A Thomas-Fermi theory with a linear scaling assumption is proposed for the breathing mode of nuclear collective motion. It leads to a general result $K_A=〈K(\rho ,\delta )〉{+K}_{\mathrm{GD}}-{2E}_C/A$ which states that the incompressibility $K_A$ of a finite nucleus $A$ mainly equals the nuclear matter incompressibility $K(\rho ,\delta )$ averaged over the nucleon density distribution $\rho \left(\mathbf{r}\right)$ of nucleus $A$, added to a term $K_{\mathrm{GD}}$ contributed from the gradients of nucleon densities, with twice the Coulomb energy per nucleon $E_C/A$ subtracted. The nuclear matter equation of state given by the Thomas-Fermi statistical model with a Seyler-Blanchard-type interaction is employed to calculate the nuclear matter incompressibility $K(\rho ,\delta )$ and a localized approximation of the Seyler-Blanchard-type interaction, which is shown to be similar to the Skyrme-type interaction, is developed to calculate the value of $K_{\mathrm{GD}}.$ $K_{\mathrm{GD}}$ and $-{2E}_C/A$ contribute about 20–10 % and 1–5 %, respectively, to the nuclear incompressibility $K_A,$ from the light to the heavy nuclei. The shell and the even-odd effects are discussed by a scaling model which shows that these effects can be neglected for medium and heavy nuclei. The anharmonic effect is shown to be significant only for light nuclei. The leptodermous expansion of $K_A$ is obtained and the contribution from the curvature term proportional to $A^{-2/3}$ is discussed. The calculated isoscalar giant monopole resonance energy $E_M$ for a variety of nuclei are shown to be in agreement with experimental measurements.

Structures of C isotopes from the proton drip line to the neutron drip line are investigated in the framework of the antisymmetrized molecular dynamics (AMD). In particular, opposite deformations between protons and neutrons near the proton drip line are discussed in detail. We make certain of this new phenomenon suggested in the AMD results by analyzing the ratios of electric moments or transitions $[Q$ or $B\left(E2\mathrm{}\right)\mathrm{}$] in ${}^{10}$C and ${}^{11}$C to those in the mirror nuclei ${}^{10}$Be and ${}^{11}$B.

We propose a method for calculating the excited-state properties of a quantum many-fermion system based on the auxiliary-field Monte-Carlo method. We have examined our method with the exactly solvable pairing-force model and the Lipkin model.

An approach describing the thermal damping width of the giant dipole resonance (GDR) in hot nuclei is presented. The GDR is generated by the $\mathrm{ph}$ excitations within the finite-temperature random-phase approximation (FTRPA), while its damping at finite temperature arises from irreversible coupling of $\mathrm{ph}$ configurations to the thermal $\mathrm{pp}$ and $\mathrm{hh}$ ones beyond the FTRPA. A semimicroscopic unification of the quantal spreading and thermal damping widths is undertaken within the framework of motional damping. The numerical calculations are performed, using a schematic model with equally degenerate equidistant shells for a hot nucleus of mass $A=112\mathrm{}$ carrying no angular momentum. The results show that the total width of the GDR increases strongly as a function of the excitation energy up to $E^{*}\sim 120–130$ MeV, where it reaches a saturation value. The limiting temperature for the GDR in very hot nuclei is discussed.

We have quantitatively analyzed the wave functions of the low-lying yrast states of deformed, heavy nuclei (specifically ${}^{238}$U and ${}^{168}$Er) given by different models to determine the relative contribution of the valence nucleons to the total angular momentum of the nucleus. In all models, an yrast state is generated, as expected, by collective contributions from both proton and neutron angular momenta. We have also examined the relative contribution of valence nucleons in the normal-parity states and in the abnormal-parity, high-$j$, intruder states to the yrast angular momentum. If the states with definite angular momenta projected from the Nilsson intrinsic state of the nucleus are assumed to provide a good approximation to the structure of the yrast band, the contribution of nucleons in the abnormal-parity states to the yrast angular momentum is shown to be about the same as that of nucleons in the normal-parity states. This result is in marked contrast to the assumption made in two prominent models (pseudo-${\mathrm{SU}}_3$ model and its symplectic extension and fermion dynamic symmetric model) that the nucleons in abnormal-parity states, do not, in the first approximation, contribute any angular momentum to the yrast band. We also find that the distribution of angular momenta contained in the intrinsic state of the abnormal-parity nucleons in the $j^n$ configuration, which does not have any ${\mathrm{SU}}_3$ symmetry, is surprisingly similar to the distribution of angular momenta contained in an ${\mathrm{SU}}_3$ intrinsic state with the same average value of angular momentum.

