Thick target deuteron breakup is a variable-energy accelerator-based source of high-energy neutrons, with applications in fundamental and applied nuclear science and engineering. However, the breakup mechanism remains poorly understood, and data on neutron yields from thick target breakup remain relatively scarce. In this work, the double-differential neutron yields from deuteron breakup have been measured on a thick beryllium target at ${\epsilon }_d=33$ and 40 MeV, using both time-of-flight and activation techniques. We have also introduced a simple hybrid model for the double-differential deuteron breakup cross section, applicable in the ${\epsilon }_d=10–100$ MeV energy range on light ($Z\le 6$) targets. This model features four empirical parameters that have been fit to reproduce experimental breakup measurements on beryllium targets, using the method of least squares. It was shown that these parameters extrapolate well to higher energies, and to other low-$Z$ target materials. We also include optimization of the parameters that modify the Kalbach systematics for compound and preequilibrium reactions, in order to better reproduce the experimental data for beryllium targets at large angles.

Measurements of the decay energy released as a function of time following the thermal neutron induced fission of ${}^{235}\mathrm{U}$ and ${}^{239,241}\mathrm{Pu}$ were performed in the 1970s at Oak Ridge National Laboratory with the purpose of quantifying possible loss of coolant accident scenarios. The derivative of this decay energy with respect to time, known in technical parlance as decay heat, is mainly composed of two terms, that of the electrons produced together with antineutrinos in the $\beta$-minus decay of the neutron-rich fission products, and that of the $\gamma$ rays produced in the subsequent decay of excited nuclear levels. In this work we study if this extensive set of decay energy measurements can be used to assess the reactor antineutrino anomaly, that is, the approximately 5% deficit of electron antineutrinos produced by nuclear reactors, first deduced by Mention and collaborators in 2011, and observed by the major reactor antineutrino experiments since. With the assistance of nuclear databases, we are able to obtain the ratio of electron spectra under equilibrium conditions for ${}^{235}\mathrm{U}$ to ${}^{239}\mathrm{Pu}$, in better agreement with the lower trend recently reported by Kopeikin and collaborators, as well as those for ${}^{235}\mathrm{U}$ to ${}^{241}\mathrm{Pu}$ and ${}^{241}\mathrm{Pu}$ to ${}^{239}\mathrm{Pu}$, which do not agree well with those measured at the Institut Laue-Langevin in the 1980s. We conclude that a new experimental campaign is needed to measure the electron spectra utilizing a high resolution and signal-to-noise-ratio electron spectrometer and a highly precise fission normalization procedure.

The electroproduction of selected $p$- and $sd$-shell hypernuclei was studied within a many-body approach using realistic interactions between the constituent baryons. The cross sections were computed in the distorted-wave impulse approximation using two elementary amplitudes for the electroproduction of the $\mathrm{\Lambda }$ hyperon. The structure of the hypernuclei was investigated within the framework of the self-consistent $\mathrm{\Lambda }$-nucleon Tamm-Dancoff approach and its extension known as the $\mathrm{\Lambda }$-nucleon equation of motion phonon method. Use was made of the ${\mathrm{NNLO}}_{\mathrm{sat}}$ chiral potential plus the effective Nijmegen-F $YN$ interaction. The method was first implemented on light nuclei for studying the available experimental data and establishing a relation to other approaches. After this proof test, it was adopted for predicting the electroproduction cross section of the hypernuclei ${}_{\mathrm{\Lambda }}{}^{40}\mathrm{K}$ and ${}_{\mathrm{\Lambda }}{}^{48}\mathrm{K}$ in view of the E12-15-008 experiment in preparation at JLab. On the grounds of these predictions, appreciable effects on the spectra are expected to be induced by the $YN$ interaction.

With neutron star applications in mind, we developed a theory of diffusion in mixtures of superfluid, strongly interacting Fermi liquids. By employing the Landau theory of Fermi liquids, we determined matrices that relate the currents of different particle species, their momentum densities, and the partial entropy currents to each other. Using these results, and applying the quasiclassical kinetic equation for the Bogoliubov excitations, we derived general expressions for the diffusion coefficients, which properly incorporate all the Fermi-liquid effects and depend on the momentum transfer rates between different particle species. The developed framework can be used as a starting point for systematic calculations of the diffusion coefficients (as well as other kinetic coefficients) in superfluid Fermi mixtures, particularly, in superfluid neutron stars.

