The radiative neutron capture cross sections for nuclei participating in the $s$-process and the $p$-process nucleosynthesis in and around the $N=50$ closed neutron shell have been calculated in a statistical semimicroscopic Hauser-Feshbach approach for the energy range of astrophysical interest. A folded optical-model potential is constructed utilizing the standard DDM3Y real nucleon-nucleon interaction. The folding of the interaction with target radial matter densities, obtained from the relativistic mean-field theory, is done in coordinate space using the spherical approximation. The standard nuclear reaction code talys1.8 is used for cross-section calculation. The cross sections are compared with experimental results. Maxwellian-averaged cross sections and astrophysical reaction rates for a number of selected nuclei are also presented.

We report on the first measurement of $p\mathrm{\Lambda }$ and $pp$ correlations via the femtoscopy method in $p$ + Nb reactions at $\sqrt{s_{\mathit{NN}}}=3.18\mathrm{GeV}$, studied with the High Acceptance Di-Electron Spectrometer (HADES). By comparing the experimental correlation function to model calculations, a source size for $pp$ pairs of $r_{0,pp}=2.02\pm 0.01{\left(\mathrm{stat}\right)}_{-0.12}^{+0.11}\left(\mathrm{sys}\right)\mathrm{fm}$ and a slightly smaller value for $p\mathrm{\Lambda }$ pairs of $r_{0,\mathrm{\Lambda }p}=1.62\pm 0.02{\left(\mathrm{stat}\right)}_{-0.08}^{+0.19}\left(\mathrm{sys}\right)\mathrm{fm}$ are extracted. Using the geometrical extent of the particle-emitting region, determined experimentally with $pp$ correlations as reference together with a source function from a transport model, it is possible to study different sets of scattering parameters. The $p\mathrm{\Lambda }$ correlation is proven to be sensitive to predicted scattering length values from chiral effective field theory. We demonstrate that the femtoscopy technique can be used as a valid alternative to the analysis of scattering data to study the hyperon-nucleon interaction.

Relativistic self-consistent mean-field (SCMF) models naturally account for the coupling of the nucleon spin to its orbital motion, whereas nonrelativistic SCMF methods necessitate a phenomenological ansatz for the effective spin-orbit potential. Recent experimental studies aim to explore the isospin properties of the effective spin-orbit interaction in nuclei. SCMF models are very useful in the interpretation of the corresponding data; however, standard relativistic mean-field and nonrelativistic Hartree-Fock models use effective spin-orbit potentials with different isovector properties, mainly because exchange contributions are not treated explicitly in the former. The impact of exchange terms on the effective spin-orbit potential in relativistic mean-field models is analyzed, and it is shown that it leads to an isovector structure similar to the one used in standard nonrelativistic Hartree-Fock models. Data on the isospin dependence of spin-orbit splittings in spherical nuclei could be used to constrain the isovector-scalar channel of relativistic mean-field models. The reproduction of the empirical kink in the isotope shifts of even Pb nuclei by relativistic effective interactions points to the occurrence of pseudospin symmetry in the single-neutron spectra in these nuclei.

Background: Octupole-deformed nuclei, such as that of ${}^{225}\mathrm{Ra}$, are expected to amplify observable atomic electric dipole moments (EDMs) that arise from time-reversal and parity-violating interactions in the nuclear medium. In 2015 we reported the first “proof-of-principle” measurement of the ${}^{225}\mathrm{Ra}$ atomic EDM.

Purpose: This work reports on the first of several experimental upgrades to improve the statistical sensitivity of our ${}^{225}\mathrm{Ra}$ EDM measurements by orders of magnitude and evaluates systematic effects that contribute to current and future levels of experimental sensitivity.

Method: Laser-cooled and trapped ${}^{225}\mathrm{Ra}$ atoms are held between two high-voltage electrodes in an ultrahigh-vacuum chamber at the center of a magnetically-shielded environment. We observe Larmor precession in a uniform magnetic field using nuclear-spin-dependent laser light scattering and look for a phase shift proportional to the applied electric field, which indicates the existence of an EDM. The main improvement to our measurement technique is an order-of-magnitude increase in spin-precession time, which is enabled by an improved vacuum system and a reduction in trap-induced heating.

Results: We have measured the ${}^{225}\mathrm{Ra}$ atomic EDM to be less than $1.4\times {10}^{-23}e$ cm ($95\%$ confidence upper limit), which is a factor of 36 improvement over our previous result.

