Using the REX-ISOLDE facility at CERN the Coulomb excitation cross sections for the $0_{\mathrm{gs}}^{+}\to 2_1^{+}$ transition in the $\beta$-unstable isotopes ${}^{100,102,104}\mathrm{Cd}$ have been measured for the first time. Two different targets were used, which allows for the first extraction of the static electric quadrupole moments $Q(2_1^{+})$ in ${}^{102,104}\mathrm{Cd}$. In addition to the $B(E2)$ values in ${}^{102,104}\mathrm{Cd}$, a first experimental limit for the $B(E2)$ value in ${}^{100}\mathrm{Cd}$ is presented. The data was analyzed using the maximum likelihood method. The provided probability distributions impose a test for theoretical predictions of the static and dynamic moments. The data are interpreted within the shell-model using realistic matrix elements obtained from a $G$-matrix renormalized CD-Bonn interaction. In view of recent results for the light Sn isotopes the data are discussed in the context of a renormalization of the neutron effective charge. This study is the first to use the reorientation effect for post-accelerated short-lived radioactive isotopes to simultaneously determine the $B(E2)$ and the $Q(2_1^{+})$ values.

The development of a continuum-bin scheme of discretization for three-body projectiles is necessary for studies of reactions of Borromean nuclei such as ${}^6\mathrm{He}$ within the continuum-discretized coupled-channels approach. Such a procedure, for constructing bin states on selected continuum energy intervals, is formulated and applied for the first time to reactions of a three-body projectile. The continuum representation uses the eigenchannel expansion of the three-body $S$ matrix. The method is applied to the challenging case of the ${}^6\mathrm{He}+{}^{208}\mathrm{Pb}$ reaction at 22 MeV, where an accurate treatment of both the Coulomb and the nuclear interactions with the target is necessary.

We investigate the photoproduction of $\rho$ mesons in ultraperipheral heavy ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC) energies in the dipole approach and within two phenomenological models based on the color glass condensate (CGC) formalism. We estimate the integrated cross section and rapidity distribution for meson production and compare our predictions with the data from the STAR Collaboration. In particular, we demonstrate that the total cross section at RHIC is strongly dependent on the energy behavior of the dipole-target cross section at low energies, which is not well determined in the dipole approach. In contrast, the predictions at midrapidities at RHIC and in the full rapidity at LHC are under theoretical control and can be used to test QCD dynamics at high energies.

Experimental $\alpha$ decay energies and half-lives are investigated systematically to extract $\alpha$ particle preformation in heavy nuclei. Formulas for the preformation factors are proposed that can be used to guide microscopic studies on preformation factors and perform accurate calculations of the $\alpha$ decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei.

The angular distributions of protons and $\alpha$ particles emitted in ${}^6\mathrm{Li}(d,p){}^7\mathrm{Li}$, ${}^6\mathrm{Li}(d,\alpha ){}^4\mathrm{He}$, and ${}^7\mathrm{Li}(d,\alpha ){}^5\mathrm{He}$(g.s.) reactions induced by 100 keV deuterons were studied at ${30}^{°}$, ${50}^{°}$, ${90}^{°}$, ${120}^{°}$, and ${140}^{°}$ laboratory angles. The differential cross sections and the total reaction cross sections have been estimated from the measured angular distribution data.

We report the preparation of a ${}^{83}\mathrm{Kr}{}^m$ source and its use in calibrating a liquid xenon detector. ${}^{83}\mathrm{Kr}{}^m$ atoms were produced through the decay of ${}^{83}\mathrm{Rb}$ and introduced into liquid xenon. Decaying ${}^{83}\mathrm{Kr}{}^m$ nuclei were detected through liquid xenon scintillation. Conversion electrons with energies of 9.4 and 32.1 keV from the decay of ${}^{83}\mathrm{Kr}{}^m$ were observed. This calibration source will allow the characterization of the response of noble liquid detectors at low energies. ${}^{83}\mathrm{Kr}{}^m$ may also be useful for measuring fluid flow dynamics, both to understand purification in noble liquid-based particle detectors, as well as for studies of classical and quantum turbulence in superfluid helium.

