We discuss a recently derived, model-independent relation that expresses the value of a medium-modified quark condensate in terms of the vacuum value of the condensate and the value of the nucleon sigma term, ${\mathrm{\sigma }}_{\mathit{N}}$. Our goal is to calculate the value of the quark condensate in nuclear matter, 〈NM‖q¯(0)q(0)‖NM〉, using some standard many-body techniques. Here, we comment on the mean-field calculations of Cohen, Furnstahl, and Griegel and others. We then calculate the value of the nuclear matter quark condensate using linear response theory. In a sigma-dominance model, the linear response calculation relates the modification of the vacuum condensate to the matrix element of the operator q¯q taken between a state of the sigma meson and the vacuum. (That matrix element may be used to define a sigma decay constant, ${\mathit{f}}_{\mathrm{\sigma }}$.) We also provide some additional insight into the relation between the dynamics of the quark condensate and the scalar fields of relativistic nuclear physics.

The two-neutron separation energy of ${}_{}{}^6{}_{}{}^{}\mathrm{He}$ has been reproduced for the first time in a realistic parameter-free microscopic multicluster model comprising the α+n+n and t+t clusterizations, with α cluster breathing excitations included. The contribution of the t+t channel is substantial. A very thick (0.85 fm) neutron halo has been found in full agreement with the results of the latest phenomenological analysis.

The electronuclear longitudinal response is studied in a large class of nuclei. Medium weight as well as heavy nuclei are considered. Beyond mean field effects short range correlations are taken into account by means of a local density approach. They are responsible for a decrease of the response up to 15% in the quasielastic region. The amount of quenching is proportional to the average proton density reaching its maximum for medium heavy nuclei.

We study the quantum foundations of a theory of large amplitude collective motion for a Hamiltonian expressed in terms of canonical variables. In previous work the separation into slow and fast (collective and noncollective) variables was carried out without the explicit intervention of the Born-Oppenheimer approach. The addition of the Born-Oppenheimer assumption not only provides support for the results found previously in leading approximation, but also facilitates an extension of the theory to include an approximate description of the fast variables and their interaction with the slow ones. Among other corrections, one encounters the Berry vector and scalar potential. The formalism is illustrated with the aid of some simple examples, where the potentials in question are actually evaluated and where the accuracy of the Born-Oppenheimer approximation is tested. Variational formulations of both Hamiltonian and Lagrangian type are described for the equations of motion for the slow variables.

The ground state properties of the even-even Zn, Ge, Se, Kr, and Sr nuclei are studied in the vicinity of the proton drip line, in a relativistic mean field approach. The knowledge of the properties of these nuclei is crucial in understanding the passage of the r process in astrophysics. The obtained binding energies are shown to be consistent with the measured masses wherever available or otherwise with the mass table of Möller and Nix. The shape coexistence between prolate and oblate structures obtained for ${}_{}{}^{70}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{72}{}_{}{}^{}\mathrm{Kr}$ isotopes is analyzed in detail.

A Λ-nucleus single particle potential, mainly suitable for relatively light hypernuclei, which gives analytic expressions for the Λ energies in the lower nodeless Λ orbits is used for an analysis of the experimental data. The results are discussed and compared with those obtained, in the same way, for a Woods-Saxon potential. It turns out that the analytic expressions for the ${\mathit{B}}_{\mathrm{\Lambda }}$ energies, in the region of their validity, give results which are close to the experimental values and compare favorably with the ones obtained with the (more realistic) Woods-Saxon hypernuclear potential. Our analysis also shows a state dependence of the depth of the Λ-nucleus potential which, however, is rather weak. Finally, the use of an effective Λ mass is also discussed.

The ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$(d${,}^3$He${)}^{26}$Mg reaction has been investigated at 29 MeV incident energy. Observations using a split-pole magnetic spectrograph have been made of 65 levels of ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ in the range of excitation energy between 0 and 9.7 MeV. These levels can be identified with the known states of ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$, which by other techniques have been assigned excitation energies with precisions of 3 keV or better. Information about the orbital angular momentum (with associated conclusions about J and π) and the single-nucleon spectroscopic factors of about 40 of these ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ levels have been obtained through distorted-wave Born approximation (DWBA) analyses of measured angular distributions. Eight levels which are populated through the pickup of a ${\mathit{l}}_{\mathit{p}}$=1 proton have been observed at ${\mathit{E}}_{\mathit{x}}$=6.878, 7.694, 7.824, 8.050, 8.902, 9.042, 9.239, and 9.618 MeV. The two most strongly excited of these levels (${\mathit{E}}_{\mathit{x}}$=7.824 and 9.042 MeV) were attributed in a previous study of the same reaction to the population of 1p hole states. The observed angular distributions of two ${\mathit{J}}^{\mathrm{\pi }}$=$6^{+}$ levels are reproduced with ${\mathit{l}}_{\mathit{p}}$=4 DWBA calculations which assume g components in the ground state of ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$. The excitation energies and spectroscopic factors for positive parity states are compared with the results of a recent, complete sd-shell space, shell-model calculation. New spectroscopic information is extracted from this comparison and from the comparison of the present results with previous knowledge.

The angular distribution of fission products has been measured as a function of mass asymmetry in the fissioning systems ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$(${\mathrm{\alpha }}_{39.1\mathrm{M}\mathrm{e}\mathrm{V}}$, f), ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$(${\mathrm{\alpha }}_{29.0\mathrm{M}\mathrm{e}\mathrm{V}}$, f), and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$(${\mathrm{\alpha }}_{39.1\mathrm{M}\mathrm{e}\mathrm{V}}$, f) using the recoil-catcher technique and off-line gamma spectrometry. The present data have been analyzed along with similar data reported earlier by us for ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$(${\mathrm{\alpha }}_{29\mathrm{M}\mathrm{e}\mathrm{V}}$, f) and ${}_{}{}^{233}{}_{}{}^{}\mathrm{U}$(${\mathrm{\alpha }}_{29\mathrm{M}\mathrm{e}\mathrm{V}}$, f) and the literature data on mass-averaged products in the same fissioning systems in the alpha energy region 16–40 MeV. The angular anisotropies of the average symmetric and asymmetric products in these fissioning systems have been evaluated based on the transition state model assuming two fission modes with characteristic shapes and barrier heights and considering the multichance fission effect at various alpha energies. Agreements between the calculated and experimental anisotropies indicate that the angular distributions for the symmetric and asymmetric modes are determined at and beyond the corresponding second saddle points in the deformation energy surface. The effects of the multichance fission are also seen to play a significant role depending on the properties of the nuclides concerned.

Emission of α particles accompanying fusion-fission processes in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ ${+}^{232}$Th reaction at E${(}^{40}$Ar) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight measurements allowed us to reconstruct the complete kinematics of each ternary event. The coincident energy spectra of α particles were analyzed by using predictions of the energy spectra of the statistical code cascade . The analysis clearly demonstrates emission from the composite system prior to fission, emission from fully accelerated fragments after fission, and also emission during scission. The analysis is presented for both symmetric and asymmetric fission. The results have been analyzed using a time-dependent statistical decay code and confronted with dynamical calculations based on a classical one-body dissipation model. The observed near-scission emission is consistent with evaporation from a dinuclear system just before scission and evaporation from separated fragments just after scission. The analysis suggests that the time scale of fission of the hot composite systems is long (about 7×${10}^{\mathrm{-}20}$ s) and the motion during the descent to scission almost completely damped.

Spallation systematics have been extended into the deep spallation mass region. Production cross sections of scandium radioisotopes from 0.8 GeV protons on ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{92,96,100}{}_{}{}^{}\mathrm{Mo}$, and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ targets were measured and the cross sections were used to generate isobaric yield curves at ${\mathit{A}}_{\mathit{p}}$=47. In the latter target, this corresponds to a mass loss of >80 nucleons. At ∼10 MeV/nucleon and for products outside the multifragmentation region, this is an extreme manifestation of the spallation process. The results prove to fit smooth extrapolations from trends developed in earlier work on less deep spallation. The influence of target composition is still evident even from ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$, in contrast to expectations, based on evaporation considerations, that this so-called memory effect would wash out.