The double differential cross sections at ${\theta }_{\mathrm{lab}}$ between $0.0°$ and $12.3°$ and the polarization transfer $D_{\mathrm{NN}}$ at $0°$ for the ${}^{90}\mathrm{Zr}\mathrm{}(p,n)\mathrm{}$ reaction are measured at a bombarding energy of 295 MeV. A multipole decomposition technique is applied to the cross sections to extract $L=0\mathrm{}$, $L=1\mathrm{}$, $L=2\mathrm{}$, and $L=3\mathrm{}$ contributions. The Gamow-Teller (GT) strength $B\left(\mathrm{GT}\right)$ in the continuum deduced from the $L=0\mathrm{}$ cross section is compared both with the perturbative calculation by Bertsch and Hamamoto and with the second-order random phase approximation calculation by Drożdż et al. The sum of $B\left(\mathrm{GT}\right)$ values up to 50 MeV excitation becomes $S_{{\beta }^{-}}$=28.0±1.6 after subtracting the contribution of the isovector spin-monopole strength. This $S_{{\beta }^{-}}$ value of 28.0$\pm$1.6 corresponds to about (93 $\pm$ 5)% of the minimum value of the sum rule $3\left(N-Z\right)$=30. The usefulness of the polarization transfer observable in the distorted wave impulse approximation is presented.

The total cross section and pion angular distributions for the reaction ${}^{12}\mathrm{C}(\gamma ,{\pi }^0)$ have been measured within 25 MeV of threshold using tagged photons and a large acceptance ${\pi }^0$ spectrometer at the Saskatchewan Accelerator Laboratory (SAL). The total cross section is in agreement with earlier measurements from Saclay and Mainz. The elementary $P$-wave photoproduction amplitude $P_3^{\mathrm{}(+)\mathrm{}}$ has been determined from a distorted-wave impulse-approximation analysis of the nuclear data and compares favorably with the corresponding free-nucleon amplitude in the threshold region. The incoherent contribution from the 4.43 MeV ${(2\mathrm{}}^{+})$ state has been deduced from the pion angular distributions and is in agreement with previous experimental estimates.

Results from a 4$\pi$ solid angle measurement of the reactions ${}^3$He$({\pi }^{+},ppp)$ and ${}^4$He$({\pi }^{+},ppp)$$n$ at incident pion energies of $T_{{\pi }^{+}}=$70, 118, 162, 239, and 330 MeV are presented. For ${}^3$He the total absorption cross sections and their decomposition into two-proton and three-proton components are evaluated; for ${}^4$He the three-proton absorption cross sections are given. The differential distributions of the three-proton multinucleon absorption mode of both nuclei are analyzed and compared to each other by making use of a complete set of variables. The data are investigated for signatures of initial and final state interactions: it is found that more than half of the three-proton yield cannot be accounted for by cascade mechanisms. The remaining strength shows dependence on the incident pion angular momentum, but also structures that are not explained by simple semiclassical models.

Cross sections for quasielastic scattering and transfer reactions have been measured for ${}^{12}$C, ${}^{16}$O+${}^{154}$Sm, and ${}^{16}$O+${}^{115}$In systems at energies above the Coulomb barrier. The transfer probabilities for one- and two-proton stripping reactions show an exponential decrease with increasing distance of closest approach for all the systems and the measured decay constants are found to be smaller than those derived from binding-energy considerations on the basis of the semiclassical model using a Coulomb trajectory. These results on the observed enhancement of transfer probabilities were further analyzed within the framework of the semiclassical model using two different formalisms: (1) considering the contribution of both Coulomb and nuclear branches of distance of closest approach to transfer probability and (2) in terms of the quantum diffractional effect in the broadening of the transfer angular distribution. It is seen that both these formalisms are able to offer a consistent explanation for the observed enhancement in the transfer probabilities and account for the “slope anomaly” seen in the transfer reactions in these systems.

Cross sections, angular distributions, and mass distributions have been measured for deep-inelastic scattering in ${}^{124}{\mathrm{X}\mathrm{e}+}^{58}\mathrm{Ni}$ and ${}^{136}{\mathrm{X}\mathrm{e}+}^{64}\mathrm{Ni}$ at laboratory energies in the vicinity of the Coulomb barrier. The mass distributions show distinct components due to deep-inelastic and fissionlike processes. The strength of deep-inelastic scattering is similar in the two systems measured and comparable to previous measurements in ${}^{58}{\mathrm{N}\mathrm{i}+}^{112,124}\mathrm{Sn}.$

Neutron multiplicities after antiproton-induced fission have been determined as a function of the total mass of the fission fragments. Pre- and postscission neutron multiplicities of the reaction $\mathrm{p¯}$+${}^{238}$U have been deduced using the moving-source parametrization of the neutron energy spectra by Maxwellian distributions. A postscission multiplicity of 6.3(6) neutrons out of 20.0(10) in total emitted neutrons in fission indicates that fission is a rather slow process. The increase of the evaporative prescission neutron multiplicity is about 80% of the total increase of evaporative neutrons as a measure of excitation energy. The postscission multiplicity gets only 20% of the total increase, thus indicating that the nucleus has only a moderate excitation energy at the moment of scission. The results are compared with standard cascade-evaporation calculations predicting a much lower number of evaporated prescission neutrons as the experiment shows. This is a strong indication of the importance of dissipative effects in the fission process. Application of dissipative effects like a saddle-to-scission delay time and nuclear viscosity in the model calculation describes the experimental results much better.

