Hyperfine structure and isotope shifts have been measured for the ground and isomeric states in the neutron-deficient isotopes ${}^{179–184}\mathrm{Tl}$ using the 276.9-nm transition. The experiment has been performed at the CERN-Isotope Separator On-Line facility using the in-source resonance-ionization laser spectroscopy technique. Spins for the ground states in ${}^{179,181,183}\mathrm{Tl}$ have been determined as $I=1/2$. Magnetic moments and changes in the nuclear mean-square charge radii have been deduced. By applying the additivity relation for magnetic moments of the odd-odd Tl nuclei the leading configuration assignments were confirmed. A deviation of magnetic moments for isomeric states in ${}^{182,184}\mathrm{Tl}$ from the trend of the heavier Tl nuclei is observed. The charge radii of the ground states of the isotopes ${}^{179–184}\mathrm{Tl}$ follow the trend for isotonic (spherical) lead nuclei. The noticeable difference in charge radii for ground and isomeric states of ${}^{183,184}\mathrm{Tl}$ has been observed, suggesting a larger deformation for the intruder-based $9/2^{-}$ and ${10}^{-}$ states compared to the ground states. An unexpected growth of the isomer shift for ${}^{183}\mathrm{Tl}$ has been found.

Neutrinoless double-$\beta$ decay $\left(0\nu \beta \beta \right)$ searches typically involve large-scale experiments for which backgrounds can be complex. One possible source of background near the $0\nu \beta \beta$ signature in the observed spectra is $\gamma$ rays arising from inelastic neutron scattering from the materials composing or surrounding the detector. In relation to searches for the $0\nu \beta \beta$ of ${}^{136}\mathrm{Xe}$ to ${}^{136}\mathrm{Ba}$, such as the EXO-200 and KamLAND-Zen projects, inelastic neutron scattering $\gamma$-ray production cross sections for ${}^{136}\mathrm{Xe}$ and ${}^{134}\mathrm{Xe}$ are of importance for characterizing such $\gamma$ rays that may inhibit the unambiguous identification of this yet-to-be-observed process. These cross sections have been measured at the University of Kentucky Accelerator Laboratory at neutron energies from 2.5 to 4.5 MeV.

Proton capture reaction is an important process concerning the astrophysical origin of the elements. In present work, we focus on giant dipole resonance (GDR) in proton capture reactions, such as ${}^{11}\mathrm{B}(p,\gamma ){}^{12}\mathrm{C}$, ${}^{27}\mathrm{Al}(p,\gamma ){}^{28}\mathrm{Si}$, ${}^{39}\mathrm{K}(p,\gamma ){}^{40}\mathrm{Ca}$, and ${}^{67}\mathrm{Co}(p,\gamma ){}^{68}\mathrm{Ni}$ in a framework of an extended quantum molecular dynamics model. The systematic properties of GDR parameters including the peak energy, the strength, and full width at half maximum (FWHM) have been studied. The dependence of FWHM on temperature has also been discussed. Some comparisons with experimental data have been presented.

Centrality and system geometry dependence of azimuthal anisotropy of charged hadrons measured in terms of the elliptic flow parameter are investigated using Au+Au event samples at incident beam energy $20\mathrm{A}$ and $40\mathrm{A}\mathrm{GeV}$ generated by ultrarelativistic quantum molecular dynamics (UrQMD) and a multiphase transport (AMPT) models. The Monte Carlo–Glauber model is employed to estimate the eccentricity of the overlapping zone at an early stage of the collisions. Anisotropies present both in the particle multiplicity distribution and in the kinetic radial expansion are examined by using standard statistical and phenomenological methods. In the context of the upcoming Compressed Baryonic Matter experiment to be held at the Facility for Antiproton and Ion Research (FAIR), the present set of simulated results provide us not only with an opportunity to examine the expected collective behavior of hadronic matter at high baryon density and moderate temperature, but when compared with similar results obtained from Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments, they also allow us to investigate how anisotropy of hadronic matter may differ or agree with its low-baryon-density and high-temperature counterpart.

We develop a set of kinetic equations for hydrodynamic fluctuations which are equivalent to nonlinear hydrodynamics with noise. The hydrokinetic equations can be coupled to existing second-order hydrodynamic codes to incorporate the physics of these fluctuations. We first show that the kinetic response precisely reproduces the renormalization of the shear viscosity and the fractional power $(\propto {\omega }^{3/2})$ which characterizes equilibrium correlators of energy and momentum for a static fluid. Then we use the hydrokinetic equations to analyze thermal fluctuations for a Bjorken expansion, evaluating the contribution of thermal noise from the earliest moments and at late times. In the Bjorken case, the solution to the kinetic equations determines the coefficient of the first fractional power of the gradient expansion $(\propto 1/{\left(\tau T\right)}^{3/2})$ for the expanding system. Numerically, we find that the contribution to the longitudinal pressure from hydrodynamic fluctuations is larger than second-order hydrodynamics for typical medium parameters used to simulate heavy ion collisions.

