The level scheme of ${}^{102}\mathrm{Zr}$ has been expanded by measuring high-fold prompt $\gamma$-ray coincidence events in the spontaneous fission of ${}^{252}\mathrm{Cf}$ with the Gammasphere array. Previous identifications have been confirmed. A two-quasi-particle band with a band head energy of 2926.4 keV has been identified for the first time, as well as two rotational collective bands, with band head energies of 1386.3 and 1652.7 keV, respectively. Spins and parties are assigned based on level systematics and angular correlation measurements.

We study pairing vibrations in ${}^{18,20,22}\mathrm{O}$ and ${}^{42,44,46}\mathrm{Ca}$ nuclei solving the time-dependent Hartree-Fock-Bogoliubov equation in coordinate space with spherical symmetry. We use the SLy4 Skyrme functional in the normal part of the energy density functional and a local density dependent functional in its pairing part. Pairing vibrations are excited by two-neutron transfer operators. Strength distributions are obtained using the Fourier transform of the time-dependent response of two-neutron pair-transfer observables in the linear regime. Results are in overall agreement with quasiparticle random phase approximation calculations for oxygen isotopes, though differences appear when increasing the neutron number. Both low-lying pairing modes and giant pairing vibrations (GPV) are discussed. The GPV is observed in the oxygen but not in the calcium isotopes.

The nuclide cross sections and longitudinal velocity distributions of residues produced in the reactions of ${}^{136}\mathrm{Xe}$ and ${}^{124}\mathrm{Xe}$ at $1A$ GeV in a lead target were measured at the high-resolution magnetic spectrometer, the fragment separator (FRS) of GSI. The data cover a broad range of isotopes of the elements between $Z=3$ and $Z=56$ for ${}^{136}\mathrm{Xe}$ and between $Z=5$ and $Z=55$ for ${}^{124}\mathrm{Xe}$, reaching down to cross sections of a few microbarns. The velocity distributions exhibit a Gaussian shape for masses above $A=20$, while more complex behavior is observed for lighter masses. The isotopic distributions for both reactions preserve a memory on the projectile $N/Z$ ratio over the whole residue mass range.

The photonuclear production of vector mesons in ultraperipheral heavy ion collisions is investigated within the collinear approach using different parametrizations for the nuclear gluon distribution. The integrated cross section and the rapidity distribution for the $\mathit{AA}\to V\hspace{0.5em}\mathit{AA}$ ($V=J/\Psi ,\hspace{0.5em}\Upsilon$) process are computed for energies of the BNL Relativisic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). A comparison with the recent PHENIX data on coherent production of $J/\Psi$ mesons is also presented. We demonstrate that the study of the exclusive quarkonium photoproduction can be used to constrain the nuclear effects in the gluon distribution.

We discuss the development of an angular-momentum-conserving variant of the Density Matrix Renormalization Group (DMRG) method for use in large-scale shell-model calculations of atomic nuclei and report a first application of the method to the ground state of ${}^{56}\mathrm{Ni}$ and improved results for ${}^{48}\mathrm{Cr}$. In both cases, we see a high level of agreement with the exact results. A comparison of the two shows a dramatic reduction in the fraction of the space required to achieve accuracy as the size of the problem grows.

The existence of a liquid-gas phase transition for hot nuclear systems at subsaturation densities is a well-established prediction of finite-temperature nuclear many-body theory. In this paper, we discuss for the first time the properties of such a phase transition for homogeneous nuclear matter within the self-consistent Green's function approach. We find a substantial decrease of the critical temperature with respect to the Brueckner-Hartree-Fock approximation. Even within the same approximation, the use of two different realistic nucleon-nucleon interactions gives rise to large differences in the properties of the critical point.

The Gamow-Teller strength distributions for the $\beta$ decay of the ground state and the lowest-excited states in the nucleus ${}^{72}\mathrm{Kr}$ to the nucleus ${}^{72}\mathrm{Br}$ are obtained within the complex excited VAMPIR variational approach using a rather large model space. The shape mixing is consistently described for both the $0^{+}$ and $2^{+}$ states in the even-even ${}^{72}\mathrm{Kr}$ and the $1^{+},2^{+}$, and $3^{+}$ states in the odd-odd ${}^{72}\mathrm{Br}$. The influence of shape mixing, comparison with the available data, and predictions concerning the half-life of the first excited $0^{+}$ and yrast $2^{+}$ states of ${}^{72}\mathrm{Kr}$ are presented.

