The deuteron electromagnetic form factors are calculated in the framework of the Bethe-Salpeter equation with multirank separable interactions. The only approximation made is the restriction to positive-energy states. A comparison is presented with the predictions of nonrelativistic, minimally relativistic, and other approximative calculations. The most important relativistic effect turns out to be the boost on the single-particle propagator due to recoil, in accordance with an earlier investigation.

The experimental measurements made in this investigation include secondary $\gamma$ rays and conversion electrons from thermal neutron capture in ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$, primary $\gamma$ rays from average resonance capture with a 2-keV neutron beam and from resonance capture with thermal neutrons, and $\alpha$ particles and $\gamma$ rays, singles and coincidences, from ${}_{}{}^{242}{}_{}{}^{}\mathrm{Am}_{}^m{}_{}{}^{}$ $\alpha$ decay. From these data and those of previous investigations, 69 excited levels in ${}_{}{}^{238}{}_{}{}^{}\mathrm{Np}$ with energies <700 keV were identified and, of these, 46 were placed in 13 rotational bands with assigned Nilsson configurations. The results are found to be in good agreement with a semiempirical model calculation. A special feature is the observation of four different $K=0\mathrm{}$ rotational bands in the low-energy structure of ${}_{}{}^{238}{}_{}{}^{}\mathrm{Np}$. Experimentally determined Gallagher-Moszkowski and Newby matrix elements show reasonable agreement with calculated values.

The energy dependence of the production cross sections in long-lived (l) and short-lived (s) isomeric states in ${}_{}{}^{236}{}_{}{}^{}\mathrm{Np}$ together with the isomeric ratio of the reaction ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$(p,3n${)}^{236}$Np near the reaction threshold was measured. The yield of ${}_{}{}^{236}{}_{}{}^{}\mathrm{Np}_{}^{\mathrm{s}}{}_{}{}^{}$ was determined from the alpha activity of ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pu}$ and the yield of ${}_{}{}^{236}{}_{}{}^{}\mathrm{Np}_{}^{\mathrm{l}}{}_{}{}^{}$ from analysis by thermal neutron fission. From the energy dependence of the isomeric ratio it follows that the long-lived state is the ground state in ${}_{}{}^{236}{}_{}{}^{}\mathrm{Np}$. Theoretical calculations of the yields support these results.

It is suggested that ${}_{}{}^{126}{}_{}{}^{}$,128Ba achieve static octupole deformation at angular momenta of 11ħ, and that ${}_{}{}^{78}{}_{}{}^{}\mathrm{Kr}$ is evolving toward octupole deformation at the highest angular momenta observed. These nuclei require higher angular frequencies to stabilize octupole deformation than those nuclei previously found to be octupole deformed in the A=145 and 222 mass regions because of their relative stiffness to octupole vibrations in their ground states.

This is the first in a series of papers describing the results of a systematic study of total, elemental, and isotopic cross sections measured in hydrogen, helium, and carbon targets. These fragmentation studies are based on measurements using 42 beams of 12 separate nuclei from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ to ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$. This has resulted in the measurement of more than 100 secondary elemental cross sections and over 300 secondary isotopic cross sections in addition to the total charge changing and mass changing cross sections reported in this paper. These measurements have been made at energies from 300 to 1700 MeV/nucleon and include ten separate energies for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, for example. The measurements have been made with the objective of interpreting the production of secondary nuclei during cosmic-ray propagation in the galaxy in order to better estimate the source elemental and isotopic composition of cosmic rays. At the same time they provide a valuable data base for nuclear physics and the understanding of peripheral interactions of energetic heavy nuclei. In the work reported in this paper ∼100 total charge changing and mass changing cross sections have been measured for various targets and energies. The mass changing cross sections we measure are found to agree with earlier cross section measurements using energetic protons incident on targets composed of heavier elements to within ∼2% in cases where a comparison can be made. The systematics of this new data set are described and a new, more accurate cross section formula is presented and discussed.

