Shape coexistence in the nuclei ${}^{182\mathrm{\text{−}}192}\mathrm{P}\mathrm{b}$ is analyzed with the Hartree-Fock-Bogoliubov approach and the Gogny force. Good agreement with the experimental energies is found for the coexisting spherical, oblate, and prolate states. Contrary to the established interpretation, it is found that the low-lying prolate and oblate $0^{+}$ states are predominantly characterized by neutron correlations whereas the protons behave, in general, rather as spectators than playing an active role.

The measured pseudorapidity distribution of primary charged particles in minimum-bias $d+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{s_{NN}}=\mathrm{200}\mathrm{G}\mathrm{e}\mathrm{V}$ is presented for the first time. This distribution falls off less rapidly in the gold direction as compared to the deuteron direction. The average value of the charged particle pseudorapidity density at midrapidity is $\langle d{N}_{\mathrm{c}\mathrm{h}}/d\eta {\rangle }_{\mid \eta \mid \le 0.6}=9.4\pm 0.7(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})$ and the integrated primary charged particle multiplicity in the measured region is $82\pm 6(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})$. Estimates of the total charged particle production, based on extrapolations outside the measured pseudorapidity region, are also presented. The pseudorapidity distribution, normalized to the number of participants in $d+\mathrm{A}\mathrm{u}$ collisions, is compared to those of $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ and $p+\overline{p}$ systems at the same energy. The $d+\mathrm{A}\mathrm{u}$ distribution is also compared to the predictions of the parton saturation model, as well as microscopic models.

We study neutrino-induced nucleon knockout from nuclei. Expressions for the induced polarization are derived within the framework of the independent-nucleon model and the nonrelativistic plane-wave approximation. Large dissimilarities in the nucleon polarization asymmetries are observed between neutrino- and antineutrino-induced processes. These asymmetries represent a potential way to distinguish between neutrinos and antineutrinos in neutral-current neutrino scattering on nuclei. We discuss astrophysical applications of these polarization asymmetries. Our findings are illustrated for neutrino scattering on ${}^{\mathrm{16}}\mathrm{O}$ and ${}^{\mathrm{208}}\mathrm{P}\mathrm{b}$.

A new experimental approach is introduced to investigate the relaxation of the nuclear deformation degrees of freedom. Highly excited fissioning systems with compact shapes and low angular momenta are produced in peripheral relativistic heavy-ion collisions. Both fission fragments are identified in atomic number. Fission cross sections and fission-fragment element distributions are determined as a function of the fissioning element. From the comparison of these new observables with a nuclear-reaction code a value for the transient time is deduced.

The decay energy of the superallowed $\beta$ decay ${}^{74}\mathrm{R}\mathrm{b}({\beta }^{+}){}^{74}\mathrm{K}\mathrm{r}$ was determined by direct Penning trap mass measurements on both the mother and the daughter nuclide using the time-of-flight resonance technique and was found to be $Q=10416.8(4.5)\mathrm{k}\mathrm{e}\mathrm{V}$. The exotic nuclide ${}^{74}\mathrm{R}\mathrm{b}$, with a half-life of only 65 ms, is the shortest-lived nuclide on which a high-precision mass measurement in a Penning trap has been carried out. Together with existing data for the partial half-life as well as theoretical corrections, the decay energy yields a comparative half-life of $Ft=3084(15)\mathrm{s}$ for this decay, in agreement with the mean value for the series of the lighter nuclides from ${}^{10}\mathrm{C}$ to ${}^{54}\mathrm{C}\mathrm{o}$. Assuming conserved vector current, this result allows for an experimental determination of the isospin-symmetry-breaking correction ${\delta }_{\mathrm{C}}$.

Multiple scattering, modified fragmentation functions, and radiative energy loss of a heavy-quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy-quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark.

Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope ${}^{23}\mathrm{O}$. The ${}^{22}\mathrm{O}$ fragments produced in one-nucleon removal from ${}^{23}\mathrm{O}$ at $938\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{\text{nucleon}}$ in a carbon target were detected in coincidence with deexciting $\gamma$ rays. The widths of the longitudinal momentum distributions of the ${}^{22}\mathrm{O}$ fragments and the one-neutron removal cross sections were interpreted in the framework of a simple theoretical model which favors the assignment of $I^{\pi }=1/2^{+}$ to the ${}^{23}\mathrm{O}$ ground state.

