Level structures of neutron-rich ${}^{140}\mathrm{Xe}$ nucleus have been reinvestigated by using a triple $\gamma$ coincidence study from the spontaneous fission of ${}^{252}\mathrm{Cf}$. Several new levels and transitions are identified. The previously observed $s=+1$ octupole band structure is confirmed and expanded. Another set of the $\mathrm{\Delta }I=2$ positive and negative parity bands connected by strong $E1$ transitions is proposed as the $s=-1$ octupole band structure. Thus, the $s=\pm 1$ doublet octupole bands are completed in ${}^{140}\mathrm{Xe}$. The experimental $B\left(E1\right)/B\left(E2\right)$ branching ratios indicate that the octupole correlations in ${}^{140}\mathrm{Xe}$ are weak. The other characteristics of the $s=\pm 1$ octupole bands have been discussed.

The negative parity non-yrast band of ${}^{106}\mathrm{Ag}$ has been studied to investigate the falling trend in magnetic dipole transition rates. In this context, the level lifetimes of the excited levels of this band have been measured using the Doppler shift attenuation method. The comparison of the experimental Routhian and the transition rates with the numerical results of the shears mechanism with the principal axis cranking calculation indicates that this band is generated due to the shears mechanism involving the three proton hole configuration.

We propose a measurable parameter $\mathcal{H}$ quantifying the halo nature of one-neutron halo nuclei $\left(a\right)$ and investigate the properties of $\mathcal{H}$, assuming the core + neutron $(c+n)$ model for $a$. The parameter $\mathcal{H}$ is defined by $\mathcal{H}=[{\sigma }_{\mathrm{abs}}\left(a\right)-{\sigma }_{\mathrm{abs}}\left(c\right)]/{\sigma }_{\mathrm{abs}}\left(n\right)$ with directly measurable absorption cross sections ${\sigma }_{\mathrm{abs}}$ of $a$, $c$, and $n$ scattering at the same incident energy per nucleon. It varies with the one-neutron separation energy $S_n$ in a range of $0\le \mathcal{H}\le 1$, and the halo structure is most developed when $\mathcal{H}=1$. This situation is realized only for $s$-wave halo nuclei in the $S_n=0$ limit. We consider ${}^{11}\mathrm{Be}$ and ${}^{15,19}\mathrm{C}$ as $s$-wave halo nuclei, ${}^{31}\mathrm{Ne}$ and ${}^{37}\mathrm{Mg}$ as $p$-wave halo nuclei, and ${}^{17}\mathrm{C}$ as an example of $d$-wave nonhalo nuclei. For each of halo nuclei, the value of $\mathcal{H}$ is deduced at a measured $S_n$ from measured total reaction cross sections for $c$, $n$, and $a$ scattering at intermediate and high incident energies where projectile breakup effects are negligible. The location of the resulting $(S_n,\mathcal{H})$ is plotted in the $S_n-\mathcal{H}$ plane. The empirical values of $\mathcal{H}$ at the measured $S_n$ are extrapolated to small $S_n$ with model calculations based on the eikonal + adiabatic approximation. In the $S_n-\mathcal{H}$ plane, the model lines are well separated into three groups of $s$-wave halo, $p$-wave halo, and $d$-wave nonhalo particularly in the vicinity of $S_n=0$, and the $s$-wave halo lines are always above the other lines, since only the $s$-wave halo lines can reach a point $(S_n,\mathcal{H})=(0,1)$ independently of the concrete form of the interaction between $c$ and $n$. The relation among the three kinds of lines may be universal for any halo nucleus with small $S_n$. The point $(S_n,\mathcal{H})=(0,1)$ can be regarded as a scale-invariant point in the sense that the $z$-integrated neutron density characterizing halo structure is invariant under the scale transformation there.

The analysis of high-precision ${\pi }^{\pm }p\to {\pi }^{\pm }p$ cross-sectional data from the EPECUR Collaboration based on the multichannel $K$-matrix approach is presented. The sharp structures seen in these data are studied in terms of both opening thresholds and new resonance contributions. Some prominent features are found to be due to the opening $K\mathrm{\Sigma }$ channel. However, a complete description of the data is improved with the addition of two narrow resonant structures at $W\sim 1.686$ and $W\sim 1.720\mathrm{GeV}$. These structures are interpreted as manifestations of $S_{11}$ and $P_{11}$ resonances. The underlying nature of the observed phenomena is discussed.

