We analyze the neutron skin thickness in finite nuclei with the droplet model and effective nuclear interactions. The ratio of the bulk symmetry energy $J$ to the so-called surface stiffness coefficient $Q$ has in the droplet model a prominent role in driving the size of neutron skins. We present a correlation between the density derivative of the nuclear symmetry energy at saturation and the $J/Q$ ratio. We emphasize the role of the surface widths of the neutron and proton density profiles in the calculation of the neutron skin thickness when one uses realistic mean-field effective interactions. Next, taking as experimental baseline the neutron skin sizes measured in 26 antiprotonic atoms along the mass table, we explore constraints arising from neutron skins on the value of the $J/Q$ ratio. The results favor a relatively soft symmetry energy at subsaturation densities. Our predictions are compared with the recent constraints derived from other experimental observables. Though the various extractions predict different ranges of values, one finds a narrow window $L~45\text{−}75$ MeV for the coefficient $L$ that characterizes the density derivative of the symmetry energy that is compatible with all the different empirical indications.

The cross sections for the reactions ${}^{204}\mathrm{Pb}(n,n^{\prime }\gamma ){}^{204}\mathrm{Pb}{}^m$, ${}^{204}\mathrm{Pb}(n,2n){}^{203}\mathrm{Pb}$, ${}^{204}\mathrm{Pb}(n,2n){}^{203}\mathrm{Pb}{}^{m1}$, ${}^{204}\mathrm{Pb}(n,3n){}^{202}\mathrm{Pb}{}^m$, ${}^{206}\mathrm{Pb}(n,3n){}^{204}\mathrm{Pb}{}^m$, ${}^{206}\mathrm{Pb}(n,\alpha ){}^{203}\mathrm{Hg}$, and ${}^{208}\mathrm{Pb}(n,p){}^{208}\mathrm{Tl}$ were determined at the IRMM van de Graaff laboratory in the neutron energy range from 14 to 21 MeV. Both natural and enriched samples were irradiated with neutrons produced via the ${}^3\mathrm{H}(d,n){}^4\mathrm{He}$ reaction. The induced activities were determined by gamma-ray spectrometry using a HPGe detector in a low-background shield. Neutron fluences were determined with the well-known cross section of the ${}^{27}\mathrm{Al}(n,\alpha ){}^{24}\mathrm{Na}$ reaction. Enriched samples were essential to determine the cross sections for the reactions with ${}^{204}\mathrm{Pb}{}^m$ and ${}^{206}\mathrm{Pb}{}^m$ isomers in the final state. Accurate results for reactions with ${}^{204,206}\mathrm{Pb}$ as target nuclei with natural lead samples were enabled through a precise measurement of the isotopic ratios. For a first investigation of the consequences of the present data for nuclear reaction models they were confronted with calculations based on global parameter systematics in a phenomenological and in a microscopic approach and with parameters selected to reproduce the available data. The TALYS code was used for the former two calculations involving parameter systematics while the STAPRE code was used for the latter calculation.

Looking for the underlying hydrodynamic mechanisms determining the elliptic flow we show that for an expanding relativistic perfect fluid the transverse flow may derive from a solvable hydrodynamic potential, if the entropy is transversally conserved and the corresponding expansion is “quasi-stationary,” that is, mainly governed by the temperature cooling. Exact solutions for the velocity flow coefficients $v_2$ and the temperature dependence of the spatial and momentum anisotropy are obtained and shown to be in agreement with the elliptic flow features of heavy-ion collisions.

Starting from the striking similarity of proton-neutron multiplets in ${}^{134}\mathrm{Sb}$ and ${}^{210}\mathrm{Bi}$, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the $V_{\mathrm{low}-\mathrm{k}}$ approach. The calculated results for ${}^{136}\mathrm{Sb}$, ${}^{212}\mathrm{Bi}$, ${}^{136}\mathrm{I}$, and ${}^{212}\mathrm{At}$ are in very good agreement with the available experimental data. The similarity between ${}^{132}\mathrm{Sn}$ and ${}^{208}\mathrm{Pb}$ regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.

