Assignments of natural [π${=\left(\mathrm{-}1\right)}^J$] or unnatural [π${=\left(\mathrm{-}1\right)}^{J+1\mathrm{}}$] parity are made for states in ${}_{}{}^{44}{}_{}{}^{}$,46Sc on the basis of cross-section measurements of the polarized (d,α) reaction near zero degrees.

Rosenbluth separations of electron scattering response functions for uranium targets were made with data using measurements from five laboratory angles (60°, 90°, 134.5°, 140°, and 160°) at three-momentum transfers ranging from 280 to 500 MeV/c. The separations were made to determine if previously reported quenching of the longitudinal response function persisted in targets with large atomic number. The results are compared to relativistic Fermi gas calculations and calculations following the formalism of Rosenfelder. The measured transverse response functions agree quite well with the Rosenfelder-type calculations and almost as well with the relativistic Fermi gas calculations. The measured longitudinal response functions show significant quenching at low q. This quenching diminishes with increasing q but is never quite overcome.

The oscillations observed in the experimental α${+\mathrm{}}^{40}$Ca fusion excitation function between $E_{\alpha }$=10 and 27 MeV are described within the frame of the optical model. Use is made of an existing optical potential giving a precise description of the elastic scattering data for $E_{\alpha }$>24 MeV on a broad angular range, which is extrapolated to lower incident energies. A correct description of elastic scattering experimental excitation functions between $E_{\alpha }$=12 and 18 MeV, as well as of the fusion excitation function, is achieved by using different imaginary geometries for both processes. The oscillations appearing in the calculated fusion excitation function are due to maxima in the even-l transmission coefficients, for l ranging from 6 to 12; these maxima correspond to shape resonances in the underlying potential, which are associated with states belonging to an excited positive parity band with N=14 in the α${+\mathrm{}}^{40}$Ca system. The same potential predicts an N=12 positive parity band of states whose energies are in good agreement with the ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ experimental ground state band. It is shown that the correct reproduction of the spacing between the fusion oscillations achieved here results from the use of a deep real potential, which automatically yields a decoupling between positive and negative parity bands.

The stripping reaction (α,${\mathrm{}}^3$He) at 183 MeV incident energy has been used to study the neutron-particle response function on a ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ target nucleus up to 15 MeV excitation energy. Detailed spectroscopic information has been obtained on the low-lying neutron states (0–4 MeV) through angular distribution measurements and standard distorted wave Born approximation analysis. A large enhancement of cross section is observed between 5 and 15 MeV. It appears as a broad bump superimposed on a continuous background which has been analyzed within the framework of the plane wave breakup model. The excitation energies, angular distributions, and strengths of these high-lying transitions suggest that they arise from neutron stripping to high-spin outer subshells, i.e., 2$h_{11/2}$, 1$k_{17/2}$, and 1$j_{13/2}$ in ${}_{}{}^{209}{}_{}{}^{}\mathrm{Pb}$. The results are compared with predictions from the core-particle model and from the quasiparticle-phonon model.

The low-lying levels of ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$ up to 1662 keV excitation energy were investigated by measuring thick target yields and angular anisotropies of the deexcited gamma rays with a high resolution 57 ${\mathrm{cm}}^3$ Ge(Li) detector using 2–4 MeV protons. The ambiguity in the branching ratios for the 939, 1409, and 1662 keV levels has been resolved. The existence of weak gamma-ray transitions of 166 and 708 keV energies has been supported. The reaction mechanism for this range of proton energies in ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$ has been established. The ambiguity in the mode of excitation for 543 and 974 keV levels has been resolved. The reliable values of B(Eλ) for 377, 543, 720, and 974 keV levels excited with protons have been measured by considering the contribution of compound nucleus formation. The ambiguity in the $J^{\pi }$ values for 974 and 1409 keV levels has been resolved by the ${\chi }^2$-fit method. The 708 keV gamma ray has been assigned a new δ value. The results have been discussed in view of the various nuclear models.

Transverse-momentum data are analyzed for the presence of collective flow of nuclear matter in interactions of Au and Xe in nuclear emulsion at energies from 0.5 to 1.2 GeV/nucleon. Evidence of such flow is obtained from 122 interactions involving AgBr in nuclear emulsion by adapting a recently proposed method of transverse-momentum analysis.