Isomeric states in ${}^{194}\mathrm{Po}$ and ${}^{192}\mathrm{Po}$ were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions ${}^{141}\mathrm{Pr}$(${}^{56}\mathrm{Fe}, \mathrm{p}2\mathrm{n}){}^{194}\mathrm{Po}$ and ${}^{144}\mathrm{Sm}$(${}^{51}\mathrm{V}, \mathrm{p}2\mathrm{n}){}^{192}\mathrm{Po}$. Several new $\gamma$-ray transitions were attributed to the isomers and $\gamma -\gamma$ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in ${}^{194}\mathrm{Po}$, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (${11}^{-}$) to (${10}^{-}$). The de-excitation of the (${11}^{-}$) isomeric level in ${}^{192}\mathrm{Po}$ by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV ($E3$) transition to ($8^{+}$) level of the ground-state band was suggested. Moreover, side feeding to the ($4^{+}$) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting ${11}^{-}$ isomers in neighboring Po and Pb isotopes.

The $\beta$ decay of ${}^{76}\mathrm{Ga}$ was studied using the technique of total absorption spectroscopy for the first time. The experiment was performed at the National Superconducting Cyclotron Laboratory using the Summing NaI(Tl) detector. The extracted $\beta$-decay feeding intensity distribution and Gamow-Teller transition strength distribution are compared to shell-model calculations to help constrain nuclear matrix elements relevant to the neutrinoless double-$\beta$ decay of ${}^{76}\mathrm{Ge}$.

Collinear laser spectroscopy on ${}^{58–75}\mathrm{Cu}$ isotopes was performed at the CERN-ISOLDE radioactive ion beam facility. In this paper we report on the isotope shifts obtained from these measurements. State-of-the-art atomic physics calculations have been undertaken in order to determine the changes in mean-square charge radii $\delta {\langle r^2\rangle }^{A,A^{\prime }}$ from the observed isotope shifts. A local minimum is observed in these radii differences at $N=40$, providing evidence for a weak $N=40$ sub-shell effect. However, comparison of $\delta {\langle r^2\rangle }^{A,A^{\prime }}$ with a droplet model prediction including static deformation deduced from the spectroscopic quadrupole moments, points to the persistence of correlations at $N=40$.

We report on measurements of the differential cross section $d\sigma /d\mathrm{\Omega }$ and the first measurement of the analyzing power $A_y$ in the $\mathrm{\Delta }\left(1232\right)$ excitation energy region of the reaction $pp\to {\left\{pp\right\}}_s{\pi }^0$ where ${\left\{pp\right\}}_s$ is a ${}^{1}S_0$ proton pair. The experiment has been performed with the ANKE spectrometer at COSY-Jülich. The data reveal a peak in the energy dependence of the forward ${\left\{pp\right\}}_s$ differential cross section, a minimum at zero degrees of its angular distribution, and a large analyzing power. The results present a direct manifestation of two two-baryon resonance-like states with $J^P=2^{-}$ and $0^{-}$ and an invariant mass of $2.2\mathrm{GeV}/c^2$.

We determine the charge radius of the proton by analyzing the published low momentum transfer electron-proton scattering data from Mainz. We note that polynomial expansions of the form factor converge for momentum transfers squared below $4m_{\pi }^2$, where $m_{\pi }$ is the pion mass. Expansions with enough terms to fit the data, but few enough not to overfit, yield proton radii smaller than the CODATA or Mainz values and in accord with the muonic atom results. We also comment on analyses using a wider range of data, and overall obtain a proton radius $R_E=0.840(16$) fm.

Background: The “pasta” phase of nuclear matter may play an important role in the structure and evolution of neutron stars. Recent works suggest nuclear pasta has a high resistivity which could be explained by the presence of long-lived topological defects. The defects act as impurities that decrease thermal and electrical conductivity of the pasta.

Purpose: To quantify how topological defects affect transport properties of nuclear pasta and estimate this effect using an impurity parameter $Q_{\text{imp}}$.

Methods: Contrast molecular dynamics simulations of up to 409 600 nucleons arranged in parallel nuclear pasta slabs (perfect pasta) with simulations of pasta slabs connected by topological defects (impure pasta). From these simulations we compare the viscosity and heat conductivity of perfect and impure pasta to obtain an effective impurity parameter $Q_{\text{imp}}$ due to the presence of defects.

Results: Both the viscosity and thermal conductivity calculated for both perfect and impure pasta are anisotropic, peaking along directions perpendicular to the slabs and reaching a minimum close to zero parallel to them. In our 409 600 nucleon simulation topological defects connecting slabs of pasta reduce both the thermal conductivity and viscosity on average by about 37%. We estimate an effective impurity parameter due to the defects of order $Q_{\text{imp}}\sim 30$.