A separable form of pairing interaction in the ${}^1{S}_0$ channel has been introduced and successfully applied in the description of both static and dynamic properties of superfluid nuclei. By adjusting the parameters to reproduce the pairing properties of the Gogny force in nuclear matter, this separable pairing force is successful in depicting the pairing properties of ground states and vibrational excitations of spherical nuclei on almost the same footing as the original Gogny force. In this article, we extend these investigations for relativistic Hartree-Bogoliubov theory in deformed nuclei with axial symmetry (RHBZ) using the same separable pairing interaction. To preserve translational invariance we construct one- and two-dimensional Talmi-Moshinsky brackets for the cylindrical harmonic oscillator basis. We show that the matrix elements of this force can then be expanded in a series of separable terms. The convergence of this expansion is investigated for various deformations. We observe a relatively fast convergence. This allows for a considerable reduction in computing time as compared to RHBZ calculations with the full Gogny force in the pairing channel. As an example we solve the RHBZ equations with this separable pairing force for the ground states of the chain of Sm isotopes. Good agreement with the experimental data as well as with other theoretical results is achieved.

The semiclassical, dynamical description of diffraction dissociation of weakly bound nuclei is applied to analyze the decay-energy spectra of ${}^{15}\mathrm{C}$ that have been measured at 68 MeV/nucleon on a Pb target. The optical potentials that are used to describe the nuclear interaction of ${}^{15}\mathrm{C}$ with the target nucleus are realistic because the fits to the two measured spectra, one with a small and one with a very large acceptance angle, are consistent and of similar quality. The cross section for the radiative neutron capture on ${}^{14}\mathrm{C}$ to the ${1/2}^{+}$ ground state of ${}^{15}\mathrm{C}$ is deduced from the analysis. When combined with an estimated contribution from the capture to the ${5/2}^{+}$ excited state of ${}^{15}\mathrm{C}$, an excellent agreement with a recent direct capture measurement is achieved.

An approach to calculate microscopic optical potential with the real part obtained by a folding procedure and with the imaginary part inherent in the high-energy approximation is applied to study the ${}^8\mathrm{He}+p$ elastic-scattering data at energies of tens of MeV/nucleon. The neutron and proton density distributions obtained in different models for ${}^8\mathrm{He}$ are used in the calculations of the differential cross sections. The role of the spin-orbit potential is studied. Comparison of the calculations with the available experimental data on the elastic-scattering differential cross sections at beam energies of 15.7, 26.25, 32, 66, and 73 MeV/nucleon is performed. The problem of the ambiguities of the depths of each component of the optical potential is considered by means of the imposed physical criterion related to the known behavior of the volume integrals as functions of the incident energy. It is shown also that the role of the surface absorption is rather important, in particular for the lowest incident energies (e.g., 15.7 and 26.25 MeV/nucleon).

In s-wave neutron resonances of ${}^{40}\mathrm{Ca}$ at $E_n⩽2.5\hspace{0.5em}\mathrm{MeV}$, $S_n/E_n$ for many levels is found to be of the form $17(n/m)$ where $n$, $m$ are small integers. Statistical tests show small probabilities for the observed dispositions of many levels at $E_n=(j/k)(1/70)G$ ($j$, $k$; small integers). To meet the requirement of time periodicity of the compound nucleus at resonance, a breathing model is developed, where the excitation energies $E_x$ are written as a sum of inverse integers; $E_x=S_n+E_n=G\sum (1/k)$ ($k$: integer). In ${}^{40}\mathrm{Ca}+n$, the separation energy $S_n=8362\hspace{0.5em}\mathrm{keV}$ is written as $S_n=(17/70)G=(1/7+1/10)G$, where $G=34.4$ MeV. $G$ is almost equal to the Fermi energy of the nucleus. It is suggested that two oscillators of energy $(1/7)G$ and $(1/10)G$ are excited in ${}^{40}\mathrm{Ca}$ by neutron incidence, in which the recurrence energy $(1/70)G$ is resonat with neutrons of energies at $(j/k)(1/70)G$, forming a simple compound nucleus.

The forward-backward multiplicity correlation strength is calculated for arbitrary nucleus-nucleus collision in the framework of the wounded nucleon model. Discussion of our results in the context of the recent STAR data in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s}=200$ GeV is presented. It is suggested that the observed (i) growth of the correlation coefficient with centrality and (ii) approximately flat pseudorapidity dependence of the correlation strength for central collisions are due to the fluctuations of the number of wounded nucleons at a given centrality bin.