A magnetic spectrograph and position-sensitive detectors were used to measure the total nuclear reaction probability ${\mathrm{\eta }}_{\mathit{R}}$ for α+CsI at 116 MeV, ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$+CsI at 265 and 385 MeV, and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$+Si at 271 and 390 MeV. From these ${\mathrm{\eta }}_{\mathit{R}}$’s, average reaction cross sections ${\mathrm{\sigma }}_{\mathit{R}}$ were deduced for α and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ on CsI; these agree with optical and strong absorption model predictions. These same models predict ${\mathrm{\sigma }}_{\mathit{R}}$’s for ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$+Si which vary by nearly a factor of 2; our measurement favors the smaller predictions.

At intermediate energies, the interaction of two nucleons with pions is often described in terms of nonrelativistic time-ordered perturbation theory. The field theory is usually further simplified by restricting the Hilbert space to states having some maximum number of pions. One outstanding difficulty with such approaches is an inconsistent treatment of the dressed two-nucleon propagator. In the NN-πNN model, for example, states can have at mos t one pion, so that only one of the nucleons is allowed to undergo dressing at any one time. Thus each nucleon cannot obtain its full dressing and this leads to problems of wave function normalization. We have found a way to dress both nucleons at the same time, where each nucleon retains its full dressing. The method, involving a convolution integral, determines the full two-nucleon dressed propagator in a practical but exact way. Numerical calculations have been performed using a model of the πN interaction in the one-pion approximation. We find a significant difference between the fully dressed two-nucleon propagator and the different-time propagator as used in NN-πNN models.

Differential cross sections for 40, 50, and 65 MeV ${\mathrm{\pi }}^{+}$ and ${\mathrm{\pi }}^{\mathrm{-}}$ inelastic scattering to $1^{\mathrm{-}}$ excitations in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been measured and compared to distorted wave impulse approximation (DWIA) reaction model predictions. Strengths are presented in terms of sum rules for the $1^{\mathrm{-}}$ state at 10.84 MeV and for the giant dipole resonance from 18 to 25 MeV. An excitation function at q=224 MeV/c for the $1^{\mathrm{-}}$ state at 10.84 MeV is displayed in the energy range from 50 to 291 MeV showing a non-spin-flip pattern. We find inadequacies in the detailed comparison of the shapes of the data to DWIA calculations using several standard nuclear models.

We have measured the analyzing power ${\mathit{A}}_{\mathit{N}\mathit{O}}$ and the spin transfer ${\mathit{K}}_{\mathit{N}\mathit{N}}$ for np-elastic scattering from about 60° to 170° c.m. at 485, 635, and 788 MeV. The new data clarify previous discrepancies and complete the first-order determination of nucleon-nucleon elastic scattering at these energies.

Projectilelike fragments were detected and characterized in terms of A, Z, and energy for the reactions ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ at E=7.3 MeV/nucleon, and ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$ on ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ at E=15 MeV/nucleon, at angles close to the grazing angle. Mass and charge distributions were generated in the N-Z plane as a function of energy loss, and parametrized in terms of their centroids, variances, and coefficients of correlation. The results are compared to the predictions of two current models based on a stochastic nucleon exchange mechanism. The drifts of the charge and mass centroids for the system ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are consistent with a process of mass and charge equilibration mediated by nucleon exchange between the two partners, followed by evaporation. The asymmetric systems show a strong drift toward larger asymmetry, with the production of neutron-rich nuclei. It is concluded that this is the result of a net transfer of protons from the light to the heavy partner, and a net flow of neutrons in the opposite direction. Model predictions fail to reproduce in detail the evolution of the centroids for asymmetric systems. The variances for all systems increase with energy loss, as would be expected from a nucleon exchange mechanism. However, the variances for the reaction ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are higher than those expected from that mechanism, and the variances for the reaction ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$ on ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ start decreasing after about 100 MeV of energy loss. The coefficients of correlation indicate that the transfer of nucleons between projectile and target is correlated, as expected from Q-value constraints to the valley of β stability.

