The level structure of the ${}_{}{}^{137}{}_{}{}^{}\mathrm{Pr}$ nucleus has been investigated via in-beam γ-ray spectroscopy using an 81-MeV ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$${(}^{19}$F, 4n) reaction. A strongly populated positive-parity band was observed based on a proton orbital with (π,α)=(+,+(1/2); its first backbend, due to the alignment of a pair of $h_{11/2}$ protons, was seen at a rotational frequency ħω=0.34 MeV. Such a high crossing frequency is taken as evidence for a triaxial shape (γ∼30°) for the ground-state band of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Pr}$. Above the crossing, both signatures (π,α)=(+,±(1/2) were observed up to $I^{\pi }$${=(37/2\mathrm{}}^{+}$ and ${(43/2\mathrm{}}^{+}$ (for α=+1/2 and α=-1/2), respectively. A negative-parity band, based on an $h_{11/2}$ proton orbital, was also observed showing a blocked $h_{11/2}$ proton crossing frequency of ħω=0.44 MeV. In addition, a ΔI=1 band with strong M1 transitions and a small signature splitting was observed, which is believed to be based on the π$h_{11/2}$⊗(ν$h_{11/2}$${)}^2$ configuration. The alignment of the $h_{11/2}$ neutron pair drives the nuclear core towards γ=-60°, namely, the collective oblate shape, while the alignment of the $h_{11/2}$ proton pair drives the nuclear core towards γ=0°, the collective prolate shape. These results are consistent with cranked shell model calculations.

The high angular momentum structure of ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pm}$ has been studied via the ${}_{}{}^{126}{}_{}{}^{}\mathrm{Te}$${(}^{19}$F,4nγ) reaction at beam energies from 74 to 84 MeV. In-beam γ-ray spectroscopy techniques, including γ-ray excitation function, γ-γ coincidence, and γ-ray angular distribution measurements were used. A level spectrum up to an excitation energy of 4782 keV was constructed. Definite parity assignments were made up to the ${(21/2\mathrm{}}^{\mathrm{-}}$ state. The low-lying structure is discussed in terms of a weak coupling between the valence proton and the N=80 cores. The earlier treatment of ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pm}$ in terms of a particle-plus-triaxial rotor is critiqued.

The theory of dissipative, relativistic fluids due to Israel and Stewart is used to constrain the form of the nuclear equation of state. In the Israel-Stewart theory, there are conditions on the equation of state and other thermodynamic properties (the ‘‘second-order’’ coefficients) of a fluid which, if satisfied, guarantee that equilibria are stable and that fluid perturbations propagate causally and obey hyperbolic equations. The second-order coefficients in the Israel-Stewart theory, which are relaxation times for the dissipative degrees of freedom and coupling constants between different forms of dissipation, are derived for a free, degenerate Fermi gas. It is shown rigorously that the free, degenerate Fermi gas is stable (and hence causal) at all temperatures in this theory. These values for the second-order coefficients are then used in the stability conditions to constrain various proposed expressions for the nuclear ground-state energy. The stability conditions are found to provide significantly more stringent constraints on the proposed equations of state than the usual simple restriction that the adiabatic sound speed be less than the speed of light.

Neutron inclusive (singles) spectra were measured by the time-of-flight method at laboratory angles from 15° to 160°. When parametrized in the thermal model, a targetlike source was sufficient to fit the data at the largest angle, but in addition a half-beam-velocity source was required at the other angles, and at the smallest angles a projectilelike source was also needed. The model parameters are in general agreement with values obtained previously in fitting proton inclusive data. Comparison is also made with neutron coincidence data. Less phenomenological models—Fermi jet, Boltzmann-Uehling-Uhlenbeck, and Boltzmann master equation—are also able to account for the main features of the data.

Results on long-range correlations of the shower particles in the pseudorapidity space are presented for the first time for 124, 191, and 153 nearly central events produced, respectively, by sulphur and oxygen beams at 200 GeV/nucleon and an oxygen beam at 60 GeV/nucleon, in nuclear emulsion.

