Elastic scattering cross sections for 65 MeV neutrons have been measured for natural targets of C, Si, Ca, Fe, Sn, and Pb at laboratory angles from 6° to 45°. A unique, compact detection system consisting of a ${\mathrm{CH}}_2$ (proton) converter and large-acceptance, wire-chamber-based, recoil-proton telescope is utilized for the measurements. The data is compared with macroscopic optical model potentials derived from proton scattering. In addition, comparisons with the microscopic optical model potentials, those of Jeukenne-Lejeune-Mahaux and Yamaguchi-Nagata-Matsuda, give a very good fit to the data.

The absolute electrofission cross section of Au and Ta was measured in the energy interval 40–250 MeV. Pronounced inflexions of the (e,f) curves are observed for both Au and Ta around 200–220 MeV, which are signatures of structures in the corresponding photofission cross-section curves. We show that these (γ,f) structures are originated in the stage of preequilibrium emissions in the nuclear thermalization process. The question associated to a possible connection between thermalization effects and competing photoexcitation mechanisms is addressed.

Neutron time-of-flight spectra were measured for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(p,n${)}^{14}$N reaction at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and differential cross sections for the observed excitations in this reaction were extracted over the momentum transfer range from 0 to 2.5 ${\mathrm{fm}}^{\mathrm{-}1}$. The goal of this work is to identify the $4^{\mathrm{-}}$ states in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ and to determine the isovector transition strengths. The identification of the $4^{\mathrm{-}}$ states is based on comparisons of the theoretical differential cross sections, performed in a DWIA formalism, with the experimental cross sections and with information from the ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(e,e’) reaction. Isospin assignments are based primarily on comparisons of the measured (p,n) and (e,e’) isovector strengths. Candidate $4^{\mathrm{-}}$ states are identified at excitation energies of 8.49 MeV (T=0), 13.76 MeV and 19.49 MeV (T=1), and 26.61 MeV (T=2) in the ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(p,n${)}^{14}$N reaction, and the isovector strengths for the transitions leading to these states re extracted. The observed excitation energies and isovector strengths are in good agreement with the analog T=1 and T=2 $4^{\mathrm{-}}$ states observed in the (e,e’) reaction. The experimental results are compared with results from shell-model calculations.

Angular distributions of the alpha particle transfer reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{11}$B${,}^7$Li${)}^{16}$O were measured for 28, 35, 40, 50, 56, 60, and 80 MeV beam energies. Exact finite range distorted-wave Born approximation (DWBA) analysis was performed for eight states of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$: ground state, 6.13 MeV ($3^{\mathrm{-}}$), 6.92 MeV ($2^{+}$), 10.36 MeV ($4^{+}$), 11.10 MeV ($4^{+}$), 14.82 MeV ($6^{+}$), 16.28 MeV ($6^{+}$), and 20.86 MeV ($7^{\mathrm{-}}$). Values of spectroscopic factors were extracted. For low lying states they agree well with theoretical shell model predictions. No evidence for tetrahedral deformation of the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ground state was found.

Differential cross sections for the double-isobaric analog-state transition in the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$) reaction were measured at 5° for eight incident energies between 120 and 292 MeV, inclusive. The results are compared with theoretical calculations and with previous data for T=1 targets, and mass dependence is discussed.

Evaporation residue excitation functions and α-multiplicities from complete fusion of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ have been measured from the fusion threshold up to 140 MeV incident energy. The data allow the conclusion that strongly overdamped motion cannot be dominant at energies in the vicinity of the fusion barrier below ${\mathit{E}}^{\mathrm{*}}$≊50 MeV. At excitation energies above 50 MeV the residue cross section for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{208}$Pb is much greater than predicted from the statistical model with conventional parametrizations. The enhancement is not explained by incorporating dynamical effects into the analysis. An alternative suggestion based on deexcitation-chain dependent fission barriers is discussed.