Conclusions: Our evaluation of systematic effects shows that this measurement is completely limited by statistical uncertainty. Combining this measurement technique with planned experimental upgrades, we project a statistical sensitivity at the $1\times {10}^{-28}e$ cm level and a total systematic uncertainty at the $4\times {10}^{-29}e$ cm level.

In this paper we analyze the effects of the projectile resonances on the total, Coulomb, and nuclear breakup cross sections as well as on the Coulomb-nuclear interferences at different arbitrary incident energies. It is found that these resonances have non-negligible effects on the total, Coulomb, and nuclear breakup cross sections. Qualitatively, they have no effects on the constructiveness or destructiveness of the Coulomb-nuclear interferences. Quantitatively, we obtained that these resonances increase by 7.38%, 7.58%, and 20.30% the integrated total, Coulomb, and nuclear breakup cross sections, respectively at $E_{\mathrm{lab}}=35\mathrm{MeV}$. This shows that the nuclear breakup cross sections are more affected by the effects of the projectile resonances than their total and Coulomb breakup counterparts. We also obtain that the effects of the resonances on the total, Coulomb, and nuclear breakup cross sections decrease as the incident energy increases.

Neutrinoless double-$\beta$ decay ($0\nu \beta \beta$ decay) is a hypothetical process that can occur if the neutrino is its own antiparticle. The COBRA Collaboration operates a demonstrator to search for these decays at the Laboratori Nazionali del Gran Sasso in Italy using CdZnTe semiconductor detectors. The exposure of 234.7 kg d considered in this analysis was collected between September 2011 and February 2015. The analysis focuses on the decay of the nuclides ${}^{114}\mathrm{Cd},{}^{128}\mathrm{Te},{}^{70}\mathrm{Zn},{}^{130}\mathrm{Te}$, and ${}^{116}\mathrm{Cd}$. A Bayesian analysis is performed to estimate the signal strength of $0\nu \beta \beta$ decay. No signal is observed for any of these nuclides. Therefore, the following half-life limits at 90% credibility are set: $T_{1/2}^{0\nu }>1.6\times {10}^{21}\mathrm{yr} \left({}^{114}\mathrm{Cd}\right),T_{1/2}^{0\nu }>1.9\times {10}^{21}\mathrm{yr} \left({}^{128}\mathrm{Te}\right),T_{1/2}^{0\nu }>6.8\times {10}^{18}\mathrm{yr} \left({}^{70}\mathrm{Zn}\right),T_{1/2}^{0\nu }>6.1\times {10}^{21}\mathrm{yr} \left({}^{130}\mathrm{Te}\right)$, and $T_{1/2}^{0\nu }>1.1\times {10}^{21}\mathrm{yr} \left({}^{116}\mathrm{Cd}\right)$.

Fluctuations of conserved quantities are sensitive observables to probe the signature of QCD phase transition and critical point in heavy-ion collisions. With the UrQMD model, we have studied the centrality and energy dependence of various order cumulants and cumulant ratios (up to fourth order) of net-proton, net-charge, and net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=7.7$, 11.5, 19.6, 27, 39, 62.4, 200 GeV. The model results show that the production mechanism of the particles and antiparticles has significant impact on the cumulants of net-particles multiplicity distributions and shows strong energy dependence. We also made comparisons between model calculations and experimental data measured in the first phase of the beam energy scan (BES) program by the STAR experiment at the BNL Relativistic Heavy Ion Collider. The comparisons indicate that the baryon conservation effect strongly suppresses the cumulants of net-proton distributions at low energies and the nonmonotonic energy dependence for the net-proton $\kappa {\sigma }^2$ at the most central Au+Au collisions measured by the STAR experiment cannot be described by the UrQMD model. Since there has been no physics of QCD phase transition and QCD critical point implemented in the UrQMD, the model results provide us baselines and qualitative estimates about the noncritical background contributions to the fluctuations observables in heavy-ion collisions.