In this paper we describe individual elemental cross sections. Over 100 of these cross sections have been measured by studying the fragmentation of beams of 12 charges ranging from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ to ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ in hydrogen, helium, and carbon targets. The energies of the beams ranged from ∼300 to 1700 MeV/nucleon. The relative cross sections in hydrogen, helium, and carbon targets are examined as a function of both beam charge and energy. Limits are placed on the energy region in which the concept of factorization or scaling of cross sections for different beam charges and targets applies. The approach of these elemental cross sections to the asymptotic high-energy values is examined as a function of the beam charge and the charge change. The systematics of the energy dependence of these cross sections is also described in terms of the beam charge and the charge change. Another important systematic in our data is a regular decrease in the elemental cross sections into a particular charge, $Z_f$, with increasing charge change at a constant energy. It is found that this regular behavior of the cross sections follows a simple exponential law in the charge change, $Z_B$-$Z_f$. This has important implications for constructing an empirical formula to describe these cross sections, as well as having theoretical implications.

In this paper, the third in a series of papers, we discuss isotopic fragmentation cross sections measured in hydrogen, helium, and carbon targets. Over 300 of these cross sections have been measured in 24 separate runs using 12 charges from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ to ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$. Most of these isotope cross sections were measured at an energy ∼600 MeV/nucleon, however, some measurements of the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ fragmentation are available at an energy ≳1 GeV/nucleon. We observe, comparing both these data and other data, that to first order, the mass fractions for each isotope are essentially independent of energy. This indicates that the energy dependence of the isotopic cross sections is essentially the same as for the charge changing cross sections. It is also observed that the isotopic mass fractions and the width of the mass distributions for each charge are essentially independent of the H, He, and C targets involved. These systematics greatly simplify the construction of a semiempirical formula to describe these cross sections. New isotopic cross sections are presented for a number of interesting reactions, ${}_{}{}^{12}{}_{}{}^{}$C→Be, ${}_{}{}^{16}{}_{}{}^{}$O→N, ${}_{}{}^{27}{}_{}{}^{}$Al→Na, and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ into Mn and Ar among others. A large body of new data on proton and neutron stripping reactions are also presented and discussed.

In this paper we describe a new formula for calculating the partial cross sections for the production of secondary fragments with energy ≳200 MeV/nucleon in hydrogen targets. This formula and the systematics of these cross sections are based on fragmentation studies using 42 beams of 12 separate nuclei between Z=6 and 28. This has resulted in the measurement of more than 100 secondary elemental cross sections and over 300 secondary isotopic cross sections. The systematics of these cross sections allow us to write the cross section formula as a product of three essentially independent terms, one which describes the elemental cross sections, another the isotopic cross sections, and a third term describing the energy dependence. Overall, this formula, which is considerably simpler than earlier semiempirical formulations, is able to predict the cross sections in hydrogen for Z=4–28, A=7–60 nuclei above ∼200 MeV/nucleon to an accuracy ∼10% or better—a substantial improvement over earlier formulations.

In an expanding fireball model, we study dilepton production from high-energy heavy-ion collisions at the stopping regime. We find that the pion-pion annihilation gives the dominant contribution to the dilepton yield at invariant masses between 2$m_{\pi }$ and 1 GeV. The total dilepton yield in this invariant mass region increases with the incident energy of the collision, but a saturation is seen once a baryon-rich quark-gluon plasma is formed in the initial stage.

We construct microscopic form factors for the simultaneous transfer of pairs of nucleons carrying angular momentum L=0 and 2 using the deformed cylindrical harmonic oscillator basis. We perform a detailed comparison with macroscopic form factors and we specialize the discussion to the vicinity of values of the angular velocity, particle number, and energy for which degeneracies occur. At these so-called ‘‘diabolic points’’ a nuclear manifestation of Berry’s phases takes place.

Angular distributions and inclusive energy spectra of isotopes with charges of 3–7 have been measured in the ${}_{}{}^{27}{}_{}{}^{}\mathrm{O}$,X) reaction at 72, 84, 96, 110, and 125 MeV bombarding energies. The energy spectra of these isotopes exhibit broad peaks which appear at energies near the beam velocity. Two-body breakup calculations reproduce the energy spectra well at the lower energies, while the three-body calculations give better results at higher energies. The analysis of these spectra indicates that the number of ejectiles due to the breakup process is dependent upon the bombarding energy. The total breakup cross section was found to rise from 155 to 554 mb over the 72–125 MeV energy range. Furthermore, the percent yields of carbon, lithium, and beryllium varied over this energy range.