Kaon in-medium masses and mean-field potentials are calculated in isotopically symmetric pion matter to one loop of chiral perturbation theory. The results are extended to BNL RHIC temperatures using experimental data on $\pi K$ scattering phase shifts. The kaon in-medium broadening results in an acceleration of the $\varphi \to K\overline{K}$ decay. The increased apparent dilepton branching of the $\varphi$ mesons, observed recently by the NA50, NA49, and PHENIX Collaborations at RHIC, is interpreted in terms of rescattering of secondary kaons inside the pion matter.

Self-consistent solutions for the so-called planar and chiral rotational bands in ${}^{132}\mathrm{L}\mathrm{a}$ are obtained for the first time within the Skyrme-Hartree-Fock cranking approach. It is suggested that the chiral rotation cannot exist below a certain critical frequency which under the approximations used is estimated as $\hslash {\omega }_{\mathrm{c}\mathrm{r}\mathrm{i}\mathrm{t}}\approx 0.5–0.6\mathrm{M}\mathrm{e}\mathrm{V}$. However, the exact values of $\hslash {\omega }_{\mathrm{c}\mathrm{r}\mathrm{i}\mathrm{t}}$ may vary, to an extent, depending on the microscopic model used, in particular, through the pairing correlations and/or calculated equilibrium deformations. The existence of the critical frequency is explained in terms of a simple classical model of two gyroscopes coupled to a triaxial rigid body.

The slowing-down process of pointlike charged particles in matter has been investigated by measuring the stopping power for antiprotons in materials of qualitatively very different nature. Whereas the velocity-proportional stopping power observed for metal-like targets such as aluminum over a wide energy range of 1–50 keV is in agreement with expectations, it is surprising that the same velocity dependence is seen for a large band-gap insulator such as LiF. The validity of these observations is supported by several measurements with protons and several checks of the target properties. The observations call for both a qualitative explanation and a quantitative theoretical model.

Medium-induced parton energy loss is widely considered to underlie the suppression of high-$p_t$ leading hadron spectra in $\sqrt{s_{NN}}=200\mathrm{G}\mathrm{e}\mathrm{V}$ $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at the Relativistic Heavy Ion Collider (RHIC). Its description implies a characteristic $k_t$ broadening of the subleading hadronic fragments associated with the hard parton. However, this latter effect is more difficult to measure and has remained elusive so far. Here, we discuss how it affects genuine jet observables, which are accessible at the Large Hadron Collider and possibly at RHIC. We find that the $k_t$ broadening of jet multiplicity distributions provides a very sensitive probe of the properties of dense QCD matter, whereas the sensitivity of jet energy distributions is much weaker. In particular, the sensitive kinematic range of jet multiplicity distributions is almost unaffected by the high multiplicity background.

The ${}^9\mathrm{B}\mathrm{e}({}^{32}\mathrm{A}\mathrm{r},{}^{31}\mathrm{A}\mathrm{r})X$ reaction, leading to the ${\frac{5}{2}}^{+}$ ground state of a nucleus at the proton drip line, has a cross section of 10.4(13) mb at a beam energy of $65.1\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{\text{nucleon}}$. This translates into a spectroscopic factor that is only 24(3)% of that predicted by the many-body shell-model theory. We introduce refinements to the eikonal reaction theory used to extract the spectroscopic factor to clarify that this very strong reduction represents an effect of nuclear structure. We suggest that it reflects correlation effects linked to the high neutron separation energy (22.0 MeV) for this state.

Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and $158A\mathrm{G}\mathrm{e}\mathrm{V}$ beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The $\Lambda /\pi$ ratio at midrapidity and in full phase space shows a pronounced maximum between the highest BNL Alternating Gradient Synchrotron and $40A\mathrm{G}\mathrm{e}\mathrm{V}$ CERN Super Proton Synchrotron energies, whereas the $\overline{\Lambda }/\pi$ ratio exhibits a monotonic increase.