We study the evolution of the full jet shower in quark-gluon plasma by solving a set of coupled differential transport equations for the three-dimensional momentum distributions of quarks and gluons contained in full jets. In our jet evolution equations, we include all partonic splitting processes as well as the collisional energy loss and transverse momentum broadening for both the leading and radiated partons of the full jets. Combining with a realistic ($2+1$)-dimensional viscous hydrodynamic simulation for the spacetime profiles of the hot and dense nuclear medium produced in heavy-ion collisions, we apply our formalism to calculate the nuclear modification of single inclusive full jet spectra, the momentum imbalance of photon-jet and dijet pairs, and the jet shape function (at partonic level) in $\text{Pb}+\text{Pb}$ collisions at $2.76A$ TeV. The roles of various jet-medium interaction mechanisms on the full jet modification are studied. We find that the nuclear modification of jet shape is sensitive to the interplay of different interaction mechanisms as well as the energies of the full jets.

Spectator fragments resulting from relativistic heavy ion collisions, consisting of single protons and neutrons along with groups of stable nuclear fragments up to nitrogen $\left(Z=7\right)$, are measured in PHOBOS. These fragments are observed in Au+Au $\left(\sqrt{s_{{}_{NN}}}=19.6\mathrm{GeV}\right)$ and Cu+Cu (22.4 GeV) collisions at high pseudorapidity $\left(\eta \right)$. The dominant multiply-charged fragment is the tightly bound helium $\left(\alpha \right)$, with lithium, beryllium, and boron all clearly seen as a function of collision centrality and pseudorapidity. We observe that in Cu+Cu collisions, it becomes much more favorable for the $\alpha$ fragments to be released than lithium. The yields of fragments approximately scale with the number of spectator nucleons, independent of the colliding ion. The shapes of the pseudorapidity distributions of fragments indicate that the average deflection of the fragments away from the beam direction increases for more central collisions. A detailed comparison of the shapes for $\alpha$ and lithium fragments indicates that the centrality dependence of the deflections favors a scaling with the number of participants in the collision.

Fermions become polarized in a vortical fluid due to spin-vorticity coupling. Such a polarization can be calculated from the Wigner function in a quantum kinetic approach. By extending previous results for chiral fermions, we derive the Wigner function for massive fermions up to next-to-leading order in spatial gradient expansion. The polarization density of fermions can be calculated from the axial vector component of the Wigner function and is found to be proportional to the local vorticity $\mathbf{\omega }$. The polarizations per particle for fermions and antifermions decrease with the chemical potential and increase with energy (mass). Both quantities approach the asymptotic value $\hslash \mathbf{\omega }/4$ in the large energy (mass) limit. The polarization per particle for fermions is always smaller than that for antifermions, whose ratio of fermions to antifermions also decreases with the chemical potential. The polarization per particle on the Cooper-Frye freeze-out hypersurface can also be formulated and is consistent with the previous result of Becattini et al. [11,27].

High-spin states of ${}^{123}\mathrm{Ba}$ have been studied via the ${}^{108}\mathrm{Cd}({}^{19}\mathrm{F},3np){}^{123}\mathrm{Ba}$ fusion-evaporation reaction at a beam energy of 90 MeV. Several $E1$ transitions linking the positive-parity $\nu (d_{5/2}+g_{7/2})$ band and negative-parity $\nu h_{11/2}$ band are observed in ${}^{123}\mathrm{Ba}$ for the first time. Evidence for the existence of octupole correlations in ${}^{123}\mathrm{Ba}$ is presented based on the systematic comparisons of the $B\left(E1\right)/B\left(E2\right)$ branching ratios and the energy displacements in odd-$A$ Ba isotopes. The characteristics of octupole correlation in the odd-$A{}^{123,125}\mathrm{Ba}$ are explained by the state-of-the-art multidimensionally-constrained relativistic mean-field model and cluster model based on the dinuclear system concept.

By using the general triaxial rotor model (TRM) and the phonon-configuration mixing scheme within an anharmonic-vibrator (AHV) framework, a series of global correlations between electromagnetic properties of nuclear $2_1^{+}$ and $2_2^{+}$ states are analytically established. The correlations from both models can roughly describe the experimental data involving quadrupole collectivity with few exceptions. Furthermore, there seems to be a robust orthogonal transformation between the AHV and the TRM bases for realistic nuclear systems, suggesting that the two models may in fact be describing the collective features of nuclear low-lying states in similar model spaces.

Resonance plays a key role in the formation of many physical phenomena. The complex-scaled Green's function method provides a powerful tool for exploring resonance. In this paper, we combine this method with the theory describing deformed nuclei with the formalism presented. Taking ${}^{45}\text{S}$ as an example, we elaborate numerical details and demonstrate how to determine the resonance parameters. The results are compared with those obtained by the complex scaling method and the coupled-channel method and satisfactory agreement is obtained. In particular, the present scheme focuses on the advantages of the complex scaling method and the Green's function method and is more suitable for the exploration of resonance.