We present phase space distributions and multiplicities of $K^{+}$, $K^{-}$, and ϕ mesons produced in $\mathrm{Ar}+\mathrm{KCl}$ reactions at a kinetic beam energy of 1.756 GeV/nucleon and measured with the HADES spectrometer. The inverse slope parameters and yields of kaons supplement the systematics of previous measurements. The percentage of $K^{-}$ mesons coming from ϕ decay is found to be $18\pm 7\%$.

An array of sixteen $1\hspace{0.5em}{\mathrm{cm}}^3$ CdZnTe semiconductor detectors was operated at the Gran Sasso Underground Laboratory (LNGS) to further investigate the feasibility of double-$\beta$ decay searches with such devices. As one of the double-$\beta$ decay experiments with the highest granularity the $4\times 4$ array accumulated an overall exposure of $18\hspace{0.5em}\mathrm{kg}\hspace{0.5em}\mathrm{days}$. The setup and performance of the array is described. Half-life limits for various double-$\beta$ decay modes of Cd, Zn, and Te isotopes are obtained. No signal has been found, but several limits beyond ${10}^{20}\hspace{0.5em}\mathrm{years}$ have been performed. They are an order of magnitude better than those obtained with this technology before and comparable to most other experimental approaches for the isotopes under investigation. An improved limit for the ${\beta }^{+}$/EC decay of ${}^{120}\mathrm{Te}$ is given.

The corrections of two-photon exchange on deuteron electromagnetic form factors are estimated based on an effective Lagrangian approach. Numerical results for the form factors $G_{C,M,Q}$ of the deuteron with the corrections are compared to its empirical ones. Moreover, the two new form factors, due to the two-photon exchange, are analyzed. A possible way to test the two-photon exchange corrections to the deuteron form factors is discussed.

At the high temperature and density conditions of hot or explosive helium burning, the ${}^{18}\mathrm{F}(\alpha ,p){}^{21}\mathrm{Ne}$ reaction may compete successfully with the ${}^{18}\mathrm{F}({\beta }^{+}\nu )$ decay. This suggests ${}^{21}\mathrm{Ne}(\alpha ,n)$ as an alternative neutron source in the $r$-process. We have determined the total cross section of the ${}^{18}\mathrm{F}(\alpha ,p){}^{21}\mathrm{Ne}$ reaction by studying the time-reverse reaction ${}^{21}\mathrm{Ne}(p,\alpha ){}^{18}\mathrm{F}$. Using the activation technique, the total reaction yield was measured in the proton beam energy range of 2.3–4.0 MeV, which corresponds to energies of 0.5–2.1 MeV in the ${}^{18}\mathrm{F}+\alpha$ system. The resulting yield curve was analyzed in terms of the thick target formalism and the $R$-matrix theory. The reaction rate was deduced experimentally for the first time for the temperature of $0.1<T_9<1$. The experimental reaction rate was compared with Hauser-Feshbach predictions. The astrophysical implications of the new rate are discussed.

A relativistic, three-particle model of the pion-nucleon system is constructed in the instant form of relativistic quantum mechanics using the Bakamjian-Thomas procedure. The model space includes subspaces for the nucleon $(N)$, the resonances $\Delta =P_{33}(1232)$, $P_{11}(1440)$, $D_{13}(1520)$, $S_{11}(1535)$, and $S_{31}(1620)$, as well as $\pi N$, $\pi \Delta$, $\eta N$, and $\pi \pi N$ subspaces. The model specifies a Poincaré invariant mass operator that includes vertex interactions that couple the various subspaces, as well as renormalization terms. Projection operator techniques are used to reduce the equations arising from this mass operator to a set of three-dimensional Lippmann-Schwinger integral equations that couple only the $\pi N$, $\pi \Delta$, and $\eta N$ channels. After a partial wave analysis these three-dimensional equations simplify to three coupled, one-dimensional integral equations for each partial wave. The mass operator interactions are derived from effective, hadronic Lagrangians that introduce a set of coupling constants. Cutoff functions are introduced to take into account the nonelementary nature of the particles in the model. These cutoff functions introduce a set of cutoff masses. The coupling constants, cutoff masses, and bare baryon masses are determined by fitting to a partial wave analysis of pion-nucleon elastic scattering up to a c.m. energy of $W=1550$ MeV.

We present a systematic analysis of two-pion interferometry in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=62.4$ GeV and $\mathrm{Cu}+\mathrm{Cu}$ collisions at $\sqrt{s_{\mathit{NN}}}=62.4$ and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The multiplicity and transverse momentum dependences of the extracted correlation lengths (radii) are studied. The scaling with charged particle multiplicity of the apparent system volume at final interaction is studied for the RHIC energy domain. The multiplicity scaling of the measured correlation radii is found to be independent of colliding system and collision energy.