A dedicated high-statistics measurement of the ${}^{71}\mathrm{Ge}$ half-life is found to be in accurate agreement with an accepted value of $11.43\pm 0.03$ d, eliminating a recently proposed route to bypass the “gallium anomaly” affecting several neutrino experiments. Our data also severely constrain the possibility of ${}^{71}\mathrm{Ge}$ decay to low-energy excited levels of the ${}^{71}\mathrm{Ga}$ daughter nucleus as a solution to this puzzle. Additional unpublished measurements of this decay are discussed. Following the incorporation of this information, the gallium anomaly survives with high statistical significance.

Study of exotic nuclei is one of the important frontiers in nuclear physics. The coupling of weakly bound states and resonant states, deformation, and pairings play important roles at the formation of exotic phenomena. To deal with these uniformly, we develop the deformed relativistic mean field theory in complex momentum representations with BCS pairings. ${}^{44}\mathrm{Mg}$ is chosen as an illustration example. The calculated binding energy indicates that ${}^{44}\mathrm{Mg}$ is a weakly bound nucleus. There are several broad resonant states with low orbital angular momentum near the Fermi surface, and the occupation of these levels is responsible for the halo structure in ${}^{44}\mathrm{Mg}$. The available density distributions suggest that ${}^{44}\mathrm{Mg}$ is a deformed halo nucleus with prolate core and oblate halo, which agree with the deformed relativistic Hartree-Bogoliubov in continuum calculations. In particular, the role of resonances is clearly demonstrated in the halo formation, which is helpful to understand the physical mechanism of deformed exotic nuclei.

The information-geometric statistical analysis on the stability of model reductions, reported previously [Imbrišak and Nomura, Phys. Rev. C 107, 034304 (2023)] with a focus on the manifold boundary approximation method in the application to the nuclear density-dependent point-coupling model of infinite nuclear matter, is extended to the numerically more challenging case of finite nuclei. A simple procedure is presented for determining the binding energies of doubly magic nuclei within the relativistic mean-field framework using the Woods-Saxon potential. The proposed procedure, employing the Fisher information matrix combined with algorithmic differentiation, is shown to provide reliable estimates of parameter uncertainties of the nuclear energy density functional for finite nuclei, while reducing the time-consuming sampling of the parameter space, which would be required in the numerically more involved Bayesian statistical techniques.

Background: Reactions with halo nuclei from deformed regions exhibit important deviations from the inert core $+$ valence picture. Structure and reaction formalisms have recently been extended or adapted to explore the possibility of exciting the underlying core.

Purpose: We will study up to what extent transfer reactions involving halo nuclei ${}^{11}\mathrm{Be}$ and ${}^{17}\mathrm{C}$ can be reproduced with two different models that have previously shown a good success reproducing the role of the core in light halo nuclei.

Methods: We focus on the structure of ${}^{11}\mathrm{Be}$ and ${}^{17}\mathrm{C}$ with two core $+$ valence models: Nilsson and a semimicroscopic particle-rotor model using antisymmetrized molecular dynamic calculations of the cores. These models are later used to study ${}^{16}\mathrm{C}(d,p){}^{17}\mathrm{C}$ and ${}^{11}\mathrm{Be}(p,d){}^{10}\mathrm{Be}$ transfer reactions within the adiabatic distorted wave approximation. Results are compared with three different experimental data sets.

Results: A good reproduction of both the structure and transfer reactions of ${}^{11}\mathrm{Be}$ and ${}^{17}\mathrm{C}$ is found. The Nilsson model provides an overall better agreement for the spectrum and reactions involving ${}^{17}\mathrm{C}$ while the semimicroscopic model is more adequate for ${}^{11}\mathrm{Be}$, as expected, since the ${}^{17}\mathrm{C}$ core is closer to an ideal rotor.

Conclusions: Both models show promising results for the study of transfer reactions with halo nuclei. We expect that including microscopic information in the Nilsson model, following the spirit of the semimicroscopic model, can provide a useful, yet simple framework for studying newly discovered halo nuclei.

