The structure of the second $0^{+}$ state of ${}^{10}\mathrm{Be}$ is investigated using a microscopic $\alpha +\alpha +n+n$ model based on the molecular-orbit (MO) model. The second $0^{+}$ state, which has dominantly the ${(1/2\mathrm{}}^{+}{)}^2$ configuration, is shown to have a particularly enlarged $\alpha$-$\alpha$ structure. The kinetic energy of the two valence neutrons occupying along the $\alpha$-$\alpha$ axis is reduced remarkably due to the strong $\alpha$ clustering and, simultaneously, the spin-orbit interaction unexpectedly plays an important role in making the energy of this state much lower. The mixing of states with different spin structure is shown to be important in negative-parity states. The experimentally observed small-level spacing between $1^{-}$ and $2^{-}$ $(\sim 300$ keV) is found to be evidence of this spin-mixing effect. ${}^{12}\mathrm{Be}$ is also investigated using the $\alpha +\alpha +4n$ model, in which four valence neutrons are considered to occupy the ${(3/2\mathrm{}}^{-}{)}^2{(1/2\mathrm{}}^{+}{)}^2$ configuration. The energy surface of ${}^{12}\mathrm{Be}$ is shown to exhibit similar characteristics, that the remarkable $\alpha$ clustering and the contribution of the spin-orbit interaction make the binding of the state with the ${(3/2\mathrm{}}^{-}{)}^2{(1/2\mathrm{}}^{+}{)}^2$ configuration properly stronger in comparison with the closed p-shell ${(3/2\mathrm{}}^{-}{)}^2{(1/2\mathrm{}}^{-}{)}^2$ configuration.

Reaction mechanisms and multifragmentation processes have been studied for ${}^{64}\mathrm{Zn}{+}^{58}\mathrm{Ni}$ collisions at intermediate energies with the help of antisymmetrized molecular dynamics (AMD-V) model calculations. Experimental energy spectra, angular distributions, charge distributions, and isotope distributions, classified by their associated charged particle multiplicities, are compared with the results of the AMD-V calculations. In general the experimental results are reasonably well reproduced by the calculations. The multifragmentation observed experimentally at all incident energies is also reproduced by the AMD-V calculations. A detailed study of AMD-V events reveals that, in nucleon transport, the reaction shows some transparency, whereas in energy transport the reaction is much less transparent at all incident energies studied here. The transparency in the nucleon transport indicates that, even for central collisions, about 75% of the projectile nucleons appear in the forward direction. In energy transport about 80% of the initial kinetic energy of the projectile in the center- of-mass frame is dissipated. The detailed study of AMD-V events also elucidates the dynamics of the multifragmentation process. The study suggests that, at $35A\hspace{0.5em}\mathrm{MeV},$ the semitransparency and thermal expansion are the dominant mechanisms for the multifragmentation process, whereas at $49A\hspace{0.5em}\mathrm{MeV}$ and higher incident energies a nuclear compression occurs at an early stage of the reaction and plays an important role in the multifragmentation process in addition to that of the thermal expansion and the semitransparency.

The differential cross sections and analyzing powers from the elastic scattering of 25 and 40 MeV protons from many nuclei have been studied. Analyses have been made using a fully microscopic model of proton-nucleus scattering seeking to establish a means appropriate for use in analyses of radioactive beam scattering from hydrogen with ion energies $25A$ and $40A\hspace{0.5em}\mathrm{MeV}.$

Using an isobar model and the new SAPHIR data we show that a better explanation of $K^0{\Sigma }^{+}$ photoproduction can be achieved by including the $P_{13}\mathrm{}\left(1720\right)\mathrm{}$ resonance. We find that the inclusion of this state does not influence the $K^{+}{\Sigma }^0$ channel appreciably, in contrast to the other three $K\Sigma$ channels, where the prominent effect is found in the $K^0{\Sigma }^{+}$ channel. The extracted fractional decay width is consistent with the prediction of the quark model, whose magnitude is almost one order smaller than the value given by the Particle Data Group.

