The cross section of the ${}^{88}\mathrm{Sr}(p,\gamma {)}^{89}\mathrm{Y}$ reaction was determined by in-beam measurements at energies $E_p=1.4\mathrm{}–5\mathrm{MeV}$ relevant to the nucleosynthetic p process. At $E_p>~3.5\mathrm{MeV},$ the γ angular distributions were obtained by using one HPGe detector of 80% relative efficiency, whereas at $E_p<~3.5\mathrm{MeV}$ they were measured by means of an array of four HPGe detectors all shielded with BGO crystals for Compton background supression. Three of them had a relative efficiency ${\epsilon }_r\approx 100\%,$ whereas the remaining one had ${\epsilon }_r\approx 78\%.$ From the resulting cross sections, that lie in the 0.5-μb–5-mb range, astrophysical S factors and reaction rates have been derived. Cross sections, S factors, and reaction rates have also been calculated by means of the statistical model code MOST. A very good agreement between the experimental data and the theoretical predictions has been found.

The charge distribution of the intermediate mass fragments produced in p $\left(8.1\mathrm{}\mathrm{GeV}\right)+\mathrm{Au}$ collisions is analyzed in the framework of the statistical multifragmentation model with the critical temperature for the nuclear liquid-gas phase transition $T_c$ as a free parameter. It is found that $T_c=20\mathrm{}\pm 3\mathrm{MeV}$ (90% C.L.).

The elastic scattering of ${}^9\mathrm{Li}{+}^{12}\mathrm{C}$ and ${}^{11}\mathrm{Li}{+}^{12}\mathrm{C}$ has been measured at an incident energy of 50 MeV per nucleon over the angular range from 2° to 15° in the center-of-momentum frame. The elastic and inelastic reaction channels were cleanly separated in the critical forward-angle region where a predicted nearside/far-side interference minimum should be observed. The angular distributions obtained in this experiment are consistent with existing quasielastic measurements at 60 MeV per nucleon. In particular, the ${}^9\mathrm{Li}$ data display the interference minimum, while it is absent for ${}^{11}\mathrm{Li}.$ This difference is shown to occur in the elastic channel, and the results are discussed in terms of strongly enhanced surface refraction in the ${}^{11}\mathrm{Li}$ case.

The Doppler broadening of photons emitted during the n-p capture process in a nuclear reactor is considered in view of a new finding concerning the zero-point motion of the H atom in the sample. The kinetic energy of the H atoms of the sample was measured directly at 296 K and found to be very high, corresponding to an effective temperature of 991 K, attributable mainly to the zero-motion of the H atom. The measurement was carried out using the pulsed neutron source (ISIS) at the Rutherford Appleton Laboratory (U.K.). A simple expression for calculating the Doppler broadening of the emitted photons in terms of the kinetic energies of the neutron and the proton is deduced. The expression is applicable to any capturing nucleus and not just to the proton.

A recent paper has reported the observation of the rotational band of ${}^{254}\mathrm{No}$ for spins up to $I=20,$ showing that the compound nucleus was formed and survived fission decay at angular momenta $I>~20.$ We show that this survival is consistent with the leading effects of angular momentum on the fission barrier height.

The ${\pi }^{-}/{\pi }^{+}$ ratio is examined as a function of isospin asymmetry and beam energy for central collisions induced by neutron-rich nuclei within an isospin-dependent hadronic transport model. The ${\pi }^{-}/{\pi }^{+}$ ratio is found to increase with the isospin asymmetry, but decrease with the beam energy of the reaction. For neutron-rich systems, such as, ${}^{124}\mathrm{Sn}{+}^{124}\mathrm{Sn}$ and ${}^{132}\mathrm{Sn}{+}^{124}\mathrm{Sn},$ the sensitivity of ${\pi }^{-}/{\pi }^{+}$ ratio to nuclear symmetry energy is almost beam energy independent.

The phase-shift analysis of elastic ${\Sigma }^{+}p$ scattering at an incident energy $\left({\Sigma }^{+}\right)$ of 12 MeV has been carried out. Two kinds of solutions have been found, for which the sign of the ${}^3{S}_1$ phase shift is different. It has been found that measurement of the polarization in ${\Sigma }^{+}p$ scattering could contribute to distinguishing among various models for $\mathrm{YN}$ scattering.

We analyze the contribution of perturbative QCD based semihard parton (re)scattering to the reaction dynamics of relativistic heavy-ion collisions at SPS and RHIC. While such processes are able to account for the measured yield of high-momentum direct photons at SPS energies, the conditions necessary for jet quenching are not fulfilled. The situation changes dramatically at RHIC energies.

The reactions ${}^{152}\mathrm{Sm}(\alpha ,3n)$ at 37 MeV and ${}^{124}\mathrm{Sn}{(}^{36}\mathrm{S},\alpha 3n)$ at 165 MeV were used to produce high-spin states in the transitional rare-earth nucleus ${}^{153}\mathrm{Gd}.$ Significant extensions in angular momentum and excitation energy with respect to earlier work were achieved and several new rotational sequences were observed. The rotational behavior of ${}^{153}\mathrm{Gd}$ is described in terms of quasiparticle assignments and the observed alignment properties are analyzed within the framework of the cranked shell model. Detailed comparisons with other $N=89\mathrm{}$ nuclei are presented. These have led to corrections to the ${}^{157}\mathrm{Er}$ level scheme.