High spin states in ${}_{}{}^{79}{}_{}{}^{}\mathrm{Sr}$ were populated via the reaction ${}_{}{}^{58}{}_{}{}^{}\mathrm{Mg}$,2pn) at 80 and 85 MeV beam energy. Twelve lifetimes in the range from 0.5 to 150 ps and four lifetime limits were measured with Doppler-shift methods. By comparing lifetimes in ${}_{}{}^{79}{}_{}{}^{}$,80,82Sr obtained with the recoil distance and Doppler-shift attenuation methods, the appropriate electronic stopping power of Sr ions recoiling in Ta was determined. In addition, lifetimes of yrast states in ${}_{}{}^{80}{}_{}{}^{}\mathrm{Sr}$ and ${}_{}{}^{79}{}_{}{}^{}\mathrm{Rb}$ were determined in the concurrent reactions ${}_{}{}^{58}{}_{}{}^{}\mathrm{Mg}$,2p) and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Mg}$,3p). The ΔI=2 E2 transition strengths and the E2/M1 mixing ratios of the ΔI=1 transitions in ${}_{}{}^{79}{}_{}{}^{}\mathrm{Sr}$ confirm the picture of extremely prolate deformed rotational bands (${\beta }_2$≊0.42), based on the [301]${(3/2\mathrm{}}^{\mathrm{-}}$ and [422]${(5/2\mathrm{}}^{+}$ Nilsson orbits. A reduction in B(E2) values is observed at the onset of (3qp) alignment. The band structure of ${}_{}{}^{79}{}_{}{}^{}\mathrm{Sr}$ is discussed in terms of the cranked shell and the Woods-Saxon cranking model with pairing.

Delayed fission following the electron-capture decay of ${}_{}{}^{234}{}_{}{}^{}\mathrm{Am}$ was studied. The ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$(α,7n${)}^{234}$Am reaction with multiple ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$ targets was used to produce ${}_{}{}^{234}{}_{}{}^{}\mathrm{Am}$. The fission properties and half-life of ${}_{}{}^{234}{}_{}{}^{}\mathrm{Am}$ were measured using a rotating-wheel system. The half-life of ${}_{}{}^{234}{}_{}{}^{}\mathrm{Am}$ was determined to be 2.32±0.08 min from measurements of the fission activity. A highly asymmetric mass-yield distribution was observed for the fission activity, and the average total kinetic energy of the fission fragments was found to be 173±5 MeV. Radiochemical separations confirmed the elemental assignment of the fissioning species to americium or fission from short-lived excited states in its EC daughter, plutonium. The cross section for ${}_{}{}^{234}{}_{}{}^{}\mathrm{Am}$ produced by this reaction and decaying by electron capture was determined to be 5.4±1.3 μb by measuring the intensities of the daughter plutonium K x rays in radiochemically separated americium samples. The branching ratio of the 6.46-MeV α peak of ${}_{}{}^{234}{}_{}{}^{}\mathrm{Am}$ was found to be (3.9±1.2)×${10}^{\mathrm{-}4}$ in on-line measurements. The delayed-fission probability was determined to be (6.6±1.8)×${10}^{\mathrm{-}5}$ from the measured ratio of fissions to plutonium K x rays. The observed fissions were unambiguously assigned to an EC-delayed fission process by measuring fissions coincident with the K-capture x rays.

We have measured the mass and kinetic-energy distributions of fragments from the spontaneous fission of ${}_{}{}^{256}{}_{}{}^{}\mathrm{No}$ produced via the ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$${(}^{12}$C,4n) reaction. The production cross section using 71-MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ projectiles was found to be 250 nb. The total kinetic energy for spontaneous fission of ${}_{}{}^{256}{}_{}{}^{}\mathrm{No}$ is 196±3 MeV. The mass distribution is very broad (full width at half maximum of ∼50 mass units) with no appreciable decrease in yield for symmetric mass division. ${}_{}{}^{256}{}_{}{}^{}\mathrm{No}$ seems to be the transition nucleus between the asymmetric mass division observed for spontaneous fission of the lighter No isotopes and the symmetric mass division observed for the heavier No isotopes. Its properties are similar to those of ${}_{}{}^{257}{}_{}{}^{}\mathrm{Fm}$, the isotope at which this transition occurs in the Fm isotopes, but the ${}_{}{}^{256}{}_{}{}^{}\mathrm{No}$ mass distribution is broader than that for ${}_{}{}^{257}{}_{}{}^{}\mathrm{Fm}$, and its average total kinetic energy for symmetric mass division is about 15 MeV lower. We determined the half-life of ${}_{}{}^{256}{}_{}{}^{}\mathrm{No}$ to be 2.91±0.05 s by measuring its α decay. We measured a spontaneous fission to α ratio of 0.${0053}_{\mathrm{-}0.0003}^{+0.0006\mathrm{}}$, which gives a partial half-life for spontaneous fission of ${550}_{\mathrm{-}70}^{+40\mathrm{}}$ s. An energy of 8.448±0.006 MeV was measured for the α-particle decay to the ground state of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Fm}$, allowing us to calculate the mass excess for ${}_{}{}^{256}{}_{}{}^{}\mathrm{No}$ as 87820±8 keV. The energy of the $2^{+}$ rotational level in the ${}_{}{}^{252}{}_{}{}^{}\mathrm{Fm}$ daughter is 47±5 keV, and the intensity of the 8.402-MeV α group populating this level is (13±2)%.

