The effect of the isovector imaginary optical potential has been studied experimentally by using the particle-evaporation technique for the ${}^{11}\mathrm{B}+{}^{48}\mathrm{Ca}$ reaction with a 21.8 MeV ${}^{11}\mathrm{B}$ beam. Spectra of neutron, proton, and $\alpha$ particles emitted from the neutron-rich compound nucleus ${}^{59}\mathrm{Mn}$ have been measured and analyzed with traditional optical model potentials with their original parametrizations as well as with adjusted isovector imaginary components. It is shown that the isovector component of the imaginary potential is indispensable in the reproduction of proton and $\alpha$-particle yields from this reaction and even needs to be enhanced compared with the suggestions of the original model parametrizations. This can lead to important consequences for astrophysical reaction-rate calculations.

The ${}^{137}\mathrm{La}$ nucleus was populated by the reaction ${}^{130}\mathrm{Te}({}^{11}\mathrm{B}, 4n$) at 40-MeV beam energy and the lifetime of the $11/2^{-}$ state at $1004.6\mathrm{keV}$ was measured using a hybrid array of HPGe clover and ${\mathrm{LaBr}}_3$(Ce) detectors by electronic fast-timing technique, providing the value $T_{1/2}=263\pm 12\mathrm{ps}$. The reduced transition probability $B\left(E3\right)=23.3\pm 2.4\mathrm{W}.\mathrm{u}.$ is found to be significantly larger compared to the values observed in lighter odd-$A$ La isotopes. The experimentally determined $B\left(E3\right)$ value is compared with theoretical calculations of random-phase approximation which explains the enhanced transition probability to be arising from higher contribution of the $g_{9/2}$ orbital to the proton transition density.

We discuss high-order calculations in perturbative effective field theory for fermions at low energy scales. The Fermi-momentum or $k_{\mathrm{F}}{a}_s$ expansion for the ground-state energy of the dilute Fermi gas is calculated to fourth order, both in cutoff regularization and in dimensional regularization. For the case of spin one-half fermions we find from a Bayesian analysis that the expansion is well converged at this order for $|k_{\mathrm{F}}{a}_s|\lesssim 0.5$. Furthermore, we show that Padé-Borel resummations can improve the convergence for $|k_{\mathrm{F}}{a}_s|\lesssim 1$. Our results provide important constraints for nonperturbative calculations of ultracold atoms and dilute neutron matter.

We report on spectroscopic information and lifetime measurements in the neutron-rich ${}^{135,137,139}\mathrm{I}$ isotopes. This is the first lifetime data on iodine isotopes beyond $N=82$. Excited states were populated in fast neutron-induced fission of ${}^{238}\mathrm{U}$ at the ALTO facility of IJCLab with the LICORNE neutron source and detected using the hybrid $\nu$-ball spectrometer. The level schemes of the ${}^{135,137,139}\mathrm{I}$ isotopes are revised in terms of excited states with up to maximum spin-parity of $(33/2^{+})$, populated for the first time in fast neutron-induced fission. We provide first results on the lifetimes of the $(9/2_1^{+})$ and $(13/2_1^{+})$ states in ${}^{137}\mathrm{I}$ and ${}^{139}\mathrm{I}$, and the $(17/2_1^{+})$ state in ${}^{137}\mathrm{I}$. In addition, we give upper lifetime limits for the $(11/2_1^{+})$ states in ${}^{135-139}\mathrm{I}$, the $(15/2_1^{+})$ state in ${}^{137}\mathrm{I}$, the $(17/2_1^{+})$ state in ${}^{139}\mathrm{I}$, and reexamine the $(29/2_1^{+})$ state in ${}^{137}\mathrm{I}$. The isomeric data in ${}^{135}\mathrm{I}$ are reinvestigated, such as the previously known $(15/2_1^{+})$ and $(23/2_1^{-})$ isomers with $T_{1/2}$ of 1.64(14) and 4.6(7) ns, respectively, as obtained in this work. The new spectroscopic information is compared to that from spontaneous or thermal-neutron induced fission and discussed in the context of large scale shell-model (LSSM) calculations for the region beyond ${}^{132}\mathrm{Sn}$, indicating the behavior of collectivity for the three valence-proton iodine chain with $N=82,84,86$.

