Excitation functions and mean projected recoil-ion ranges of the isomeric nuclei produced in proton-, ${}_{}{}^3{}_{}{}^{}\mathrm{-}$, and α-particle-induced reactions on ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ were measured by an activation technique for bombarding energies ${\mathit{E}}_{\mathit{p}}$≲50 MeV, and E${\mathrm{}}^3$He, α≲40 MeV. Isomeric yield ratios (${\mathrm{\sigma }}_{\mathit{m}}$/${\mathrm{\sigma }}_{\mathit{g}}$) were determined as a function of the incident particle energy. The experimental excitation functions and isomeric yield ratios were compared with those from statistical model calculations based on the Hauser-Feshbach formalism. From the analysis of excitation functions, recoil-ion ranges, and isomeric yield ratios, the observed reactions were able to be grouped into three distinctly different ones in the energy region studied: (i) compoundlike reaction for (p,3n), ${(}^3$He,4n), (α,3n), and (p,pn${)}^{196}$${\mathrm{Au}}^{\mathit{m}}$, (ii) one-neutron stripping reaction for ${(}^3$He,2p), and (iii) nonequilibrium one-neutron knockout or pickup reactions with transfer of a small amount of angular momentum for the ${(}^3$He,α), (α,αn), and (p,pn${)}^{196}$${\mathrm{Au}}^{\mathit{g}}$ that are intermediate between (i) and (ii). We propose a semiempirical method which predicts isomeric yield ratios in the compoundlike reactions, within a factor of 0.7 to 1.4, from the spin distribution of the compound nucleus.

The asymptotic D-state to S-state ratio of the deuteron (η) is deduced from new measurements of tensor analyzing powers in sub-Coulomb (d,p) reactions. The complete set of analyzing power measurements is presented. Ten statistically independent values are obtained for η from measurements of two analyzing powers using multiple targets, final states, and beam energies. These values are consistent to within their statistical uncertainties. A weighted average of the individual values gives the result η=0.0256±0.0004, where the quoted uncertainty includes systematic and statistical contributions. This result is compared with previous measurements and with the predictions obtained from a variety of theories.

Fusion excitation functions were obtained for ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$${+}^{70,72,73,74,76}$Ge at energies from about 6 MeV below to 7 MeV above the Coulomb barrier. One-dimensional barrier penetration model calculations with one free parameter yield parameters in good agreement with the systematics for fusion above the barrier. Large low-energy enhancements are observed whose trend suggests the presence of a structural change between ${}_{}{}^{70,72}{}_{}{}^{}\mathrm{Ge}$ and ${}_{}{}^{73,74,76}{}_{}{}^{}\mathrm{Ge}$. Within the context of simple model calculations, this trend is explained as arising from the odd-A structure of ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$ on one hand, and from a spherical (or oblate) to prolate shape transition between ${}_{}{}^{70,72,73}{}_{}{}^{}\mathrm{Ge}$ and ${}_{}{}^{74,76}{}_{}{}^{}\mathrm{Ge}$, on the other hand.

The excitation and electromagnetic decay of the giant resonance region (8–15 MeV) in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ have been measured with the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$${(}^{17}$O${,}^{17}$O’) reaction at 84 MeV/nucleon. The study of coincidences between scattered ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ ions and photon decays to the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ ground state, including angular correlations, serves to isolate the isovector giant dipole resonance and enable us to investigate the mechanisms of its excitation and decay in detail. The angular correlations and yields are accounted for quantitatively by a pure Coulomb excitation model of the reaction process. The distribution in energy of the ground-state photon decay cross section is well described by an approximate application of the multistep theory of nuclear reactions. The photon coincidence measurements enable us to extract the differential cross sections for the 10.6-MeV giant quadrupole and 13.9-MeV monopole resonances with low uncertainty. An analysis of the Coulomb-nuclear interference for the 10.6-MeV excitation indicates that the ratio of neutron to proton matrix elements, ${\mathit{M}}_{\mathit{n}}$/${\mathit{M}}_{\mathit{p}}$, is 1.7±0.4, consistent with a predominantly isoscalar character for the giant quadrupole resonance.

It is argued that the real and imaginary parts of the effective potential operator for scattering problems obey a dispersion relation also when the Hamiltonian is not Hermitian. Model calculations are used to demonstrate that the equivalent local potential approximately satisfies the dispersion relation when absorption is present. It is also shown that the equivalent local potential is insensitive to the bare potential used in the entrance channel.