Based on the optical model, simultaneous ${\chi }^2$ analyses are performed on elastic scattering and fusion cross sections measured for the ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$+${}_{}{}^{58,64}{}_{}{}^{}\mathrm{Ni}$ systems at several energies around the Coulomb barrier. We take the imaginary part of the optical potential used to consist of a surface-type direct and a volume-type fusion terms, $W_D$ and $W_F$, respectively, the latter of which accounts for fusion. It is shown that such analyses can determine $W_F$ and $W_D$ fairly unambiguously, and that the potentials thus determined explain all of the characteristic features observed in the elastic scattering, fusion, and direct reaction cross sections. It is also shown that the potential satisfies the dispersion relation at the strong absorption radius.

Energy spectra of neutrons emitted in the damped reaction ${}_{}{}^{139}{}_{}{}^{}\mathrm{Ar}$ at $E_{\mathrm{lab}=400\mathrm{}}$ MeV were measured at eight angles in coincidence with projectile-like reaction fragments, using a time-of-flight technique. Apart from a small high-energy component, the angular and energy distributions of neutrons were found to be well described by assuming two sources moving at the velocities of the light and heavy reaction fragments emitting isotropically in their rest frames. The logarithmic slopes of the neutron energy spectra and the corresponding multiplicities of neutrons from the two sources suggest that the projectile-like fragment receives more than its equilibrium share of excitation energy for all values of total kinetic energy loss. Detailed statistical calculations indicate that the amount of excitation energy generated in each fragment is well described by the one-body nucleon exchange model. The high-energy component in the neutron energy spectra has properties that are consistent with preequilibrium neutron emission. Averaged over all energy losses greater than 20 MeV, this ‘‘preequilibrium’’ neutron multiplicity is approximately equal to 0.1. However, the intensity of this component increases as the impact parameter decreases.

The excitation functions have been measured in the energy range $E_{\alpha }$=26–37 MeV for the reaction ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$${(}^4$He${,}^{12}$C${)}^{16}$O at ${\theta }_{\mathrm{lab}=30\mathrm{}}$°, 40°, and 50° and for ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$${(}^4$He${,}^4$He’${)}^{24}$Mg at ${\theta }_{\mathrm{lab}=152\mathrm{}}$°–160°. Prominent structures are observed in the excitation functions. The cross sections are compared with the Hauser-Feshbach statistical-model calculations. Probability distributions of the deviations from the average are calculated for all the excitation functions and compared with the statistical-model expectations for the fluctuations. The coherence width is estimated to be 176–214 keV from the observed number of maxima in the excitation functions and it is in agreement with the expected value for the excitation region of 32–42 MeV in the compound nucleus. Cross-channel correlations have been calculated between the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ channel and alpha elastic and inelastic scattering channels. At $E_{\alpha }$=27.8 and 28.6 MeV where large cross-channel correlations have been observed, angular distributions of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been measured and found to follow the pattern [$P_{11}$(cosθ${\left)\right]}^2$. These results show that the excitation functions are all generally in agreement with the fluctuations expected from the statistical model. However, at $E_{\alpha }$=27.8 and 28.6 MeV where large cross-channel correlations are observed, though there is a small chance of less than 6×${10}^{\mathrm{-}4}$ for these to be due to statistical fluctuations, the possibility that these structures at these two energies are nonstatistical in origin cannot also be ruled out.

The 7.6-h isotope ${}_{}{}^{256}{}_{}{}^{}\mathrm{Es}_{}^{\mathrm{m}}{}_{}{}^{}$ was produced from a 2.5-μg/${\mathrm{cm}}^2$ target of ${}_{}{}^{254}{}_{}{}^{}\mathrm{Es}$ by the (t,p) reaction. The reaction products were separated radiochemically, and the decay properties of ${}_{}{}^{256}{}_{}{}^{}\mathrm{Es}_{}^{\mathrm{m}}{}_{}{}^{}$ were determined via β-γ, γ-γ, and β-fission correlation techniques. From these measurements we were able to assign 57 γ rays to 26 levels in the daughter ${}_{}{}^{256}{}_{}{}^{}\mathrm{Fm}$. An isomeric level was observed at 1425 keV and assigned a spin and parity of $7^{\mathrm{-}}$. This level has a $t_{1/2}$ of (70±5) ns and we observed two β-delayed fissions with delay times in the proper time range to be associated with fission from this level. This gives a β-delayed fission probability of 2×${10}^{\mathrm{-}5}$ for this level and a partial fission half-life of ${0.8}_{\mathrm{-}0.7}^{+8.8\mathrm{}}$ ms at the 95% confidence level.