With the improved particular isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model including the nucleon-nucleon short-range correlations, the ratios and yields of ${\pi }^{-}$ and ${\pi }^{+}$ in $\mathrm{Sn}+\mathrm{Sn}$ systems with different asymmetries at 270 MeV/nucleon are studied. It is found that the yields of ${\pi }^{-}$ and ${\pi }^{+}$ and their ratios in $\mathrm{Sn}+\mathrm{Sn}$ systems characterized by different neutron to proton ratios obtained from very recent $\mathrm{S}\pi \mathrm{RIT}$ pion data are quite well described by the model, especially when a soft symmetry energy with $L\left({\rho }_0\right)=66.75\pm 24.75$ MeV is used. The calculations also clearly demonstrate that the high-momentum tail of the nucleon initialization in momentum space strongly affects the yields and ratios of pion production in $\mathrm{Sn}+\mathrm{Sn}$ systems with different asymmetries near or below threshold. In addition, given many insoluble theoretical uncertainties in transport models, multisystem experimental measurements with various $N/Z$ asymmetries are proposed to extract the symmetry energy less model dependently by using heavy-ion collisions.

The variational principle is used to build a model which describes open shell nuclei with ground state deformations. Hartree-Fock equations are solved by using single particle wave functions whose radial parts depend on the projection of the angular momentum on the quantisation axis. Pairing effects are taken into account by solving Bardeen-Cooper-Schrieffer equations in each step of the minimization procedure. The Gogny D1S finite-range interaction and an extension of it that includes tensor terms are consistently used in both parts of our calculations. The model is applied to study a set of isotopes with 34 protons and of isotones with 34 neutrons. Total energies, density distributions, their radii, and single particle energies are analyzed and the results of our calculations are compared with the available experimental data. We focused our attention on the effects of the deformation and of the tensor force on these observables. Our model describes open shell nuclei from a peculiar perspective and opens the possibility of future theoretical developments.

A simple calculation indicates that the observed energy and width of a state at 6.02(15) MeV in ${}^{12}\mathrm{Be}$, populated in the ${}^{11}\mathrm{Be}(d,p)$ reaction, are consistent with expectation for the first $3^{+}$ state with dominant configuration ${}^{10}\mathrm{Be}$(ground state) $\times \left(2s_{1/2}\right)\left(1d_{5/2}\right)$.

Background: Recently, novel statistical methods such as neural networks and Bayesian learning methods are implemented to describe the nuclear masses.

Purpose: Based on previous studies, an improved naive Bayesian probability (iNBP) classifier is proposed to study the nuclear masses by refining the results of sophisticated nuclear models.

Method: In the iNBP method, the prediction for nuclear masses is treated as a classification problem. The residuals are classified into several groups to generate prior and conditional probabilities, and the posterior probabilities are further determined by the Bayesian formula. We choose the expectation with maximum probability as the final prediction. Reliability of the iNBP method is assessed by analyzing the global optimizations and the extrapolating capabilities.

Results: The iNBP method exhibits impressive improvements on global descriptions for different mass models. Moreover, the method shows robust extrapolating capabilities. Results demonstrate the iNBP method can be applied to predict the nuclear masses of unknown regions.

Conclusions: Considering the local mass relations, the iNBP method can offer considerable fine-tuning of the mass descriptions from nuclear models. The methodology proposed in this paper can also be applied to other model-based extrapolations of nuclear observables.

The Hauser-Feshbach fission-fragment decay $\left(\mathrm{HF}{}^3\mathrm{D}\right)$ model is extended to calculate the prompt fission neutron spectrum (PFNS) for the thermal-neutron-induced fission on ${}^{235}\mathrm{U}$, where the evaporated neutrons from all possible fission-fragment pairs are aggregated. By studying model parameter sensitivities on the calculated PFNS as well as nonstatistical behavior of low-lying discrete level spin distribution, we conclude that discrepancies between the aggregation calculation and the experimental PFNS seen at higher neutron emission energies can be attributed to both the primary fission-fragment yield distribution and the possible high spin states that are not predicted by the statistical theory of nuclear structure.

The bright scintillation of pure CsI operated at liquid-nitrogen temperature makes of this material a promising dark matter and neutrino detector. We present the first measurement of its quenching factor for nuclear recoils. Our findings indicate it is indistinguishable from that for sodium-doped CsI at room temperature. Additional properties such as light yield, afterglow, scintillation decay properties for electron and nuclear recoils, and energy proportionality are studied over the 108–165 K temperature range, confirming the vast potential of this medium for rare-event searches.

Astrophysical nucleosynthesis is a family of diverse processes by which atomic nuclei undergo nuclear reactions and decay to form new nuclei. The complex nature of nucleosynthesis, which can involve as many as tens of thousands of interactions between thousands of nuclei, makes it difficult to study any one of these interactions in isolation using standard approaches. In this work, we present a new technique, nucleosynthesis tracing, that we use to quantify the relative fraction of nuclear abundances that pass through individual nuclear reaction, decay, and fission processes at any point during nucleosynthesis. We apply this technique to study fission and ${\beta }^{-}$ decay as they occur in the rapid neutron capture ($r$) process of nucleosynthesis.