Triangular flow $v_3$ of identified and inclusive particles in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV is studied as a function of centrality and transverse momentum within the hydjet++ model. The model enables one to investigate the influence of both hard processes and final-state interactions on the harmonics of particle anisotropic flow. Decays of resonances are found to increase the magnitude of the $v_3\left(p_T\right)$ distributions at $p_T\ge 2\text{GeV}/c$ and shift their maxima to higher transverse momenta. The $p_T$-integrated triangular flow, however, becomes slightly weakened for all centralities studied. The resonance decays also modify the spectra towards the number-of-constituent-quark scaling fulfillment for the triangular flow, whereas jets are the main source of the scaling violation at the energies available at the CERN Large Hadron Collider (LHC). Comparison with the corresponding spectra of elliptic flow reveals that resonance decays and jets act in a similar manner on both $v_3\left(p_T\right)$ and $v_2\left(p_T\right)$ behavior. Obtained results are also confronted with the experimental data on differential triangular flow of identified hadrons, ratio $v_3^{1/3}\left(p_T\right)/v_2^{1/2}\left(p_T\right)$, and $p_T$-integrated triangular flow of charged hadrons.

An experiment populating low/medium-spin states in ${}^{156}\mathrm{Dy}$ was performed to investigate the possibility of tetrahedral symmetry in this nucleus. In particular, focus was placed on the low-spin, negative-parity states since recent theoretical studies suggest that these may be good candidates for this high-rank symmetry. The states were produced in the ${}^{148}\mathrm{Nd}({}^{12}\mathrm{C},4n)$ reaction and the Gammasphere array was utilized to detect the emitted $\gamma$ rays. $B\left(E2\right)/B\left(E1\right)$ ratios of transition probabilities from the low-spin, negative-parity bands were determined and used to interpret whether these structures are best associated with tetrahedral symmetry or, as previously assigned, to octupole vibrations. In addition, several other negative-parity structures were observed to higher spin and two new sequences were established.

Half-lives for 148 potentially measurable 2nd-, 3rd-, 4th-, 5th-, 6th-, and 7th-forbidden unique beta transitions are predicted. To achieve this, the ratio of the nuclear matrix elements (NMEs), calculated by the proton-neutron quasiparticle random-phase approximation (pnQRPA), $M_{\mathrm{pnQRPA}}$, and a two-quasiparticle (two-qp) model, $M_{\mathrm{qp}}$, is studied and compared with earlier calculations for the allowed Gamow-Teller (GT) $1^{+}$ and first-forbidden spin-dipole (SD) $2^{-}$ transitions. The present calculations are done using realistic single-particle model spaces and $G$-matrix based microscopic two-body interactions. In terms of the ratio $k=M_{\mathrm{pnQRPA}}/M_{\mathrm{qp}}$ the studied decays fall into two groups: for GROUP 1, which consists of transitions involving non-magic nuclei, the ratio turns out to be $k=0.29\pm 0.15$. For GROUP 2, consisting of transitions involving semimagic nuclei, the ratio is 0.5–0.8 for half of the decays and less than $5\times {10}^{-3}$ for the other half. The magnitudes of the NMEs for several nuclei of GROUP 2 depend sensitively on the size of the used single-particle space and the energies of few key single-particle orbitals used in the pnQRPA calculation, while no such dependence is found for the transitions involving nuclei of GROUP 1. Comparing the NME ratios $k$ of GROUP 1 with those of the earlier GT and SD calculations, where also experimental data are available, the expected “experimental” half-lives for the decays between the $0^{+}$ ground state of the even-even reference nuclei and the $J^{\pi }=3^{+},4^{-},5^{+},6^{-},7^{+},8^{-}$ states of the neighboring odd-odd nuclei are derived for possible experimental verification. The present results could also shed light to the magnitudes of the NMEs corresponding to the high-forbidden unique $0^{+}\to J^{\pi }=3^{+},4^{-},5^{+},6^{-},7^{+},8^{-}$ virtual transitions taking part in the neutrinoless double beta decays.