An attempt has been made to synthesize the extremely neutron-rich isotope ${}_{}{}^{26}{}_{}{}^{}\mathrm{O}$ in the nuclear reaction 44 MeV/nucleon ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$+n/rTa. Use was made of magnetic separation and identification methods including time-of-flight and ΔE,E measurements. The ${}_{}{}^{26}{}_{}{}^{}\mathrm{O}$ nucleus appears to be unstable against particle emission since no events attributable to the ${}_{}{}^{26}{}_{}{}^{}\mathrm{O}$ nucleus were observed at a level one order of magnitude lower than that predicted from the extrapolated yields. The previously unobserved isotope ${}_{}{}^{32}{}_{}{}^{}\mathrm{Ne}$ was found to be particle stable and the isotope ${}_{}{}^{31}{}_{}{}^{}\mathrm{Ne}$ particle unstable. Neutron-separation energies calculated with different models are tabulated.

Mass and charge distributions have been measured for damped projectile-like fragments in the reaction ${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$${+}^{165}$Ho at 8.5 MeV per nucleon bombarding energy. Coincidences were measured between Z- and A-identified projectile-like fragments and angle-correlated heavy reaction partners in order to derive the primary mass distribution for projectile-like fragments. Centroids and variances of the primary and post-evaporative Z, N, and A distributions are presented. The evolution of the primary N and Z distributions as a function of energy loss is found to deviate from predictions of the nucleon exchange transport model.

The excitation-energy distribution of projectilelike fragments formed in the E/A=8.5 MeV ${}_{}{}^{74}{}_{}{}^{}\mathrm{d}$/rGe${+}^{165}$Ho reaction has been obtained by applying a statistical evaporation calculation to the difference between primary fragment mass yields derived from kinematic coincidence measurements and directly measured yields. A gradual transition from approximate equipartition of excitation energy for small energy losses to a division that favors the targetlike fragment for highly damped events is observed, in agreement with previous measurements. For a given energy loss, heat partition is found to correlate with the direction of net nucleon transfer. The variances of the excitation-energy distributions are shown to increase monotonically as a function of energy loss. The average data are compared with predictions of the nucleon exchange transport model. The results suggest that energy-loss mechanisms in addition to nucleon exchange may be important in the early stages of the collision.

We have measured the target fragment production cross sections and angular distributions for the interaction of 16 MeV/nucleon ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$, 32 MeV/nucleon ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, and 44 MeV/nucleon ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ with ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$. We have deduced the fragment isobaric yield distributions and moving frame angular distributions from these data. The fission cross sections decrease with increasing projectile energy and the heavy residue cross sections (which are much larger than previous counter measurements) increase. There is an unusual change in the fragment isobaric yield distributions in the reactions induced by 32 MeV/nucleon ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ and 44 MeV/nucleon ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$. We have used the symmetry properties of the moving frame distributions to show the relative time scale of the reaction mechanisms involved. The fission fragments associated with the peripheral collision peak in the folding angle distribution originate in a normal, slow fission process in which statistical equilibrium has been established. At the two lowest projectile energies, the fission fragments associated with the central collision peak in the folding angle distribution originate in part in fast, nonequilibrium processes. At the highest projectile energies, there are no fission fragments associated with high-momentum-transfer events. The intermediate mass fragments originate primarily in events in which statistical equilibrium has not been established.

Measurements of the fusion cross section of ${}_{}{}^{28,30}{}_{}{}^{}\mathrm{s}$/rSi${+}^{24,26}$Mg have been made for energies ranging from well below to above the Coulomb barrier. The fusion cross sections increased from about 40 μb at the lowest energy, to 400 mb or more at the highest energy measured. Surprisingly, a crossover in the excitation functions for ${}_{}{}^{28,30}{}_{}{}^{}\mathrm{f}$/rSi${+}^{24}$Mg is observed at the lowest sub-barrier energies. The data could not be reproduced by either a one-dimensional tunneling calculation or an approximate coupled-channels calculation within the constant coupling scheme. However, the use of an exact coupled-channels code, together with incoming-wave boundary conditions, led to good agreement between the calculated and measured fusion cross sections.

The total absorption from the elastic channel due to transfer and inelastic processes in peripheral heavy-ion collisions at low bombarding energies is calculated in a microscopic coupled-channel approach. It is demonstrated for the first time that considering the depopulation of the entrance channel as an incoherent depopulation due to transfer processes is a good approximation. Using the corresponding absorptive potential within the framework of the Born approximation to calculate the transfer to individual channels, the results of full coupled-channels calculations are accurately reproduced.

Electromagnetic dissociation of 200 GeV/nucleon ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ projectiles has been investigated in nuclear emulsion. It constitutes about 15% of the total number of events observed. The production cross section for the electromagnetic process has been found to increase with the projectile charge when compared with that of the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ beam at the same energy per nucleon.

