We study the reaction channels ${}^7\text{Li}+\gamma \to n+{}^6\text{Li}\left(2.19\right), {}^7\text{Li}+\gamma \to n+{}^6\text{Li}\left(3.56\right)$, and ${}^7\text{Li}+\gamma \to d+{}^5\text{He}\left(1.27\right)\to n+d+{}^4\text{He}$ by detecting neutrons produced by photodisintegration events. We find absolute cross sections and angular dependence for ${}^7\text{Li}+\gamma \to n+{}^6\text{Li}\left(2.19\right)$ at photon energies 13 and 15 MeV and for ${}^7\text{Li}+\gamma \to n+{}^6\text{Li}\left(3.56\right)$ at the photon energy 15 MeV. The incident photons are linearly polarized and we report dependence of the cross sections on polarization. For the reaction channel ${}^7\text{Li}+\gamma \to d+{}^5\text{He}\left(1.27\right)\to n+d+{}^4\text{He}$ we obtain an upper bound on its cross section at photon energies 12, 13, and 15 MeV.

Dynamics of pseudoscalar mesons ($\pi ,\eta ,K$, and $\overline{K}$) and hyperons ($\mathrm{\Lambda }$ and $\mathrm{\Sigma }$) produced in heavy-ion collisions near threshold energies has been investigated within the Lanzhou quantum molecular dynamics transport model. The in-medium modifications on particle production in dense nuclear matter are implemented in the model through corrections on the elementary cross sections and by inclusion of the meson-nucleon (or hyperon-nucleon) potentials, in which the isospin effects are considered. It is found that the transportation of particles are influenced with the in-medium corrections. The total number of pions is reduced with an isospin-, density-, and momentum-dependent pion-nucleon potential. However, the ratios of charged pions is enhanced with inclusion of the potential. The production of eta in the domain of midrapidities and high momenta is sensitive to the $\eta$-nucleon potential but weakly depends on symmetry energy. The attractive antikaon-nucleon potential enhances the subthreshold $\overline{K}$ production and also influences the structure of phase-space distributions. The dynamics of etas, kaons, antikaons, and hyperons is also influenced by the pion potential because of collisions between pions and nucleons (resonances). The impacts of mean-field potentials on particle dynamics are investigated, such as the phase-space distributions from rapidity and transverse momentum spectra, inclusive invariant spectra, collective flows, etc.

A new method to calculate cross sections for $(p,pn)$ and $(p,2p)$ reactions measured under inverse kinematics conditions is proposed. The method uses the prior form of the scattering transition amplitude and replaces the exact three-body wave function appearing in this expression with an expansion in terms of $p-n$ or $p-p$ states, covering the physically relevant excitation energies and partial waves. A procedure of discretization, similar to that used in continuum-discretized coupled-channels calculations, is applied to make this expansion finite and numerically tractable. The proposed formalism is nonrelativistic, but several relativistic kinematical corrections are applied to extend its applicability to energies of current interest. The underlying optical potentials for the entrance and exit channels are generated microscopically by folding an effective density-dependent $G$ matrix with the density of the composite nucleus. Numerical calculations for ${}^{12}\mathrm{C}$($p,2p$), ${}^{12}\mathrm{C}$($p,pn$), and ${}^{23}\mathrm{O}$($p,pn$) at $\sim 400$ MeV/nucleon are presented to illustrate the method. The role of final-state interactions and Pauli principle between the outgoing nucleons is also discussed.

Fluctuations of the proton number distribution in central Au-Au collisions have been measured by the STAR Collaboration in a beam energy scan at the Relativistic Heavy Ion Collider (RHIC). The motivation is a search for evidence of a critical point in the equation of state. It was found that the skewness and kurtosis display an interesting energy dependence. We compare these measurements to an equation of state which smoothly interpolates between an excluded volume hadron resonance gas at low energy density to a perturbative plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with the lattice QCD equation of state. The crossover equation of state can reproduce the data if the fluctuations are frozen at a temperature significantly lower than the average chemical freeze-out.