We analyze proton transfer data for the ${}^{12}$C+${}^{197}$Au system. We show that the interplay between absorption and tunneling effects explains the observed energy dependence of the transfer probabilities at large distances, including the apparently anomalous behavior at high energies.

The density of states in statistical approaches to nuclear multifragmentation includes a contribution from permutations of fragment positions in the physical space (the volume $V_F)$ occupied by the fragments. For $N$ pointlike noninteracting particles (perfect gas) this factor is simply proportional to $V_F^N$. We propose a correction due to the finite size of fragments which is based on an evaluation of the two-body overlap probability. The correction exhibits an approximate exponential dependence on the multiplicity $N$.

The $K^{+}$ scattering on the lightest nuclei, $d$, ${}^3$He, and ${}^4$He is studied in the framework of multiple-scattering theory. Effects from meson exchange currents (MEC) tied to the $K^{+}N\to \mathrm{KN}\pi$ reaction are evaluated. We found that at momentum transfers $Q^2<0.5\mathrm{}$ (GeV/${c)}^2$ contributions from MEC are much smaller than kaon rescattering corrections. This makes the conventional multiple-scattering picture a reliable tool to study these reactions in this kinematical domain and to extract the $K^{+}n$ scattering amplitude from the $K^{+}d$ data. At larger transferred momentum MEC can become more relevant.

We investigate the importance of the quantum statistics and deexcitation of primary fragments on the isotope yield ratio temperature determination. A phenomenological formula is presented which allows derivation of the temperature of the decaying nuclear system at the freeze-out time from the measured double yield ratios of two isotope pairs. This prescription is applied to the recent ALADIN and EOS Collaboration data.

The process of pion-induced pion production in nuclei has been studied with the $A({\pi }^{+},{\pi }^{+}{\pi }^{-})$ and $A({\pi }^{+},{\pi }^{+}{\pi }^{-}p)$ reactions for four nuclei ${}^2$H, ${}^{12}$C, ${}^{40}$Ca, and ${}^{208}$Pb at an incident pion energy of $T_{{\pi }^{+}}=283\mathrm{}$ MeV. The ${\pi }^{+}{\pi }^{-}$ and ${\pi }^{+}{\pi }^{-}p$ particles in the final state were detected in coincidence with the CHAOS spectrometer at TRIUMF. By looking at kinematic quantities such as missing momentum and missing energy, we have been able to draw some model-independent conclusions about the dynamics of the $\pi \to \pi \pi$ process in nuclei, which do not vary significantly with target mass. We find that the incident pion interacts mainly with one surface nucleon via the leading $\pi N\to \pi \pi N$ channel. The pion pair releases no appreciable energy to the residual nucleus, which remains substantially bound throughout the reaction. These findings underline the quasifree nature of the pion production reaction in nuclei.

We provide a microscopic calculation of neutron-proton and neutron-neutron cross sections in symmetric nuclear matter at various densities, using the Brueckner-Hartree-Fock approximation scheme with the Paris potential. We investigate separately the medium effects on the effective mass and on the scattering amplitude. We determine average cross sections suitable for application in the dynamical simulation of heavy ion collisions, including a parametrization of their energy and density dependence.

A modified form of the inverse scattering method of Newton and Sabatier is applied to generate local complex potentials for the scattering of ${\pi }^{\pm }$ on zero spin and zero isospin nuclei. The phase shifts and inelasticity parameters, used as inputs, are extracted from a partial wave analysis of the elastic differential cross-section data by parametrizing the nuclear amplitude. Analytic mapping techniques are used to get a better accuracy in the phase shift analysis. The nuclear parts of the inversion potentials for ${\pi }^{+}$ and ${\pi }^{-}$ scattering on ${}^4\mathrm{He}$ are compared as a possible test of charge symmetry breaking. The method has been repeated for several incident pion energies below the (3,3) resonance threshold.

The mass spectra of charmonium and bottonium states are analyzed in terms of the error-function-type confining force and the color screened Coulomb-type potential. The Debye screening mass at finite temperature and density is studied in the thermofield dynamics approach. The critical temperature and density for $J/\Psi$ dissociation in the hot and dense matter are obtained.

We calculate characteristic time scales for the chemical equilibration of pions in hot hadronic matter using an effective chiral Lagrangian. We find that inelastic processes involving vector and axial vector mesons reduce the chemical equilibration time by a factor of $\sim 10$ compared to the result previously calculated in chiral perturbation theory. For a temperature of $T\sim 160$ MeV we obtain a chemical relaxation time of ${\tau }_{\mathrm{ch}}\simeq 7$ $\mathrm{fm}/c,$ which is comparable with typical time scales for a hadronic system generated in SPS-energy heavy-ion collisions. The effect of baryons is also estimated and found to be negligible for SPS energies but might be important for AGS energies. We predict that chemical freeze-out should take place at considerably higher temperatures $\Delta T\simeq 40$ MeV than thermal freeze-out and that the hadronic phase would not sustain a pion chemical potential larger than 50 MeV.