Tensor couplings and Coulomb-exchange terms in the relativistic mean-field (RMF) model impact the neutron skin thickness of nuclei [N. Liliani, A. M. Nugraha, J. P. Diningrum, and A. Sulaksono, Phys. Rev. C 93, 054322 (2016)], and a significantly thicker skin of ${}^{208}\mathrm{Pb}$ predicted by PREX-II leads to the existence of a phase transition in the interior of neutron stars (NSs) [F. J. Fattoyev, J. Piekarewicz, and C. J. Horowitz, Phys. Rev. Lett. 120, 172702 (2018)]. In this work, we revisit the effects of tensors and Coulomb-exchange terms within the RMF model with the $\delta$-meson and isovector-isoscalar coupling on finite nuclei. We also perform a systematic investigation of the implicit effect of both terms on the nuclear matter and NS properties. We confirmed in our previous work [N. Liliani, A. M. Nugraha, J. P. Diningrum, and A. Sulaksono, Phys. Rev. C 93, 054322 (2016)] that the roles of tensor couplings, Coulomb exchange, and isovector-isoscalar coupling on the bulk properties of finite nuclei are crucial. Conversely, the $\delta$-meson term's inclusion yields no significant effect on the bulk properties of finite nuclei. The tensor couplings and Coulomb-exchange terms implicitly influence the isoscalar and isovector parts of nuclear matter. By contrast, the $\delta$-meson and isovector-isoscalar coupling significantly impact the isovector parts of nuclear matter predictions. Except for the binding energy and the equation of state of pure neutron matter in low-density cases, the nuclear matter property predictions of all parameter sets used are relatively compatible with experimental data and the chiral effective field theory result. Moreover, the tensor couplings, Coulomb-exchange, $\delta$-meson, and isovector-isoscalar coupling terms play a significant role in predicting the canonical NS radius but not in the maximum mass of NS. For relatively large ${\eta }_{2\rho }$, the compatibility of the canonical NS radius predicted by the model with all of the observation results used in this work is better than that with the tensor couplings and Coulomb exchange excluded. Moreover, the presence of tensor couplings, Coulomb exchange, and various isovector-isoscalar nonlinear coupling terms influence the relation between NS tidal deformation and neutron skin thickness of ${}^{208}\mathrm{Pb}$. However, tensor couplings and Coulomb-exchange terms play a crucial role in making the NS tidal deformability prediction compatible with the constraints from observations and experimental data. In conclusion, tensor couplings and Coulomb-exchange RMF models have an essential role in finite nuclei predictions and implicitly influence the nuclear matter and NS property predictions.

The quantum-number-projected generator coordinate method (QNPGCM) is applied to the neutron-rich Ge and Se isotopes where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra calculated with both axial and triaxial deformations are compared to the shell-model results and the experimental data. In both cases, the QNPGCM reproduces well the energy levels of the even-spin yrast states. However, the QNPGCM results by only assuming axial deformations are not satisfactory enough to reproduce the energy levels of the quasi-$\gamma$ bands. Taking account of triaxial deformations is essentially important to describe the yrast and quasi-$\gamma$ bands simultaneously.

The secondary component of GW190814 with a mass of 2.50–2.67 $M_{\odot }$ may be the lightest black hole or the heaviest neutron star ever observed in a binary compact object system. To explore the possible equation of state (EOS), which can support such a massive neutron star, we apply the relativistic mean-field model with a density-dependent isovector coupling constant to describe the neutron-star matter. The acceptable EOS should satisfy some constraints: the EOS model can provide a satisfactory description of the nuclei; the maximum mass $M_{\text{TOV}}$ is above 2.6 $M_{\odot }$; the tidal deformability of a canonical 1.4 $M_{\odot }$ neutron star ${\mathrm{\Lambda }}_{1.4}$ should lie in the constrained range from GW170817. In this paper, we find that nuclear symmetry energy and its density dependence play a crucial role in determining the EOS of neutron-star matter. The constraints from the mass of 2.6 $M_{\odot }$ and the tidal deformability ${\mathrm{\Lambda }}_{1.4}={616}_{-158}^{+273}$ (based on the assumption that GW190814 is a NS-BH binary) can be satisfied for the slope of symmetry energy $L\le 50$ MeV. Even including the constraint ${\mathrm{\Lambda }}_{1.4}={190}_{-120}^{+390}$ from GW170817 which suppresses the EOS stiffness at low density, the possibility that the secondary component of GW190814 is a massive neutron star cannot be excluded in this study.