Within the framework of the quantum molecular dynamics transport model, the collective flows of clusters and pions in heavy-ion collisions have been systematically investigated. The clusters are recognized by the Wigner phase-space density approach at the stage of freeze-out in nuclear collisions, i.e., deuteron, triton, ${}^3\mathrm{He}$, and $\alpha$. The directed and elliptic flows of protons and deuterons in the reaction of ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ at incident energy $1.23A$ GeV are nicely consistent with the recent HADES data. The higher order collective flows, i.e., triangular and quadrangle flows, manifest the opposite trends with the less amplitude in comparison with the rapidity distributions of directed and elliptic flows. The flow structure of ${}^3\mathrm{He}$ and $\alpha$ is very similar to the proton spectra. The influence of the pion potential on the pion production is systematically investigated and compared with the FOPI data via the transverse momentum, longitudinal rapidity, and collective flows in collisions of ${}^{197}\mathrm{Au} + {}^{197}\mathrm{Au}$. It is manifested that the pion yields are slightly suppressed in the domain of midrapidity and high momentum. The antiflow phenomena are reduced by implementing the pion potential and more consistent with the FOPI data in collisions of ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ at the incident energy $1.5A$ GeV.

In the present research, we utilized the single-folding model to develop a systematical optical potential for ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$, employing the nucleon-nucleus global potentials introduced by Koning and Delaroche (KD02). We analyzed the elastic scattering angular distributions of ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ on targets with mass numbers ranging from 24 to 209 using the single-folding potential. Incident energies between 5 and 55 MeV/nucleon were considered. The real part of the single-folding model potential was renormalized with one free parameter, while leaving its imaginary part unchanged. The resulting renormalization factors of the single-folding model potentials show consistent systematics. Our approach effectively reproduced the elastic scattering and reaction cross sections of the targets in our current study. In addition, we also compared the prediction abilities of our systematic optical potentials with those of others.

We report a study of transverse momentum ($p_{\mathrm{T}}$) spectra for ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\overline{p}$ in isobar, ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$, collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ using a multiphase transport model. Particle yields ($dN/dy$), average transverse momenta ($\langle p_{\mathrm{T}}\rangle$), and particle ratios are reported in various collision systems with different parametrizations of the Woods-Saxon distribution. We observed a maximum difference of 5% in the particle yields in peripheral collisions when we included a quadrupole and octupole deformation and a nuclear size difference between the isobars. The ${\pi }^{-}/{\pi }^{+}$ ratio is smaller in $\text{Ru}+\text{Ru}$ collisions compared with $\text{Zr}+\text{Zr}$ collisions indicating an effect of isospin due to difference in number of protons and neutrons between the two nuclei. The $K^{-}/K^{+}$ ratio is same in both the systems indicating the dominance of the pair production mechanism in the kaon production. The $\overline{p}/p$ ratio is further smaller in $\text{Ru}+\text{Ru}$ collisions than $\text{Zr}+\text{Zr}$ collisions, indicating the effect of baryon stopping in addition to the isospin effect. A system size dependence is observed in $dN/dy$ and $\langle p_{\mathrm{T}}\rangle$ when we compare the results from isobar collisions with $\text{Au}+\text{Au}$ and $\text{U}+\text{U}$ collisions.

The electroexcitation amplitudes or ${\gamma }_{v}p{N}^{*}$ electrocouplings of the $N\left(1440\right)1/2^{+}$, $N\left(1520\right)3/2^{-}$, and $\mathrm{\Delta }\left(1600\right)3/2^{+}$ resonances were obtained for the first time from the $ep\to e^{\prime }{\pi }^{+}{\pi }^{-}{p}^{\prime }$ differential cross sections measured with the CLAS detector at Jefferson Lab within the range of invariant mass $W=1.4\text{–}1.7$ GeV of the final state hadrons, for photon virtualities $Q^2=2.0\text{–}5.0$ ${\mathrm{GeV}}^2$. A good description of the nine independent onefold differential ${\gamma }_{v}p\to {\pi }^{+}{\pi }^{-}{p}^{\prime }$ cross sections achieved within the data-driven Jefferson Lab-Moscow State University (JM) meson-baryon reaction model in each bin of ($W,Q^2$) allows for separation of the resonant and nonresonant contributions. The electrocouplings were determined in the fits of the ${\pi }^{+}{\pi }^{-}p$ cross sections within three overlapping $W$ intervals with a substantial contribution from each of the three resonances listed above. Consistent results on the electrocouplings extracted from the data in these $W$ intervals provide evidence for their reliable extraction. These studies extend information on the electrocouplings of the $N\left(1440\right)1/2^{+}$ and $N\left(1520\right)3/2^{-}$ available from this channel over a broader range of $Q^2$. The electrocouplings of the $\mathrm{\Delta }\left(1600\right)3/2^{+}$, which decays preferentially into $\pi \pi N$ final states, have been determined for the first time. The reliable extraction of the electrocouplings for these states is also supported by the description of the ${\pi }^{+}{\pi }^{-}p$ differential cross sections with $Q^2$-independent masses and total/partial hadronic decay widths into the $\pi \mathrm{\Delta }$ and $\rho p$ final states.