Results from the NA49 experiment at the CERN Super Proton Synchrotron (SPS) are presented on event-by-event transverse momentum and multiplicity fluctuations of charged particles, produced at forward rapidities in central Pb + Pb interactions at beam momenta $20A, 30A, 40A, 80A$, and $158A$ GeV/c, as well as in systems of different sizes ($p+p$, C + C, Si + Si, and Pb + Pb) at $158A$ GeV/c. This publication extends the previous NA49 measurements of the strongly intensive measure ${\mathrm{\Phi }}_{p_T}$ by a study of the recently proposed strongly intensive measures of fluctuations $\mathrm{\Delta }[P_T,N]$ and $\mathrm{\Sigma }[P_T,N]$. In the explored kinematic region transverse momentum and multiplicity fluctuations show no significant energy dependence in the SPS energy range. However, a remarkable system size dependence is observed for both $\mathrm{\Delta }[P_T,N]$ and $\mathrm{\Sigma }[P_T,N]$, with the largest values measured in peripheral Pb + Pb interactions. The results are compared with NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) measurements in $p+p$ collisions, as well as with predictions of The Ultrarelativistic Quantum Molecular Dynamics and EPOS models.

The neutron-rich nuclei ${}^{34,35,36,37,38}\mathrm{P}$ were populated in binary grazing reactions initiated by a beam of ${}^{36}\mathrm{S}$ ions at 215 MeV incident on a thin ${}^{208}\mathrm{Pb}$ target. The combination of the PRISMA magnetic spectrometer and the CLARA array of escape-suppressed Ge detectors was used to detect $\gamma$ rays in coincidence with projectile-like nuclear species. Further evidence to support the observed $\gamma$ decay of excited states of the populated phosphorus isotopes is provided by $\gamma -\gamma$ coincidence measurements based on the results of an earlier thick-target deep-inelastic experiment. Level schemes for ${}^{34,35,36,37,38}\mathrm{P}$ are presented and discussed within the context of state-of-the-art shell-model calculations. In particular, new spin and parity assignments are proposed for a number of excited states of ${}^{36}\mathrm{P}$. The evolution with neutron number of the energy difference of the low-lying $J^{\pi }=3/2^{+}$ and $1/2^{+}$ states in the odd-$A$ isotopes of phosphorus, as well as the relationship to nuclear collectivity, is discussed. The evolution with neutron number of the shell-model wave functions of the first $J^{\pi }=1/2^{+}, 3/2^{+}$, and $5/2^{+}$ states of the odd-$A$ phosphorus isotopes and of the first $J^{\pi }=3^{-}, 4^{-}$, and $5^{-}$ states of the even-$A$ isotopes is also explored.

We formulated the $\mathrm{\Lambda }\left(1405\right)$ (abbreviated as ${\mathrm{\Lambda }}^{*}$) $\to {\left(\mathrm{\Sigma }\pi \right)}^0$ invariant-mass spectra produced in the $K^{-}+p\to {\mathrm{\Sigma }}^{+}\left(1660\right)+{\pi }^{-}$, followed by ${\mathrm{\Sigma }}^{+}\left(1660\right)\to \mathrm{\Lambda }\left(1405\right)+{\pi }^{+}\to \mathrm{\Sigma }\pi +{\pi }^{+}$, processes at $p\left(K^{-}\right)=4.2$ GeV/$c$, in which both the incident channel for a quasibound $K^{-}p$ state and its decay process to ${\left(\mathrm{\Sigma }\pi \right)}^0$ were taken into account realistically. We calculated $M\left(\mathrm{\Sigma }\pi \right)$ spectral shapes using mixed transition matrices, $T_{21}=T_{\mathrm{\Sigma }\pi \leftarrow K^{-}p}$ and $T_{22}=T_{\mathrm{\Sigma }\pi \leftarrow \mathrm{\Sigma }\pi }$, for various theoretical models involving ${\mathrm{\Lambda }}^{*}$. The asymmetric spectra were compared to old experimental data of Hemingway, and it was found that the mixing of the two channels, written as $(1-f)T_{21}+f{T}_{22}$, gave a better result than considering the individual channels, yielding $f=0.{376}_{-0.019}^{+0.021}, M\left({\mathrm{\Lambda }}^{*}\right)=1406.6_{-3.3}^{+3.4}$ MeV/$c^2$ and $\mathrm{\Gamma }=70\pm 2$ MeV, nearly consistent with the 2014 PDG values.

Background: Measurements of the $ft$ values for $T=1/2$ mirror ${\beta }^{+}$ decays offer a method to test the conserved vector current hypothesis and to determine $V_{\mathrm{ud}}$, the up-down matrix element of the Cabibbo-Kobayashi-Maskawa matrix. In most mirror decays used for these tests, uncertainties in the $ft$ values are dominated by the uncertainties in the half-lives.

