Decay spectroscopy of ${}^{184}\mathrm{Tl}$ has been performed at the CERN Isotope Separator On-Line (ISOLDE) facility. An excitation energy of 506.1(1) keV and a half-life of 47.1(7) ms of the intruder based $\left({10}^{-}\right)$ state have been extracted. The internal decay characteristics of this state are determined and discussed, extending the systematics of such states in the even-mass thallium nuclei below neutron midshell at $N=104$. The retardation factors of the isomeric $M2$ and $E3$ transitions are deduced and compared with retardation factors in neighboring odd-mass and even-mass thallium isotopes. The new information is combined with a review of hindered and unhindered $\alpha$-decay data of ${}^{187–192}\mathrm{Bi}$ populating levels in daughter nuclei ${}^{183–188}\mathrm{Tl}$ and supports the interpretation of the intruder character of the $\left({10}^{-}\right)$ state in ${}^{184}\mathrm{Tl}$.

Excited states in the highly neutron-deficient nucleus ${}^{162}\mathrm{W}$ have been investigated via the ${}^{92}\mathrm{Mo}({}^{78}\mathrm{Kr},{2\alpha )}^{162}\mathrm{W}$ reaction. Prompt $\gamma$ rays were detected by the JUROGAM II high-purity germanium detector array and the recoiling fusion-evaporation products were separated by the recoil ion transport unit (RITU) gas-filled recoil separator and identified with the gamma recoil electron alpha tagging (GREAT) spectrometer at the focal plane of RITU. $\gamma$ rays from ${}^{162}\mathrm{W}$ were identified uniquely using mother-daughter and mother-daughter-granddaughter $\alpha$-decay correlations. The observation of a rotational-like ground-state band is interpreted within the framework of total Routhian surface (TRS) calculations, which suggest an axially symmetric ground-state shape with a $\gamma$-soft minimum at ${\beta }_2\approx 0.15$. Quasiparticle alignment effects are discussed based on cranked shell model calculations. New measurements of the ${}^{162}\mathrm{W}$ ground-state $\alpha$-decay energy and half-life were also performed. The observed $\alpha$-decay energy agrees with previous measurements. The half-life of ${}^{162}\mathrm{W}$ was determined to be $t_{1/2}=990\left(30\right)$ ms. This value deviates significantly from the currently adopted value of $t_{1/2}=1360\left(70\right)$ ms. In addition, the $\alpha$-decay energy and half-life of ${}^{166}\mathrm{Os}$ were measured and found to agree with the adopted values.

The structure of the ${}^{24}\mathrm{F}$ nucleus has been studied at GANIL using the $\beta$ decay of ${}^{24}\mathrm{O}$ and the in-beam $\gamma$-ray spectroscopy from the fragmentation of ${}^{27,28}\mathrm{Na},{}^{25,26}\mathrm{Ne},$ and ${}^{29,30}\mathrm{Mg}$ nuclei. Combining these complementary experimental techniques, the level scheme of ${}^{24}\mathrm{F}$ has been constructed up to $3.6\text{MeV}$ by means of particle-$\gamma$ and particle-$\gamma \gamma$ coincidence relations. Experimental results are compared to shell-model calculations using the standard USDA and USDB interactions as well as ab initio valence-space Hamiltonians calculated from the in-medium similarity renormalization group based on chiral two- and three-nucleon forces. Both methods reproduce the measured level spacings well, and this close agreement allows unidentified spins and parities to be consistently assigned.

Medium spin excited levels in ${}^{88}\mathrm{Br}$ populated in fission of ${}^{235}\mathrm{U}$ induced by neutrons have been observed for the first time. The measurement of $\gamma$ radiation following fission has been performed using the EXILL array of Ge detectors at the cold-neutron beam facility PF1B of the Institut Laue-Langevin (ILL), Grenoble. The ground state of ${}^{88}\mathrm{Br}$ is proposed to be $1^{-}$, changing the adopted $\left(2^{-}\right)$ value. The low-energy, newly observed levels are members of the $\pi p_{3/2}\nu {\left(d_{5/2}\right)}^3$ and $\pi f_{5/2}^{-1}\nu {\left(d_{5/2}\right)}^3$ multiplets. A triplet of yrast levels observed at around 2 MeV is interpreted as being due to coupling of the $g_{9/2}$ proton to the $(d_{5/2}{)}^3$, seniority 3 multiplet, supporting the presence of collective effects in ${}^{88}\mathrm{Br}$. The position of the $g_{9/2}$ proton intruder in the ${}^{78}\mathrm{Ni}$ core is determined at 5.7 MeV above the $f_{5/2}$ proton level. Shell-model calculations predict the same proton-neutron excitations proposed in ${}^{88}\mathrm{Br}$.