The in-medium nucleon-nucleon cross section is calculated starting from the thermodynamic T matrix at finite temperatures. The corresponding Bethe-Salpeter equation is solved using a separable representation of the Paris nucleon-nucleon potential. The energy-dependent in-medium N-N cross section at a given density shows a strong temperature dependence. Especially at low temperatures and low total momenta, the in-medium cross section is strongly modified by in-medium effects. In particular, with decreasing temperature an enhancement near the Fermi energy is observed. This enhancement can be discussed as a precursor of the superfluid phase transition in nuclear matter.

A series of recent papers has introduced a ‘‘properly deformed folding potential’’ and applied it to the analysis of inelastic alpha-particle scattering from nuclei. We examine this procedure and find that it is no more appropriate for the folding model than other potential deformation prescriptions. To first order in the deformation for rotors, or exactly for harmonic vibrators, the procedure is equivalent to the uniform radial strain model of Onley et al. In common with other deformed potential models, it provides a transition potential which is not uniquely related to an underlying transition density. Transition moments extracted from measurements using deformed optical potentials are thus subject to uncontrolled uncertainty. We recommend that, instead, explicit folding be used to generate transition potentials. Although a choice of transition density has to be made, its relation to the transition potential, and hence to measurements, is then unambiguous. The octupole excitation of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ by alpha particles of 139 MeV is taken as an illustrative example.

We have studied the quadrupole effects in pion elastic and inelastic scattering from ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$. A single channel α-t cluster model is used to calculate the wave function for the ground and the first excited states of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$. The quadrupole effects are shown to be appreciably large in pion${\mathrm{-}}^7$Li elastic scattering. We also calculated the second-rank tensor polarization and compared it with the recent experimental data.

Starting from a parametrized canonical expression for partition weights we investigate effects of uncorrelated stochastic fluctuations in the parameters. A special class of weights which are not affected by uncorrelated fluctuations is isolated and used as a reference for a systematic analysis of fluctuations. The technique is appled to partition weights obtained from a simple bond breaking percolation simulation. Strong evidence for the existence of uncorrelated fluctuations is obtained. The effects of fluctuations and of finite size effects on scaled factorial moments of the mass distribution are analyzed and discussed.

We present a cascade model to study the measurable consequences of Δ isobars inside a nucleus. We compare the outcome of simulations with observed events from charge exchange reactions on a carbon target. We see that the inclusive energy-transfer spectrum shows differences between model and experiment, when free Δ parameters are used. By changing parameters for the Δ in the formation process to better describe the inclusive spectrum, the gross features of the decay pattern including the energy-transfer spectra for each of the observed event classes are reasonably well accounted for.

Unexplained anomalies in quasielastic (e,e’) measurements motivated (e,e’p) experiments to determine the reaction mechanisms (single-nucleon knockout, multinucleon knockout, delta production, etc.) involved in quasielastic electron scattering. In this paper we use various models to extrapolate from C(e,e’p) measurements, where an outgoing proton is detected in a small solid angle centered around the virtual photon angle, to C(e,e’) measurements, which integrate over all knockedout particles at all angles. Extrapolated single nucleon knockout (p and s shell) only accounts for 25% of the (e,e’) cross section in the dip region and only 40–60 % in the quasielastic region. This indicates that the ‘‘quasielastic’’ region has a large nonquasielastic component. Various multinucleon knockout models (two-nucleon correlations, six-quark bags, and qualitative final state rescattering) are compared to C(e,e’p) missing energy spectra and to the difference between the (e,e’) cross section and the extrapolated single-nucleon knockout; none completely describe the data.

A method is introduced to determine a potential by inversion from both bound state energies and phase shifts, based upon the iterative perturbative S matrix to potential inversion procedure. The method is applied to determine the local potential reproducing low-energy ${}_{}{}^3{}_{}{}^{}\mathrm{He}$+α phase shifts as well as the l=1 bound states and lowest l=3 resonances in ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$, for both the single channel RGM and empirical data. An even-parity potential is determined from phase shifts up to l=4, which differs significantly from the shape of the odd-parity term. The need for a pronounced parity-dependent potential underlying the RGM is confirmed, which strongly resembles that found in both α+p and α${+}^{12}$C scattering.

