In this work, we have extracted the nuclear level density (NLD) and $\gamma$-ray strength function ($\gamma \mathrm{SF}$) using the Oslo method on particle-$\gamma$ coincidence data from the ${}^{90}\mathrm{Zr}(p,p^{\prime }\gamma ){}^{90}\mathrm{Zr}$ reaction. We have applied the shape method to the same data set, providing a model-independent $\gamma \mathrm{SF}$ and a cross-check on the slope of the Oslo-method NLD and $\gamma \mathrm{SF}$. Further, we have combined the $\gamma \mathrm{SF}$ from this work with photonuclear data, thus covering the $2.5<E_{\gamma }<18\mathrm{MeV}$ energy range. We see an increase in strength in the region around $E_{\gamma }\approx 9\mathrm{MeV}$, consistent with previous $(\gamma ,{\gamma }^{\prime })$ and $(\gamma ,n)$ data. On the other hand, surprisingly, we do not observe a strong low-energy increase at low transition energies. The resulting NLD and $\gamma \mathrm{SF}$ were used as inputs to the nuclear reaction code talys to estimate the cross sections and astrophysical reaction rates for the ${}^{89}\mathrm{Zr}(n,\gamma ){}^{90}\mathrm{Zr}$ and ${}^{89}\mathrm{Y}(p,\gamma ){}^{90}\mathrm{Zr}$ reactions. We find good agreement with available experimental cross sections and JINA calculations for the ${}^{89}\mathrm{Y}(p,\gamma )$ results, but not for the ${}^{89}\mathrm{Zr}(n,\gamma )$ reaction rate for stellar temperatures above 0.7 GK. Based on our data, we provide a much more narrow uncertainty band for the ${}^{89}\mathrm{Zr}(n,\gamma )$ cross section and reaction rate.

We have developed a systematic approach to calculate the correlation function for spin-1/2 particles, incorporating both central and noncentral components of the interparticle interaction. This is achieved by extending the variable phase method to accommodate noncentral potentials and numerically solving the Schrödinger equation. Within this framework, the partial-wave contributions to the nucleon-nucleon correlation functions adopting the Reid soft-core potential are evaluated. The resulting correlation functions are then compared for Gaussian sources of different sizes.

The effects of triaxial softness on wobbling motion are investigated within the framework of the core-quasiparticle coupling model. By coupling a high-$j$ valence nucleon located in low shell or middle shell to a $\gamma$-rigid and $\gamma$-soft core, we compare energy spectra and electromagnetic transitions of odd-mass nuclei in the four characteristic scenarios. It is revealed that the wobbling motion also appears in nuclei with $\gamma$-soft cores, however, exclusively as longitudinal wobbling. Only a rigid triaxial core supports the appearance of transverse wobbling at low spin which changes to longitudinal wobbling at higher spin states. The differences in interband $B{\left(E2\right)}_{\text{out}}$ transitions provide clear signatures for distinguishing the softness of core, which may serve as the experimental probes. These findings offer clearer light on wobbling motion, thereby expanding our understanding of this fundamental collective mode.

The isomers in the very neutron-deficient isotopes ${}^{179m,181m}\mathrm{Hg}$ and ${}^{179m}\mathrm{Tl}$ were populated via fusion-evaporation reaction ${}^{78}\mathrm{Kr}+{}^{107}\mathrm{Ag}\to {}^{185}\mathrm{Bi}^{*}$. Using the gas-filled recoil separator SHANS (Lanzhou), the nuclei of interest were efficiently transported and separated from scattered beam particles and unwanted reaction products. In this study, conversion electrons (CEs) associated with isomeric transitions (ITs) of these isomers were observed for the first time. The CE-$\alpha$ correlation measurements provided crucial insights into their decay properties. For ${}^{179m}\mathrm{Tl}$, a previously unknown IT branch was identified, and a tentative IT decay scheme was proposed. For ${}^{179m,181m}\mathrm{Hg}$, the analysis of CEs served to validate and update their IT decay pathways.

Background: The synthesis of superheavy elements (SHEs) beyond Oganesson, such as $Z=119$, remains a formidable challenge, primarily because the dominant quasifission (QF) channel severely hinders the formation of compound nuclei. A microscopic understanding of the QF dynamics is therefore essential for guiding future experiments.

Purpose: We investigate the microscopic mechanisms of QF in the ${}^{54}\mathrm{Cr}+{}^{243}\mathrm{Am}$ reaction, a key candidate system for synthesizing SHE 119, with particular emphasis on the roles of projectile orientation and incident energy.

Method: The calculations are performed using the fully microscopic time-dependent Hartree-Fock theory based on the Skyrme energy density functional. We perform systematic simulations covering a broad set of initial orientations of the deformed ${}^{54}\mathrm{Cr}$ and ${}^{243}\mathrm{Am}$ nuclei, together with a finely spaced range of incident energies extending from below to well above the Coulomb barrier.