The $B(E2;0^{+}\to 2^{+})$ value in ${}^{68}\mathrm{Ni}$ has been measured using Coulomb excitation at safe energies. The ${}^{68}\mathrm{Ni}$ radioactive beam was postaccelerated at the CERN on-line isotope mass separator (ISOLDE) facility to 2.9 MeV/u and directed to a ${}^{108}\mathrm{Pd}$ target. The emitted $\gamma$ rays were detected by the MINIBALL detector array. Not only directly registered but also indirectly deduced information on the nucleus emitting the $\gamma$ ray was used to perform the Doppler correction, leading to a larger center-of-mass angular range to infer the excitation cross section. The obtained value of $2.8_{-1.0}^{+1.2}\times {10}^2{e}^2\hspace{0.5em}{\mathrm{fm}}^4$ is in good agreement with the value measured at intermediate energy Coulomb excitation, confirming the low $0^{+}\to 2^{+}$ transition probability.

Gamow-Teller transitions from ${}^{24}\mathrm{Mg}$ to ${}^{24}\mathrm{Na}$ were studied via the ($t,{}^3\mathrm{He}$) reaction at $115A$ MeV using a secondary triton beam produced via fast fragmentation of $150A$ MeV ${}^{16}\mathrm{O}$ ions. Compared to previous ($t,{}^3\mathrm{He}$) experiments at this energy that employed a primary $\alpha$ beam, the secondary beam intensity is improved by about a factor of five. Despite the large emittance of the secondary beam, an excitation-energy resolution of $~200$ keV is achieved. A good correspondence is found between the extracted Gamow-Teller strength distribution and those available from other charge-exchange probes. Theoretical calculations using the newly developed USDA and USDB $\mathit{sd}$-shell model interactions reproduce the data well.

The $E1(T=1)$ isovector dipole giant resonance (GDR) in heavy and superheavy deformed nuclei is analyzed over a sample of 18 rare-earth nuclei, four actinides, and three chains of superheavy elements ($Z=102$, 114, and 120). The basis of the description is the self-consistent separable random-phase approximation (SRPA) using the Skyrme force SLy6. The model well reproduces the experimental data in the rare-earth and actinide regions. The trend of the resonance peak energies follows the estimates from collective models, showing a bias to the volume mode for the rare-earth isotopes and a mix of volume and surface modes for actinides and superheavy elements. The widths of the GDR are mainly determined by the Landau fragmentation, which in turn is found to be strongly influenced by deformation. A deformation splitting of the GDR can contribute to about one-third of the width, and about 1 MeV further broadening can be associated with mechanisms beyond the SRPA description (e.g., escape widths and coupling with complex configurations).

Using a unique two-arm detector system for heavy ions (the BRS, binary reaction spectrometer), coincident fission events have been measured from the decay of ${}^{60}\mathrm{Zn}$ compound nuclei formed at 88 MeV excitation energy in the reactions with ${}^{36}\mathrm{Ar}$ beams on a ${}^{24}\mathrm{Mg}$ target at $E_{\mathrm{lab}}({}^{36}\mathrm{Ar})=195$ MeV. The detectors consisted of two large-area position-sensitive ($x,y$) gas telescopes with Bragg-ionization chambers. From the binary coincidences in the two detectors, inclusive and exclusive cross sections for fission channels with differing losses of charge were obtained. Narrow out-of-plane correlations corresponding to coplanar decay are observed for two fragments emitted in binary events, and in the data for ternary decay with missing charges from 4 up to 8. After subtraction of broad components, these narrow correlations are interpreted as a ternary fission process at high angular momentum through an elongated shape. The lighter mass in the neck region consists dominantly of two or three $\alpha$ particles. Differential cross sections for the different mass splits for binary and ternary fission are presented. The relative yields of the binary and ternary events are explained using the statistical model based on the extended Hauser-Feshbach formalism for compound nucleus decay. The ternary fission process can be described by the decay of hyper-deformed states with angular momenta around $4552\hslash$.