Background: Recent experiments on $\alpha$-decay of odd-odd superheavy nuclei give important information on the structure of the low-lying states of these nuclei. For this reason, it is interesting to calculate the excitation spectra of superheavy nuclei in the framework of different approaches and compare the results with the experimental data.

Purpose: To calculate the excitation energies of the two-quasiparticle states of nuclei belonging to the $\alpha$-decay chain of ${}^{288}115$ nucleus.

Method: Two different single-particle potentials, modified two-center and Skyrme-based potentials, are used to calculate the energies of two-quasiparticle states.

Results: The spectra of the low-lying states are calculated. An evolution of the splitting of the pseudospin doublets and an evolution of the energies of the unique parity single-particle states with the nuclear mass number are investigated. The $\alpha$-decay spectra of nuclei belonging to the $\alpha$-decay chain of ${}^{288}115$ are obtained and compared with the experimental data. A possibility of the $E1$ transitions in ${}^{276}\mathrm{Mt}$ following $\alpha$ decay of ${}^{288}115$ is considered.

Conclusion: The $E1$ transitions in ${}^{276}\mathrm{Mt}$ might be related to the transitions $n9/2\left[604\right]\to n11/2\left[725\right],n11/2\left[725\right]\to n9/2\left[615\right]$, and $p9/2\left[505\right]\to p11/2\left[615\right]$. Besides the $E1$ transitions, the strong $M1$ and $M2$ transitions are expected in ${}^{276}\mathrm{Mt}$.

Dilepton invariant-mass spectra for heavy-ion collisions at GSI Schwerionensynchroton (SIS 18) and LBNL Bevalac energies are calculated using a coarse-grained time evolution from the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model. The coarse graining of the microscopic UrQMD simulations makes it possible to calculate thermal dilepton-emission rates by the application of in-medium spectral functions from equilibrium quantum-field theoretical calculations. The results show that extremely high baryon chemical potentials dominate the evolution of the created hot and dense fireball. Consequently, a significant modification of the $\rho$ spectral shape becomes visible in the dilepton invariant-mass spectrum, resulting in an enhancement in the low-mass region $M_{ee}=200$ to 600 MeV/$c^2$. This enhancement, mainly caused by baryonic effects on the $\rho$ spectral shape, can fully describe the experimentally observed excess above the hadronic cocktail contributions in $\mathrm{Ar}+\mathrm{KCl}$ $(E_{\mathrm{lab}}=1.76A$ GeV) reactions, as measured by the HADES Collaboration and also gives a good explanation of the older DLS $\mathrm{Ca}+\mathrm{Ca}$ $(E_{\mathrm{lab}}=1.04A$ GeV) data. For the larger $\mathrm{Au}+\mathrm{Au}$ $\left(E_{\mathrm{lab}}=1.23A\mathrm{GeV}\right)$ system, we predict an even stronger excess from our calculations. A systematic comparison of the results for different system sizes from $\mathrm{C}+\mathrm{C}$ to $\mathrm{Au}+\mathrm{Au}$ shows that the thermal dilepton yield increases more strongly $\left(\propto A^{4/3}\right)$ than the hadronic background contributions, which scale with $A$, owing to its sensitivity on the time evolution of the reaction. We stress that the findings of the present work are consistent with our previous coarse-graining results for dilepton production at the top energy available at the CERN Super Proton Synchrotron (SPS). We argue that it is possible to describe the dilepton results from SIS 18 up to SPS energies by considering the modifications of the $\rho$ spectral function inside a hot and dense medium within the same model.