Conclusions: Topological defects in the pasta phase of nuclear matter have an effect similar to impurities in a crystal lattice. The irregularities introduced by the defects reduce the thermal and electrical conductivities and the viscosity of the system. This effect can be parametrized by a large impurity parameter $Q_{\text{imp}}\sim 30$.

The $\beta$-decay half-lives of ${}^{128–130}\mathrm{Cd}$ have been measured with the newly commissioned GRIFFIN $\gamma$-ray spectrometer at the TRIUMF-ISAC facility. The time structures of the most intense $\gamma$ rays emitted following the $\beta$ decay were used to determine the half-lives of ${}^{128}\mathrm{Cd}$ and ${}^{130}\mathrm{Cd}$ to be $T_{1/2}=246.2\left(21\right)$ ms and $T_{1/2}=126\left(4\right)$ ms, respectively. The half-lives of the $3/2^{+}$ and $11/2^{-}$ states of ${}^{129}\mathrm{Cd}$ were measured to be $T_{1/2}(3/2^{+})=157\left(8\right)$ ms and $T_{1/2}(11/2^{-})=147\left(3\right)$ ms. The half-lives of the Cd isotopes around the $N=82$ shell closure are an important ingredient in astrophysical simulations to derive the magnitude of the second $r$-process abundance peak in the $A\sim 130$ region. Our new results are compared with recent literature values and theoretical calculations.

The purpose of the paper is mainly to test the validity of the Liège intranuclear cascade (INCL) model in calculating the cross sections of proton-induced reactions for cosmogenic nuclei using the newly compiled database of proton cross sections. The model calculations of ${}^3\mathrm{He}$ display the rising tendency of cross sections with the increase of energy, in accordance with the experimental data. Meanwhile, the differences between the theoretical results and experimental data of production cross sections (${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$) are generally within a factor of 3, meaning that the INCL model works quite well for the proton-induced reactions. Based on the good agreement, we predict the production cross sections of ${}^{26}\mathrm{Al}$ from reactions $n\hspace{0.17em}+\hspace{0.17em}{}^{27}\mathrm{Al}, n\hspace{0.17em}+\hspace{0.17em}{}^{28}\mathrm{Si}$, and $n\hspace{0.17em}+\hspace{0.17em}{}^{40}\mathrm{Ca}$ and those of ${}^{10}\mathrm{Be}$ from reactions $n\hspace{0.17em}+\hspace{0.17em}{}^{16}\mathrm{O}$ and $n\hspace{0.17em}+\hspace{0.17em}{}^{28}\mathrm{Si}$. The results also show a good agreement with a posteriori excitation functions.

In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic $\pi N$ scattering, however, usually the partial waves of the SAID (Scattering Analysis Interactive Database) or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated ${\chi }^2$ fits, in which the obtained ${\chi }^2$ equals the actual ${\chi }^2$ up to nonlinear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign any uncertainty on results. The influence of systematic errors is also considered.

An elastic backscattering experiment has been performed at energies below the Coulomb barrier to investigate static and dynamic effects in the interaction of ${}^6\text{He}$ with ${}^{209}\text{Bi}$. The measured cross sections are presented in terms of the $\mathrm{d}\sigma /\mathrm{d}{\sigma }_{Ruth}$ ratio, as a function of the distance of closest approach on a Rutherford trajectory. The data are compared with a three-body CDCC calculation and good agreement is observed. In addition, the critical distance of interaction was extracted. A larger value was obtained for the exotic ${}^6\text{He}$ nucleus as compared with the weakly bound ${}^6\text{Li}$ and ${}^9\text{Be}$ nuclei and the tightly bound ${}^4\text{He}, {}^{12}\text{C}$, and ${}^{16}\text{O}$ nuclei.

Assuming that the recently observed hidden-charm pentaquark state, $P_c\left(4450\right)$, is of molecular nature as predicted in the unitary approach, we propose to study the decay of ${\mathrm{\Xi }}_b^{-}\to J/\psi K^{-}\mathrm{\Lambda }$ to search for the strangeness counterpart of the $P_c\left(4450\right)$. There are three ingredients in the decay mechanism: the weak decay mechanism, the hadronization mechanism, and the final state interactions in the meson-baryon system of strangeness $S=-2$ and isospin $I=1/2$ and of the $J/\psi \mathrm{\Lambda }$. All these have been tested extensively. As a result, we provide a genuine prediction of the invariant mass distributions where a strangeness hidden-charm pentaquark state, the counterpart of the $P_c\left(4450\right)$, can be clearly seen. The decay rate is estimated to be of similar magnitude as the ${\mathrm{\Lambda }}_b^0\to J/\psi K^{-}p$ measured by the LHCb Collaboration.