The physical nucleon is modeled as a bare nucleon surrounded by a pion cloud using a psuedoscalar pion-nucleon coupling to examine its implications for the neutron form factor, $F_1(Q^2)$, and the corresponding transverse charge density, $\rho (b)$, in the infinite momentum frame. Two versions, one with a tunable Pauli-Villars parameter and another with light-front cloudy-bag pion-nucleon form factors, are examined. A qualitative agreement with the experimental form factor ($F_1<0$ for all $Q^2$) and transverse charge density is achieved when the nucleon is treated as having a finite extent. The bare nucleon must have a finite extent if this model is to account for a negative definite $F_1$ and consequently a negative transverse charge density of the neutron at its center.

We have performed a dynamical coupled-channels analysis of available $p(e,e^{\prime }\pi )N$ data in the region of $W⩽1.6$ GeV and $Q^2⩽1.45$ (GeV/$c$)${}^2$. The channels included are ${\gamma }^{*}N$, $\pi N$, $\eta N$, and $\pi \pi N$ that has $\pi \Delta$, $\rho N$, and $\sigma N$ components. With the hadronic parameters of the model determined in our previous investigations of $\pi N\to \pi N$, $\pi \pi N$ reactions, we have found that the available data in the considered $W⩽1.6$ GeV region can be fitted well by only adjusting the bare ${\gamma }^{*}N\to N^{*}$ helicity amplitudes for the lowest $N^{*}$ states in $P_{33}$, $P_{11}$, $S_{11}$, and $D_{13}$ partial waves. The sensitivity of the resulting parameters to the amount of data included in the analysis is investigated. The importance of coupled-channels effect on the $p(e,e^{\prime }\pi )N$ cross sections is demonstrated. The meson cloud effect, as required by the unitarity conditions, on the ${\gamma }^{*}N\to N^{*}$ form factors are also examined. Necessary future developments, both experimentally and theoretically, are discussed.

The double-$\beta$-decay $Q$ values of ${}^{130}\mathrm{Te}$, ${}^{128}\mathrm{Te}$, and ${}^{120}\mathrm{Te}$ have been determined from parent-daughter mass differences measured with the Canadian Penning Trap mass spectrometer. The ${}^{132}\mathrm{Xe}\text{−}{}^{129}\mathrm{Xe}$ mass difference, which is precisely known, was also determined to confirm the accuracy of these results. The ${}^{130}\mathrm{Te}$ $Q$ value was found to be $2527.01\pm 0.32$ keV, which is 3.3 keV lower than the 2003 Atomic Mass Evaluation recommended value and is consistent with another recent Penning trap measurement. The ${}^{128}\mathrm{Te}$ and ${}^{120}\mathrm{Te}$ $Q$ values were found to be $865.87\pm 1.31$ and $1714.81\pm 1.25$ keV, respectively. For ${}^{120}\mathrm{Te}$, this reduction in uncertainty of nearly a factor of 8 opens up the possibility of using this isotope for sensitive searches for neutrinoless double-electron capture and electron capture with ${\beta }^{+}$ emission.

The neutron capture cross sections of ${}^{184}\mathrm{W}$ and ${}^{186}\mathrm{W}$ have been determined by means of the activation technique. The measurements were carried out at the Karlsruhe 3.75-MV Van de Graaff accelerator using the ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ reaction for neutron production. Samples of natural composition were irradiated in a quasistellar neutron spectrum for a thermal energy of $\mathit{kT}=25$ keV. Systematic uncertainties were investigated by variation of the experimental parameters in repeated activations. The induced activities were counted with HPGe detectors via the strongest $\gamma$-ray lines in the decay of the respective product nuclei. The measured data were converted into Maxwellian averaged cross sections at $\mathit{kT}=30$ keV, yielding $221\pm 12$ mb and $231\pm 11$ mb for ${}^{184}\mathrm{W}$ and ${}^{186}\mathrm{W}$, respectively. Together with the result of a previously reported measurement on ${}^{180}\mathrm{W}$, the present values can be used to improve the cross-section trend with neutron number, which is important for extrapolation into the regions of unstable isotopes. These results are of interest for stellar and explosive nucleosynthesis in nuclear astrophysics as well as for technological applications.