The $\beta$ feeding probability of ${}^{102,104,105,106,107}\mathrm{Tc}$, ${}^{105}\mathrm{Mo}$, and ${}^{101}\mathrm{Nb}$ nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the $\gamma$ component of the decay heat for ${}^{239}\mathrm{Pu}$ in the 4–3000 s range.

A study of cooled ${}^{197}\mathrm{Au}$ projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides ${}^{183,184,186}\mathrm{Hf}$ and ${}^{186,187}\mathrm{Ta}$. The results support the prediction of a strongly favored isomer region near neutron number 116.

We obtained an unprecedentedly large number of $s$-wave neutron widths through $\mathcal{R}$-matrix analysis of neutron cross-section measurements on enriched Pt samples. Careful analysis of these data rejects the validity of the Porter-Thomas distribution with a statistical significance of at least 99.997%.

The symmetry energy of nuclear matter is a fundamental ingredient in the investigation of exotic nuclei, heavy-ion collisions, and astrophysical phenomena. New data from heavy-ion collisions can be used to extract the free symmetry energy and the internal symmetry energy at subsaturation densities and temperatures below 10 MeV. Conventional theoretical calculations of the symmetry energy based on mean-field approaches fail to give the correct low-temperature, low-density limit that is governed by correlations, in particular, by the appearance of bound states. A recently developed quantum-statistical approach that takes the formation of clusters into account predicts symmetry energies that are in very good agreement with the experimental data. A consistent description of the symmetry energy is given that joins the correct low-density limit with quasiparticle approaches valid near the saturation density.

We show that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons. We demonstrate that this takes place in all strongly coupled, large-$N_c$ plasmas with a gravity dual. The energy loss is exactly calculable in these models despite being an $\mathcal{O}(1/N_c)$ effect. We discuss implications for heavy-ion collision experiments.

The discovery of a new chemical element with atomic number $Z=117$ is reported. The isotopes ${}^{293}117$ and ${}^{294}117$ were produced in fusion reactions between ${}^{48}\mathrm{Ca}$ and ${}^{249}\mathrm{Bk}$. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with $Z\ge 111$, validating the concept of the long sought island of enhanced stability for superheavy nuclei.

We present lattice results for the ground state energies of tritium, helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our analysis includes isospin breaking, Coulomb effects, and interactions up to next-to-next-to-leading order in chiral effective field theory.

A first experiment is reported that makes use of a new kind of spectrometer uniquely suited to the study of reactions with radioactive beams in inverse kinematics, the helical orbit spectrometer, HELIOS. The properties of some low-lying states in the neutron-rich $N=8$ nucleus ${}^{13}\mathrm{B}$ were studied with good resolution. From the measured angular distributions of the $(d,\text{}p)$ reaction and the relative spectroscopic factors, spin and configuration assignments of the first- and third-excited states of this nucleus can be constrained.

The production of $e^{+}{e}^{-}$ pairs for $m_{e^{+}{e}^{-}}<0.3\mathrm{GeV}/c^2$ and $1<p_T<5\mathrm{GeV}/c$ is measured in $p+p$ and $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central $\mathrm{Au}+\mathrm{Au}$ collisions, the excess of the direct photon yield over $p+p$ is exponential in transverse momentum, with an inverse slope $T=221\pm {19}^{\mathrm{stat}}\pm {19}^{\mathrm{syst}}\mathrm{MeV}$. Hydrodynamical models with initial temperatures ranging from $T_{\mathrm{init}}\sim 300–600\mathrm{MeV}$ at times of $\sim 0.6–0.15\mathrm{fm}/c$ after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at $\sim 170\mathrm{MeV}$.

Reaction cross sections (${\sigma }_R$) for ${}^{19}\mathrm{C}$, ${}^{20}\mathrm{C}$ and the drip-line nucleus ${}^{22}\mathrm{C}$ on a liquid hydrogen target have been measured at around $40A\mathrm{MeV}$ by a transmission method. A large enhancement of ${\sigma }_R$ for ${}^{22}\mathrm{C}$ compared to those for neighboring C isotopes was observed. Using a finite-range Glauber calculation under an optical-limit approximation the rms matter radius of ${}^{22}\mathrm{C}$ was deduced to be $5.4\pm 0.9\mathrm{fm}$. It does not follow the systematic behavior of radii in carbon isotopes with $N\le 14$, suggesting a neutron halo. It was found by an analysis based on a few-body Glauber calculation that the two-valence neutrons in ${}^{22}\mathrm{C}$ preferentially occupy the $1s_{1/2}$ orbital.

We compare the azimuthal correlations arising from three and two hadron production in $p+p$ and $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$. We show that in $\mathrm{Au}+\mathrm{Au}$, the two away side partons in two-to-three processes have in average a smaller and a greater path length than the average path length of the away-side parton in two-to-two processes. Since in average the particle with the shortest path length in two-to-three processes loses less energy, with respect to the away-side particle in two-to-two processes, this effect leads to a relative enhancement of the ratio of two-to-three to two-to-two processes in $\mathrm{Au}+\mathrm{Au}$ compared to $p+p$ collisions. We argue that this phenomenon may be responsible for the shape of the away side in azimuthal correlations at the Relativistic Heavy-Ion Collider.