Vector and tensor analyzing powers (${\mathit{iT}}_{11}$, ${}_{}{}^{\mathit{T}}{}_{}{}^{}$${\mathit{T}}_{20}$, ${\mathit{T}}_{20}$, and ${\mathit{T}}_{22}$) for the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${(}^6$Li→${,}^6$Li${)}^9$Be elastic scattering and inelastic scattering leading to the 5/$2^{\mathrm{-}}$ (2.43 MeV) excited state in ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ are presented for a ${}_{}{}^6{}_{}{}^{}\to$ bombarding energy of 32 MeV over the c.m. angular range 13°–87°. The results of coupled-channels calculations show that the relatively large observed values of the vector analyzing power ${\mathit{iT}}_{11}$ for the inelastic scattering can only be accounted for by an explicit spin-orbit term in the optical potential. For the elastic scattering, the vector analyzing power and the relatively small tensor analyzing powers are described reasonably well by coupled-channels calculations with no explicit spin-orbit or tensor terms in the interaction, and provide a severe constraint on the coupled-channels calculations, with a preference for an optical potential with a double-folded rather than a Woods-Saxon real part.

The energy spectra and angular distributions of protons, deuterons, tritons, and alpha particles from 215 MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ bombardment of Tb, Ta, and Au have been measured in coincidence with both evaporation residues and fission fragments. The evaporation residue and fission fragment triggers together with the angular momentum dependence of the evaporation residue-fission competition have enabled us to extract the impact parameter dependence of the light charged particle preequilibrium multiplicities within the fusionlike impact parameter domain. The light charged particle spectra can be parametrized as originating from a source with approximately 1/2 to 2/3 of the beam velocity and with a slope parameter of ∼5–7 MeV. The proton multiplicities increase with decreasing impact parameter, in agreement with a nucleon exchange transport model prediction. The ratio of the complex particle to proton multiplicities decrease with decreasing impact parameter, suggesting dynamical effects in the complex particle production mechanism.

Elastic and inelastic scattering, one-nucleon transfers [mostly ${(}^8$Li, ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$)] and the ${(}^8$Li,α) fusion-evaporation reaction have been studied on a variety of targets (A=1–58) at E${(}^8$Li)≊13–20 MeV using the University of Michigan–University of Notre Dame radioactive nuclear beam (RNB) facility. The latter, which produces an energy-resolved (∼500 keV FWHM), focused beam with intensity ≳${10}^6$ ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$/s, permitted measurements to selected nuclear levels with cross sections down to approximately 1 mb/sr. Based on the systematics of the measured ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ elastic scattering an appropriate ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ optical potential was deduced. Large inelastic scattering cross sections (and B[E2↑]) are observed for ${}_{}{}^8{}_{}{}^{}\to _{}^8{}_{}{}^{}$${\mathrm{Li}}_{0.98}^{\mathrm{*}}$. Large cross sections are also observed for the ${(}^8$Li${,}^7$Li) transfer reaction corresponding to quasielastic (viz., Q≊0) neutron transfer to selected high spin excited levels in the residual nucleus. The ${(}^8$Li,α) fusion-evaporation reaction also appears to be significant and can produce very-high-energy α particles, viz., ${\mathit{E}}_{\mathrm{\alpha }}$≫${\mathit{E}}_{\mathrm{beam}}$. Although observed using ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$, these features appear to be important for many RNB-induced reactions and they must be considered, for example, in nucleosyntheis calculations involving ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ and other short-lived radioactive nuclei.

The ground state rotational band populations for the 4n evaporation channel have been measured at three ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ bombarding energies. The populations for the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$${+}^{166}$Er reaction, which populates the same residual nucleus at above-barrier energies, have also been measured to calibrate the statistical model which has been used to relate the observed populations to the compound nuclear spin distribution. The mean compound nuclear angular momenta are somewhat less than obtained in a previous gamma ray multiplicity investigation and are in better agreement with coupled channels calculations.

We have calculated the momentum distributions of the three fragments emitted in the breakup reaction ${(}^{11}$Li${,}^9$Li+n+n), induced by the Coulomb field from a heavy target, and made comparisons to recent three-body coincidence measurements. Our three-body model for ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ provides a good description of the measured relative momentum distribution for the two emitted neutrons, and also for the single-neutron momentum distribution. The predicted distribution for the ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ recoil is much narrower than observed; a plausible explanation is presented.