Photoneutron cross sections were measured for ${}^{80}\mathrm{Se}$ immediately above the neutron separation energy with quasimonochromatic $\gamma$-ray beams to experimentally constrain the $E1$ $\gamma$ strength function for ${}^{80}\mathrm{Se}$. Two sets of the $\gamma$ strength function and the level density that equally meet the experimental constraint predict largely different neutron capture cross sections for ${}^{79}\mathrm{Se}$. Based on the Maxwellian-averaged cross sections of the latest compilation complemented with the predicted cross sections for ${}^{79}\mathrm{Se}$, we calculated $\sigma N$ values of the main $s$-process component using a phenomenological model and deduced empirical abundances of the weak $s$-process component. An attempt is made of considering the implications of the abundance ratios of ${}^{80}\mathrm{Kr}$ and ${}^{82}\mathrm{Kr}$ within the framework of phenomenological models for the weak $s$ process.

The results of two recent papers concerning $(\alpha ,\gamma )$ and $(\alpha ,n)$ reaction cross sections close to the reaction thresholds are discussed with regard to predictions of a recent $\alpha$-particle regional optical potential. It is found that the new measured cross sections are rather well described especially for the dominant reaction channels. Particular features of the $\alpha$-particle optical potential at energies below the Coulomb barrier explain the failure of a former regional potential obtained by analysis of $\alpha$-particle elastic scattering alone at higher energies. Additional limitations of statistical model calculations for minor reaction channels are also discussed.

We calculate the elliptic flow of thermal photons from $\mathrm{Au}+\mathrm{Au}$ collisions at RHIC energies for a range of values for the formation time ${\tau }_0$ but a fixed entropy (or particle rapidity density). The results are found to be quite sensitive to ${\tau }_0$. The value of $v_2$ for photons decreases as ${\tau }_0$ decreases and admits a larger contribution from the quark gluon plasma phase, which has a smaller $v_2$. The elliptic flow coefficient for hadrons, however, is only marginally dependent on ${\tau }_0$.

The investigation in the work of the reaction $e^{+}{e}^{-}\to \omega {\pi }^0$ in the ${}^3{P}_0$ nonrelativistic quark model reveals that the $e^{+}{e}^{-}\to \omega {\pi }^0$ process at the energy region from the $\omega \pi$ threshold to 2.0 GeV is dominated by the two-step process in which the primary $\overline{q}q$ pair first forms ρ and ${\rho }^{\text{'}}$ mesons and then the vector mesons decay into ω and π. With $\rho (1450)$ and $\rho (1700)$ mainly in $2S$ and $1D$ states, respectively, the experimental data for the cross section of the reaction $e^{+}{e}^{-}\to \omega {\pi }^0$ are well produced in the ${}^3{P}_0$ quark model. The work supports the argument that $\rho (1450)$ is mainly a $2S$ meson and $\rho (1700)$ a $1D$ meson.

The $\gamma$-ray cascades following the ${}^{95}\mathrm{Mo}(n,\gamma ){}^{96}\mathrm{Mo}$ reaction were studied with the $\gamma$ calorimeter DANCE (Detector for Advanced Neutron Capture Experiments) consisting of 160 ${\mathrm{BaF}}_2$ scintillation detectors at the Los Alamos Neutron Science Center. The $\gamma$-ray energy spectra for different multiplicities were measured for $s$- and $p$-wave resonances below 2 keV. The shapes of these spectra were found to be in very good agreement with simulations using the DICEBOX statistical model code. The relevant model parameters used for the level density and photon strength functions were identical with those that provided the best fit of the data from a recent measurement of the thermal ${}^{95}\mathrm{Mo}(n,\gamma ){}^{96}\mathrm{Mo}$ reaction with the two-step-cascade method. The reported results strongly suggest that the extreme statistical model works very well in the mass region near $A=100$.

We present a quantum Monte Carlo method with exact projection on parity and angular momentum that is free of a sign problem for seniority-conserving nuclear interactions. This technique allows the microscopic calculation of angular momentum and parity-projected nuclear level densities. We present results for the ${}^{55}\mathrm{Fe}$, ${}^{56}\mathrm{Fe}$, and ${}^{57}\mathrm{Fe}$ isotopes. Signatures of the pairing phase transition are observed in the angular momentum distribution of the nuclear level density.

We present the results of the model-independent analysis of Airy structures in the ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ elastic scattering differential cross sections at 13–22 MeV/nucleon. The analysis has been performed with help of a procedure based on the application of the evolutionary algorithm, which enables us to extract the nuclear part of the scattering matrix $S_N(l)$ as a complex function of angular momentum directly from the scattering data. Contrary to the commonly used model approaches, our procedure gives the better fits and leads to the $S_N(l)$ representations defined by the moduli and the nuclear phases exhibiting smooth monotonic dependencies on $l$.