The Gamow-Teller beta-strength distributions for 19 neutron-rich nuclei, including ten of interest for the production of the actinide cosmochronometers, are computed microscopically with a code that treats nuclear deformation explicitly. The strength distributions are then used to calculate the beta-delayed fission, neutron emission, and gamma deexcitation probabilities for these nuclei. Fission is treated both in the complete damping and WKB approximations for penetrabilities through the nuclear potential-energy surface. The resulting fission probabilities differ by factors of 2 to 3 or more from the results of previous calculations using microscopically computed beta-strength distributions around the region of greatest interest for production of the cosmochronometers. The indications are that a consistent treatment of nuclear deformation, fission barriers, and beta-strength functions is important in the calculation of delayed fission probabilities and the production of the actinide cosmochronometers. Since we show that the results are very sensitive to relatively small changes in model assumptions, large chronometric ages for the Galaxy based upon high beta-delayed fission probabilities derived from an inconsistent set of nuclear data calculations must be considered quite uncertain.

Recent experimental data on elastic and inelastic scattering of ≊180 MeV antiprotons from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ have been analyzed. The calculations have been performed by using the formulations based on a phenomenological model given by one of the authors in an earlier paper. It is found that the calculated differential cross sections for elastic and inelastic scattering and those measured experimentally in most cases are in very good agreement. Furthermore, the effective values of the equilibrium radius and surface thickness derived from the present analysis for each of the nuclei investigated as well as the estimated values of the $C_{\lambda }$ associated with the nuclear restoring force are very satisfactory. The results of the analysis also suggest that it is mainly the geometrical structure of the target nuclei which, in effect, determines the elastic and inelastic scattering cross sections for exciting the low-lying collective states.

Certain basic features, common to all phenomenological models of hadron structure based on the picture of confinement at large distances and effective one-gluon exchange within the confinement region, necessarily lead to the prediction of the existence of a nonstrange dibaryon resonance with quantum numbers ${\mathrm{IJ}}^P$${=03\mathrm{}}^{+}$, the $d^{\mathrm{*}}$, independent of more detailed features of the dynamics of any of the models. We discuss the qualitative physics underlying this claim, comment on the probable mass and decay properties of the resulting state, and provide estimates of the expected production cross sections in np→$d^{\mathrm{*}}$ and ${\pi }^{\pm }$d→${\pi }^{\pm }$$d^{\mathrm{*}}$. .AE

We consider radiative capture of a ${\pi }^{\mathrm{-}}$ from an atomic orbital around deuterium into a bound NNπ system with two units of isospin. It is found that it is a feasible method to search for such hypothetical states.

A one-body Dirac equation is used to model ${}_{}{}^3{}_{}{}^{}$He${+}^{40}$Ca elastic scattering at 197 and 217 MeV. A relativistic analogue of the Watanabe model is employed to constrain the real parts of the ${}_{}{}^3{}_{}{}^{}\mathrm{nucleus}$ potentials. This procedure results in an accurate description of the experimental differential cross-section data, as well as a prediction of the elastic spin observables. Calculations for triton-nucleus scattering are also performed. Implications for relativistic models of nuclear scattering are discussed.

We comment on the description of electromagnetic reactions involving hadrons, when the internal structure of the hadrons is taken into account. General off-shell vertex operators, only constrained by Lorentz and gauge invariance, are used. The electromagnetic production of pions on a nucleon is discussed as an example. Commonly used ad hoc recipes involving phenomenological form factors are discussed in the framework of an exact formulation.

Differential cross sections for the emission of intermediate-mass fragments (3≤$Z_f$≤14) at 48.5° and 131.5° in the interaction of xenon with 1–19 GeV protons have been measured. The excitation functions rise sharply with energy up to ∼10 GeV and then level off. The energy spectra were fitted with an expression based on the phase transition droplet model. Excellent fits with reasonable parameters were obtained for $E_p$≥9 GeV. Below 6 GeV, the fits show an increasing contribution with decreasing energy from another mechanism, believed to be binary breakup. A droplet model fit to the cross sections ascribed to the multifragmentation component is able to reproduce the variation of the yields with both fragment mass and proton energy. The results are interpreted in terms of the phase diagram of nuclear matter.

