The decay branchings of a resonance in the ${}^{12}$C(${}^{12}$C,$\gamma$)${}^{24}$Mg reaction at $E_{\mathrm{c}.\mathrm{m}.}$ = 8.0 MeV have been studied with high resolution using the Gammasphere array. Radiative capture residues were discriminated from scattered beam and the dominant evaporation channels using the fragment mass analyzer coupled to a multistage Parallel Grid Avalanche Counter (PGAC)/ion chamber system. The clean selection of residues has allowed the population of excited states up to 10 MeV in ${}^{24}$Mg to be examined in detail. Strong feeding of an excited $K$${}^{\pi }=0^{-}$ band is observed. A $J^{\pi }$ = 4${}^{+}$ assignment to the resonance is strongly favored.

In the framework of the Hartree-Fock-Bogoliubov (HFB) approach with Skyrme interactions SLy5+T, SLy5+T${}_w$ and several sets of the TIJ parametrizations, the evolution of the proton single-particle energy difference between the 2$s$${}_{1/2}$ and 1$d$${}_{3/2}$ orbits in Ca isotopes is investigated for the cases with and without the tensor force. It is shown that the energy difference evolution trends by using different Skyrme interactions without the tensor force are similar to each other. However, the energy differences are obviously influenced by the tensor force. Meanwhile, it is found that the inversion between the two orbits (2$s$${}_{1/2}$-1$d$${}_{3/2}$ inversion) induced by the tensor force occurs around ${}^{48}$Ca (by SLy5+T${}_w$) as well as in the nuclei very far from the stability. We understand the inversion phenomenon by analyzing the tensor contributions to the spin-orbit potentials and the radial wave functions of the two orbits. Finally, the proton density distributions of ${}^{46}$Ar and ${}^{206}$Hg are calculated by using several sets of Skyrme interactions with and without the tensor component. It is found that the parametrization SLy5+T${}_w$ favors the bubble structure of ${}^{46}$Ar resulting from the 2$s$${}_{1/2}$-1$d$${}_{3/2}$ inversion. However, for ${}^{206}$Hg any tensor parametrizations do not favor its bubble structure.

The neutron-induced fission cross section of ${}^{236}$U was measured at the neutron Time-of-Flight (n_TOF) facility at CERN relative to the standard ${}^{235}$U($n$,$f$) cross section for neutron energies ranging from above thermal to several MeV. The measurement, covering the full range simultaneously, was performed with a fast ionization chamber, taking advantage of the high resolution of the n_TOF spectrometer. The n_TOF results confirm that the first resonance at 5.45 eV is largely overestimated in some nuclear data libraries. The resonance triplet around 1.2 keV was measured with high resolution and resonance parameters were determined with good accuracy. Resonances at high energy have also been observed and characterized and different values for the cross section are provided for the region between 10 keV and the fission threshold. The present work indicates various shortcomings of the current nuclear data libraries in the subthreshold region and provides the basis for an accurate re-evaluation of the ${}^{236}$U($n$,$f$) cross section, which is of great relevance for the development of emerging or innovative nuclear reactor technologies.

Double-differential cross sections for neutron production were measured in 96-MeV neutron-induced reactions at The Svedberg Laboratory in Uppsala, Sweden. Measurements for Fe and Pb targets were performed using two independent setups: DECOI-DEMON, time-of-flight telescope dedicated to the detection of emitted neutrons with energies between a few and $50\text{MeV}$ and CLODIA-SCANDAL device devoted to measuring emitted neutrons with energies above $40\text{MeV}$. Double-differential cross sections were measured for an angular range between 15 and 98 deg and with low-energy thresholds ($\approx$2 MeV). Angular and energy distributions and total neutron emission cross sections have been obtained from those measurements. Results have been compared with predictions given by different models included in several transport codes (MCNPX, GEANT, TALYS, PHITS, and DYWAN) and with other experimental data (the EXFOR database).