Phase shifts for an optical potential representing the nuclear scattering of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ by ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ at 60 MeV laboratory energy are calculated by means of an arbitrary-order phase-integral formula taking account of two turning points. The results are found to be in excellent agreement with previously published numerical calculations.

In the present work we use the energy density formalism derived from the Skyrme density dependent interaction to study the orientation and energy dependence of the real part of the ion-ion potential for the ${}_{}{}^{238}{}_{}{}^{}$U${+\mathrm{}}^{238}$U system. It is found that both the nuclear part and the total potential (nuclear plus Coulomb) depend strongly on the relative orientation of the two interacting nuclei. Pockets are predicted in the total potential whose depths are found to depend on the orientation angle.

Fusion-like reactions induced on medium mass targets by 27 MeV per nucleon argon projectiles were studied. The properties of evaporation residues and binary fission fragments, both cold remnants of fusion nuclei, show that highly excited nuclei were produced, near the temperature of instability of nuclear matter. Fission-evaporation competition in the deexcitation of these nuclei is reflected in the ratio of fission and residue cross sections, which provides a way of studying the role of prefission evaporation and fission barriers in the deexcitation process.

The connection between the fragment yield and the associated specific entropy of participant matter produced in the course of a relativistic heavy ion collision is studied within the cascade approach. The essential impact parameter dependence of the fragment yield indicates that the specific entropy increases with impact parameter and that the breakup density is the larger the more central the collision process is. The results show that the bulk equilibrium limit for the entropy production is not reached for such heavy systems as Nb+Nb at 400 MeV/nucleon and that the finite size effects and the dynamical freeze-out process are dominant factors in determining the cluster abundances.

Cross sections of one- and few-nucleon transfers in the reaction ${}_{}{}^{28}{}_{}{}^{}$Si${+\mathrm{}}^{28}$Si at $E_{\mathrm{lab}=151.25\mathrm{}}$ MeV have been measured with a quadrupole-dipole-dipole-dipole magnetic spectrometer. The one-neutron and one-proton transfers to corresponding shell model states in the pairs of mirror nuclei ${}_{}{}^{29}{}_{}{}^{}\mathrm{-}_{}^{29}{}_{}{}^{}$P and ${}_{}{}^{27}{}_{}{}^{}\mathrm{-}_{}^{27}{}_{}{}^{}$Al are found to be approximately equal. The cross sections for few-nucleon transfers to states with excitation energies $E_x$<5 MeV exhibit a strong enhancement of 1n1p over 2n and 2p and of 2n2p (i.e., 1α) over 2n1p or 1n2p transfers. A distorted-wave Born approximation analysis of the 1n and 1p transfers was performed. The derived spectroscopic factors display a high degree of symmetry with respect to isospin and are consistent with the widely varying values obtained in light ion studies.

We discuss the possibility that nuclei with very large baryon numbers can exist in the form of large quark blobs in their ground states. A calculation based on the picture of quark bags shows that, in principle, the appearance of such exotic nuclear states in present laboratory experiments cannot be excluded. Some speculations in connection with the recently observed anomalous positron production in heavy-ion experiments are presented.

We study nucleus-nucleus collisions at high energy on the basis of Boltzmann’s kinetic theory under the assumption that the incident energy per nucleon is high enough for nucleon-nucleon collisions to dominate the strength of the mean field so that the latter may be treated perturbatively. Then, by use of multiple collision expansion as well as linearization techniques and the eikonal approximation, we obtain the stationary distribution function from the Boltzmann equation with the nuclear mean field as external force. The distribution consists of an infinite sum over multiple collision components. Their momentum dependent parts obey a transport equation linear in the nuclear mean force field, and can be evaluated analytically. They differ from the solution of a Fokker-Planck-type equation without external forces, obtained previously, only by a shift in the momentum caused by the nuclear mean field. The present investigation confirms a recently developed phenomenological approach which has been successful in explaining the sideward kinetic energy flow of the particles emitted in individual nucleus-nucleus collision events.

We report measurements on the angular distributions of, and correlation between, projectile and target fragments emitted in high-multiplicity, peripheral collisions of 0.85A GeV ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ nuclei with Ag(Br) nuclei. The observations are amenable to an interpretation based on elemental two-body kinematics.

