The first measurement of the momentum distribution for one-neutron removal from ${}^{24}\mathrm{O}$ at $920A\mathrm{MeV}$ performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of $99\pm 4\mathrm{MeV}/c$ in the projectile rest frame and a one-neutron removal cross section of $63\pm 7\mathrm{mb}$. The results are well explained with a nearly pure $2s_{1/2}$ neutron spectroscopic factor of $1.74\pm 0.19$ within the eikonal model. This large $s$-wave probability shows a spherical shell closure thereby confirming earlier suggestions that ${}^{24}\mathrm{O}$ is a new doubly magic nucleus.

The $A/Z$ dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of ${}^{124}\mathrm{Sn}$ and radioactive beams of ${}^{124}\mathrm{La}$ and ${}^{107}\mathrm{Sn}$ at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the $A/Z$ of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects ($\Delta T\approx 0.6\mathrm{MeV}$) appear for residue production near the onset of multifragmentation.

The energetic properties of nuclear clusters inside a low-density, finite-temperature medium are studied with a lattice gas model including isospin dependence and Coulomb forces. Important deviations are observed with respect to the Fisher approximation of an ideal gas of noninteracting clusters, but a simple modified energy-density functional can still describe the global energetics. The multifragmentation regime is dominated by combinatorial effects, but the isoscaling of the largest fragment appears to be a promising observable for the experimental measurement of the symmetry energy.

The $V_{ud}$ element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix has traditionally been determined from the analysis of data in nuclear superallowed $0^{+}\to 0^{+}$ transitions, neutron decay, and pion beta decay. After providing a new test of the conserved vector current hypothesis, we present here a new independent determination of $|V_{ud}|$ from a set of five $T=1/2$ nuclear mirror transitions. The extracted value, $|V_{ud}|=0.9719\pm 0.0017$, is at 1.2 combined standard deviations from the value obtained from superallowed $0^{+}\to 0^{+}$ transitions and has a precision comparable to the value obtained from neutron decay experiments.

The $\beta$-delayed neutron branching ratios ($P_{\beta n}$) for nuclei near doubly magic ${}^{78}\mathrm{Ni}$ have been directly measured using a new method combining high-resolution mass separation, reacceleration, and digital $\beta \mathrm{\text{−}}\gamma$ spectroscopy of ${}^{238}\mathrm{U}$ fission products. The $P_{\beta n}$ values for the very neutron-rich isotopes ${}^{76–78}\mathrm{Cu}$ and ${}^{83}\mathrm{Ga}$ were found to be much higher than previously reported and predicted. Revised calculations of the $\beta n$ process, accounting for new mass measurements and an inversion of the $\pi 2p_{3/2}$ and $\pi 1f_{5/2}$ orbitals, are in better agreement with these new experimental results.

We present the first measurements of the pseudorapidity distribution of primary charged particles in $\mathrm{Cu}+\mathrm{Cu}$ collisions as a function of collision centrality and energy, $\sqrt{s_{NN}}=22.4$, 62.4, and 200 GeV, over a wide range of pseudorapidity, using the PHOBOS detector. A comparison of $\mathrm{Cu}+\mathrm{Cu}$ and $\mathrm{Au}+\mathrm{Au}$ results shows that the total number of produced charged particles and the rough shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants. More detailed studies reveal that a more precise matching of the shape of the $\mathrm{Cu}+\mathrm{Cu}$ and $\mathrm{Au}+\mathrm{Au}$ pseudorapidity distributions over the full range of pseudorapidity occurs for the same $N_{\mathrm{part}}/2A$ rather than the same $N_{\mathrm{part}}$. In other words, it is the collision geometry rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence at RHIC energies.

The results of measurements of the production of neutron-rich nuclei by the fragmentation of a ${}^{76}\mathrm{Ge}$ beam are presented. The cross sections were measured for a large range of nuclei including 15 new isotopes that are the most neutron-rich nuclides of the elements chlorine to manganese (${}^{50}\mathrm{Cl}$, ${}^{53}\mathrm{Ar}$, ${}^{55,56}\mathrm{K}$, ${}^{57,58}\mathrm{Ca}$, ${}^{59,60,61}\mathrm{Sc}$, ${}^{62,63}\mathrm{Ti}$, ${}^{65,66}\mathrm{V}$, ${}^{68}\mathrm{Cr}$, ${}^{70}\mathrm{Mn}$). The enhanced cross sections of several new nuclei relative to a simple thermal evaporation framework, previously shown to describe similar production cross sections, indicates that nuclei in the region around ${}^{62}\mathrm{Ti}$ might be more stable than predicted by current mass models and could be an indication of a new island of inversion similar to that centered on ${}^{31}\mathrm{Na}$.