Using the self-consistent Hartree-Fock plus Tamm-Dancoff approximation with Skyrme interactions, the response of some $\beta$ stable closed-shell nuclei to charge-exchange ${(t}_{\pm })$ spin monopole fields is estimated in the coordinate space. Both the isoscalar and isovector spin-correlation are included simultaneously. The excitation energy of $t_{+}$ giant resonance decreases considerably as the neutron excess (and consequently the nuclear mass number) increases, while that of $t_{-}$ giant resonance remains nearly constant. We have tried to separate out the Gamow-Teller strength from the present charge-exchange spin monopole strength, both of which have the same quantum numbers, $J^{\pi }{=1\mathrm{}}^{+}.$

The ${}^{13}\mathrm{C}{(}^3\mathrm{He}{,d)}^{14}\mathrm{N}$ proton transfer reaction has been measured at an incident energy of 26.3 MeV. Angular distributions for proton transfer to the ground state and excited states at $2.313$ and 3.948 MeV in ${}^{14}\mathrm{N}$ are analyzed within the framework of the modified DWBA. Asymptotic normalization coefficients (ANC’s) defining the amplitude of the tails of the ${}^{14}\mathrm{N}$ bound-state wave functions in the ${}^{13}\mathrm{C}+p$ channel are extracted that are in excellent agreement with values found previously with the ${}^{13}\mathrm{C}{(}^{14}\mathrm{N}{,}^{13}\mathrm{C}{)}^{14}\mathrm{N}$ reaction. We conclude that $C_{p_{1/2}}^2=18.2\mathrm{}\left(9\right)\mathrm{}\hspace{0.5em}{\mathrm{fm}}^{-1}$ and $C_{p_{3/2}}^2=0.91\mathrm{}\left(14\right)\mathrm{}\hspace{0.5em}{\mathrm{fm}}^{-1}$ for the virtual decay ${}^{14}\mathrm{N}(\mathrm{g}.\mathrm{s}.\mathrm{}{)}^{13}\mathrm{C}+p.\mathrm{}$ These are necessary for the analysis of the ${}^{14}\mathrm{N}{(}^7\mathrm{Be}{,}^8\mathrm{B}{)}^{13}\mathrm{C}$ and ${}^{14}\mathrm{N}{(}^{11}\mathrm{C}{,}^{12}\mathrm{N}{)}^{13}\mathrm{C}$ reactions to extract the ANC’s for ${}^7\mathrm{Be}+p^8\mathrm{B}$ and ${}^{11}\mathrm{C}+p^{12}\mathrm{N},$ which determine the direct radiative capture cross sections ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ and ${}^{11}\mathrm{C}(p,\gamma {)}^{12}\mathrm{N}$ at astrophysical energies.

Very high spin states $(I=50\mathrm{}–60ħ)$ have been observed in the transitional nuclei ${}^{161}\mathrm{Er}$ and ${}^{162}\mathrm{Er}$ using the Euroball $\gamma$-ray spectrometer. In ${}^{161}\mathrm{Er},$ three bands are observed well above spin $50ħ.$ In the positive parity, positive signature $(+,+\frac{1}{2})$ band a discontinuity in the regular rotational behavior occurs at ${\frac{109}{2}}^{+}$ and a splitting into two branches occurs at ${\frac{97}{2}}^{-}$ in the negative parity, positive signature $(-,+\frac{1}{2})$ band. The $(-,-\frac{1}{2})$ band continues in a regular fashion to ${\frac{115}{2}}^{-},$ tentatively $\left({\frac{119}{2}}^{-}\right).\mathrm{}$ In ${}^{162}\mathrm{Er}$ the positive parity, even spin (+,0) yrast band is observed to continue smoothly up to ${58}^{+}$ ${(60\mathrm{}}^{+})$ and the negative parity, even spin $(-,0)$ and odd spin $(-,1)$ bands are extended from ${30}^{-}$ to ${34}^{-}$ and from ${31}^{-}$ to ${47}^{-}$ ${(49\mathrm{}}^{-}),$ respectively. The high spin experimental spectra are compared with both a simple model involving the occupation of specific single neutron states in the absence of neutron pair correlations and with more detailed cranked Nilsson-Strutinsky calculations in which both proton and neutron pairing correlations are neglected. The very high spin domain is found to comprise a series of unpaired rotational bands. Unpaired band crossings between bands with different neutron and proton configurations are identified in ${}^{161}\mathrm{Er}.$ There is no evidence for aligned oblate or terminating states being close to the yrast line in ${}^{161,162}\mathrm{Er}$ up to spin $\approx 60ħ$ in contrast to the lighter Er isotopes.