Recently, $0^{+}$ excitations, especially in the rare-earth region, were studied extensively. We extend this work by studying the excited $0^{+}$ states in ${}^{170}\mathrm{Yb}$ using the ${}^{172}\mathrm{Yb}$$(p,t)$${}^{170}\mathrm{Yb}$ reaction. Eighteen excited $0^{+}$ states, 14 of which are new, are observed up to an energy of $3.5$ MeV. The results are analyzed using the $\mathit{sd}$ and $\mathit{spdf}$ interacting boson models.

A new isomer with a half-life of $0.48(2)$ ms was identified in the nuclide ${}^{181}\mathrm{Hg}$, which was produced in the complete fusion reaction ${}^{40}\mathrm{Ca}+{}^{144}\mathrm{Sm}\to {}^{184}\mathrm{Pb}$${}^{*}$ at the velocity filter SHIP (GSI, Darmstadt). The isomeric state was tentatively assigned a spin-parity of $13/2^{+}$. We propose that this isomer de-excites by a yet unobserved low-energy, strongly converted $\gamma$-ray transition, followed by a newly identified cascade composed of a $90.3$ keV $M1$ and a $71.4$ keV $E2$ $\gamma$-ray transition.

The particle number projected BCS (PBCS) approximation is tested against the exact solution of the SO(5) Richardson-Gaudin model for isovector pairing in a system of nondegenerate single-particle orbits. Two isovector PBCS wave functions are considered. One is constructed as a single proton-neutron pair condensate; the other corresponds to a product of a neutron pair condensate and a proton pair condensate. The PBCS equations are solved using a recurrence method and the analysis is performed for systems with an equal number of neutrons and protons distributed in a sequence of equally spaced fourfold (spin-isospin) degenerate levels. The results show that although PBCS offers significant improvement over BCS, the agreement of PBCS with the exact solution is less satisfactory than in the case of the SU(2) Richardson model for pairing between like particles.

High-statistics differential cross sections for the reactions $\gamma p\to p\eta$ and $\gamma p\to p{\eta }^{\text{'}}$ have been measured using the CEBAF large acceptance spectrometer (CLAS) at Jefferson Lab for center-of-mass energies from near threshold up to 2.84 GeV. The ${\eta }^{\text{'}}$ results are the most precise to date and provide the largest energy and angular coverage. The $\eta$ measurements extend the energy range of the world’s large-angle results by approximately 300 MeV. These new data, in particular the ${\eta }^{\text{'}}$ measurements, are likely to help constrain the analyses being performed to search for new baryon resonance states.

We derive the leading two-pion-exchange contributions to the two-nucleon electromagnetic current operator in the framework of chiral effective field theory using the method of unitary transformation. Explicit results for the current and charge densities are given in momentum and coordinate space.

The effects of $\delta$ mesons on the dynamical instabilities of cold and warm nuclear and stellar matter at subsaturation densities are studied in the framework of relativistic mean-field hadron models $(\mathrm{NL}3$, $\mathrm{NL}\rho$, and $\mathrm{NL}\rho \delta )$ with the inclusion of the electromagnetic field. The distillation effect and the spinodals for all the models considered are discussed. The crust-core transition density and pressure are obtained as a function of temperature for $\beta$-equilibrium matter with and without neutrino trapping. An estimation of the size of the clusters formed in the nonhomogeneous phase and the corresponding growth rates are made. It is shown that cluster sizes increase with temperature. The effects of the $\delta$ meson on the instability region are larger for low temperatures, very asymmetric matter, and densities close to the spinodal surface. It increases the distillation effect above $~0.4{\rho }_0$ and has the opposite effect below that density.

The mass excess of the proton-rich nucleus ${}^{23}\mathrm{Al}$ has been measured with the JYFLTRAP Penning trap setup. As a result of our experiment we obtain a mass excess of 6748.07(34) keV, and by combining the value to existing experimental data we have tested the validity of the isobaric multiplet mass equation $(\mathrm{IMME})$ for the $T=3/2$ quartet in the $A=23$ isobar. The fit to the IMME results in a vanishing cubic term equivalent to zero with high precision [$0.22(42)$ keV].