The excited states in the neutron-deficient isotopes ${}^{200,202,204}\mathrm{Rn}$ have been populated using the ${}^{168}\mathrm{Er}{(}^{36}\mathrm{Ar},4n),{}^{166}\mathrm{Er}{(}^{40}\mathrm{Ar},4n),$ and ${}^{168}\mathrm{Er}{(}^{40}\mathrm{Ar},4n)$ reactions at beam energies of 175, 182, and 177 MeV, respectively. Evaporation residues were selected using an in-flight gas-filled separator and implanted at the focal plane into a 16-element position-sensitive, passivated ion-implanted planar silicon detector. Prompt $\gamma$ rays were observed at the target position using an array of Compton-suppressed germanium detectors. Correlation with the subsequent radioactive decay of associated recoiling ions in the silicon detector, recoil-$\gamma$ and recoil-$\gamma$-$\gamma$ coincidences were used to construct decay schemes of light radon isotopes. Measurements of delayed $\gamma$ rays at the focal plane have also been made, and microsecond isomers have been observed in ${}^{200,202}\mathrm{Rn},$ but not in ${}^{204}\mathrm{Rn}.$ Comparison of the results with those for polonium isotopes indicate a common mechanism for the onset of deformation. Candidates have been found in ${}^{202,204}\mathrm{Rn}$ for deformed intruder states which coexist with the spherical ground-state shape.

In this paper we discuss in detail the $P\left(I\right)\mathrm{}’\mathrm{s},$ angular momentum I probabilities in the ground states, of many-body systems interacting via a two-body random ensemble (TBRE). In particular, we extensively apply an approach introduced in an earlier paper and compare the predicted $P\left(I\right)\mathrm{}’\mathrm{s}$ with those obtained by diagonalizing a TBRE Hamiltonian. We begin with a few solvable cases, such as fermions in a small single-$j$ shell and d boson systems, where elegant agreements between the predicted $P\left(I\right)\mathrm{}’\mathrm{s}$ and those obtained by diagonalizing a TBRE Hamiltonian are achieved. We find that d boson systems systematically present counterexamples of angular momentum 0 ground state dominance when the number of d bosons is $6\kappa \pm 1$ with $\kappa$ a natural number, which suggests that certain fundamental symmetry (say, time reversal invariance) of the Hamiltonian cannot ensure the occurrence of angular momentum 0 ground state dominance. Next, we apply the same approach to more complicated cases, such as even or odd number of fermions in a large single-$j$ shell or a many-$j$ shell, $\mathrm{sd}$-boson or $\mathrm{sdg}$-boson systems, etc. We find that the simple approach proposed in an earlier paper is also well applicable, and thus it is a universal approach. The numerical experiments provide a guideline to tell which interactions are essential to produce a sizable $P\left(I\right)\mathrm{}$ in a many-body system. This disproves a popular idea that the angular momentum 0 ground state (0 g.s.) dominance may be independent of two-body interactions. Some matrix elements which are useful to understand the observed regularities are given or addressed in detail. In this paper we also report a synchronous staggering between the 0 g.s. probabilities of even numbers of fermions in a single-$j$ shells and j g.s. probabilities of odd numbers of fermions in a single-$j$ shell when j is small. The low seniority chain of 0 g.s. using the same set of two-body interactions is confirmed, but it is noted that contribution to the total 0 g.s. probability beyond this chain may be more important for even numbers of fermions in a single-$j$ shell. Some interesting results taking a displaced two-body random ensemble are presented for the I ground state probabilities.

In this paper, we discuss the regularities of average energies with a fixed angular momentum I (denoted as $E_I’\mathrm{s})$ in many-body systems interacting via a two-body random ensemble. It is found that $E_I’\mathrm{s}$ with $I\sim I_{\min }$ (minimum of $I)$ or $I\sim I_{\max }$ (maximum of $I)$ have large probabilities [denoted as $\mathcal{P}\mathrm{}\left(I\right)\mathrm{}]$ to be the smallest in energy, and $\mathcal{P}\mathrm{}\left(I\right)\mathrm{}$ is close to zero elsewhere. A simple argument assuming the randomness of the two-particle coefficients of fractional parentage is given to explain these observations. A compact trajectory of the energy $E_I$ vs $I(I+1\mathrm{})\mathrm{}$ is found to be robust. Other regularities, such that there are two or three sizable $\mathcal{P}\mathrm{}\left(I\right)\mathrm{}’\mathrm{s}$ with $I\sim I_{\min }$ but $\mathcal{P}\mathrm{}\left(I\right)\mathrm{}\ll \mathcal{P}{(I}_{\max })’\mathrm{s}$ with $I\sim I_{\max },$ and that the coefficients C defined by $〈E_I{〉}_{\min }=CI(I+1\mathrm{})\mathrm{}$ are sensitive to the orbits and not sensitive to particle number, etc., are discovered and studied for the first time.