In this paper we investigate the role of single-particle energies on the low-lying states of ${}^{132}\mathrm{Ba},$ a typical O(6) nucleus in the IBM and the fermion dynamical symmetric model (FDSM). It is found that one can reproduce the physical quantities of a realistic system with nondegenerate single-particle energies using degenerate single-particle levels and a slightly different parametrization of the two-body interaction. However, if the single-particle splittings are enlarged by a factor of 1.5, the O(6)-like behavior of the nucleus is lost and a model that assumes degenerate levels cannot describe its collective structure. Contributions from interactions other than monopole and quadrupole pairing and a quadrupole-quadrupole force are found to be unimportant. Although the role of the abnormal-parity level depends on the details of the single-particle structure, its effects can be “compensated” by using different Hamiltonian parameters and degenerate single-particle levels in a FDSM treatment.

The ${}^{29}\mathrm{Si}(p,\gamma {)}^{30}\mathrm{P}$ reaction was studied for 32 resonances in the energy range $E_p=1.0\mathrm{}–2.5$ MeV. Angular distributions were measured for 230 primary and secondary transitions. Results from the analysis of these data were combined with previous measurements of the ${}^{29}\mathrm{Si}{(p,p}_0{)}^{29}\mathrm{Si}$ and ${}^{29}\mathrm{Si}(p,\gamma {)}^{30}\mathrm{P}$ reactions to determine the spin J, parity $\pi ,$ and isospin T of many levels. Remaining ambiguities were eliminated by comparison with the spectrum of the parent nucleus ${}^{30}\mathrm{Si}$ and with the calculated shell-model spectrum. J, $\pi ,$ and T have been assigned for 103 states up to an excitation energy of 8.0 MeV.

The multiplicity distributions of projectile light fragments and target black fragments produced in oxygen-emulsion collisions at $3.7A\mathrm{GeV}$ have been analyzed. The Koba-Nielsen-Olesen scaling presentation of $\psi \mathrm{}\left(z\right)=4z\exp \left(-2z\right)$ can describe well the multiplicity distributions of nuclear fragments.

This paper introduces a new method for the selection of central single-source events, based on classical multivariate techniques. The resulting discriminating variable is shown to be valid for different hypotheses on the nuclear source deexcitation mechanism. It enables the selection of events which are representative of the whole set of single-source events. Application to the Ni+Ni at 32A MeV system measured with the INDRA multidetector has allowed the determination of the fusion probability as a function of the impact parameter and the evaluation of the corresponding cross section.

Fission fragment cross sections and angular anisotropies have been measured to high accuracy following fusion of ${}^{16}\mathrm{O}$ with the strongly deformed nucleus ${}^{182}\mathrm{W},$ at bombarding energies spanning the fusion barrier region. Together with existing evaporation residue data, they show that at all the beam energies, the statistical transition state model adequately describes the fission properties measured. No significant evidence was found for a memory of the different configurations at fusion resulting from the target nucleus deformation, in contrast with previous measurements for deformed actinide nuclei.

Multifragmentation in fully reconstructed events from $1A$ GeV Kr and La collisions with C has been studied. Results are compared with similar data for $1A$ GeV Au+C. The emitted charged particles and fragments are identified with emission from either a prompt first stage or a second stage in which the remnant resulting from the first stage breaks up. The nuclear charge, mass, and excitation energy distributions of the remnant are determined. The total charged multiplicity, as well as those of the first and second stages are obtained. Freeze-out temperatures and thermal excitation energy permit the determination of the caloric curve. The fragment charge distribution as well as the IMF multiplicity distribution and those of individual fragments are obtained. The various results are examined as to the extent of universal behavior when scaled for varying system size. Comparisons are made with intranuclear cascade and statistical multifragmentation model calculations.

We have calculated the ratio between the charge and magnetic form factors of the proton, making use of the hypercentral constituent quark model with relativistic corrections. The parameters of the model have been fixed in order to reproduce the baryon spectrum. The predicted values of this ratio are compared with the recent experimental results.

The QED radiative corrections to virtual Compton scattering (reaction $e\overrightarrow{p}\mathrm{ep}\gamma )$ are calculated to first order in ${\alpha }_{\mathrm{em}}\equiv e^2/4\mathrm{}\pi .$ A detailed study is presented for the one-loop virtual corrections and for the first order soft-photon emission contributions. Furthermore, a full numerical calculation is given for the radiative tail, corresponding to photon emission processes, where the photon energy is not very small compared with the lepton momenta. We compare our results with existing works on elastic electron-proton scattering, and show for the $e\overrightarrow{p}\mathrm{ep}\gamma$ reaction how the observables are modified due to these first order QED radiative corrections. We show results for both unpolarized and polarized observables of virtual Compton scattering in the low energy region (where one is sensitive to the generalized polarizabilities of the nucleon), as well as for the deeply virtual Compton scattering.