Intermediate mass fragments of 4≤Z≤17 have been studied from the reaction 640 MeV ${}_{}{}^{86}{}_{}{}^{}\mathrm{o}$/rKr${+}^{63}$Cu. Inclusive energy and angular distribution measurements have been made as well as coincidence measurements with fissionlike fragments of 18≤Z≤40. The coincidence configuration was such that two-body exit channels were excluded; nevertheless, heavy fragments were recorded both in plane and out of plane with respect to light fragments of 4≤Z≤10. Three mechanisms have been identified for intermediate mass fragment production. The dominant pathway for all intermediate mass fragments is two-body breakup of fission or evaporationlike character. A second pathway for Z≤10 is intermediate mass fragment ejection from the composite nucleus followed by sequential fission. The third path is simultaneous ternary breakup for 4≤Z≤9 that resembles ternary alpha-accompanied fission at low energies.

The effects of breakup to singlet spin states on elastic scattering observables for the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$(d→,d${)}^{58}$Ni reaction at 400 MeV is studied. The singlet breakup contribution to the elastic amplitude is estimated through an approximate two-step calculation, in which we exploit an adiabatic approximation and closure over the intermediate continuum states. The inclusion of the singlet channel coupling has a large effect on the reaction tensor analyzing power ${\mathit{A}}_{\mathit{y}\mathit{y}}$ originating from a dynamically induced ${\mathit{T}}_{\mathit{L}}$ tensor interaction.

The Riemann rotational model is an extension of the Bohr-Mottelson collective model which allows for linear nuclear currents, indexed by the rigidity r, between the limits of rigid rotation r=1 and irrotational flow r=0. The Riemann moment of inertia and transverse form factors are shown to be weighted linear combinations of the corresponding rigid and irrotational values. The resulting simple analytic formulas for the transverse factors are useful for the analysis and interpretation of data from state of the art electron scattering experiments.

The original W-matrix approach, introduced recently by the Bonn group, represents the T matrix by a rank-one separable term. The method is exactly half on shell, but a nonzero remainder R occurs fully off shell. For potentials for which the scattering phase shift has a zero, the remainder can be non-negligible, even for energies far from the zero. We present expressions for W and R in terms of the scattering K matrix for the case that the potential is separable of finite rank. We show that the rank of R is one less than the rank of the potential. Then, for a rank-two analytical S-wave example of the potential, which is designed to produce a zero in the phase shift, we examine numerically the fully off-shell properties of the W method. We find pathologies at both negative and positive energies, in that the remainder R gives a significant off-shell contribution even far from the singularity.

In order to analyze multiparticle reactions in which a small number of particles are created, it is necessary to ensure that model multiparticle amplitudes are properly unitarized. Multiparticle partial-wave amplitudes can be thought of as elements in a multiparticle Hilbert space; it is shown how to modify the lengths of model partial-wave amplitudes so that they will satisfy inelastic unitarity conditions.

A relativistic Lippmann-Schwinger equation for production reactions is developed. To obtain such equations a relativistic generalization of the Schrödinger and Lippmann-Schwinger equations is given, which, when applied to a Fock space appropriate for particles of mass m and zero spin, describes production reactions. Separable potentials are used for the production channels, which then incorporate the correct inelasticity in the elastic channel. Exact solutions to the relativistic Lippmann-Schwinger equations are given for potentials that are separable on all subspaces of the full Fock space.

The fourth $2^{+}$ state in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ at an excitation energy of 8.21 MeV has been studied by high-resolution electron scattering. The Coulomb form factor for this state was measured in the momentum-transfer range 0.9≤q≤2.1 ${\mathrm{fm}}^{\mathrm{-}1}$ and the extracted B(C2)↑ value was determined to be 7.3±4.2 $e^2$${\mathrm{fm}}^4$. The level at 8.21 MeV is identified as a four-particle, two-hole (4p2h) state of the type $p^{\mathrm{-}2}$(sd${)}^4$. Form-factor measurements in the range 1.0≤q≤1.9 ${\mathrm{fm}}^{\mathrm{-}1}$ are also presented for a strongly excited normal-parity state at 9.36 MeV. Preliminary measurements of the differential cross section for exciting this state by 135-MeV protons suggest a $2^{+}$ assignment; the measured Coulomb form factor of this state allows it to be identified as the best experimental candidate for a predicted K=2 4p2h state with the four sd-shell nucleons coupled to T=0. The excitation of these states and other members of rotational bands in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ are discussed within the framework of structure models. Shell-model calculations for the C4 form factors of the first three $4^{+}$ states in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ are compared to existing data.

The partial radiation widths of three (two electric dipole and one electric quadrupole) primary γ transitions in ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, subsequent to neutron capture by the 153-keV, $2^{+}$ resonance in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, have been remeasured. Both electric dipole transitions, accounting for more than 80% of the total radiation width, can be explained as valence neutron transitions. The deduced total radiation width of ${0.215}_{\mathrm{-}0.035}^{+0.084\mathrm{}}$ eV for this resonance disagrees with the previous value of 2.4±0.9 eV and significantly affects the production of A≥14 nuclei in primordial nucleosynthesis.