Background: The ${}^{22}$Ne${(\alpha ,n)}^{25}$Mg reaction is an important source of neutrons for $s$-process nucleosynthesis. The neutron production from the reaction is quite sensitive to the low-energy cross section, which is dominated by narrow resonances. The high level density of the ${}^{26}\mathrm{Mg}$ compound nucleus above the $\alpha$ separation energy prevents simple extrapolations from higher energy and the high Coulomb barrier makes the direct measurements extremely difficult. For this reason, indirect methods must be employed to study the level properties of ${}^{26}\mathrm{Mg}$.

Purpose: The current measurement utilizes the reaction ${}^{26}\mathrm{Mg}$${(\gamma ,n)}^{25}$Mg to probe the level structure of the ${}^{26}\mathrm{Mg}$ compound nucleus from the neutron-separation energy at 11.093 MeV up to $E_x\approx$ 12 MeV.

Methods: The High-Intensity $\gamma$-ray Source of the Triangle Universities Nuclear Laboratory was used to bombard a $\sim$16 g sample of enriched ${}^{26}\mathrm{Mg}$ oxide and the resulting decay neutrons were detected with an array of nine liquid scintillator detectors. Neutron time-of-flight peaks with corresponding energies as low as $\sim$50 keV were detected. An efficiency measurement of the detectors was made at the University of Notre Dame's nuclear science laboratory to energies as low as 45 keV.

Results: Five resonances were observed at $E_{\gamma }$ = 11.150, 11.289, 11.329, 11.506, and 11.749 MeV and their strengths have been extracted.

Conclusion:. The resulting strengths at $E_{\gamma }$ = 11.289, 11.329, 11.506, and 11.749 MeV are in good agreement with previous measurements. The strength of the resonance at $E_{\gamma }$ = 11.150 MeV is somewhat lower than previously measured but is in reasonable agreement when systematic uncertainties are considered. The results are also consistent with those of ${}^{25}$Mg${(n,\gamma )}^{26}$Mg studies where a comparison shows that many of the resonances observed here are the result of multiple unresolved narrow resonances.

The drag force of charm quarks propagating through a thermalized system of Quark Gluon Plasma (QGP) has been considered within the framework of both conformal and nonconformal anti–de Sitter (AdS) correspondence. A newly derived Einstein fluctuation-dissipation relation has been used to calculate the heavy flavor diffusion coefficients. Using the drag and diffusion coefficients as inputs, the Langevin equation has been solved to study the heavy flavor suppression factor. It has been shown that within conformal AdS correspondence the $D$-meson suppression at Large Hadron Collider energy can be reproduced, whereas the nonconformal AdS correspondence fails to reproduce the experimental results. This suggests collisional loss alone within nonconformal AdS correspondence cannot reproduce the experimental results, and inclusion of radiative loss becomes important.

We report the first measurement of the photoproduction cross section of the $\varphi$ meson in its neutral decay mode in the reaction $\gamma p\to p\varphi \left(K_S{K}_L\right)$. The experiment was performed with a tagged photon beam of energy $1.6\le E_{\gamma }\le 3.6$ GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The $p\varphi$ final state is identified via reconstruction of $K_S$ in the invariant mass of two oppositely charged pions and by requiring the missing particle in the reaction $\gamma p\to p{K}_{S}X$ to be $K_L$. The presented results significantly enlarge the existing data on $\varphi$ photoproduction. These data, combined with the data from the charged decay mode, will help to constrain different mechanisms of $\varphi$ photoproduction.

We present recent improvements in the crisp code for nuclear reaction simulation. The photoproduction of vector mesons was included in the code, which can evaluate also final state interaction of these mesons with the nucleus. Effects such as shadowing, subthreshold production, and Pauli blocking can be observed. The model is described in detail and some important quantities, such as cross section and nuclear transparency, are calculated as examples of the potential of our code.