Recent measurements on the energy spectra of ejectiles in the (p,n) and ${(}^3$He,t) reactions in coincidence with the p${\mathrm{\pi }}^{+}$ charged particles and integrated over their energies and angles are analyzed theoretically in the DWIA framework. It is assumed that the p${\mathrm{\pi }}^{+}$ events are generated by the direct decay of ${\mathrm{\Delta }}^{++}$. Due to the peripheral nature of the reaction the ${\mathrm{\Delta }}^{++}$ itself is assumed to be produced through the quasifree pp→n${\mathrm{\Delta }}^{++}$ process. The interaction for this process is described by the pseudovector one-pion-exchange relativistic Lagrangian. The parameters of this Lagrangian are taken such that it reproduces the measured spin averaged cross sections on the pp→n${\mathrm{\Delta }}^{++}$ reaction very well, over a wide energy range. Our calculated cross sections for the ejectile spectra on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ agree very well with the corresponding measured cross sections.

Optical potentials obtained from elastic proton scattering have been successfully used to describe the final state interaction in (e,e’p) reactions. However, spectroscopic factors extracted from experimental data are often quite different depending on whether relativistic calculations or nonrelativistic calculations are used. Since the calculation of the (e,e’p) cross section requires the wave functions of the outgoing proton in the nuclear interior, different optical potential models could cause the differences in these calculations. We use a model which can take either nonrelativistic or relativistic optical potentials while keeping all other aspects of the calculation the same, and find that a relativistic optical potential compared with a nonrelativistic optical potential can cause a difference as much as 14%. We examined several optical models as well as the use of the Perey factor in nonrelativistic calculations.

The Faddeev-Yakubovsky equations for four identical spinless particles in three-dimensional space interacting via harmonic-oscillator two-body potentials are solved analytically for any excitation and for an arbitrary value of the total angular momentum.

It is shown that in the Ginzburg-Landau description of first-order quark-hadron phase transition the normalized factorial moments exhibit scaling behavior. The scaling exponent ν depends on only one effective parameter g, which characterizes the strength of the transition. For a strong first-order transition, we find ν=1.45. For weak transition it is 1.30 in agreement with the earlier result on second-order transition.

We calculate the subthreshold production of antiprotons in the Lorentz-covariant relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) approach employing a weighted testparticle method to treat the antiproton propagation and absorption nonperturbatively. We find that the antiproton differential cross sections are highly sensitive to the baryon and antiproton self-energies in the dense baryonic environment. Adopting the baryon scalar and vector self-energies from the empirical optical potential for proton-nucleus elastic scattering and from Dirac-Brueckner calculations at higher density ρ>${\mathrm{\rho }}_0$ we examine the differential antiproton spectra as a function of the antiproton self-energy. A detailed comparison with the available experimental data for p-nucleus and nucleus-nucleus reactions shows that the antiproton feels a moderately attractive mean field at normal nuclear matter density ${\mathrm{\rho }}_0$ which is in line with a dispersive potential extracted from the free annihilation cross section.

We study the cooling (heating) of a glue-parton gas due to production (destruction) of particles and determine the associated evolution of entropy. We incorporate sharing of the system energy among a changing number of particles. We find that the entropy of an evolving glue-parton gas hardly changes, once the initial thermalized state has been formed, despite a significant change in particle number and temperature.

We examine the Nambu–Jona-Lasinio model in its SU(2) form, and compare this with chiral perturbation theory (CPT). We use a consistent Hartree approximation as being the leading term in a 1/${\mathit{N}}_{\mathit{c}}$ expansion for our mean field calculations and we make implicit chiral expansions of all the physical quantities directly from their defining equations. This enables us to extract explicit expressions for the observable scale-independent constants that are used in CPT. We find that this procedure gives reasonable agreement for the scale-independent constants. We compare our results with existing direct calculations in the literature, and point out difficulties in interpretation, especially with regard to l${\mathrm{¯}}_5$ and ${\mathit{l}}_7$. Our results appear to be in line with the agreement obtained via methods of bosonization, although, due to the different approximations made, these methods are not directly comparable.