Gamow-Teller (GT) unit cross sections, ${\widehat{\sigma }}_{\mathrm{GT}}$, are obtained at 198 and 297 MeV by measuring the double differential cross sections at $0^{°}$ for the $(p,n)$ reaction on ${}^{58}\mathrm{Ni}$, ${}^{70}\mathrm{Zn}$, ${}^{114}\mathrm{Cd}$, ${}^{118}\mathrm{Sn}$, and ${}^{120}\mathrm{Sn}$. The mass dependence of ${\widehat{\sigma }}_{\mathrm{GT}}$ and the ratio of ${\widehat{\sigma }}_{\mathrm{GT}}$ to the Fermi unit cross section, ${\widehat{\sigma }}_{\mathrm{F}}$, $(R^2)$ are also derived in the mass region of $58⩽A⩽120$. The ${\widehat{\sigma }}_{\mathrm{GT}}$ value for ${}^{90}\mathrm{Zr}$ at 297 MeV interpolated using the $A$-dependence obtained herein agrees with that used in a previous analysis where the GT transition strength over a wide energy region up to the continuum was discussed. However, the deduced ${}^{64}\mathrm{Ni}$${\widehat{\sigma }}_{\mathrm{GT}}$ value at 198 MeV is 20% smaller than that obtained from the analysis of a previous $(n,p)$ measurement. The present $R^2$ values in the mass region heavier than ${}^{42}\mathrm{Ca}$ are larger than those in the region up to ${}^{42}\mathrm{Ca}$ and increase as a function of $A$.

The possibility of observing neutrinoless double $\beta$ decay offers the opportunity of determining the effective neutrino mass if the nuclear matrix element were known. Theoretical calculations are uncertain, and the occupation of valence orbits by nucleons active in the decay is likely to be important. The occupation of valence proton orbits in the ground states of ${}^{76}\mathrm{Ge}$, a candidate for such decay, and ${}^{76}\mathrm{Se}$, the corresponding daughter nucleus, is determined by precisely measuring cross sections for proton-removing transfer reactions. As in previous work on neutron occupation, we find that the Fermi surface for protons is much more diffuse than previously thought, and the occupancies of at least three orbits change significantly between the two $0^{+}$ ground states.

The excitation spectra in the deformed nucleus ${}^{230}\mathrm{Th}$ were studied by means of the $(p,t)$ reaction, using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons are measured for about 200 excitations seen in the triton spectra up to 3.3 MeV. Firm $0^{+}$ assignments are made for 16 excited states by comparison of experimental angular distributions with the calculated ones using the CHUCK code. Additional assignments are possible, with assignments for four states relatively firm and another four tentative. Assignments up to spin $6^{+}$ are made for other states. Sequences of the states are selected that can be treated as rotational bands and as multiplets of excitations. Experimental data are compared with interacting boson model (IBM) and quasiparticle-phonon model (QPM) calculations.

The possibility of the existence of stable tetrahedral deformations at spin zero is investigated using the Skyrme-HFBCS approach and the generator coordinate method (GCM). The study is limited to nuclei in which the tetrahedral mode has been predicted to be favored on the basis of non-self-consistent models. Our results indicate that a clear identification of tetrahedral deformations is unlikely because they are strongly mixed with the axial octupole mode. However, the excitation energies related to the tetrahedral mode are systematically lower than those of the axial octupole mode in all the nuclei included in this study.

The nuclear level densities of ${}^{116,117}\mathrm{Sn}$ below the neutron separation energy have been determined experimentally from the $({}^3\mathrm{He},\alpha \gamma )$ and $({}^3\mathrm{He},{}^3\mathrm{He}{}^{\text{'}}\gamma )$ reactions, respectively. The level densities show a characteristic exponential increase and a difference in magnitude due to the odd-even effect of the nuclear systems. In addition, the level densities display pronounced step-like structures that are interpreted as signatures of subsequent breaking of nucleon pairs.

Isomeric yield ratios ${}^{190}\mathrm{Ir}{}^{m2,m1+g}$, ${}^{150}\mathrm{Eu}{}^{m,g}$, ${}^{152}\mathrm{Eu}{}^{m1,m2}$ have been measured in $(\gamma ,n)$-reactions for the end point energies of bremmsstrahlung photons about 12, 12.5, and 16 MeV for ${}^{190}\mathrm{Ir}{}^{m2,m1+g}$ and 12 MeV for ${}^{150}\mathrm{Eu}{}^{m,g}$, ${}^{152}\mathrm{Eu}{}^{m1,m2}$. Experimental values of the isomeric yield ratios have been compared with the theoretical values, which were calculated by using codes TALYS and MCEM. The low influence of nonstatistical effects has been observed for all these energies.