Complete and incomplete fusion of an ${}^{16}\mathrm{O}$ projectile with an ${}^{115}\mathrm{In}$ target is studied. Forward recoil range distributions of several evaporation residues were measured at 105 MeV beam energy. The recoil catcher activation technique followed by offline gamma ray spectroscopy was used. The disentanglement of the complete and incomplete fusion processes was done in terms of full and partial linear momentum transfer from the projectile to the target nucleus. Results indicate the occurrence of incomplete fusion involving the breakup of ${}^{16}\mathrm{O}$ into ${}^4$He + ${}^{12}$C and/or ${}^8$Be + ${}^8$Be followed by fusion of one of the fragments with the target nucleus ${}^{115}\mathrm{In}$. The complete fusion contributions deduced from the recoil range distribution data were found to be consistent with the predictions of the theoretical model code pace4. An attempt was also made to separate out the relative contributions of complete and incomplete fusion components from the analysis of the measured recoil range distribution data. The study indicates that the incomplete fusion contribution increases with the projectile energy and the mass asymmetry of the interacting partners. The projectile structure effect also plays an important role in the underlying reaction dynamics.

Evolution of the width of the rapidity distribution on beam rapidity has been studied for a number of produced particles with UrQMD-3.3p1 generated events at various FAIR (Facility for Antiproton and Ion Research) energies. The results for the width of the rapidity distribution with beam rapidity, obtained with UrQMD generated events, are compared with the existing experimental data (E802, E877, E896, E917, NA49). For both UrQMD and experimental data, the width of the rapidity distribution is found to bear scaling behavior with beam rapidity for all the hadrons. Such scaling behavior is found to follow separate mass ordering for the studied mesons and baryons.

We investigate with a transport approach the cold and hot nuclear matter effects on the charmonium transverse momentum distributions in relativistic heavy ion collisions. The newly defined nuclear modification factor $r_{AA}={\langle p_T^2\rangle }_{AA}/{\langle p_T^2\rangle }_{pp}$ and elliptic flow $v_2$ for $J/\psi$ are sensitive to the nature of the hot medium and the thermalization of heavy quarks. From Super Proton Synchrotron (SPS) through Relativistic Heavy Ion Collider (RHIC) to Large Hadron Collider (LHC) colliding energies, we observe dramatic changes in the centrality dependence of $r_{AA}$. We find that, at LHC energy, the finally observed charmonia are dominated by the regeneration from thermalized heavy quarks.

We solve the one-dimensional boost-invariant kinetic equation for a relativistic massive system with the collision term treated in the relaxation time approximation. The result is an exact integral equation which can be solved numerically by the method of iteration to arbitrary precision. We compare predictions for the shear and bulk viscosities of a massive system with those obtained from the exact solution. Finally, we compare the time evolution of the bulk pressure obtained from our exact solution with results obtained from the dynamical equations of second-order viscous hydrodynamics.

The framework of anisotropic hydrodynamics is generalized to include finite particle masses. Two schemes are introduced and their predictions compared with exact solutions of the kinetic equation in the relaxation time approximation. The first formulation uses the zeroth and first moments of the kinetic equation, whereas the second formulation uses the first and second moments. For the case of one-dimensional boost-invariant expansion, our numerical results indicate that the second formulation yields much better agreement with the exact solutions.

This paper addresses the analysis of the set of observables of the bound-state ${\beta }^{-}$ decay, which can be used for the experimental investigation of contributions of (i) interactions beyond the standard model (SM) and (ii) the left-handed polarization state of antineutrinos. For this aim we calculate the branching ratio, probabilities, and angular distributions of probabilities of hydrogen in the hyperfine states and the proton-electron pair in different spinorial states, induced by left-handed and right-handed hadronic and leptonic currents. The branching ratio of the bound-state ${\beta }^{-}$ decay is calculated by taking into account radiative corrections. We show that the probabilities of the bound-state ${\beta }^{-}$ decay can be good observables for experimental investigations of contributions of interactions beyond the SM, whereas the angular distributions of probabilities are good observables for experimental searches of contributions of the left-handed polarization state of antineutrinos.