The effect of core polarization on isoscalar dipole one-particle moments due to the coupling with isoscalar giant dipole resonance (compression mode) is estimated. Numerical calculations with the core nucleus ${}_{82}^{208}{\mathrm{Pb}}_{126}$ show that a small enhancement of one-particle moments is obtained, of which the magnitude depends sensitively on relevant one-particle orbitals. The results are important for a microscopic understanding of the electric dipole moments (Schiff moments) measured for nuclei in this mass region.

We investigate the structure of the nucleon resonance $N^{*}\mathrm{}\left(1440\right)\mathrm{}$ (Roper) within a coupled-channel meson exchange model for pion-nucleon scattering. The coupling to $\pi \pi N$ states is realized effectively by the coupling to the $\sigma N,$ $\pi \Delta ,$ and $\rho N$ channels. The interaction within and between these channels is derived from an effective Lagrangian based on a chirally symmetric Lagrangian, which is supplemented by well known terms for the coupling of the $\Delta$ isobar, the $\omega$ meson, and the $“\sigma ,”$ which is the name given here to the strong correlation of two pions in the scalar-isoscalar channel. In this model the Roper resonance can be described by meson-baryon dynamics alone; no genuine $N^{*}\mathrm{}\left(1440\right)\mathrm{}$ (three quark) resonance is needed in order to fit $\pi N$ phase shifts and inelasticities.

Excited states in the light lead nucleus, ${}^{182}\mathrm{Pb},$ have been observed for the first time, by means of the recoil-decay tagging technique. A rotational band has been observed which has features in common with bands attributed to a prolate configuration in the heavier neutron deficient lead nuclei, ${}^{184-188}\mathrm{Pb}.$ A variable moment of inertia fit to the states in this band suggests that the prolate minimum has risen significantly in energy compared to the next even lead nucleus, ${}^{184}\mathrm{Pb}.$ This constitutes firm evidence for the minimization of this configuration with respect to the spherical ground state around $N=103.\mathrm{}$

Based on available experimental data, a new set of Nilsson parameters is proposed for proton-rich nuclei with proton or neutron numbers $28<~N<~40.$ The resulting single-particle spectra are compared with those from relativistic and nonrelativistic mean field theories. Collective excitations in some even-even proton-rich nuclei in the upper $\mathrm{pf}$ shell are investigated using the projected shell model with the new Nilsson basis. It is found that the regular bands are sharply disturbed by band crossings involving ${1g}_{9/2}$ neutrons and protons. Physical quantities for exploring the nature of the band disturbance and the role of the ${1g}_{9/2}$ single-particle are predicted, which may be tested by new experiments with radioactive beams.

We consider interference effects between p-wave resonance scattering amplitude and background s-wave amplitude in low-energy neutron scattering from a heavy nucleus which goes through the compound nucleus stage. The first effect is in the difference between the forward and backward scattering cross sections (the ${\mathbf{p}}_i\cdot {\mathbf{p}}_f$ correlation). Because of the chaotic nature of the compound states, this effect is a random variable with zero mean. However, a statistical consideration shows that the probability distribution of this effect does not obey the standard central limit theorem. That is, the probability density for the effect averaged over n resonances does not become a Gaussian distribution with the variance decreasing as $n^{-1/2}$ (“violation” of the theorem). We derive the probability distribution of the effect and the limit distribution of the average. It is found that the width of this distribution does not decrease with the increase of n, i.e., fluctuations are not suppressed by averaging. Furthermore, we consider the $\mathit{\sigma }\cdot ({\mathbf{p}}_i\times {\mathbf{p}}_f)$ correlation and find that this effect, although much smaller, shows fluctuations which actually increase upon averaging over many measurements. This behavior holds for $\epsilon >{\Gamma }_p$ where $\epsilon$ is the distance to the resonance, and ${\Gamma }_p$ is the resonance width. Limits of the effects due to finite resonance widths are also considered. In the Appendix we present a simple derivation of the limit theorem for the average of random variables with infinite variances.