The Kondo effect for isospin-exchange interaction between a $\overline{D}, B$ meson and a valence nucleon in charm and bottom atomic nuclei including the discrete energy levels for valence nucleons is discussed. To investigate the binding energy by the Kondo effect, I introduce the mean-field approach for the bound state of the $\overline{D}, B$ meson in charm and bottom nuclei. Assuming a simple model, I examine the validity of the mean-field approximation by comparing the results with the exact solutions. The effect of the quantum fluctuation is estimated beyond the mean-field approximation. The competition between the Kondo effect and the other correlations in valence nucleons, the isospin symmetry breaking and the nucleon pairings, are discussed.

Background: The observed mass excesses of analog nuclear states with the same mass number $A$ and isospin $T$ can be used to test the isobaric multiplet mass equation (IMME), which has, in most cases, been validated to a high degree of precision. A recent measurement [Kankainen et al., Phys. Rev. C 93, 041304(R) (2016)] of the ground-state mass of ${}^{31}\mathrm{Cl}$ led to a substantial breakdown of the IMME for the lowest $A=31,T=3/2$ quartet. The second-lowest $A=31,T=3/2$ quartet is not complete, due to uncertainties associated with the identity of the ${}^{31}\mathrm{S}$ member state.

Purpose: Our goal is to populate the two lowest $T=3/2$ states in ${}^{31}\mathrm{S}$ and use the data to investigate the influence of isospin mixing on tests of the IMME in the two lowest $A=31,T=3/2$ quartets.

Methods: Using a fast ${}^{31}\mathrm{Cl}$ beam implanted into a plastic scintillator and a high-purity Ge $\gamma$-ray detection array, $\gamma$ rays from the ${}^{31}\mathrm{Cl}\left(\beta \gamma \right){}^{31}\mathrm{S}$ sequence were measured. Shell-model calculations using USDB and the recently-developed USDE interactions were performed for comparison.

Results: Isospin mixing between the ${}^{31}\mathrm{S}$ isobaric analog state (IAS) at 6279.0(6) keV and a nearby state at 6390.2(7) keV was observed. The second $T=3/2$ state in ${}^{31}\mathrm{S}$ was observed at $E_x=7050.0\left(8\right)$ keV. Calculations using both USDB and USDE predict a triplet of isospin-mixed states, including the lowest $T=3/2$ state in ${}^{31}\mathrm{P}$, mirroring the observed mixing in ${}^{31}\mathrm{S}$, and two isospin-mixed triplets including the second-lowest $T=3/2$ states in both ${}^{31}\mathrm{S}$ and ${}^{31}\mathrm{P}$.

Conclusions: Isospin mixing in ${}^{31}\mathrm{S}$ does not by itself explain the IMME breakdown in the lowest quartet, but it likely points to similar isospin mixing in the mirror nucleus ${}^{31}\mathrm{P}$, which would result in a perturbation of the ${}^{31}\mathrm{P}$ IAS energy. USDB and USDE calculations both predict candidate ${}^{31}\mathrm{P}$ states responsible for the mixing in the energy region slightly above $E_x=6400$ keV. The second quartet has been completed thanks to the identification of the second ${}^{31}\mathrm{S} T=3/2$ state, and the IMME is validated in this quartet.

The phenomenological optical potential parameters are known to vary with incident energy due to sources of nonlocalities in the nucleon-nucleus elastic scattering process. Here we investigate the effect of one source, which is coupling the ground-state elastic channel to collective inelastic excitations on the energy dependence of the optical potential parameters. For incident energies in the range 10–70 MeV, we considered elastic and inelastic nucleon scattering from light, medium, and heavy nuclei ranging from ${}^6\mathrm{Li}$ to ${}^{208}\mathrm{Pb}$. The potential parameters were first determined by fitting the elastic angular distributions only. Then we included coupling to collective excitation channels and determined the potential parameters that reproduced the elastic and inelastic angular distribution data simultaneously. Our results show that coupling to inelastic excitations reduces the energy variations of the potential parameters compared to that of the elastic scattering case. In particular, the our best fit values for the real part of the spin-orbit term are highly stable as a function of energy. The values of the surface imaginary term are not only more stable but are also reduced compared to the elastic case. The reduction is a direct consequence of the channel coupling accounting explicitly for part of the flux removed from the elastic channel. In the fitting process we also searched for the best fit values of the deformation parameters. Our values compare well with the corresponding ones obtained in previous works. Finally, we used our best fit values for the potential and deformation parameters to theoretically predict the total elastic, total cross section, and polarization data. The predicted values are in very good agreement with the experimental data.