The dark matter interpretation of the DAMA modulation signal depends on the NaI(Tl) scintillation efficiency of nuclear recoils. Previous measurements for Na recoils have large discrepancies, especially in the DAMA/LIBRA modulation energy region. We report a quenching effect measurement of Na recoils in NaI(Tl) from 3 to $52 {\mathrm{keV}}_{\text{nr}}$, covering the whole DAMA/LIBRA energy region for dark matter-Na scattering interpretations. By using a low-energy, pulsed neutron beam, a double time-of-flight technique, and pulse-shape discrimination methods, we obtained the most accurate measurement of this kind for NaI(Tl) to date. The results differ significantly from the DAMA reported values at low energies but fall between the other previous measurements. We present the implications of the new quenching results for the dark matter interpretation of the DAMA modulation signal.

Spectra of $\gamma$ rays following the ${}^{97}\mathrm{Mo}(n,\gamma )$ reaction were measured as a function of incident neutron energy with the DANCE (Detector for Advanced Neutron Capture Experiments) array of $160 {\mathrm{BaF}}_2$ scintillation detectors at the Los Alamos Neutron Science Center using an enriched ${}^{97}\mathrm{Mo}$ target. These spectra were used for the assignment of spins of the ${}^{97}\mathrm{Mo}$ resonances up to neutron energy $E_n=1.7$ keV, as well as in the study of photon strength functions (PSFs) in ${}^{98}\mathrm{Mo}$. Analysis of the spectra with the nuclear statistical model showed that they can be well reproduced with the same PSF models which well described the $\gamma$ decay following slow neutron capture in ${}^{95}\mathrm{Mo}$. On the other hand, the spectra are inconsistent with PSFs describing some other experimental data in ${}^{98}\mathrm{Mo}$.

We investigate three of the most frequently used methods to reduce fusion and total reaction excitation functions. For this purpose, we apply them in two situations. First, we consider theoretical cross sections obtained by single-channel calculations based on standard optical potentials. In this case, the cross sections are not influenced by any particular nuclear property. Thus, the method is successful if the cross sections for different systems are about the same. In the case of fusion excitation functions, we found that the fusion function method works very well, being much better than the other two methods. Regarding total reaction excitation functions, none of the methods is satisfactory. Their reduced reaction cross sections maintain a strong dependence on the atomic and mass numbers of the collision partners. However, they perform reasonably well when compared to similar systems. Next, we use the three methods to reduce experimental fusion and reaction cross sections for many systems, over a broad mass range. Our conclusions are consistent with the ones reached for our theoretical cross sections, resulting from single-channel calculations. That is, the fusion function method is the best for fusion data, whereas none of the three methods works for total reaction.

We investigate the effects of the long-range dynamic polarization (LRDP) potential, which consists of the Coulomb dipole excitation (CDE) potential and the long-range nuclear (LRN) potential, for the ${}^{11}\mathrm{Be}$ projectile on ${}^{64}\mathrm{Zn}$. To study these effects, we perform a ${\chi }^2$ analysis of an optical model including the LRDP potential as well as a conventional short-range nuclear (SRN) potential. To take these effects into account, we argue that both the CDE and LRN potentials are essential to explaining the experimental values of $P_E$, which is the ratio of the elastic scattering cross section to the Rutherford cross section. The Coulomb and nuclear parts of the LRDP potential are found to contribute to a strong absorption effect. Strong absorption occurs because the real part of the CDE and LRN potentials lowers the barrier, and the imaginary part of the CDE and LRN potentials removes the flux from the elastic channel in the ${}^{11}\mathrm{Be}+{}^{64}\mathrm{Zn}$ system. Finally, we extract the total reaction cross section ${\sigma }_R$ including the inelastic, breakup, and fusion cross sections. The contribution of the inelastic scattering by the first excited state at ${\varepsilon }_{\mathrm{x}}^{1\mathrm{st}}=0.32\mathrm{MeV}(1/2^{-})$ is found to be relatively large and cannot be ignored. In addition, our results are shown to agree quite well with the experimental breakup reaction cross section by using a fairly large radius parameter.