We address the issue of energy and charge dependence of global polarization of ${\displaystyle \mathrm{\Lambda }}$ hyperons in peripheral ${\displaystyle \text{Au-Au}}$ collisions recently observed by the STAR Collaboration at Relativistic Heavy Ion Collider (RHIC). We compare different contributions to the anomalous mechanism relating polarization to vorticity and hydrodynamic helicity in QCD matter. We stress that the suppression of the gravitational anomaly contribution in strongly correlated matter observed in lattice simulations confirms our earlier prediction of rapid decrease of polarization with increasing collision energy. Our mechanism leads to polarization of ${\displaystyle \overline{\mathrm{\Lambda }}}$ of the same sign and larger magnitude than the polarization of ${\displaystyle \mathrm{\Lambda }}$. The energy and charge dependence of polarization is suggested as a sensitive probe of fine details of QCD matter structure.

In simulations of high energy heavy ion collisions that employ viscous hydrodynamics, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasiparticle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. We show how distortions of the single particle distribution functions due to both shear and bulk viscous effects can be done rigorously in the quasiparticle approximation and illustrate it with the linear $\sigma$ model at finite temperature.

We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial-wave analysis, applied to the photoproduction of pseudoscalar mesons. The approach is pedagogical, showing in detail how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles).

The nuclear reactions ${}^{12}\mathrm{C}({}^{12}\mathrm{C},\alpha ){}^{20}\mathrm{Ne}$, ${}^{12}\mathrm{C}({}^{12}\mathrm{C},p){}^{23}\mathrm{Na}$, and ${}^{12}\mathrm{C}({}^{12}\mathrm{C},n){}^{23}\mathrm{Mg}$ are the primary reactions in carbon burning, which occurs as part of several stellar processes. The Gamow window, which describes the energy range where most of these reactions take place, is typically around 1.5 MeV in the center-of-mass frame. Direct measurements of the cross sections at this energy are difficult due to the large Coulomb barrier present between the carbon nuclei; however, a successful surrogate measurement can provide the branching ratios between these reactions while avoiding the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ Coulomb barrier. An experiment was performed using inelastic scattering of 40 MeV $\alpha$ particles on ${}^{24}\mathrm{Mg}$ as a possible surrogate for the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ compound nucleus.

The ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ reaction is one of the most uncertain reactions in the NeNa cycle and plays a crucial role in the creation of ${}^{23}\mathrm{Na}$, the only stable Na isotope. Uncertainties in the low-energy rates of this and other reactions in the NeNa cycle lead to ambiguities in the nucleosynthesis predicted from models of thermally pulsing asymptotic giant branch (AGB) stars. This in turn complicates the interpretation of anomalous Na-O trends in globular cluster evolutionary scenarios. Previous studies of the ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$, ${}^{22}\mathrm{Ne}({}^3\mathrm{He},d){}^{23}\mathrm{Na}$, and ${}^{12}\mathrm{C}({}^{12}\mathrm{C},p){}^{23}\mathrm{Na}$ reactions disagree on the strengths, spins, and parities of low-energy resonances in ${}^{23}\mathrm{Na}$ and the direct-capture ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ reaction rate contains large uncertainties as well. In this work we present new measurements of resonances at $E_r^{\text{c.m.}}=417$, 178, and 151 keV and of the direct-capture process in the ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ reaction. The resulting total ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ rate is approximately a factor of 20 higher than the rate listed in a recent compilation at temperatures relevant to hot-bottom burning in AGB stars. Although our rate is close to that derived from a recent ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ measurement by Cavanna et al. in 2015, we find that this large rate increase results in only a modest 18% increase in the ${}^{23}\mathrm{Na}$ abundance predicted from a 5 ${\mathrm{M}}_{\odot }$ thermally pulsing AGB star model from Ventura and D'Antona (2005). The estimated astrophysical impact of this rate increase is in marked contrast to the factor of $\sim 3$ increase in ${}^{23}\mathrm{Na}$ abundance predicted by Cavanna et al. and is attributed to the interplay between the ${}^{23}\mathrm{Na}(p,\alpha ){}^{20}\mathrm{Ne}$ and ${}^{20}\mathrm{Ne}(p,\gamma ){}^{21}\mathrm{Na}$ reactions, both of which remain fairly uncertain at the relevant temperature range.

We study the spectral fluctuations of the ${}^{208}\mathrm{Pb}$ nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.20 MeV recently identified at the Maier-Leibnitz Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of random matrix theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter $\omega$, which takes the value $\omega =0$ for regular systems and $\omega \simeq 1$ for chaotic systems. We obtain $\omega =0.85$ which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in ${}^{208}\mathrm{Pb}$, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition, our results show that chaotic and nonchaotic nuclear states coexist in the same energy region of the spectrum.