Symmetry energy for asymmetric nuclear matter at subsaturation densities was investigated in the framework of an isospin-dependent quantum molecular dynamics model. A single ratio of neutrons and protons is compared with the experimental data of Famiano et al. [Phys. Rev. Lett. 97, 052701 (2006)] We have also performed a comparison for the double ratio with experimental as well as different theoretical results of Boltzmann-Uehling-Uhlenbeck in 1997, Isospin-dependent Boltzmann-Uehling-Uhlenbeck in 2004, Boltzmann-Nordeim-Vlasov, and Improved Quantum Molecular Dynamics models. It is found that the double ratio predicts the softness of symmetry energy, which is a little underestimated in the single ratio. Furthermore, the study of the single ratio is extended for different kinds of fragments, while the double ratio is extended for different neutron-rich isotopes of Sn.

The event-by-event fission model freya is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view toward possible applications for detection of special nuclear materials.

A blast-wave parametrization, including a full set of hadronic resonances, is used to model a small system, with total particle multiplicity comparable to the one measured in the high-multiplicity $pp$ collisions at the Large Hadron Collider (LHC). Calculations are preformed for three cases: with negligible, moderate, and strong radial flow on the blast-wave hypersurface. We investigate the effects of flow on inclusive $p_T$ spectra as well as on 1D and 3D femtoscopic radii for pions. Special emphasis is put on the role of pions from resonance decays. In particular we show that they magnify the flow effects present in the blast-wave stage and significantly influence the shape of the correlation functions. A specific observable, the $R_{\mathrm{out}}^E/R_{\mathrm{side}}^G$ ratio is proposed as a sensitive probe of the collective effects. Model results for the high multiplicity $pp$ collisions, for scenarios with small and large radial flow are compared. Several features of soft particles production in the medium multiplicity $pp$ events at the LHC are identified as sensitive probes of the collective behavior of the medium.

In ultrarelativistic heavy-ion collisions at $\sqrt{s_{NN}}\approx 200$ GeV, the azimuthal emission anisotropy of hadrons with low and intermediate transverse momentum ($p_T\lesssim 4$ GeV/c) displays an intriguing scaling. In particular, the baryon (meson) emission patterns are consistent with a scenario in which a bulk medium of flowing quarks coalesces into three-quark (two-quark) “bags.” While a full understanding of this number-of-constituent-quark (NCQ) scaling remains elusive, it is suggestive of a thermalized bulk system characterized by colored dynamical degrees of freedom—a quark-gluon plasma (QGP). In this scenario, one expects the scaling to break down as the central energy density is reduced below the QGP formation threshold; for this reason, NCQ-scaling violation searches are of interest in the energy scan program at the Relativistic Heavy Ion Collider. However, as $\sqrt{s_{NN}}$ is reduced, it is not only the initial energy density that changes; there is also an increase in the net baryon number at midrapidity, as stopping transports entrance-channel partons to midrapidity. This phenomenon can result in violations of simple NCQ scaling. Still in the context of the quark coalescence model, we describe a specific pattern for the breakdown of the scaling that includes different flow strengths for particles and their antipartners. Related complications in the search for recently suggested exotic phenomena are also discussed.

The KATRIN (Karlsruhe Tritium Neutrino) experiment will analyze the tritium $\beta$ spectrum to determine the mass of the neutrino with a sensitivity of $0.2$ eV (90$\%$ C.L.). This approach to a measurement of the absolute value of the neutrino mass relies only on the principle of energy conservation and can in some sense be called model-independent as compared to cosmology and neutrinoless double $\beta$ decay. However, by model independent we only mean in case of the minimal extension of the standard model. One should therefore also analyze the data for nonstandard couplings to, e.g., right-handed or sterile neutrinos. As an alternative to the frequentist minimization methods used in the analysis of the earlier experiments in Mainz and Troitsk we have been investigating Markov chain Monte Carlo (MCMC) methods which are very well suited for probing multiparameter spaces. We found that implementing the KATRIN ${\chi }^2$ function in the cosmomc package—an MCMC code using Bayesian parameter inference—solved the task at hand very nicely.