The $\beta$ decay of the semi-magic nucleus ${}^{130}\mathrm{Cd}$ has been studied at the RIBF facility at the RIKEN Nishina Center. The high statistics of the present experiment allowed for a revision of the established level scheme of ${}^{130}\mathrm{In}$ and the observation of additional $\beta$ feeding to high-lying core-excited states in ${}^{130}\mathrm{In}$. The experimental results are compared to shell-model calculations employing a model space consisting of the full major $N=50–82$ neutron and $Z=28–50$ proton shells and the NA-14 interaction, and good agreement is found.

The production cross sections for primary and residual fragments with charge number from $Z=70$ to 120 produced in the collision of ${}^{238}\text{U}+{}^{238}\text{U}$ at 7.0 MeV/nucleon are calculated by the improved quantum molecular dynamics (ImQMD) model incorporated with the statistical evaporation model (hivap code). The calculation results predict that about 60 unknown neutron-rich isotopes from elements Ra ($Z=88$) to Db ($Z=105$) can be produced with the production cross sections above the lower bound of ${10}^{-8}$ mb in this reaction. And almost all of the unknown neutron-rich isotopes are emitted at the laboratory angles ${\theta }_{\mathrm{lab}}\le {60}^{\circ }$. Two cases, i.e., the production of the unknown uranium isotopes with $A\ge 244$ and that of rutherfordium with $A\ge 269$, are investigated to understand the production mechanism of unknown neutron-rich isotopes. It is found that for the former case the collision time between two uranium nuclei is shorter and the primary fragments producing the residues have smaller excitation energies of $\le 30$ MeV and the outgoing angles of those residues cover a range of ${30}^{\circ }–{60}^{\circ }$. For the latter case, a longer collision time is needed for a large number of nucleons being transferred and thus it results in higher excitation energies and smaller outgoing angles of primary fragments, and eventually results in a very small production cross section for the residues of Rf with $A\ge 269$ which have a small interval of outgoing angles of ${\theta }_{\mathrm{lab}}={40}^{\circ }–{50}^{\circ }$.

Starting from a set of different two- and three-nucleon interactions from chiral effective field theory, we use the importance-truncated no-core shell model for ab initio calculations of excitation energies as well as electric quadrupole $\left(E2\right)$ and magnetic dipole $\left(M1\right)$ moments and transition strengths for selected $p$-shell nuclei. We explore the sensitivity of the excitation energies to the chiral interactions as a first step towards and systematic uncertainty propagation from chiral inputs to nuclear structure observables. The uncertainty band spanned by the different chiral interactions is typically in agreement with experimental excitation energies, but we also identify observables with notable discrepancies beyond the theoretical uncertainty that reveal insufficiencies in the chiral interactions. For electromagnetic observables we identify correlations among pairs of $E2$ or $M1$ observables based on the ab initio calculations for the different interactions. We find extremely robust correlations for $E2$ observables and illustrate how these correlations can be used to predict one observable based on an experimental datum for the second observable. In this way we circumvent convergence issues and arrive at far more accurate results than any direct ab initio calculation. A prime example for this approach is the quadrupole moment of the first $2^{+}$ state in ${}^{12}\mathrm{C}$, which is predicted with an drastically improved accuracy.

Background: The search for new opportunities to investigate the low-energy level in the ${}^{229}\mathrm{Th}$ nucleus, which is nowadays intensively studied experimentally, has motivated us to theoretical studies of the magnetic hyperfine (MHF) structure of the $5/2^{+}$ (0.0 eV) ground state and the low-lying $3/2^{+}$ (7.8 eV) isomeric state in highly charged ${}^{229}\mathrm{Th}^{89+}$ and ${}^{229}\mathrm{Th}^{87+}$ ions.

Purpose: The aim is to calculate, with the maximal precision presently achievable, the energy of levels of the hyperfine structure of the ${}^{229}\mathrm{Th}$ ground-state doublet in highly charged ions and the probability of radiative transitions between these levels.

Methods: The distribution of the nuclear magnetization (the Bohr-Weisskopf effect) is accounted for in the framework of the collective nuclear model with Nilsson model wave functions for the unpaired neutron. Numerical calculations using precise atomic density functional theory methods, with full account of the electron self-consistent field, have been performed for the electron structure inside and outside the nuclear region.