We consider a chiral baryon-meson model for nucleons and their parity partners in mirror assignment interacting with pions and sigma and omega mesons to describe the liquid-gas transition of nuclear matter together with chiral symmetry restoration in the high density phase. Within the mean-field approximation the model is known to provide a phenomenologically successful description of the nuclear-matter transition. Here, we go beyond this approximation and include mesonic fluctuations by means of the functional renormalization group. While these fluctuations do not lead to major qualitative changes in the phase diagram of the model, beyond the mean-field approximation, one is no longer free to adjust the parameters so as to reproduce the binding energy per nucleon, the nuclear saturation density, and the nucleon sigma term all at the same time. However, the prediction of a clear first-order chiral transition at low temperatures inside the high baryon-density phase appears to be robust.

The asymptotic normalization coefficient (ANC) is an important quantity in the calculation of radiative width amplitudes, providing limits on the radiative width. Here we present some examples showing the connection between the ANC and radiative width. In particular, the radiative width of the $E1$ transition ${}^{17}\text{F}(1/2^{-},E_x=3.104\mathrm{MeV})$ to ${}^{17}\mathrm{F}(1/2^{+},E_x=0.495\mathrm{MeV})$ reported by Rolfs [Nucl. Phys. A 217, 29 (1973)] is $(1.2\pm 0.2)\times {10}^{-2}$ eV. Meanwhile the ANC for the first excited state in ${}^{17}\text{F}$ puts a lower limit on the radiative width, which is $(3.4\pm 0.50)\times {10}^{-2}$ eV. Such a strong disagreement between the measured radiative width and the lower limit imposed by the ANC calls for a new measurement of this radiative width. Other examples are also considered.

We study the character of the first excited $1/2^{+}$ state of ${}^9\mathrm{Be}$, which is observed as a low-lying sharp peak in the cross section of ${}^9\mathrm{Be}(\gamma ,n)2{}^4\mathrm{He}$ just above the ${}^8\mathrm{Be}+n$ threshold. Using the $\alpha +\alpha +n$ three-body model, we describe the ground and excited unbound states of ${}^9\mathrm{Be}$ above the $\alpha +\alpha +n$ threshold. Applying the complex scaling method to the three-body model, we find no $1/2^{+}$ resonant solutions with the scaling angle of $\theta \le {15}^{\circ }$, while the low-lying peak in the photodisintegration cross section is reproduced in the present calculation. It is found that the ${}^8\mathrm{Be}+n$ continuum states dominate the low-lying peak in the cross section. Furthermore, using the analytical continuation of the coupling constant of the three-body interaction for the $\alpha +\alpha +n$ system, we discuss the virtual-state character of the $1/2^{+}$ state.

We present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. We also study the faint interband transitions within the effective theory and focus on the $E2$ transitions from the $0_2^{+}$ band (the “$\beta$ band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.

For the central collision events of ${}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}$, generated by an antisymmetrized molecular dynamics model in the intermediate energy range of 35 to 300 MeV/nucleon, the density and temperature of a fragmenting source have been extracted using a self-consistent method with the modified Fisher model. Rather flat density values, $\rho /{\rho }_0\sim 0.65$ to 0.7, are evaluated at the incident energies studied, even though the maximum density of the system achieved during the collisions increases monotonically from $\rho /{\rho }_0\sim 1.3$ at 35 MeV/nucleon to 1.8 at 300 MeV/nucleon. Flat temperature values of $T\sim 5.9$ to 6.5 MeV are also extracted in this incident energy range. These extracted values indicate that, in average, intermediate mass fragments are formed at a later stage when the hot nuclear matter reaches at a “freezeout” volume by the expansion, which is not assumed in any transport models, but assumed generally in statistical multifragmentation models. This is the first time to demonstrate quantitatively a direct connection between the freezeout concept and transport model simulations in a multifragmenting regime of heavy ion collisions.