We investigate the changes of the masses and widths of ${\chi }_{c0}$ and ${\chi }_{c1}$ in hot gluonic matter near $T_c$ and in a nuclear medium using QCD sum rules. As in the previous works for the $J/\psi$ and ${\eta }_c$, in-medium effects are incorporated through the changes of gluon condensates. Twist-2 terms for the ${}^3{P}_0({\chi }_{c0})$ and ${}^3{P}_1({\chi }_{c1})$ are also included for the first time. The results show that larger mass shifts and width broadenings take place as compared to the $S$-wave states. As the critical change take place near $T_c$, related measurements can reveal critical phenomenon in QCD.

We have measured the angular distribution of recoiling daughter nuclei emitted from the Gamow-Teller $\beta$ decay of spin-polarized ${}^{80}\mathrm{Rb}$. The asymmetry of this distribution vanishes to lowest order in the standard model (SM) in pure Gamow-Teller decays, producing an observable very sensitive to new interactions. We measure the non-SM contribution to the asymmetry to be $A_T=0.015\pm 0.029$ (stat) ±0.019 (syst), consistent with the SM prediction. We constrain higher-order SM corrections using the measured momentum dependence of the asymmetry, and their remaining uncertainty dominates the systematic error. Future progress in determining the weak magnetism term theoretically or experimentally would reduce the final errors. We describe the resulting constraints on fundamental four-Fermi tensor interactions.

The measured occupancies of valence orbits in ${}^{76}\mathrm{Ge}$ and ${}^{76}\mathrm{Se}$ are used as a guideline for modification of the effective mean field energies that results in better description of these quantities. With them, in combination with the self-consistent renormalized quasiparticle random phase approximation (SRQRPA) method that ensures conservation of the mean particle number in the correlated ground state, we show that the resulting $0\nu \beta \beta$ nuclear matrix element for the ${}^{76}\mathrm{Ge}\to {}^{76}\mathrm{Se}$ transition is reduced by $~25\%$ compared to the previous QRPA value, and therefore the difference between the present approach and the interacting shell model predictions becomes correspondingly smaller. Analogous modification of the mean field energies for the $A=82$ system also results in a reduction of $0\nu \beta \beta$ matrix element for the ${}^{82}\mathrm{Se}\to {}^{82}\mathrm{Kr}$ transition, making it also closer to the shell model prediction.

The very neutron-rich nucleus ${}^{20}\mathrm{C}$ has been investigated by inelastic scattering on ${}^{208}\mathrm{Pb}$ and liquid hydrogen targets. Through distorted wave analysis, the reduced electric quadrupole transition probability $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})<18.4$ (stat) $e^2\hspace{0.5em}{\mathrm{fm}}^4$ and the neutron transition probability $M_n^2=292\pm 52$ (stat) ${\mathrm{fm}}^4$ have been derived. A simple shell model calculation has shown a need for a factor of about 0.4 decrease of the normal polarization charges to elucidate the results. This is interpreted as a decoupling of the valence neutrons from the nuclear core in carbon isotopes heavier than ${}^{14}\mathrm{C}$.

High-spin states in ${}^{194}\mathrm{Pb}$ have been populated in the ${}^{168}\mathrm{Er}({}^{30}\mathrm{Si},4n)$ reaction at 142 MeV. The emitted $\gamma$ rays were detected by the EUROBALL III multidetector array. The level scheme was considerably extended and many previously observed $\gamma$-ray transitions were reordered. Four new magnetic rotational bands were observed. The energies and spins of the bandheads of all previously observed magnetic rotational bands were corrected based on the observation of new transitions. From nine observed bands, only one could not be connected to the lower lying states. Based on comparison systematics with neighboring Pb isotopes and tilted-axis cranking model calculations previously reported, configuration assignments to the observed bands have been made.

Branching ratios of $\alpha$ decay to members of the ground state rotational band and excited $0^{+}$ states of even-even nuclei are calculated in the framework of the generalized liquid drop model (GLDM) by taking into account the angular momentum of the $\alpha$ particle and the excitation probability of the daughter nucleus. The calculation covers isotopic chains from Hg to Fm in the mass regions $180<A<202$ and $A⩾224$. The calculated branching ratios of the $\alpha$ transitions are in good agreement with the experimental data and some useful predictions are provided for future experiments.

Two investigations by the parity violating electron scattering are performed theoretically: one is to investigate the properties of the surface for neutron-rich nuclei such as ${}^{124}\mathrm{Sn}$ and ${}^{208}\mathrm{Pb}$, and the other is to predict the parity violating asymmetries for some isotopic chains, such as Ba and Pb, which have been proposed for the atomic parity nonconservation experiments. For the first topic, the neutron and proton densities are taken to be the 2pF distributions. Results show that the parity violating asymmetries are very sensitive to the type of neutron density. It means that the parity violating electron scattering can be used to verify the type of neutron distribution in neutron-rich stable nuclei. For the second topic, the neutron and proton densities are obtained from the relativistic mean-field (RMF) theory. By combining the results for these two topics, we find that for various proton and neutron densities the amplitudes of the parity violating asymmetries correspond to the distances between the minima of the proton and neutron form factors. Our results can provide useful references for future experiments.