The $\gamma$ decay in the quasicontinuum from selected configurations of the rotational nucleus ${}^{163}\mathrm{E}\mathrm{r}$ has been measured with the EUROBALL array. A new analysis technique has allowed for the first time to directly measure the compound and rotational damping widths ${\Gamma }_{\mu }$ and ${\Gamma }_{\mathrm{r}\mathrm{o}\mathrm{t}}$. Values of ${\Gamma }_{\mu }\approx 20\mathrm{k}\mathrm{e}\mathrm{V}$ and ${\Gamma }_{\mathrm{r}\mathrm{o}\mathrm{t}}\approx 200\mathrm{k}\mathrm{e}\mathrm{V}$ are obtained in the spin region $I\approx 30–40\mathrm{\hbar }$, in good agreement with microscopic cranked shell model calculations. A dependence of ${\Gamma }_{\mu }$ and ${\Gamma }_{\mathrm{r}\mathrm{o}\mathrm{t}}$ on the $K$-quantum number of the nuclear states is also presented.

Two-particle correlations of direct photons were measured in central ${}^{208}\mathrm{P}\mathrm{b}+{}^{208}\mathrm{P}\mathrm{b}$ collisions at $158A\mathrm{G}\mathrm{e}\mathrm{V}$. The invariant interferometric radii were extracted for $100<K_T<300\mathrm{M}\mathrm{e}\mathrm{V}/c$ and compared to radii extracted from charged pion correlations. The yield of soft direct photons, $K_T<300\mathrm{M}\mathrm{e}\mathrm{V}/c$, was extracted from the correlation strength and compared to theoretical calculations.

We present the results of a systematic study of the shape of the pion distribution in coordinate space at freeze-out in $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at BNL RHIC using two-pion Hanbury Brown–Twiss (HBT) interferometry. Oscillations of the extracted HBT radii versus emission angle indicate sources elongated perpendicular to the reaction plane. The results indicate that the pressure and expansion time of the collision system are not sufficient to completely quench its initial shape.

Fusion-evaporation cross sections for ${}^{64}\mathrm{N}\mathrm{i}+{}^{64}\mathrm{N}\mathrm{i}$ have been measured down to the 10 nb level. For fusion between two open-shell nuclei, this is the first observation of a maximum in the $S$-factor, which signals a strong sub-barrier hindrance. A comparison with the ${}^{58}\mathrm{N}\mathrm{i}+{}^{58}\mathrm{N}\mathrm{i}$, ${}^{58}\mathrm{N}\mathrm{i}+{}^{60}\mathrm{N}\mathrm{i}$, and ${}^{58}\mathrm{N}\mathrm{i}+{}^{64}\mathrm{N}\mathrm{i}$ systems indicates a strong dependence of the energy where the hindrance occurs on the stiffness of the interacting nuclei.

Configuration-constrained calculations of potential-energy surfaces in even-even superheavy nuclei reveal systematically the existence at low excitation energies of multiquasiparticle states with deformed axially symmetric shapes and large angular momenta. These results indicate the prevalence of long-lived, multiquasiparticle isomers. In a quantal system, the ground state is usually more stable than the excited states. In contrast, in superheavy nuclei the multiquasiparticle excitations decrease the probability for both fission and $\alpha$ decay, implying enhanced stability. Hence, the systematic occurrence of multiquasiparticle isomers may become crucial for future production and study of even heavier nuclei. The energies of multiquasiparticle states and their $\alpha$ decays are calculated and compared to available data.

The angular-momentum induced transition from a deformed state of collective rotation to a noncollective configuration has been studied. In ${}^{157}\mathrm{Er}$ this transition manifests itself as favored band termination near $I=45\hslash$. The feeding of these band terminating states has been investigated for the first time using the Gammasphere spectrometer. Many weakly populated states lying at high excitation energy that decay into these special states have been discovered. Cranked Nilsson-Strutinsky calculations suggest that these states arise from weakly collective “core-breaking” configurations.

We present a complete systematics (excitation functions and system-size dependences) of global stopping and side flow for heavy ion reactions in the energy range between $0.09A$ and $1.93A\mathrm{GeV}$. For the heaviest system, $\mathrm{Au}+\mathrm{Au}$, we observe a plateau of maximal stopping extending from about $0.2A$ to $0.8A\mathrm{GeV}$ with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amount of side flow.