Sudden single-nucleon removal reactions from fast radioactive beams are now key to studies of the structure of rare isotopes. The sensitivity of the heavy residue’s parallel momentum distribution to the orbital angular momentum of the removed nucleon is a crucial feature with a high spectroscopic value. Two-nucleon removal reactions provide experimental reach toward the rarest nuclear species. We show that the residue parallel momentum distributions in these reactions offer a clear spectroscopic signal of the angular momentum of the pair of nucleons removed, and thus of the residue final state spins and spectroscopy. Our formalism is applied successfully to new final-state-inclusive measurements of like-nucleon pair removal reactions to states in neutron-rich ${}^{36}\mathrm{Mg}$ and neutron-deficient ${}^{20}\mathrm{Mg}$. We also confront a new final-state-exclusive decomposition of two-proton knockout data to states in neutron-rich ${}^{26}\mathrm{Ne}$.

High-precision Penning-trap mass measurements of the $N\approx Z\approx 34$ nuclides ${}^{68}\mathrm{Se}$, ${}^{70}\mathrm{Se}$, ${}^{70m}\mathrm{Br}$, and ${}^{71}\mathrm{Br}$ were performed, reaching experimental uncertainties of 0.5–15 keV. The new and improved mass data together with theoretical Coulomb displacement energies were used as input for $rp$ process network calculations. An increase in the effective lifetime of the waiting point nucleus ${}^{68}\mathrm{Se}$ was found, and more precise information was obtained on the luminosity during a type I x-ray burst along with the final elemental abundances after the burst.

Time-resolved Schottky mass spectrometry has been applied to uranium projectile fragments which yielded the mass value for the ${}^{208}\mathrm{Hg}$ ($Z=80$, $N=128$) isotope. The mass excess value of $\mathrm{ME}=-13265(31)\mathrm{keV}$ has been obtained, which has been used to determine the proton-neutron interaction strength in ${}^{210}\mathrm{Pb}$, as a double difference of atomic masses. The results show a dramatic variation of the strength for lead isotopes when crossing the $N=126$ neutron shell closure, thus confirming the empirical predictions that this interaction strength is sensitive to the overlap of the wave functions of the last valence neutrons and protons.

We describe a relation between the symmetry energy coefficients $c_{\mathrm{sym}}(\rho )$ of nuclear matter and $a_{\mathrm{sym}}(A)$ of finite nuclei that accommodates other correlations of nuclear properties with the low-density behavior of $c_{\mathrm{sym}}(\rho )$. Here, we take advantage of this relation to explore the prospects for constraining $c_{\mathrm{sym}}(\rho )$ of systematic measurements of neutron skin sizes across the mass table, using as example present data from antiprotonic atoms. The found constraints from neutron skins are in harmony with the recent determinations from reactions and giant resonances.

Collisions involving ${}^{112}\mathrm{Sn}$ and ${}^{124}\mathrm{Sn}$ nuclei have been simulated with the improved quantum molecular dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at subnormal density are obtained. The results from the present work are compared to constraints put forward in other recent analyses.

The expanded level structure of ${}^{240}\mathrm{Pu}$ available from the present study highlights the role of strong octupole correlations in this nucleus. In addition to a delayed alignment in the yrast band, the observations include the presence of both $I^{+}\to (I-1{)}^{-}$ and $I^{-}\to (I-1{)}^{+}E1$ transitions linking states of the yrast and negative-parity bands at high spin and the presence of an additional even-spin, positive-parity band deexciting exclusively to the negative-parity sequence. The observations appear to be consistent with expectations based on the recently proposed concept of octupole phonon condensation.

A generic procedure is proposed to construct many-body quantum Hamiltonians with partial dynamical symmetry. It is based on a tensor decomposition of the Hamiltonian and allows the construction of a hierarchy of interactions that have selected classes of solvable states. The method is illustrated in the SO(6) limit of the interacting boson model of atomic nuclei and applied to the nucleus ${}^{196}\mathrm{Pt}$.