A recent experiment by D. Bhetuwal et al. [Phys. Rev. Lett. 126, 082301 (2021)] used the $(e,e^{\prime }p)$ reaction on ${}^{12}\mathrm{C}$ to search for the effects of color transparency (the absence of final-state interactions). Color transparency was said to be ruled out. Observing the effects of color transparency depends on the ability of a putative point-like-configuration (PLC), formed in a high-momentum transfer coherent reaction, to escape the nucleus without expanding its size. We study the expansion aspect of color transparency using superconformal baryon-meson symmetry and light-front holographic QCD. A new formalism is obtained and used to analyze the recent experiment. The resulting conclusion is that effects of expansion would not be sufficiently significant in causing final-state interactions to occur. Therefore, we conclude that a PLC was not formed. This means that the Feynman mechanism involving virtual photon absorption on a single high-momentum quark is responsible for the high-momentum electromagnetic form factor of the proton.

Background: Response to spin-dependent operators has been investigated in the magnetic dipole and Gamow-Teller transitions that provide magnetic properties of a nuclear system.

Purpose: I investigate an isotopic dependence of the collectivity generated by the spin-dependent interactions in the Ca and Ni isotopes through the isovector- (IV-) spin-flip excitations. The responses in the neutral $\left(t_z\right)$ and charge-exchange $\left(t_{\pm }\right)$ channels are considered in a unified way.

Method: A nuclear energy-density functional approach is employed for calculating the response functions based on the Skyrme-Kohn-Sham-Bogoliubov method and the quasiparticle-random-phase approximation (QRPA). I adopt the like-particle QRPA and the proton-neutron QRPA for the neutral and charge-exchange channels, respectively. I consider the fluctuation of the proton-neutron pair fields.

Results: The collective shift due to RPA correlations for the response in the neutral channel is explained by the occupation probability of neutrons in the $j_{>}=\ell +1/2$ orbital. Many particle-hole or two-quasiparticle excitations have a coherent contribution to form a giant resonance in neutron-rich nuclei for the charge-exchange channel. The IV-spin susceptibility displays the isotopic evolution of the collectivity and the underlying shell structure.

Conclusions: A repulsive character of the residual interaction in the spin-isospin channel diminishes the IV-spin susceptibility due to the collectivity, whereas the dynamic ${}^{3}S$ pairing appearing in the charge-exchange channel opposes the reduction.

A consistent measurement of the inclusive single-neutron removal cross sections of ${}^{14,15,16}\mathrm{C}$ on a carbon target at around 240 MeV/nucleon has been performed at the External Target Facility, HIRFL-CSR, and compared with Glauber model predictions using shell-model spectroscopic strengths between the initial projectile ground state and configurations of bound core state $+$ valence neutron state as input. For the dependence of the spectroscopic factor reduction characterized by the ratio $R_s$ of the experimental over theoretical single-nucleon removal cross section on the bounding depth $\mathrm{\Delta }S$ of the removed nucleon established in single-nucleon removals with beam energies mainly over 80–120 MeV/nucleon, our measurement gives $R_s$ values that conform to the earlier $R_s\text{−}\mathrm{\Delta }S$ systematics, where the relatively higher incident beam energy facilitates the applicability of the eikonal and sudden approximation used in the Glauber model.

The shape method, a novel approach to obtain the functional form of the $\gamma$-ray strength function $\left(\gamma \mathrm{S}\mathrm{F}\right)$, is introduced. In connection with the Oslo method the slope of the nuclear level density (NLD) and $\gamma \mathrm{S}\mathrm{F}$ can be obtained simultaneously even in the absence of neutron resonance spacing data. The foundation of the shape method lies in the primary $\gamma$-ray transitions which preserve information on the functional form of the $\gamma \mathrm{S}\mathrm{F}$. The shape method has been applied to ${}^{56}\mathrm{Fe}$, ${}^{92}\mathrm{Zr}$, and ${}^{164}\mathrm{Dy}$, which are representative cases for the variety of situations encountered in typical NLD and $\gamma \mathrm{S}\mathrm{F}$ studies. The comparisons of results from the shape method to those from the Oslo method demonstrate that the functional form of the $\gamma \mathrm{S}\mathrm{F}$ is retained regardless of nuclear structure details or $J^{\pi }$ values of the states fed by the primary transitions.