Lifetimes of the yrast states up to ${12}^{+}$ and of a negative parity $5^{-}$ state in ${}^{100}\mathrm{Pd}$ were measured by means of the recoil distance Doppler shift technique. The experiment was performed at the Cologne FN Tandem accelerator with the Cologne Plunger using the reaction ${}^{92}\mathrm{Mo}$$($${}^{11}\mathrm{B}$,$p2n)$ to populate excited states in ${}^{100}\mathrm{Pd}$. Lifetimes were determined by analyzing the transitions in coincidence mode employing the differential decay curve method. The obtained $E2$ transition strengths were compared to predictions from collective models and the shell model.

Statistical modeling of nuclear data provides a novel approach to nuclear systematics complementary to established theoretical and phenomenological approaches based on quantum theory. Continuing previous studies in which global statistical modeling is pursued within the general framework of machine learning theory, we implement advances in training algorithms designed to improve generalization, in application to the problem of reproducing and predicting the half-lives of nuclear ground states that decay $100\%$ by the ${\beta }^{-}$ mode. More specifically, fully connected, multilayer feed-forward artificial neural network models are developed using the Levenberg-Marquardt optimization algorithm together with Bayesian regularization and cross-validation. The predictive performance of models emerging from extensive computer experiments is compared with that of traditional microscopic and phenomenological models as well as with the performance of other learning systems, including earlier neural network models as well as the support vector machines recently applied to the same problem. In discussing the results, emphasis is placed on predictions for nuclei that are far from the stability line, and especially those involved in $r$-process nucleosynthesis. It is found that the new statistical models can match or even surpass the predictive performance of conventional models for $\beta$-decay systematics and accordingly should provide a valuable additional tool for exploring the expanding nuclear landscape.

I rederive the formula for the $B(p,d)A$ and $A(d,p)B$ transition amplitudes used by Timofeyuk and Johnson [Phys. Rev. C 59, 1545 (1999)] in their study of reactions involving halo nuclei. The method of derivation is to use the coupled equations for the three-body problem in the version of the Faddeev equations reported by Alt, Grassberger, and Sandhas [Nucl. Phys. B2, 167 (1967)].

We examine the characteristic quantities of pion-emitting sources extracted by model-independent imaging analysis in relativistic heavy ion collisions. The moments of the spatial separation of pion pair emission can provide the characteristic information about the source geometry and coherence. They are better for describing the non-Gaussian sources with granular and core-halo structures. An improved granular source model of quark-gluon plasma droplets can reproduce the main characteristics of the two-pion correlation functions and source functions in the experiment of $\sqrt{s_{\mathit{NN}}}=200$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions. The transverse-momentum dependence of the normalized first-order moments of the separation for the granular source is consistent with that of the usual interferometry results of source radii, after taking into account the Lorentz contraction in the direction of the transverse momentum of the pion pair.

High-spin states of the ${}^{75}\mathrm{Kr}$ nucleus have been populated via the ${}^{50}\mathrm{Cr}$$($${}^{28}\mathrm{Si}$,$2\mathit{pn})$${}^{75}\mathrm{Kr}$ reaction at an incident beam energy of $90$ MeV. Lifetimes of nine states up to spin $I=33/2$ for the positive-parity band and seven states up to $I=27/2$ for the negative-parity band have been measured using the Doppler-shift attenuation method. The deduced transition quadrupole moments $Q_t$ of these bands have been compared to the projected shell-model calculations to gain insight into the evolution of collectivity for the two experimentally studied bands in ${}^{75}\mathrm{Kr}$.

The STAR Collaboration at the Relativistic Heavy Ion Collider presents measurements of $J/\psi \to e^{+}{e}^{-}$ at midrapidity and high transverse momentum ($p_T>5\hspace{0.5em}\mathrm{GeV}/c$) in $p+p$ and central $\mathrm{Cu}+\mathrm{Cu}$ collisions at $\sqrt{s_{{}_{\mathit{NN}}}}=200$ GeV. The inclusive $J/\psi$ production cross section for $\mathrm{Cu}+\mathrm{Cu}$ collisions is found to be consistent at high $p_T$ with the binary collision-scaled cross section for $p+p$ collisions. At a confidence level of $97\%$, this is in contrast to a suppression of $J/\psi$ production observed at lower $p_T$. Azimuthal correlations of $J/\psi$ with charged hadrons in $p+p$ collisions provide an estimate of the contribution of $B$-hadron decays to $J/\psi$ production of $13\%\pm 5\%$.