Strangeness enhancement in heavy-ion collisions is studied at the parton level by examining the partition of the new sea quarks generated by gluon conversion into the strange and non-strange sectors. The CTEQ parton distribution functions are used as a baseline for the quiescent sea before gluon conversion. By quark counting simple constraints are placed on the hadron yields in different channels. The experimental values of particle ratios are fitted to determine the strangeness enhancement factor. A quantitative measure of Pauli blocking is determined. Energy dependence between CERN-SPS and relativistic heavy-ion collider energies is well described. No thermal equilibrium or statistical model is assumed.

Using Dyson-Schwinger equations, the nucleon propagator is analyzed nonperturbatively in a field-theoretical model for the pion-nucleon interaction. Infinities are circumvented by using pion-nucleon form factors which define the physical scale. It is shown that the correct, finite, on-shell nucleon renormalization is important for the value of the mass shift and the propagator. For physically acceptable forms of the pion-nucleon form factor the rainbow approximation together with renormalization is inconsistent. Going beyond the rainbow approximation, the full pion-nucleon vertex is modeled by its bare part plus a one-loop correction including an effective $\Delta .$ It is found that a consistent value for the nucleon mass shift can be obtained as a consequence of a subtle interplay between wave function and vertex renormalization. Furthermore, the bare and renormalized pion-nucleon coupling constants are approximately equal, consistent with results from the cloudy bag model.

A new model is proposed for fusion mechanisms of massive nuclear systems where so-called fusion hindrance exists. The model describes two-body collision processes in an approaching phase and shape evolutions of an amalgamated system into the compound nucleus formation. It is applied to ${}^{48}\mathrm{Ca}$-induced reactions and is found to reproduce the experimental fusion cross sections extremely well, without any free parameter. Combined with the statistical decay theory, residue cross sections for the superheavy elements can be readily calculated. Examples are given.

We report the first observation of $K^{*}{\mathrm{}\left(892\right)\mathrm{}}^0\to \pi K$ in relativistic heavy ion collisions. The transverse momentum spectrum of ${(K}^{*0}+K^{*0})/2\mathrm{}$ from central $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=130\mathrm{}\mathrm{GeV}$ is presented. The ratios of the $K^{*0}$ yield derived from these data to the yields of negative hadrons, charged kaons, and $\phi$ mesons have been measured in central and minimum bias collisions and compared with model predictions and comparable $e^{+}{e}^{-},$ $pp,$ and $\overline{p}p$ results. The data indicate no dramatic reduction of $K^{*0}$ production in relativistic heavy ion collisions despite expected losses due to rescattering effects.

The large-$N_c$ nuclear potential puzzle arose because three- and higher-meson exchange contributions to the nucleon-nucleon potential did not automatically yield cancellations that make these contributions consistent with the general large-$N_c$ scaling rules for the potential. Here it is proposed that the resolution to this puzzle is that the scaling rules only apply for energy-independent potentials while all of the cases with apparent inconsistencies were for energy-dependent potentials. It is shown explicitly how energy-dependent potentials can have radically different large-$N_c$ behavior than an equivalent energy-independent one. One class of three-meson graphs is computed in which the contribution to the energy-independent potential is consistent with the general large-$N_c$ rules even though the energy-dependent potential is not.

Quantum algebras $(q$ algebras) are used to describe interactions between fermions and bosons. Particularly, the concept of a ${\mathrm{su}}_q\mathrm{}\left(2\right)\mathrm{}$ dynamical symmetry is invoked in order to reproduce the ground state properties of systems of fermions and bosons interacting via schematic forces. The structure of the proposed ${\mathrm{su}}_q\mathrm{}\left(2\right)\mathrm{}$ Hamiltonians, and the meaning of the corresponding deformation parameters, are discussed.

Lifetimes of the excited states of the ground state band in ${}^{118}\mathrm{Xe}$ are newly measured using the recoil-distance Doppler-shift technique. The reaction ${}^{93}\mathrm{Nb}{(}^{29}\mathrm{Si}{,p3n)}^{118}\mathrm{Xe}$ at a beam energy of 135 MeV was used for this experiment. The lifetimes of the $2^{+},$ $4^{+},$ $6^{+},$ $8^{+},$ and ${10}^{+}$ states of the ground state band were extracted using the computer code LIFETIME which includes the corrections due to the side feeding and the nuclear deorientation effects. The present $B\left(E2\mathrm{}\right)\mathrm{}$ values are in good agreement with the extracted $B\left(E2\mathrm{}\right)\mathrm{}$ values from the Hartee-Fock-Bogoliubov calculations. The measured $B\left(E2\mathrm{}\right)\mathrm{}$ values are also compared with the standard algebraic and the geometrical models. The $B\left(E2\mathrm{}\right)\mathrm{}$ values for the $2^{+}$ state for this nucleus and the other Xe nuclei as a function of the neutron number are well reproduced in the framework of the algebraic model IBA-1 with O(6) symmetry and the geometrical finite range droplet model.