We report on a $\gamma \gamma$ angular-correlation experiment investigating ${}^{200}$Hg after cold-neutron capture. The experiment was performed using eight high-purity germanium detectors mounted on an array installed at the PF1B neutron beam line of the research reactor of the Institut Laue-Langevin in Grenoble, France. The geometry of the array allows $\gamma \gamma$ angular-correlation analyses that can be used for the determination of level spins and multipole mixing ratios in ${}^{200}$Hg. We present multipole mixing ratios for secondary $\gamma$ rays and investigate the nature of the ${}^{200}$Hg neutron-capture state by analyzing the observed primary $\gamma$ rays of this nucleus.

Charged-current neutrino-nucleus cross sections for ${}^{54,56}$Fe and ${}^{58,60}$Ni are calculated and compared using frameworks based on relativistic and Skyrme energy-density functionals and on the shell model. The current theoretical uncertainties in modeling neutrino-nucleus cross sections are assessed in relation to the predicted Gamow-Teller transition strength and available data, to multipole decomposition of the cross sections, and to cross sections averaged over the Michel flux and Fermi-Dirac distribution. By employing different microscopic approaches and models, the decay-at-rest (DAR) neutrino-${}^{56}$Fe cross section and its theoretical uncertainty are estimated to be ${\langle \sigma \rangle }_{\mathrm{th}}=(258\pm 57)\times {10}^{-42}{\mathrm{cm}}^2$, in very good agreement with the experimental value ${\langle \sigma \rangle }_{\exp }=(256\pm 108\pm 43)\times {10}^{-42}{\mathrm{cm}}^2$.

We construct the effective transition operators relevant for neutrinoless double electron capture leading to final nuclear states different than $0^{+}$. From the structure of these operators we see that if such a process is observed experimentally, it will be very helpful in singling out the very important light neutrino mass contribution from the other lepton violating mechanisms.

The multipole dependent effects induced by tensor correlations on the charge-exchange spin-dipole (SD) modes of the light nucleus ${}^{16}$O are studied within a Hartree-Fock (HF) plus self-consistent random-phase approximation (RPA), using Skyrme-type interactions. The role played by the triplet-even and triplet-odd tensor terms are examined separately to explain either the softening or hardening of the excitation energies of SD modes. The unperturbed and RPA summed strengths, calculated with and without the tensor force, are discussed and compared with the results of shell-model calculations.

Understanding the detailed production and hadronization mechanisms for heavy quarkonia and their modification in a nuclear environment presents one of the major challenges in QCD. Calculations including nuclear-modified parton distribution functions (nPDFs) and the fitting of breakup cross sections (${\sigma }_{br}$) as parameters have been successful at describing many features of $J/\psi$ modifications in proton (deuteron)-nucleus collisions. In this paper, we extend these calculations to explore different geometric dependencies of the modifications and confront them with new experimental results from the PHENIX experiment. We find that no combination of nPDFs and ${\sigma }_{br}$, regardless of the nPDF parameter set and the assumed geometric dependence, can simultaneously describe the entire rapidity and centrality dependence of $J/\psi$ modifications in $d+\mathrm{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV. We extend these calculations to incorporate initial-state parton energy loss, which results in an improved description of the experimental data. Finally, we compare the data with previously published calculations, including coherence effects, and find them unable to describe the full rapidity and centrality dependence.