Supernova explosions are the most powerful neutrino sources. The neutrino emission is also the dominating cooling mechanism for a proto–neutron star, whose interior is mainly composed of extremely dense and hot nuclear matter. Neutrino transport is an essential part of the simulation of these phenomena, and modern codes are able to implement inelastic neutrino scattering and also to some extent its angle distribution. We therefore study the energy and angle dependence of neutrino scattering rates in proto–neutron star and supernova matter with the full Skyrme random phase approximation (RPA) response functions. We confirm earlier findings obtained in the Landau approximation that the RPA reduces neutrino scattering, but the detailed differential scattering rates in hot and dense matter depend sensitively on the adopted interaction. The scattering angle distribution is different for different interactions because it depends strongly on the neutron Fermi velocity. We also find that many Skyrme interactions present an unphysical feature that the Fermi velocity of neutrons exceeds the speed of light already at relatively low densities.

Nuclear symmetry energy is a fundamental quantity currently under intense investigation in both nuclear physics and astrophysics. The softness or stiffness of symmetry energy is still under debate and the extraction of symmetry energy from neutron skin thickness $R_{\mathrm{skin}}$ remains a challenge. Parity-violating measurements PREX and CREX provide important opportunities for constraining $R_{\mathrm{skin}}$ in ${}^{208}\mathrm{Pb}$ and ${}^{48}\mathrm{Ca}$. We investigate the occurrence of an $\alpha$ cluster at the surface of nuclei and its impact on the extraction of symmetry energy from $R_{\mathrm{skin}}$. Our result indicates that the $\alpha$-clustering probability in ${}^{208}\mathrm{Pb}$ is small and the extracted density slope of symmetry energy $L$ is almost unaffected. In contrast, the $\alpha$-clustering probability in ${}^{48}\mathrm{Ca}$ is sizable and the corresponding correction to $L$ should be taken into account. This correction progressively increases with the $\alpha$-clustering probability, leading to a modification of the $L\text{−}{R}_{\mathrm{skin}}$ correlation, a fact that may have important implications in constraining nuclear symmetry energy.

We model fission at barrier-top energies in a simplified model space that permits comparison of different components of the residual nucleon-nucleon interaction. The model space is built on particle-hole excitations of reference configurations. These are Slater determinants of uniformly spaced orbitals characterized only by their quantum numbers and orbital energies. The residual interaction in the Hamiltonian includes the diabatic interaction connecting similar orbitals at different deformations, the pairing interaction between like nucleons, and a schematic off-diagonal neutron-proton interaction. We find that the fission reaction probability is sensitive to the off-diagonal neutron-proton interaction much more than to the pairing and the diabatic interactions. In particular, the transmission coefficients become insensitive to the strength of the pairing interaction when the neutron-proton interaction is large. We also find that the branching ratio is insensitive to the final-state scission dynamics, as is assumed in the well-known Bohr-Wheeler theory.

We present a Poincaré covariant cascade algorithm based on the constrained Hamiltonian dynamics in an $8N$-dimensional phase space to simulate the Boltzmann-type two-body collision term. We compare this covariant cascade algorithm with traditional $6N$-dimensional phase-space cascade algorithms. To validate the covariant cascade algorithm, we perform box calculations. We examine the frame dependence of the algorithm in a one-dimensionally expanding system as well as the compression stages of colliding two nuclei. We confirm that our covariant cascade method is reliable to simulate high-energy nuclear collisions. Furthermore, we present Lorentz-covariant equations of motion for the $N$-body system interacting via potentials, which can be efficiently solved numerically.

Background: In the current understanding, the rapid neutron capture process in explosive scenarios primarily produces heavy elements. Though the precise astronomical sites are under consideration, it has been proposed that in explosive environments such as core-collapse supernovae, light and medium-mass neutron-rich nuclei play a role in the $r$ process.

Purpose: Proper nuclear physics inputs for neutron-rich exotic nuclei are essential in determining the final abundances. The statistical Hauser-Feshbach model is not always reliable in the $A\approx 30$ mass region, especially for exotic nuclei. Therefore, inputs derived from models that account for the structure and reactions of exotic nuclei are necessary, which could affect the abundance patterns considerably.