Purpose: Two precision half-life measurements were performed for the $T=1/2{\beta }^{+}$ emitters, ${}^{17}\mathrm{F}$ and ${}^{33}\mathrm{Cl}$, in order to eliminate the half-life as the leading source of uncertainty in their $ft$ values.

Method: Half-lives of ${}^{17}\mathrm{F}$ and ${}^{33}\mathrm{Cl}$ were determined using $\beta$ counting of implanted radioactive ion beam samples on a moving tape transport system at the Système de Production d'Ions Radioactifs Accélérés en Ligne low-energy identification station at the Grand Accélérateur National d'Ions Lourds.

Results: The ${}^{17}\mathrm{F}$ half-life result, 64.347 (35) s, precise to $\pm 0.05\%$, is a factor of 5 times more precise than the previous world average. The half-life of ${}^{33}\mathrm{Cl}$ was determined to be 2.5038 (22) s. The current precision of $\pm 0.09\%$ is nearly 2 times more precise compared to the previous world average.

Conclusions: The precision achieved during the present measurements implies that the half-life no longer dominates the uncertainty of the $ft$ values for both $T=1/2$ mirror decays ${}^{17}\mathrm{F}$ and ${}^{33}\mathrm{Cl}$.

The nuclear matrix elements for two-neutrino double-$\beta$ and zero-neutrino double-$\beta$ decay of ${}^{76}\mathrm{Ge}$ are evaluated in terms of the configuration-interaction (CI), quasiparticle random-phase approximation (QRPA), and interacting boson model methods. We point out deficiencies in all of these models and suggest ways that some of them can be corrected. The final results are obtained from the CI method corrected for configuration admixtures involving orbitals outside of the CI configuration space by using results from QRPA, many-body-perturbation theory, and the connections to related observables. The CI two-neutrino matrix element is reduced due to the inclusion of spin-orbit partners and to many-body correlations connected with Gamow-Teller $\beta$ decay. The CI zero-neutrino matrix element for the heavy neutrino is enhanced due to particle-particle correlations that are connected with the odd-even oscillations in the nuclear masses. The CI zero-neutrino matrix element for the light neutrino contains both types of correlations that approximately cancel each other. The uncertainty from short-range correlations is also considered.

We present the first missing mass spectrum of the unbound nucleus ${}^{10}\mathrm{He}$, measured at RIKEN using the ${}^{11}\mathrm{Li}\left(d,{}^3\mathrm{He}\right)$ reaction at 50A MeV. ${}^{10}\mathrm{He}$ is believed to be a three-body ${}^8\mathrm{He}+n+n$ resonance beyond the limit of nuclear binding. Our observation of a new decay branch, ${}^6\mathrm{He}+4n$, and of a puzzling reduction of the ${}^{11}\mathrm{Li}\left(d,{}^3\mathrm{He}\right){}^{10}\mathrm{He}$ cross section challenges this view. Moreover, our experiment shows a new trend in the evolution of the proton spectroscopic strength in Li isotopes deduced from the comparison of the $\left(d,{}^3\mathrm{He}\right)$ cross sections on ${}^{7,8,9,11}\mathrm{Li}$ with theoretical predictions. We discuss new questions about physics beyond the limits of nuclear existence raised by these findings.

On the basis of systematic calculations for 1364 heavy and superheavy (SH) nuclei, including odd systems, we have found a few candidates for high-$K$ ground states in superheavy nuclei. The macroscopic-microscopic model based on the deformed Woods-Saxon single-particle potential that we use offers a reasonable description of SH systems, including known nuclear masses, $Q_{\alpha }$ values, fission barriers, ground state (g.s.) deformations, and super- and hyperdeformed minima in the heaviest nuclei. Exceptionally untypical high-$K$ intruder contents of the g.s. found for some nuclei, accompanied by a sizable excitation of the parent configuration in the daughter, suggest a dramatic hindrance of the $\alpha$ decay. Multidimensional hypercube configuration-constrained calculations of the potential energy surfaces (PESs) for one especially promising candidate, ${}^{272}\mathrm{Mt}$, shows a $\backsimeq$ 6 MeV increase in the fission barrier above the configuration-unconstrained barrier. There is a possibility that one such high-$K$ ground or low-lying state may be the longest-lived superheavy isotope.