Results: The deviations of the MHF structure for the ground and isomeric states from their values in a model of a pointlike nuclear magnetic dipole are calculated. The influence of the mixing of the states with the same quantum number $F$ on the energy of sublevels is studied. Taking into account the mixing of states, the probabilities of the transitions between the components of the MHF structure are calculated.

Conclusions: Our findings are relevant for experiments with highly ionized ${}^{229}\mathrm{Th}$ ions in a storage ring at an accelerator facility.

A systematic study of both the observed positive-parity magnetic rotation band and the negative-parity $\mathrm{\Delta }I=1$ doublet bands in an odd-odd ${}^{106}\mathrm{Ag}$ nucleus is carried out. The negative-parity doublet bands depict some unusual features that have not been observed in any isotope in the mass $A=100$ region. For instance, (i) the moment of inertia of the partner band is quite different from that of the yrast band, and (ii) these bands cross each other at an angular momentum of $I=14\hslash$. Also, the observed significantly large but constant $B\left(M1\right)$ transitions confirm that the strong $M1$ transitions are being reinforced by the contributions from collective rotation. To explain these features, a collective model has been developed whose kinetic and potential energies are extracted from the tilted-axis cranking model. Instead of the triaxial parameter $\gamma$, a second-order phase transition is found to be responsible for the spontaneous breakdown of chiral symmetry. Analytical solution of the Schrödinger equation has generated a doublet nondegenerate eigenvalue spectrum. The ensuing model results based on the two-quasiparticle configuration $\pi g_{\frac{9}{2}}\otimes \nu h_{\frac{11}{2}}$ exhibit similarities with many observed features of the negative-parity doublet bands and hence confirm their chiral character. The cranking mass parameter in kinetic energy plays an important role in diabatic crossing between these emerged chiral twin bands.

Background: In the design of deuteron accelerator neutron sources, accurate nuclear data of deuteron-induced reactions are indispensable over a wide range of incident energy. Reliable model calculations play an important role in completing the necessary nuclear data since currently available experimental data are insufficient. We have been developing a code system dedicated for the deuteron-induced reactions, called deuteron-induced reaction analysis code system (DEURACS). It was applied successfully to $(d,xp)$ reactions at 56 and 100 MeV.

Purpose: The purpose of the present work is to investigate the applicability of DEURACS to $(d,xn)$ reactions on ${}^9\mathrm{Be}$ and ${}^{12}\mathrm{C}$ for incident energies below 50 MeV and to clarify neutron production mechanism.

Methods: Double-differential thick target neutron yields (TTNYs) from deuteron bombardment on thick Be and C targets are analyzed. The TTNYs are derived using the double differential $(d,xn)$ cross sections calculated by DEURACS and the stopping power of deuteron in the target. The calculated TTNYs are decomposed into individual components corresponding to elastic breakup, proton stripping, and statistical decay reactions.

Results: The calculated TTNYs reproduced the experimental data quantitatively well in the incident energy range up to 50 MeV. From the analysis, it was found that the proton stripping reaction makes the most dominant contribution to neutron production.

Conclusions: DEURACS is applicable to $(d,xn)$ reactions on ${}^9\mathrm{Be}$ and ${}^{12}\mathrm{C}$ for incident energies below 50 MeV. Modeling of the stripping reaction is essential to predict neutron production yields accurately in the design of deuteron accelerator neutron sources.

A set of global optical potential parameters, DA1p, for deuterons with the $1p$-shell nuclei is obtained by simultaneously fitting 67 sets of experimental data of deuteron elastic scattering from ${}^6\mathrm{Li}$, ${}^9\mathrm{Be}$, ${}^{10}\mathrm{B}$, ${}^{11}\mathrm{B}$, ${}^{12}\mathrm{C}$, ${}^{13}\mathrm{C}$, ${}^{14}\mathrm{N}$, ${}^{16}\mathrm{O}$, and ${}^{18}\mathrm{O}$ with incident energies between 5.25 and 170 MeV. DA1p improves the description of the deuteron elastic scattering from the $1p$-shell nuclei with respect to the existing systematic deuteron potentials and can give satisfactory reproduction of the experimental data with radiative nuclei such as ${}^9\mathrm{Li}$, ${}^{10}\mathrm{Be}$, ${}^{14}\mathrm{C}$, and ${}^{14}\mathrm{O}$.