We have made the first measurement of the number of neutrons emitted from the spontaneous fission of a nuclide in which very high fragment energies dominate the fission process. In bombardments of ${}_{}{}^{254}{}_{}{}^{}\mathrm{Es}$, we produced a large sample of 28-d ${}_{}{}^{260}{}_{}{}^{}\mathrm{Md}$, which was neutron counted in a 1-m-diameter spherical tank containing a Gd-doped scintillator solution. The average number of neutrons emitted per fission is only 2.58±0.11, substantially less than for other actinides. A linear dependence of neutron multiplicity on fragment-excitation energy is observed to the highest values of total kinetic energy.

The elastic electromagnetic form factors of the deuteron are calculated in a relativized quark cluster model, with approximate constant quark density. Gluon, pion, and sigma quark interactions give strong interactions and meson exchange currents with no hadronic form factor parameters. The relative importance of meson exchange currents and quark interchange is studied.

The pion angular distribution for ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(γ,${\mathrm{\pi }}^{+}$${)}^{14}$${\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ has been measured at photon energies of 230 and 260 MeV. These data are consistent with the trend of our earlier data at 200 and 320 MeV. Additional forward angle data were obtained at 320 MeV. The results are compared to several calculations based on the distorted-wave impulse approximation and on the delta-hole model. The data are best fit by the calculations of Tiator et al. which use the delta-hole model in the resonance channel. These calculations fit the 230 MeV data well and underestimate the 260 and 320 MeV data by about 25%.

A nucleon plus pion model for deep inelastic lepton-nucleus scattering is studied in a field theoretic framework. Pionic effects are emphasized and different pion excess models are derived in our formalism, depending on whether the pion fields are quantized on the light cone or at equal time.

Low energy antiproton-proton elastic, charge exchange, charged pion, and charged kaon production reactions are studied in a coupled-channels model. The need for a coupled-channels approach to antiproton-proton reactions is first demonstrated. Meson exchange potentials describe the long-range N¯N interaction; smooth phenomenological forms are used for the N¯N interaction at short distances. Effective channels are introduced to simulate strong absorptive effects, such as multimeson production processes. Transition potentials for kaon and pion production are derived in coordinate space and shown to include an important spin-times-derivative coupling form. These transition potentials, along with a one-boson-exchange model with effective absorptive channels, are used to determine the role of multistep processes of the type π¯π⇆p¯p⇆n¯n⇆K¯K. Control over such coupled-channels effects is sought as a step toward unfolding short-distance quark effects in a reliable way. The p¯p elastic and charge exchange differential cross sections at three p¯p laboratory momenta (780, 690, and 590 MeV/c) are examined first, since ${\pi }^{\mathrm{-}}$${\pi }^{+}$ and $K^{\mathrm{-}}$$K^{+}$ data also exist at these energies. Results are then presented that manifest strong coupling effects, especially between the pion and kaon production channels. Based on that result, a full coupled-channels fit to the p¯p, n¯n, $K^{\mathrm{-}}$$K^{+}$, and ${\pi }^{\mathrm{-}}$${\pi }^{+}$ data is presented and analyzed.

The cascade-evaporation model of proton-induced spallation reactions is used to study the relationship between the recoil momentum of the target residue in the cascade stage and the mass loss in the evaporation stage. The intranuclear cascade is treated by using a simplified version of Glauber’s multiple scattering theory. The evaporation stage is treated as a Poisson random process. An analytical expression is obtained for the longitudinal momentum transfer to the target residue in the first stage of the reaction that involves no free parameters. This expression is found to be in reasonable agreement with the experimental data for the interaction of protons with gold at incident energies ranging from 1 to 300 GeV.