Excited states in ${}^{212}\mathrm{Po}$ were populated by $\alpha$ transfer using the ${}^{208}\mathrm{Pb}({}^{18}\mathrm{O},{}^{14}\mathrm{C})$ reaction, and their deexcitation $\gamma$ rays were studied with the Euroball array. Several levels were found to decay by a unique $E1$ transition ($E_{\gamma }<1\mathrm{MeV}$) populating the yrast state with the same spin value. Their lifetimes were measured by the Doppler-shift attenuation method. The values, found in the range 0.1–1.4 ps, lead to very enhanced transitions, $B(E1)=2\times {10}^{-2}–1\times {10}^{-3}\mathrm{W}.\mathrm{u}.$ These results are discussed in terms of an $\alpha$-cluster structure which gives rise to states with non-natural-parity values, provided that the composite system cannot rotate collectively, as expected in the “$\alpha +{}^{208}\mathrm{Pb}$” case. Such states due to the oscillatory motion of the $\alpha$-core distance are observed for the first time.

Novel simple properties of the monopole component of effective nucleon-nucleon interactions are presented, leading to the so-called monopole-based universal interaction. Shell structures are shown to change as functions of $N$ and $Z$, consistent with experiments. Some key cases of this shell evolution are discussed, clarifying the effects of central and tensor forces. The validity of the present tensor force is examined in terms of the low-momentum interaction $V_{\mathrm{lowk}}$ and the $Q_{\mathrm{box}}$ formalism.

A modern variation of the Rutherford experiment to probe the tunneling of exotic nuclear matter from the measurement of the residues formed in the bombardment of ${}^{197}\mathrm{Au}$ by extremely neutron-rich ${}^8\mathrm{He}$ nuclei is presented. Using a novel off-beam technique the most precise and accurate measurements of fusion and neutron transfer involving reaccelerated unstable beams are reported. The results show unusual behavior of the tunneling of ${}^8\mathrm{He}$ compared to that for lighter helium isotopes, highlighting the role of the intrinsic structure of composite many-body quantum systems and pairing correlations.

New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from ${}^2\mathrm{H}$, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, ${}^9\mathrm{Be}$ and ${}^{12}\mathrm{C}$ for $0.3<x<0.9$, $Q^2\approx 3–6{\mathrm{GeV}}^2$. These data represent the first measurement of the EMC effect for ${}^3\mathrm{He}$ at large $x$ and a significant improvement for ${}^4\mathrm{He}$. The data do not support previous $A$-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.

Present ultrafast laser optics is at the frontier between atto- and zeptosecond photon pulses, giving rise to unprecedented applications. We show that high-energetic photon pulses down to the yoctosecond time scale can be produced in heavy-ion collisions. We focus on photons produced during the initial phase of the expanding quark-gluon plasma. We study how the time evolution and properties of the plasma may influence the duration and shape of the photon pulse. Prospects for achieving double-peak structures suitable for pump-probe experiments at the yoctosecond time scale are discussed.

For the first time, in-gas-cell laser spectroscopy study of the ${}^{57,59,63,65}\mathrm{Cu}$ isotopes has been performed using the 244.164 nm optical transition from the atomic ground state of copper. The nuclear magnetic dipole moments for ${}^{57,59,65}\mathrm{Cu}$ relative to that of ${}^{63}\mathrm{Cu}$ have been extracted. The new value for ${}^{57}\mathrm{Cu}$ of $\mu ({}^{57}\mathrm{Cu})=+2.582(7){\mu }_N$ is in strong disagreement with the previous literature value but in good agreement with recent theoretical and systematic predictions.

We report results from a search for strangelets (small chunks of strange quark matter) in lunar soil using the Yale WNSL accelerator as a mass spectrometer. We have searched over a range in mass from $A=42$ to $A=70\mathrm{amu}$ for nuclear charges 5, 6, 8, 9, and 11. No strangelets were found in the experiment. For strangelets with nuclear charge 8, a concentration in lunar soil higher than ${10}^{-16}$ is excluded at the 95% confidence level. The implied limit on the strangelet flux in cosmic rays is the most sensitive to date for the covered range and is relevant to both recent theoretical flux predictions and a strangelet candidate event found by the AMS-01 experiment.

The momentum transfer $\Delta k$ required for a photon to scatter from a target and emerge as a ${\rho }^0$ decreases as the photon energy $k$ rises. For $k>3\times {10}^{14}\mathrm{eV}$, $\Delta k$ is small enough that the interaction cannot be localized to a single nucleus. At still higher energies, photons may coherently scatter elastically from bulk matter and emerge as a ${\rho }^0$, in a manner akin to kaon regeneration. Constructive interference from the different nuclei coherently raises the cross section and the interaction probability rises linearly with energy. At energies above ${10}^{23}\mathrm{eV}$, coherent conversion is the dominant process; photons interact predominantly as ${\rho }^0$. We compute the coherent scattering probabilities in slabs of lead, water, and rock, and discuss the implications of the increased hadronic interaction probabilities for photons on ultrahigh energy shower development.

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.