The masses of the neutron-rich radon isotopes ${}^{223–229}\mathrm{Rn}$ have been determined for the first time, using the ISOLTRAP setup at CERN ISOLDE. In addition, this experiment marks the first discovery of a new nuclide, ${}^{229}\mathrm{Rn}$, by Penning-trap mass measurement. The new, high-accuracy data allow a fine examination of the mass surface, via the valence-nucleon interaction $\delta V_{pn}$. The results reveal intriguing behavior, possibly reflecting either a $N=134$ subshell closure or an octupolar deformation in this region.

${}^{40}\mathrm{Ca}+{}^{40,48}\mathrm{Ca},{}^{46}\mathrm{Ti}$ reactions at $25\mathrm{MeV}/\mathrm{\text{nucleon}}$ have been studied using the $4\pi$ CHIMERA detector. An isospin effect on the competition between fusionlike and binarylike reaction mechanisms has been observed. The probability of producing a heavy residue is lower in the case of $N\approx Z$ colliding systems as compared to the case of reactions induced on the neutron rich ${}^{48}\mathrm{Ca}$ target. Predictions based on constrained molecular dynamics II calculations show that the competition between fusionlike and binary reactions in the selected centrality bins can constrain the parametrization of the symmetry energy and its density dependence in the nuclear equation of state.

In ultraperipheral relativistic heavy-ion collisions, a photon from the electromagnetic field of one nucleus can fluctuate to a quark-antiquark pair and scatter from the other nucleus, emerging as a ${\rho }^0$. The ${\rho }^0$ production occurs in two well-separated (median impact parameters of 20 and 40 F for the cases considered here) nuclei, so the system forms a two-source interferometer. At low transverse momenta, the two amplitudes interfere destructively, suppressing ${\rho }^0$ production. Since the ${\rho }^0$ decays before the production amplitudes from the two sources can overlap, the two-pion system can only be described with an entangled nonlocal wave function, and is thus an example of the Einstein-Podolsky-Rosen paradox. We observe this suppression in 200 GeV per nucleon-pair gold-gold collisions. The interference is $87\%\pm 5\%(\mathrm{stat}.)\pm 8\%(\mathrm{syst}.)$ of the expected level. This translates into a limit on decoherence due to wave function collapse or other factors of 23% at the 90% confidence level.

We show that far zone Mach and diffusion wake “holograms” produced by supersonic strings in anti–de Sitter space/conformal field theory (AdS/CFT) correspondence do not lead to observable conical angular correlations in the strict $N_c\to \infty$ supergravity limit if Cooper-Frye hadronization is assumed. However, a special nonequilibrium “neck” zone near the jet is shown to produce an apparent sonic boom azimuthal angle distribution that is roughly independent of the heavy quark’s velocity. Our results indicate that a measurement of the dependence of the away-side correlations on the velocity of associated identified heavy quark jets at the BNL Relativistic Heavy Ion Collider and CERN LHC will provide a direct test of the nonperturbative dynamics involved in the coupling between jets and the strongly coupled quark-gluon plasma implied by AdS/CFT correspondence.

We carried out a demonstrative electron scattering experiment using a novel ion-trap target exclusively developed for short-lived highly unstable nuclei. Using stable ${}^{133}\mathrm{Cs}$ ion as a target, this experiment completely mimicked electron scattering off short-lived nuclei. Achieving a luminosity higher than ${10}^{26}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ with around only ${10}^6$ trapped ions on the electron beam, the angular distribution of elastic scattering was successfully measured. This experiment clearly demonstrates that electron scattering off rarely produced short-lived nuclei is practical with this target technique.

The $\gamma$ decay from Coulomb excitation of ${}^{68}\mathrm{Ni}$ at $600\mathrm{MeV}/\mathrm{\text{nucleon}}$ on a Au target was measured using the RISING setup at the fragment separator of GSI. The ${}^{68}\mathrm{Ni}$ beam was produced by a fragmentation reaction of ${}^{86}\mathrm{Kr}$ at $900\mathrm{MeV}/\mathrm{\text{nucleon}}$ on a ${}^9\mathrm{Be}$ target and selected by the fragment separator. The $\gamma$ rays produced at the Au target were measured with HPGe detectors at forward angles and with ${\mathrm{BaF}}_2$ scintillators at backward angles. The measured spectra show a peak centered at approximately 11 MeV, whose intensity can be explained in terms of an enhanced strength of the dipole response function (pygmy resonance). Such pygmy structure has been predicted in this unstable neutron-rich nucleus by theory.