Zero-degree (p,n) cross sections, measured with approximately 1-MeV energy resolution at $E_p$=492 MeV, are reported for ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, and ${}_{}{}^{12}{}_{}{}^{}$,13,14C. Measurements for ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$(p,n) and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(p,n) were also obtained at 590 MeV. The cross sections for Gamow-Teller and Fermi type transitions are used to estimate the strengths of the isovector spin-dependent ($J_{\sigma \tau }$) and spin-independent ($J_{\tau }$) terms of the effective interaction. The measured zero-degree cross sections for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(p,n${)}^{14}$N transitions to the 2.31 MeV isobaric analog state and the 3.95-MeV $J^{\pi }$${=1\mathrm{}}^{+}$ state are compared with calculated values. Values for the unit cross-section ratio $R^2$=σ${^}_{\mathrm{GT}}$/σ${^}_F$ =($J_{\sigma \tau }$/$J_{\tau }$${)}^2$ ($N_{\sigma \tau }$/$N_{\tau }$) obtained from the present data are compared with results for other energies.

The $2_1^{+}$, $4_1^{+}$, and $0_2^{+}$ states in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been observed with ${\pi }^{+}$ scattering at 50 MeV. These data, along with existing data for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ are compared to coupled channel calculations. This analysis produces a larger ${\beta }_2$ than previously found in low energy distorted wave calculations and is consistent with results from resonance energy studies. The interference of the one- and two-step contributions make the calculated $4^{+}$ cross section quite sensitive to the sign of ${\beta }_4$. The sensitivity to the πA optical model is discussed.

The formation of sigmas through low-energy kaon photoproduction from nucleons is described by using Feynman diagrams. Different models for the production process are compared, including pseudovector versus pseudoscalar coupling for the KNΣ vertex. The elementary coupling constants are fitted to the cross-section data up to 2.2 GeV and agree with previous fits obtained from the photoproduction of lambdas from protons. This operator is then implanted into the nucleus via the impulse approximation. Using Woods-Saxon shell-model wave functions for the sigma and the nucleon and a particle-hole basis for the nucleus, angular distributions are obtained for the formation of ${}_{{}_{\mathrm{\Sigma }}{}^{16}{}_{}{}^{}}{}^{}{}_{}{}^{}\mathrm{N}$, ${}_{{}_{\mathrm{\Sigma }}{}^{40}{}_{}{}^{}}{}^{}{}_{}{}^{}\mathrm{K}$, and ${}_{{}_{\mathrm{\Sigma }}{}^{208}{}_{}{}^{}}{}^{}{}_{}{}^{}\mathrm{Tl}$. Cross sections for processes employing the reaction ${}_{}{}^1{}_{}{}^{}\mathrm{H}$(γ,$K^{+}$)${\Sigma }^0$ are about one fifth of those corresponding to lambda hypernuclei, while reactions involving n(γ,$K^{+}$)${\Sigma }^{\mathrm{-}}$ yield counting rates comparable to those of lambda-hypernuclear photoproduction.

The proton-proton parity-violating analyzing power is calculated at laboratory energies up to 1000 MeV using a parity-violating weak meson-exchange potential with form factors and coupling constants consistent with the nonrelativistic Bonn potential. A real distorted-wave Born-approximation formulation of the weak scattering amplitude is introduced using real standing waves with distortions by Coulomb and strong interactions. This formulation includes a new and simplified expression for the S matrix in terms of strong and real weak amplitudes. The form-factor contributions to the weak potential significantly reduce the overall magnitude of the analyzing power, but do not qualitatively affect the relative energy or angular dependence. Results using, alternatively, Paris, Reid soft-core, Hamada-Johnston, and pure Coulomb distorted waves with the same weak potential are compared. The angular and total analyzing powers are calculated with long-range Coulomb contributions for scattering and transmission experiments. The long-range Coulomb effects can be removed, leading to a reduced analyzing power  that depends only on short-range forces.