It was pointed out [Phys. Rev. C 91, 021302(R) (2015)] that the isotope shifts of the Pb nuclei, the kink at $N=126$ in particular, can be well described by Hartree-Fock-Bogolyubov calculations if a density-dependent LS interaction derived from the $3N$ interaction is incorporated. Effects of the density dependence in the LS channel on the isotope shifts are extensively investigated for the Ca, Ni, and Sn isotopes, using the semirealistic M3Y-P6 interaction and its LS modified variant M3Y-P6a, as in the Pb case. It is found that almost equal charge radii between ${}^{40}\mathrm{Ca}$ and ${}^{48}\mathrm{Ca}$ are reproduced, as well as the isotope shifts in a long chain of the Sn nuclei, owing to the density dependence in the LS channel. A kink is predicted at $N=82$ for the isotope shifts of the Sn nuclei, in clear contrast to the interactions without the density dependence.

A recently reported laboratory experiment with a high-voltage long discharge in the open atmosphere producing neutrons “…up to energies above 10 MeV…” [Agafonov et al., Phys. Rev. Lett. 111, 115003 (2013)] is critically analyzed. Known elementary processes, namely, nuclear synthesis ${}^2\mathrm{H}\left({}^2\mathrm{H},n\right){}^3\mathrm{He}$ and ${}^2\mathrm{H}\left({}^{14}\mathrm{N},n\right){}^{15}\mathrm{O}$, photonuclear, electrodisintegration ${}_m{}^{n}A\left(e^{-},n\right){}_m{}^{n-1}A$ and opposite to the β-decay $e^{-}\left(p^{+},n\right){\nu }_e$ reactions, as well as unconventional mechanisms and the hypothetical increase in the nuclear synthesis cross sections are not capable of accounting for the neutron generation under conditions of the experiment analyzed. In particular, total energy yields of reactions ${}^2\mathrm{H}\left({}^2\mathrm{H},n\right){}^3\mathrm{He}$ and ${}^2\mathrm{H}\left({}^{14}\mathrm{N},n\right){}^{15}\mathrm{O}$ are less than the claimed neutron energy above 10 MeV. Trustworthiness of the neutron measurements on the basis of the available study of the C-39 track detectors behavior carried out by Faccini et al. [Eur. Phys. J. C 74, 2894 (2014)] in connection with claimed observations of neutron emission in electrolytic cells is discussed. Real-time measurements of x-ray and neutron pulses by Agafonov et al. are commented on using the thorough study of the x-ray emissions by discharges under similar conditions [Kochkin et al., J. Phys. D: Appl. Phys. 45, 425202 (2012)].

We study $\text{SU}\left(3\right)$ flavor-breaking corrections to the relation between the octet baryon masses and the nucleon-meson $\mathit{CP}$-violating interactions induced by the QCD $\overline{\theta }$ term. We work within the framework of $\text{SU}\left(3\right)$ chiral perturbation theory and work through next-to-next-to-leading order in the $\text{SU}\left(3\right)$ chiral expansion, which is $\mathcal{O}\left(m_q^2\right)$. At lowest order, the $\mathit{CP}$-odd couplings induced by the QCD $\overline{\theta }$ term are determined by mass splittings of the baryon octet, the classic result of Crewther et al. [Phys. Lett. B 88, 123 (1979)]. We show that for each isospin-invariant $\mathit{CP}$-violating nucleon-meson interaction there exists one relation that is respected by loop corrections up to the order we work, while other leading-order relations are violated. With these relations we extract a precise value of the pion-nucleon coupling ${\overline{g}}_0$ by using recent lattice QCD evaluations of the proton-neutron mass splitting. In addition, we derive semiprecise values for $\mathit{CP}$-violating coupling constants between heavier mesons and nucleons with $\sim 30\%$ uncertainty and discuss their phenomenological impact on electric dipole moments of nucleons and nuclei.

Background: Double-$\beta$ decay is a rare second-order nuclear decay. The importance of this decay stems from the possibility of neutrinoless double-$\beta$ decay and its applications to neutrino physics.

Purpose: A search was conducted for the $2\nu \beta \beta$ decay of ${}^{96}\mathrm{Zr}$ to excited final states of the daughter nucleus, ${}^{96}\mathrm{Mo}$. Measurements of this decay are important to test nuclear matrix element calculations, which are necessary to extract the neutrino mass from a measurement of the neutrinoless double-$\beta$ decay half-life.

Method: Two coaxial high-purity germanium detectors were used in coincidence to detect $\gamma$ rays produced by the daughter nucleus as it de-excited to the ground state. The experiment was carried out at the Kimballton Underground Research Facility and produced 685.7 d of data with a 17.91 g enriched sample.