Multiplicity-selected angular distributions of low-energy neutrons from collisions of 390 MeV/nucleon Ne+Pb are peaked forward, in contrast to relatively flat distributions of protons from Ne+U. A model that includes both Coulomb repulsion and composite-fragment formation accounts for the neutron and proton distributions, and the dependence on nucleon energy of the n/p ratio of inclusive cross sections. This comparison casts doubt on the interpretation of the suppression of forward proton emission as a signal of collective flow.

A method is presented for the calculation of form factors for the interaction of two axially symmetric deformed nuclei via a proximity-plus-Coulomb potential. A distorted-wave Born approximation calculation for the inelastic scattering of 150 MeV ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ from ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$ indicates that the proximity and centerline interactions produce significantly different M-substate populations in the final nuclear states.

The mean-square spin value of the compound nucleus ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cf}$ has been determined from fission fragment angular distributions for the ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{236}$U and ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{232}$Th reactions at sub-barrier bombarding energies. The anisotropy and hence the mean-square spin values are much larger than predicted by models which reproduce the cross section enhancement observed in the sub-barrier fusion excitation functions. A similar experiment with the spherical target ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ also leads to larger anisotropies and mean-square spin values than predicted by various fusion models, including an especially complete coupled channels calculation. Supplementary fragment-fragment coincidence experiments have been performed with the heavier targets to confirm that the observed fission is associated with full momentum transfer. The mass distribution for the ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{236}$U reaction has been measured at two angles and found to be independent of angle. This last result suggests that quasifission processes are not playing a significant role.

It is suggested that the deviations from pure Hauser-Feshbach predictions found in the already published analysis of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{16}$O,α) data might be due to neglect of important multistep compound contributions. An appropriate multiclass fluctuation analysis clearly indicates the presence of two correlation widths, which can be associated with the population of two classes of overlapping states: one made up of doorway states, revealed by the largest of the observed coherence widths, and another made up of compound nucleus states connected with the fine structure of the fluctuating excitation functions. This interpretation was reinforced by new measurements on both excitation functions and complete α spectra. In addition, comparison of these data with calculations based on the quantum statistical multistep compound theory confirmed the importance of precompound effects and shed light on the nature of such doorway states which were found to be made up of 5p-1h configurations. These results support the hypothesis of Voit et al. that the first interaction between such light heavy-ion systems is dominated by the formation of α-particle doorway states.

We have measured the coincidence cross sections ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$(e,e’f) at three values of momentum transfer (q≊0.26, 0.40, and 0.55 ${\mathrm{fm}}^{\mathrm{-}1}$) over the range from 5 to 23 MeV in excitation energy; these values of q correspond approximately to the first maxima of the electric dipole, quadrupole/monopole, and octupole form factors, respectively. The angular distribution of fission fragments is peaked along the direction of q near fission threshold, indicating the dominance of K=0 states, but becomes isotropic above 10 MeV. We have integrated our cross sections over fission angle and compared them to recent calculations of multipole strength derived in the quasiparticle random phase approximation. Using model-dependent form factors generated from the Tassie model and the quasiparticle random phase approximation, we have extracted strength functions for the lowest electric multipoles. The deduced E1 strength agrees well with photofission results for reasonable choices of the model form factors. The E2/E0 distribution displays resonant structures at 10 and 13 MeV which agree in position with the collective E2 and E0 strength, respectively, predicted in the quasiparticle random phase approximation. If we make such an assignment for the multipolarity of these two structures, the observed E0 strength agrees with the theoretical prediction, whereas the E2 strength is low by a factor of 2–3. Higher order multipoles also contribute substantially to the cross section at our highest value of q.

Correlation of time intervals between two modes of decay has been used to determine unequivocally the atomic and mass numbers of ${}_{}{}^{258}{}_{}{}^{}\mathrm{Fm}$, a nuclide which rapidly decays by spontaneous fission. We measured the time interval between the emission of Fm K x rays, due to electron capture by 60-min ${}_{}{}^{258}{}_{}{}^{}\mathrm{Md}_{}^{\mathrm{m}}{}_{}{}^{}$, and the detection of fission fragments from the spontaneous fission of ${}_{}{}^{258}{}_{}{}^{}\mathrm{Fm}$ to establish a genetic relationship and to determine the mean lifetime of ${}_{}{}^{258}{}_{}{}^{}\mathrm{Fm}$. We obtained a half-life of 360±20 μs, which is in good agreement with our much earlier value of 380±60 μs measured by another method.