We report on a shell model study of ${}^{43}S$ and ${}^{44}S$. Quadrupole rotational invariants proposed by Kumar about 40 years ago allow us to estimate axial and triaxial deformation parameters from shell model calculations. Present results, showing the large impact of the triaxial degree of freedom on the low-lying structure of studied sulfur isotopes, resolve several inconsistencies in previous interpretations of experimental data. In ${}^{43}S$ the prolate ground-state band coexists with a triaxial band built on the 7/2${}_1^{-}$ isomer and an excited prolate structure built on the $K^{\pi }$ = 5/2${}^{-}$ deformed orbit originating from the $\nu f_{7/2}$ shell. In ${}^{44}S$ coexistence of two deformed bands built on mixed 0${}_{1,2}^{+}$ states is reported as well as a pseudo-$\gamma$-band and an excited triaxial structure for which a particle-hole neutron excitation couples to proton collectivity. Present results are in good global agreement with recent antisymmetrized molecular dynamics and beyond-mean-field calculations.

All the ${}^{16}\mathrm{F}$ levels are unbound by proton emission. To date the four low-lying ${}^{16}\mathrm{F}$ levels below 1 MeV have been experimentally identified with well established spin-parity values and excitation energies with an accuracy of 4 – 6 keV. However, there are still considerable discrepancies in their level widths. The present work aims to explore these level widths through an independent method. The angular distributions of the ${}^{15}N$(${}^7\mathrm{Li}$, ${}^6\mathrm{Li}$)${}^{16}\mathrm{N}$ reaction leading to the first four states in ${}^{16}\mathrm{N}$ were measured using a high-precision Q3D magnetic spectrograph. The neutron spectroscopic factors and the asymptotic normalization coefficients for these states in ${}^{16}\mathrm{N}$ were then derived based on distorted wave Born approximation analysis. The proton widths of the four low-lying resonant states in ${}^{16}\mathrm{F}$ were obtained according to charge symmetry of strong interaction.

The $g$ factor of the first excited $2^{+}$ state in ${}^{72}\mathrm{Zn}$ has been measured using the transient-field (TF) technique in combination with Coulomb excitation in inverse kinematics. This experiment presents only the third successful application of the TF method to a short-lived radioactive beam in 10 y, highlighting the intricacies of applying this technique to present and future isotope separator on-line facilities. The significance of the experimental result, $g\left(2_1^{+}\right)=+0.47\left(14\right)$, for establishing the structure of the Zn isotopes near $N=40$ is discussed on the basis of shell-model and beyond-mean-field calculations, the latter accounting for the triaxial degree of freedom, configuration mixing, and particle number and angular momentum projections.

Background: Density functional theory (DFT) is the microscopic tool of choice to describe properties of nuclei over the entire nuclear landscape, with a focus on medium-mass and heavy complex systems. Modern energy density functionals (EDFs) often offer a level of accuracy typical of phenomenological approaches based on parameters locally fitted to the data. It is clear, however, that in order to achieve high quality of predictions to guide spectroscopic studies, current functionals must be improved, especially in the isospin channel. In this respect, experimental studies of short-lived nuclei far from stability offer a unique test of isospin aspects of the many-body theory.

Purpose: We develop the isospin-invariant Skyrme-EDF method by considering local densities in all possible isospin channels and proton-neutron ($p$-$n$) mixing terms as mandated by the isospin symmetry. The EDF employed has the most general form that depends quadratically on the isoscalar and isovector densities. We test and benchmark the resulting $p$-$n$ EDF approach, and study the general properties of the new scheme by means of the cranking in the isospin space.

Methods: We extend the existing axial DFT solver hfbtho to the case of isospin-invariant EDF approach with all possible $p$-$n$ mixing terms. Explicit expressions have been derived for all the densities and potentials that appear in the isospin representation. In practical tests, we consider the Skyrme EDF SkM${}^{*}$ and, as a first application, concentrate on Hartree-Fock aspects of the problem, i.e., pairing has been disregarded.

Results: Calculations have been performed for the ($A=78,T\simeq 11$), ($A=40,T\simeq 8$), and ($A=48,T\simeq 4$) isobaric analog chains. Isospin structure of self-consistent $p$-$n$ mixed solutions has been investigated with and without the Coulomb interaction, which is the sole source of isospin symmetry breaking in our approach. The extended axial hfbtho solver has been benchmarked against the symmetry-unrestricted hfodd code for deformed and spherical states.

Conclusions: We developed and tested a general isospin-invariant Skyrme-EDF framework. The new approach permits spin-isospin densities that may give rise to hitherto unexplored modes in the excitation spectrum. The new formalism has been tested in the Hartree-Fock limit. A systematic comparison between hfodd and hfbtho results show a maximum deviation of about 10 keV on the total binding energy for deformed nuclei when the Coulomb term is included. Without this term, the results of both solvers agree down to a $\sim$10 eV level.

