resolved and found to be quite weak. The data are interpreted in the context of both the dynamic collective model and interacting boson model. In these models, the photon decays of the gdr to excited states are a consequence of the coupling between the giant resonance and collective surface degrees of freedom, such as rotations and vibrations. The present data provide the first experimental test of the photon-decay predictions of these models across an entire transitional chain. Both models give an excellent account of the data.

Use has been made of the interference between the nuclear and Coulomb amplitudes in the scattering of 84 MeV/nucleon ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ ions by ${}_{}{}^{124}{}_{}{}^{}\mathrm{Sn}$ to study the isospin character of the giant quadrupole transition. The data are well described by assuming the transition is ‘‘isoscalar,’’ i.e., ${\mathit{M}}_{\mathit{n}}$/${\mathit{M}}_{\mathit{p}}$=N/Z. This is in disagreement with the results of ${\mathrm{\pi }}^{+}$/${\mathrm{\pi }}^{\mathrm{-}}$ scattering on ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$ and recent (e,e’n) measurements on ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$. Cross sections for excitation of the $2^{+}$ state at 1.132 MeV, $3^{\mathrm{-}}$ state at 2.614 MeV, and giant monopole resonance are included with corresponding coupled-channels calculations.

Several rotational bands have been populated in the Z=55 nucleus ${}_{}{}^{125}{}_{}{}^{}\mathrm{Cs}$ using the fusion evaporation reaction ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$${(}^{19}$F,4n), at a beam energy of 74 MeV. The resultant γ rays were detected using standard γ-ray spectroscopic techniques with an array of six Compton-suppressed Ge detectors and a fourteen-element bismuth-germanate ball. The low-lying yrast structure is found to be dominated by the unique parity π${\mathit{h}}_{11/2}$ orbital, manifest as a decoupled band with a large signature splitting. A crossing occurs in this band at ħ${\mathrm{\omega }}_{\mathit{c}}$=0.42 MeV, which is interpreted as [ν${\mathit{h}}_{11/2}$${]}^2$ pair alignment. In addition, a strongly coupled negative-parity structure with large B(M1)/B(E2) ratios is observed feeding both signatures of the π${\mathit{h}}_{11/2}$ band. Bands built on the normal-parity π${\mathit{g}}_{7/2}$ and π${\mathit{g}}_{9/2}^{\mathrm{-}1}$ orbitals have also been confirmed and extended. These structures are compared to cranked-shell-model calculations and the systematics of the region.

Differential cross sections for inelastic scattering from ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$ have been measured for excitation energies less than 3.3 MeV over a range of momentum transfer of 0.4 to 2.5 ${\mathrm{fm}}^{\mathrm{-}1}$. The data have been analyzed to extract transition charge densities. These densities are interpreted in terms of a quasiparticle-phonon approach and finite Fermi system theory to disentangle the collective and noncollective modes of excitation.

Inelastic ${\mathrm{\pi }}^{\pm }$ cross-section measurements at pion incident energies of 150 and 180 MeV were made on $6^{\mathrm{-}}$ states in ${}_{}{}^{24,26}{}_{}{}^{}\mathrm{Mg}$. In particular, we have determined the (${\mathit{f}}_{7/2}$${\mathit{d}}_{5/2}^{\mathrm{-}1}$${)}_6^{\mathrm{-}}$ isoscalar ${\mathit{Z}}_0$=0.21±0.02 strength for the strongest T=0, ${\mathit{J}}^{\mathrm{\pi }}$=$6^{\mathrm{-}}$ state located at 12.11±0.05 MeV in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, and the isoscalar ${\mathit{Z}}_0$=0.17±0.04 and isovector ${\mathit{Z}}_1$=0.21±0.02 strength for the strongest T=1, ${\mathit{J}}^{\mathrm{\pi }}$=$6^{\mathrm{-}}$ state located at 9.18 MeV in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$. The distorted-wave impulse-approximation pion cross-section calculations required a multiplicative normalization factor of 1.2±0.1 in order to reproduce the pure isovector strength deduced from electron scattering for the well-known T=1, ${}_{}{}^{\mathrm{\pi }}{}_{}{}^{}$=$6^{\mathrm{-}}$ state at 15.15 MeV in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ and the T=2, ${\mathit{J}}^{\mathrm{\pi }}$=$6^{\mathrm{-}}$ state at 18.05 MeV in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$.

Neutron total cross-section measurements for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been made with the white neutron source at Los Alamos Meson Physics Facility for neutron energies between 4 and 600 MeV. Very good resolution (≊0.2 ns/m) was obtained. The detailed structure at low energies is found to be different than obtained in previous measurements, although at energies 7<${\mathit{E}}_{\mathit{n}}$<15 MeV the agreement is quite good. The cross section becomes quite smooth above 15 MeV. An Ericson analysis is performed to yield values for the level density of ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ between 13 and 22 MeV.