Results: No counts were seen above background. For the decay to the first excited $0^{+}$ state, a limit of $T_{1/2}>3.1\times {10}^{20}$ yr was produced. Limits to higher excited states are also reported.

Conclusion: The new limits on double-$\beta$ decay are an improvement over previous experiments by a factor of 2 to 5 for the various excited states. The nuclear matrix element for the double-$\beta$ decay to the first excited $0^{+}$ state is found to be $<0.13$.

We report the first direct measurement of the transition energy $Q_{\mathrm{EC}}$ of the ${}^{21}\mathrm{Na}$ mixed Fermi–Gamow-Teller decay. This is the first of the $T=1/2$ mirror nuclei decays used for the determination of $V_{\mathrm{ud}}$ to be measured with Penning trap mass spectrometry. In addition, the ${}^{29}\mathrm{P}$ mass was measured directly for the first time and used along with the mass of its daughter, ${}^{29}\mathrm{Si}$, for the independent $Q_{\mathrm{EC}}$ determination of this decay. The obtained $Q_{\mathrm{EC}}\left({}^{21}\mathrm{Na}\right)=3547.11\left(9\right)$ keV and $\mathrm{ME}\left({}^{29}\mathrm{P}\right)=-16953.15\left(47\right)$ keV significantly improve the latest published values and reduce the contribution of the $Q_{\mathrm{EC}}$ uncertainty on $\mathcal{F}{t}^{\mathrm{mirror}}$ to the same order as the theoretical corrections.

The pairing correlations in hot nuclei ${}^{162}\text{Dy}$ are investigated in terms of the thermodynamical properties by covariant density functional theory. The thermodynamical quantities are evaluated by the canonical ensemble theory and the paring correlations are treated by a shell-model-like approach, in which the particle number is conserved exactly. An S-shaped heat capacity curve as a function of temperature has been obtained. The properties of hot nuclei, such as entropy and level density are studied in terms of defined seniority component. It is found that the one-pair-broken states play crucial roles in the appearance of the S shape of the heat capacity curve. Moreover, due to the effect of the particle-number conservation, the pairing gap varies smoothly with the temperature, which indicates a gradual transition from the superfluid to the normal state.

Cross sections of the ${}^{56}\mathrm{Fe}\left(n,\alpha \right){}^{53}\mathrm{Cr}$ and ${}^{54}\mathrm{Fe}\left(n,\alpha \right){}^{51}\mathrm{Cr}$ reactions were measured at $E_n=5.5\mathrm{and}6.5\mathrm{MeV}$ and $E_n=4.0,4.5,5.5,\mathrm{and}6.5\mathrm{MeV}$, respectively, using a double-section gridded ionization chamber as the $\alpha$-particle detector. Natural iron and enriched ${}^{56}\mathrm{Fe}$ and ${}^{54}\mathrm{Fe}$ foil samples were prepared. A deuterium gas target was used to produce monoenergetic neutrons through the ${}^2\mathrm{H}\left(d,n\right){}^3\mathrm{He}$ reaction. Two rounds of experiments were performed at the 4.5-MV Van de Graaff Accelerator of Peking University. The foreground and background were measured in separate runs. The neutron flux was monitored by a $\mathrm{B}{\mathrm{F}}_3$ long counter, and the cross sections of the ${}^{238}\mathrm{U}\left(n,f\right)$ reaction were used as the standard. Present results are compared with those of the talys-1.6 code calculations, existing measurements, and evaluations.

Using event-by-event viscous fluid dynamics to evolve fluctuating initial density profiles from the Monte Carlo–Glauber model for U+U collisions, we study the predicted “knee”-like structure in the elliptic flow as a function of collision centrality. The knee arises in the two-component Monte Carlo–Glauber model when the initial source ellipticity is plotted as a function of centrality. It results from the preferential selection of tip-on-tip collision geometries by a high-multiplicity trigger. We find that the knee survives hydrodynamic evolution, and that it is located around the 0.5% most central collisions as measured by the final charged multiplicity. Such a knee structure is not seen in the STAR data. This rules out the two-component MC-Glauber model for initial energy and entropy production. Hence an enrichment of tip-tip configurations by triggering solely on high-multiplicity in the U+U collisions does not work. On the other hand, by using zero degree calorimeters (ZDCs) coupled with event-shape engineering such a selection is possible. We identify the selection purity of body-body and tip-tip events in full-overlap U+U collisions. By additionally constraining the asymmetry of the ZDC signals we can further increase the probability of selecting tip-tip events in U+U collisions.