The Barcelona-Catania-Paris-Madrid functional recently proposed to describe nuclear structure properties of finite nuclei is generalized as to include a realistic effective mass. The resulting functional is as good as the previous one in describing binding energies, radii, deformation properties, etc. In addition, the description of giant quadrupole resonance energies is greatly improved.

$\alpha$ decay is usually associated with both ground and low-lying isomeric states of heavy and superheavy nuclei, and the unpaired nucleon plays a key role in $\alpha$ decay. In this work, we systematically studied the $\alpha$ decay half-lives of odd-$A$ nuclei, including both favored and unfavored $\alpha$ decay within the two-potential approach based on the isospin dependent nuclear potential. The $\alpha$ preformation probabilities are estimated by using an analytic formula taking into account the shell structure and proton-neutron correlation, and the parameters are obtained through the $\alpha$ decay half-lives data. The results indicate that, in general, the $\alpha$ preformation probabilities of even-$Z$, odd-$N$ nuclei are slightly smaller than the odd-$Z$, even-$N$ ones. We found that the odd-even staggering effect may play a more important role on spontaneous fission than $\alpha$ decay. The calculated half-lives can well reproduce the experimental data.

We develop a multidimensionally constrained relativistic Hartree-Bogoliubov (MDC-RHB) model in which the pairing correlations are taken into account by making the Bogoliubov transformation. In this model, the nuclear shape is assumed to be invariant under the reversion of $x$ and $y$ axes; i.e., the intrinsic symmetry group is $V_4$ and all shape degrees of freedom ${\beta }_{\lambda \mu }$ with even $\mu$ are included self-consistently. The RHB equation is solved in an axially deformed harmonic oscillator basis. A separable pairing force of finite range is adopted in the MDC-RHB model. The potential energy curves of neutron-rich even-even Zr isotopes are calculated with relativistic functionals DD-PC1 and PC-PK1 and possible tetrahedral shapes in the ground and isomeric states are investigated. The ground state shape of ${}^{110}\mathrm{Zr}$ is predicted to be tetrahedral with both functionals and so is that of ${}^{112}\mathrm{Zr}$ with the functional DD-PC1. The tetrahedral ground states are caused by large energy gaps around $Z=40$ and $N=70$ when ${\beta }_{32}$ deformation is included. Although the inclusion of the ${\beta }_{30}$ deformation can also reduce the energy around ${\beta }_{20}=0$ and lead to minima with pear-like shapes for nuclei around ${}^{110}\mathrm{Zr}$, these minima are unstable due to their shallowness.

Multinucleon transfer in ${}^{86}\mathrm{Kr}+{}^{64}\mathrm{Ni}$ at an incident energy of 25 MeV/nucleon is for the first time investigated with a microscopic dynamics model: improved quantum molecular dynamics (ImQMD) model. The measured isotope distributions are reasonably well reproduced by using the ImQMD model together with a statistical code (gemini) for describing the secondary decay of fragments. The reaction mechanism is explored with the microscopic dynamics simulations from central to peripheral collisions. In central collisions there exists a strong competition among fusion, deep-inelastic scattering, and multifragmentation at such an incident energy. In semiperipheral collisions, binary scattering together with nucleon transfer is dominant, and the probability of elastic + inelastic scattering events increases rapidly with impact parameter in peripheral collisions and approaches one when $b>14$ fm. The mass-total kinetic energy distribution in central collisions due to the competition is quite different from those in peripheral collisions and the distribution of total kinetic energy loss for binary events with nucleon transfer is much more broader than those without transfer.

Collective behavior has been observed in hadronic measurements of high multiplicity $\text{proton}+\text{lead}$ collisions at the Large Hadron Collider, as well as in (proton, deuteron, helium-3) + gold collisions at the Relativistic Heavy Ion Collider. To better understand the evolution dynamics and the properties of the matter created in these small systems, a systematic study of the soft hadronic observables together with electromagnetic radiation from these collisions is performed by using a hydrodynamic framework. Quantitative agreement is found between theoretical calculations and existing experimental hadronic observables. The validity of the fluid-dynamical description is estimated by calculating Knudsen and inverse Reynolds numbers. Sizeable thermal yields are predicted for low-$p_T$ photons. Further predictions of higher-order charged hadron anisotropic flow coefficients and of thermal photon enhancement are proposed.

$\alpha \text{−}\mathrm{decay}$ properties of the yet unknown nucleus ${}^{296}118$ are predicted using the systematic behavior of parameters of $\alpha$-nucleus double-folding potentials. The results are $Q_{\alpha }=11.655\pm 0.095\mathrm{MeV}$ and $T_{1/2}=0.825\mathrm{ms}$ with an uncertainty of about a factor of 4.