The ${}^{86}\mathrm{Kr}(n,\gamma ){}^{87}\mathrm{Kr}$ neutron-capture cross section was measured at 11 energies between 0.37 and 14.8 MeV. Cross-section data for the ${}^{86}\mathrm{Kr}(n,2n){}^{85}\mathrm{Kr}^m$ reaction were obtained at 9 energies between 10.9 and 14.8 MeV. The data are important for testing calculations used to predict the $s$-process cross section in the unmeasured energy range above 1 MeV for the ${}^{86}\mathrm{Kr}(n,\gamma ){}^{87}\mathrm{Kr}$ reaction, and to check on the consistency of parameters used in talys calculations for the ${}^{86}\mathrm{Kr}(\gamma ,n){}^{85}\mathrm{Kr}^{m+g}$ cross section. The two data sets could also be used as a nuclear physics based diagnostic tool for studying properties of the deuterium-tritium plasma created in inertial confinement fusion reactions at the National Ignition Facility at Lawrence Livermore National Laboratory.

Using a multiphase transport (AMPT) model, we investigate the effect of shear viscosity to entropy density ratio on the Hanbury-Brown–Twiss (HBT) parameters and freeze-out eccentricity from the azimuthal angle dependence of the HBT radii with a constant specific shear viscous approach. The specific shear viscosity gives smaller values of $R_{\mathrm{o}},R_{\mathrm{l}}$ and $R_{\mathrm{o}}/R_{\mathrm{s}}$, but increases value of $R_{\mathrm{s}}$. The freeze-out eccentricity increases with decreasing $\eta /s$ which suggests a possible slow drop of ${\varepsilon }_{\mathrm{f}}$ in the excitation function with increasing energy in relativistic heavy-ion collisions.

We study charm production in ultrarelativistic heavy-ion collisions by using the parton-hadron-string dynamics (PHSD) transport approach. The initial charm quarks are produced by the pythia event generator tuned to fit the transverse-momentum spectrum and rapidity distribution of charm quarks from fixed-order next-to-leading logarithm calculations. The produced charm quarks scatter in the quark-gluon plasma (QGP) with the off-shell partons whose masses and widths are given by the dynamical quasiparticle model (DQPM), which reproduces the lattice QCD equation of state in thermal equilibrium. The relevant cross sections are calculated in a consistent way by employing the effective propagators and couplings from the DQPM. Close to the critical energy density of the phase transition, the charm quarks are hadronized into $D$ mesons through coalescence and fragmentation. The hadronized $D$ mesons then interact with the various hadrons in the hadronic phase with cross sections calculated in an effective Lagrangian approach with heavy-quark spin symmetry. Finally, the nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$ of $D^0$ mesons from PHSD are compared with the experimental data from the STAR Collaboration for $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200$ GeV. We find that in the PHSD the energy loss of $D$ mesons at high $p_T$ can be dominantly attributed to partonic scattering while the actual shape of $R_{AA}$ versus $p_T$ reflects the heavy-quark hadronization scenario, i.e., coalescence versus fragmentation. Also, the hadronic rescattering is important for the $R_{AA}$ at low $p_T$ and enhances the $D$-meson elliptic flow $v_2$.

The stable existence of rod-shaped structures in highly excited states of ${}^{24}\mathrm{Mg}$ is studied based on a systematic cranked Hartree-Fock calculation with various Skyrme-type interactions. Its stability is examined by allowing the transition of the clusterlike structure to the shell-model-like structure. Especially, the rod-shaped state is exposed to two major instabilities: the bending motion, which is the main path for the transition to low-lying states, and the spin-orbit interaction, which is the driving force to break the $\alpha$ clusters and enhance the independent motion of the nucleons. The rod-shaped structure with large angular momentum is obtained as a metastable stationary state.

A goal of nuclear theory is to make quantitative predictions of low-energy nuclear observables starting from accurate microscopic internucleon forces. A major element of such an effort is applying unitary transformations to soften the nuclear Hamiltonian and hence accelerate the convergence of ab initio calculations as a function of the model space size. The consistent simultaneous transformation of external operators, however, has been overlooked in applications of the theory, particularly for nonscalar transitions. We study the evolution of the electric dipole operator in the framework of the similarity renormalization group method and apply the renormalized matrix elements to the calculation of the ${}^4\mathrm{He}$ total photoabsorption cross section and electric dipole polarizability. All observables are calculated within the ab initio no-core shell model. We find that, although seemingly small, the effects of evolved operators on the photoabsorption cross section are comparable in magnitude to the correction produced by including the chiral three-nucleon force and cannot be neglected.