Strong odd-even staggering (OES) of the yields of fragments, produced by fragmenting ${}^{78}\mathrm{Kr}$ projectiles, has been measured by employing the combination of an in-flight fragment separator and a storage ring. It is shown that the OES of fragment yields of $T_z=-1/2$ and $T_z=1/2$ mirror nuclei critically depends on both pairing and shell structure, especially at the closed shells $Z=20$ and 28. A comparison of the relative OES of yields and of particle-emission threshold energies reveals unambiguously that the origin of the OES of fragment yields is mainly determined by the OES of the particle-emission threshold energies, which contain both pairing and shell effects.

We argue that the relative yields of ${\rm Y}$ states observed at the Large Hadron Collider can be understood as bottomonium states coming to thermal equilibrium and then freezing out before the medium. The bottomonium freezeout temperature is approximately 220 MeV. We examine its systematics as a function of centrality. We remark on the interesting differences recorded by the CMS and ALICE experiments in the charmonium sector.

New experimental data for the ${}^{33}\mathrm{S}(\alpha ,p){}^{36}\mathrm{Cl}$ reaction show a very unusual energy dependence. Contrary to common findings for many other $\alpha$-induced reactions, statistical model calculations underestimate the measured cross sections at very low energies. The relatively huge cross sections at these low energies require a significant amount of single-particle strength in the measured energy range which exceeds, by far, 100% as soon as the additional strength from the competing ${}^{33}\mathrm{S}(\alpha ,n){}^{36}\mathrm{Ar}$ reaction is taken into account. In addition, the new data deviate from a general trend for the energy dependence of $\alpha$-induced reaction cross sections.

Cross section measurements of the ${}^{58}\mathrm{Ni(}\alpha$,$\gamma$)${}^{62}\mathrm{Zn}$ reaction were performed in the energy range $E_{\alpha }=5.5\text{to}9.5$ MeV at the Nuclear Science Laboratory of the University of Notre Dame, using the NSCL Summing NaI(Tl) detector and the $\gamma$-summing technique. The measurements are compared to predictions in the statistical Hauser-Feshbach model of nuclear reactions using the SMARAGD code. It is found that the energy dependence of the cross section is reproduced well but the absolute value is overestimated by the prediction. This can be remedied by rescaling the $\alpha$ width by a factor of 0.45. Stellar reactivities were calculated with the rescaled $\alpha$ width and their impact on nucleosynthesis in type Ia supernovae has been studied. It is found that the resulting abundances change by up to 5% when using the new reactivities.

We present a new approach for calculating the electromagnetic excitation of nuclei as well as probabilities of emission and different distributions of neutrons from decays of excited nuclear systems for ultrarelativistic, ultraperipheral heavy ion collisions. Excitation functions for $\gamma$ + Pb $\to$ Pb${}^{*}$ and $\gamma$ + Au $\to$ Au${}^{*}$ are parametrized using physics-motivated components: the excitation of giant resonances, quasideuteron absorption mechanism, excitation of nucleon resonances, as well as high-energy dissociation of protons and neutrons. Neutron emission (up to ten neutrons) from low-energy excitations of ${}^{208}$Pb and ${}^{197}$Au is modeled in terms of the Hauser-Feshbach formalism. The probabilities of a given number of neutrons are calculated as a function of excitation energy in a Monte Carlo code gemini++. These probabilities are parametrized by smooth analytical functions. The results are compared to appropriate data for the $\gamma$ Pb $\to$ Pb${}^{*}\to kn$ and $\gamma$ Au $\to$ Au${}^{*}\to kn$ reaction. As an example, the approach is used for calculating electromagnetic excitation in ultraperipheral heavy ion collisions (UPC) processes. Both single-photon and double-photon excitations are included and discussed. Topological cross sections with a given number of neutrons in the forward and backward directions are calculated at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies. Excitation functions are presented. The results of the calculation are compared to Super Proton Synchrotron (SPS), RHIC, and more recent A Large Ion Collider Experiment (ALICE) experimental data and good agreement is achieved.