The hydrodynamical description of the “Little Bang” in heavy-ion collisions is surprisingly successful, mostly owing to the very small viscosity of the quark-gluon plasma. In this paper we systematically study the propagation of small perturbations, also treated hydrodynamically. We start with a number of known techniques allowing for the analytic calculation of the propagation of small perturbations on top of the expanding fireball. The simplest approximation is the “geometric acoustics,” which substitutes the wave equation by mechanical equations for the propagating “phonons.” Next we turn to the case in which variables can be separated, where one can obtain not only the eikonal phases but also the amplitudes of the perturbation. Finally, we focus on the so-called Gubser flow, a particular conformal analytic solution for the fireball expansion, on top of which one can derive closed equations for small perturbations. Perfect hydrodynamics allows all variables to be separated and all equations to be solved in terms of known special functions. We can thus collect the analytical expression for all the harmonics and reconstruct the complete Green's function of the problem. In the viscous case the equations still allow for variable separation, but one of the equations has to be solved numerically. Summing all the harmonics we show real-time perturbation evolution, observing the viscosity-induced changes in the spectra and the correlation functions. The calculated angular shape of the correlation function is remarkably similar to the shape emerging from the experimental data, for sufficiently large viscosity. We predict a minimum at $m\sim 7$ and maximum at $m\sim 9$ harmonics, which also have some experimental evidence for it. We conclude that local “hot spots” in the initial state are the only visible origin of the observed correlations.

We formulate a low-energy effective theory describing phases of matter that are both solid and superfluid. These systems simultaneously break translational symmetry and the phase symmetry associated with particle number. The symmetries restrict the combinations of terms that can appear in the effective action and the lowest order terms featuring equal number of derivatives and Goldstone fields are completely specified by the thermodynamic free energy or, equivalently, by the long-wavelength limit of static correlation functions in the ground state. We show that the underlying interaction between particles that constitute the lattice and the superfluid gives rise to entrainment, and mixing between the Goldstone modes. As a concrete example we discuss the low-energy theory for the inner crust of a neutron star, where a lattice of ionized nuclei coexists with a neutron superfluid.

The $g$ factors of the first $2^{+}$ and $4^{+}$ states of the radioactive ${}^{100}$Pd nucleus have been investigated for the first time, using an $\alpha$-particle transfer reaction from ${}^{12}$C to ${}^{96}$Ru. The transient magnetic field technique in inverse kinematics was used. The ${}_{46}^{100}$Pd${}_{54}$ nucleus is a suitable candidate for studying single-particle proton and neutron effects in the nuclear wave functions near the $N=Z=50$ shell closures. The results are discussed within the frameworks of both large-scale shell-model calculations and collective-model predictions.

A chiral model is introduced that is based on the parity doublet formulation of chiral symmetry including hyperonic degrees of freedom. The phase structure of the model is determined. Depending on the masses of the chiral partners, the transition to the chirally restored phase shows a first-order line with critical end points as a function of chemical potential and temperature in additional to the standard liquid-gas phase transition of self-bound nuclear matter. We extend the parity doublet model to describe the deconfinement phase transition which is in quantitative agreement with lattice data at ${\mu }_B=0$. The phase diagram of the model is presented which shows a decoupling of chiral symmetry restoration and deconfinement. Loosening the constraint of strangeness conservation, we also investigate the phase diagram at net strangeness density. We calculate the strangeness per baryon fraction and the baryon-strangeness correlation factor, two quantities that are sensitive on deconfinement and that can be used to interpret lattice calculations.

Near-threshold singularities of elastic scattering amplitudes in the coupled-channel reduction for collisions of weakly bound projectiles with nuclear targets are studied within the framework of the three-body scattering problem. The initial three-body scattering amplitudes are demonstrated to have artificial nonphysical singularities near the pseudo-thresholds of inelastic channels. These singularities, similar to the atomic physics applications, are originated from the discretization of the projectile sub-Hamiltonian continuum. However, in nuclear physics applications, the presence of imaginary parts in optical potentials for the projectile fragments and target suppresses strongly all the irregularities. The complete wave-packet discretization of three-body continuum is shown to lead to quite smooth approximations for elastic partial amplitudes as functions of the total energy. Simultaneously we prove that the pseudostate-continuum approximation for the channel three-body resolvent is rather accurate when solving the three-body scattering problems.