Method: We perform an abundance calculation in the deformed $A\approx 30$ mass region for a network of neutron-rich Na, Mg, and Al isotopes adopting constant temperatures, 3.4 GK and 0.62 GK, and corresponding densities in a core-collapse supernova. We consider selected neutron capture and photodisintegration rates calculated with the finite-range distorted wave Born approximation (FRDWBA) method, including deformation effects, and shell model $\beta$ decay rates, wherever possible, along with those from the JINA-REACLIB database. A comparison is also made with rates from the talys estimates.

Results: We observe a significant difference in abundances calculated by incorporating FRDWBA inputs along with the statistical inputs, compared with the results calculated using only the statistical model inputs, especially at 0.62 GK. The abundance patterns suggest that neutron capture reactions are not dominant at 3.4 GK, while at 0.62 GK, $(n,\gamma )$ reactions mostly dominate, and more neutron-rich elements near the drip line are produced.

Conclusion: Incorporating the exotic structure of nuclei involved in reaction networks is important, even though the deformation effects may not have a major significance. At $T_9=0.62$, ${}^{35}\mathrm{Na}$ and ${}^{36}\mathrm{Mg}$ prefer to undergo $\beta$ decay rather than capturing a neutron.

Background: This paper presents the extended-soft-core (ESC) potentials ESC16 for baryon-baryon ($BB$) channels with total strangeness $S=-3$ and $-4$. For these channels no experimental scattering data exist, apart from very recently measured preliminary correlations. Also, there is no information from hypernuclei or hyperonic matter.

Purpose: The aim is to calculate the predictions of the ESC16 model for the $S=-3$ and $S=-4 BB$ channels.

Methods: The potential models for $S=-3$ and $-4$ are based on SU(3) extensions of potential models for the $S=0$ and $-1$ and $S=-2$ sectors, which are fitted to experimental data. Flavor SU(3) symmetry is broken “kinematically” by the masses of the baryons and the mesons. The fit to the $S=0$ and $-1$ sectors provides the necessary constraints to fix all free parameters, i.e., baryon-baryon-meson couplings and cutoff masses. The $S=-2$ systems are constrained by the $\mathrm{\Delta }{B}_{\mathrm{\Lambda }\mathrm{\Lambda }}$ value from the Nagara event and the requirement of $U_{\mathrm{\Xi }}\approx -10$ MeV.

Results: Various properties of the potentials are illustrated by giving results for scattering lengths, bound states, and phase parameters.

Conclusions: No $\mathrm{\Xi }\mathrm{\Xi }, \mathrm{\Xi }\mathrm{\Lambda }$, and $\mathrm{\Xi }\mathrm{\Sigma }$ bound states are predicted by the ESC16 model.

Faddeev calculations of hypertriton (${}_{\mathrm{\Lambda }}^3\mathrm{H}$) separation energy are performed, incorporating $2\pi$-exchange $\mathrm{\Lambda }NN$ three-baryon force. Repulsive contributions of the three-baryon force in the order of 20 keV are found, depending on the $NN$ interactions employed. The effect is not negligible compared with the small separation energy of ${}_{\mathrm{\Lambda }}^3\mathrm{H}$.

In this work, the previously unmeasured ${}^{232}\mathrm{Th}(d,5n){}^{229}\mathrm{Pa}$ reaction is reported at deuteron energies of 31.0, 35.2, 41.4, and 49.6 MeV. The irradiation took place at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The target processing and analysis were performed at Oak Ridge National Laboratory. The experiment used four thin foils $\left(\approx 17\mathrm{mg}/\mathrm{c}{\mathrm{m}}^2\right)$ of natural thorium metal in a stacked-target configuration, which were irradiated with a deuteron beam (1 µA) for approximately 11 continuous hours. Column chromatography techniques were implemented to directly assay ${}^{229}\mathrm{Pa}$ and its low intensity γ-ray emissions. The measured peak of the excitation function of ${}^{232}\mathrm{Th}\left(d,5n\right){}^{229}\mathrm{Pa}$ is $121.9\pm 12.7$ mb at $E_d=35.2\mathrm{MeV}$. In addition to ${}^{229}\mathrm{Pa}$, the production cross sections of the ${}^{232}\mathrm{Th}\left(d,xn\right){}^{234-x}\mathrm{Pa}$ reactions, where $x=1$, 2, 4, and 6, are also reported and compared to previous measurements. The experimental cross sections were compared with calculated cross sections using several reaction modeling codes including phits, talys, alice, coh, and empire as well as the evaluated nuclear reaction database TENDL.