We study the properties of $K$ and $\overline{K}$ mesons in nuclear matter at finite temperature from a chiral unitary approach in coupled channels that incorporates the $s$ and $p$ waves of the kaon-nucleon interaction. The in-medium solution accounts for Pauli blocking effects, mean-field binding on all the baryons involved, and π and kaon self-energies. We calculate $K$ and $\overline{K}$ (off-shell) spectral functions and single-particle properties. The $\overline{K}$ effective mass gets lowered by about $-50$ MeV in cold nuclear matter at saturation density and by half this reduction at $T=100$ MeV. The $p$-wave contribution to the $\overline{K}$ optical potential, due to $\Lambda ,\Sigma$, and ${\Sigma }^{*}$ excitations, becomes significant for momenta larger than 200 MeV/$c$ and reduces the attraction felt by the $\overline{K}$ in the nuclear medium. The $\overline{K}$ spectral function spreads over a wide range of energies, reflecting the melting of the $\Lambda (1405)$ resonance and the contribution of ${\mathit{YN}}^{-1}$ components at finite temperature. In the $\mathit{KN}$ sector, we find that the low-density theorem is a good approximation for the $K$ self-energy close to saturation density due to the absence of resonance-hole excitations. The $K$ potential shows a moderate repulsive behavior, whereas the quasiparticle peak is considerably broadened with increasing density and temperature. We discuss the implications for the decay of the $\varphi$ meson at GSI Schwerionen Synchrotron energies as well as in the future Facility for Antiproton and Ion Research project.

We suggest an extension of the standard concept of statistical ensembles. Namely, we introduce a class of ensembles with extensive quantities fluctuating according to an externally given distribution. As an example, the influence of energy fluctuations on multiplicity fluctuations in limited segments of momentum space for a classical ultra-relativistic gas is considered. The system volume fluctuations are also discussed.

We use the quasiparticle random-phase approximation (QRPA) and the Skyrme interactions $\mathrm{SLy}4$ and ${\mathrm{SkM}}^{*}$ to systematically calculate energies and transition strengths for the lowest $2^{+}$ state in spherical even-even nuclei. The ${\mathrm{SkM}}^{*}$ functional, applied to 178 spherical nuclei between $Z=10$ and 90, produces excitation energies that are on average 11% higher than experimental values, with residuals that fluctuate about the average by $-35\%$ to $+55\%$. The predictions of ${\mathrm{SkM}}^{*}$ and $\mathrm{SLy}4$ have significant differences, in part because of differences in the calculated ground state deformations; ${\mathrm{SkM}}^{*}$ performs better in both the average and dispersion of energies. Comparing the QRPA results with those of generator-coordinate-method (GCM) calculations, we find that the QRPA reproduces trends near closed shells better than the GCM, and that it overpredicts the energies less severely in general.

We evaluate the coincidence spectra in the nonmesonic weak decay (NMWD) $\Lambda N\to \mathit{nN}$ of Λ hypernuclei ${}_{\Lambda }^4\mathrm{He}$, ${}_{\Lambda }^5\mathrm{He}$, ${}_{\Lambda }^{12}\mathrm{C}$, ${}_{\Lambda }^{16}\mathrm{O}$, and ${}_{\Lambda }^{28}\mathrm{Si}$, as a function of the sum of kinetic energies $E_{\mathit{nN}}=E_n+E_N$ for $N=n,p$. The strangeness-changing transition potential is described by the one-meson-exchange model, with commonly used parametrization. Two versions of the independent-particle shell model (IPSM) are employed to account for the nuclear structure of the final residual nuclei. They are as follows: (a) IPSM-a, where no correlation, except for the Pauli principle, is taken into account and (b) IPSM-b, where the highly excited hole states are considered to be quasistationary and are described by Breit-Wigner distributions, whose widths are estimated from the experimental data. All np and nn spectra exhibit a series of peaks in the energy interval 110 MeV $<E_{\mathit{nN}}<170$ MeV, one for each occupied shell-model state. Within the IPSM-a, and because of the recoil effect, each peak covers an energy interval proportional to $A^{-1}$ , going from $\cong 4$ MeV for ${}_{\Lambda }^{28}\mathrm{Si}$ to $\cong 40$ MeV for ${}_{\Lambda }^4\mathrm{He}$. Such a description could be pretty fair for the light ${}_{\Lambda }^4\mathrm{He}$ and ${}_{\Lambda }^5\mathrm{He}$ hypernuclei. For the remaining, heavier, hypernuclei it is very important, however, to consider as well the spreading in strength of the deep-hole states and bring into play the IPSM-b approach. Notwithstanding the nuclear model that is employed the results depend only very weakly on the details of the dynamics involved in the decay process proper. We propose that the IPSM is the appropriate lowest-order approximation for the theoretical calculations of the of kinetic energy sum spectra in the NMWD. It is in comparison to this picture that one should appraise the effects of the final-state interactions and of the two-nucleon-induced decay mode.

Experimental values of the astrophysical $S$ factor for the ${}^{15}\mathrm{N}(p,{\alpha }_0){}^{12}\mathrm{C}$ reaction are available both from direct measurements and from the Trojan horse method. We here use $R$-matrix formulas to fit these values and to extrapolate to zero energy to obtain values of $S(0)$.

Experimental values of the astrophysical $S$ factor for the ${}^{15}\mathrm{N}(p,{\gamma }_0){}^{16}\mathrm{O}$ reaction are fitted using both an $R$-matrix formula and an alternative formula, and values of the zero-energy $S$ factor are derived.

The nucleosynthetic origin of ${}^{26}\mathrm{Al}$ ($t_{1/2}=0.72$ Myr) in the early solar system is still an open question. Several models predict that short-lived radionuclides could be produced by irradiation of circumsolar material by light charged particles emitted by the young sun. Within some models, most of the ${}^{26}\mathrm{Al}$ is produced by ${}^3\mathrm{He}$-induced reactions on ${}^{24}\mathrm{Mg}$. Little experimental data exist on ${}^3\mathrm{He}$ reactions so that irradiation models have had to rely on theoretical cross sections deduced from statistical nuclear reaction codes. We performed a direct measurement of the ${}^{26}\mathrm{Al}$ production on Mg target by means of $\gamma$ ray spectroscopy and accelerator mass spectrometry (AMS). The data indicate that the theoretical cross section used in previous approaches was overestimated by a factor of 3. Taking the particle spectra considered in theoretical approaches these data lead to a net reduction of the ${}^{26}\mathrm{Al}$ production of a factor of 2. We calculated the relative contribution of the different ${}^{26}\mathrm{Al}$ production channels depending on the irradiation scenario. We show that extremely large particles fluxes would be necessary to reach the canonical ${}^{26}\mathrm{Al}{/}^{27}\mathrm{Al}$ $=5\times {10}^{-5}$ in solids that were present in the early solar system. An in situ origin of this important isotopic chronometer by irradiation is unlikely.

A stochastic approach to fission dynamics based on three-dimensional Langevin equations was applied to calculation of the mass-energy and angular distributions of fission fragments. The dependence of the mass-energy distribution parameters on the angular momentum and the anisotropy of the fission-fragment angular distribution on excitation energy have been studied in a wide range of the fissility parameter. A temperature-dependent finite-range liquid-drop model was used in a consistent way to calculate the functional of the Helmholtz free energy and level-density parameter. The modified one-body mechanism of nuclear dissipation (the so-called surface-plus-window dissipation) was used to determine the dissipative forces in Langevin equations. The evaporation of light prescission particles was taken into account on the basis of a statistical model combined with Langevin dynamics. The calculated parameters of the mass-energy distribution and their angular dependencies are in good quantitative agreement with the available experimental data at the value of the reduction coefficient of the contribution from the wall formula equal to $0.25$. Analysis of the anisotropy of the fission-fragment angular distribution performed with the saddle-point transition state model and scission-point transition state model indicates that it is necessary to take into account the dynamical aspects of the fission-fragment angular distribution formation.