Results: Our fixed-energy simulations show that projectile side collisions are strongly shell driven, with heavy and light fragments tending toward the spherical $Z=82$ and deformed $N=52–56$ shell regions, respectively, whereas tip collisions exhibit weaker shell influence. These shell-driven reactions are associated with shorter contact times, consistent with faster neck rupture caused by the enhanced rigidity of shell-stabilized fragments. In the tip-tip channel, the energy dependence further reveals a transition from an octupole-deformed region around $Z\approx 88$ to a spherical shell-driven regime at higher energy, while shell steering is comparatively weak in a near-barrier region at a center-of-mass energy of approximately 226 MeV.

Conclusions: Our microscopic study demonstrates that the manifestation of shell effects in the final QF fragment distributions is a dynamical outcome sensitively dependent on both the initial collision geometry and the incident energy. This pronounced energy dependence indicates that the competition between QF and fusion may be affected by the beam energy. The comparatively weak shell steering found in the near-barrier tip-tip region therefore suggests a possible low-energy window of potential interest for SHE synthesis.

Background: Experimental setups commonly used to study fission properties of nuclei in the exotic neutron-deficient ${}^{180}\mathrm{Hg}$ region are based on the time-of-flight technique for the fission-product identification. In best cases, the obtained fragments mass (FFMD) and total kinetic energy (TKE) resolution does not exceed 2 u and 6 MeV, respectively. In addition, the nuclei of interest are created via fusion reactions and at excitation energies of several tens of MeV. The deduced final FFMDs are in general structureless, which makes the identification of fission modes, along with their properties, ambiguous and analysis dependent.

Purpose: To develop a robust analysis approach aiming at identification of a number of major fission modes in FFMDs from fusion-fission reactions.

Method: FFMD data with known composition are used to calculate the second derivative which is then inspected for presence of minima. Number of detected minima is relevant to the number of fission modes present in the FFMD and thus determines the structure of the fit function to use for the FFMD and TKE data description.

Results: The resolution effect is found to broaden the simulated FFMD and TKE data, as well as to smear structures in the second derivatives thus limiting the sensitivity of the method to a few per-cent level in the fission-mode weight. Direct fit of the resolution-affected FFMD data is shown unable to find the asymmetric-mode positions nor to reproduce the modes weights, especially if the used fit-function composition does not correspond to the input data. The fission-modes characteristic TKE values are also not reproduced in a non-constrained fit. In contrario, the simulated data could be safely reproduced with fit functions constructed with help of the second derivative curves, the detected minima being the signature of number of fission modes detectable in the resolution-affected data. The power of the derivative method is demonstrated on example of real experimental FFMDs for the ${}^{180}\mathrm{Hg}$ nucleus.

Conclusions: The derivative analysis applied to limited-resolution FFMDs appears to provide consistent results on the number and parameters of fission modes, even in cases of strong symmetric-mode dominance, i.e., for Gaussian-like FFMD shapes. The method is shown to work also on data sets with limited statistics (real experimental data with integral of a few tens of thousands of events).

We compute the transport coefficient $\widehat{q}$ which quantifies the transverse momentum broadening of hard probes passing through the evolving glasma from the earliest stage of relativistic heavy-ion collisions. We use a proper-time expansion method which is designed to study the glasma at very early times. In our earlier calculations of $\widehat{q}$ we used an approximation that greatly simplifies the complexity of the calculation but introduces a violation of gauge invariance. Based on these results we argued that the glasma plays an important role in jet quenching. In this paper we have used a gauge invariant formulation to calculate $\widehat{q}$. The results for the momentum broadening coefficient are quantitatively very close to those of our previous simplified version of the calculation and confirm our earlier conclusion about the importance of the glasma contribution to jet quenching.

The production of ${\mathrm{\Lambda }}_c^{+}$ baryons in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02$ TeV is investigated within the quark recombination framework, including the energy loss of light and charm quarks inside the hot and dense medium. The model simultaneously describes the transverse momentum ($p_T$) spectra of ${\mathrm{\Lambda }}_c^{+}$ baryons, ${\mathrm{\Lambda }}_c^{+}/D^0$ yield ratio, which is attributed to the dominance of the quark recombination mechanism in the quark-gluon plasma), and the second harmonic coefficient of ${\mathrm{\Lambda }}_c^{+}$ baryons with emphasis on the effects of minijets on the azimuthal anisotropy. Furthermore, we extend the theoretical calculation to $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV and make predictions for ${\mathrm{\Lambda }}_c^{+}$ baryons and ${\mathrm{\Lambda }}_c^{+}/D^0$ yield ratio. The simultaneous description of the yield, baryon-to-meson ratio, and azimuthal anisotropy further validates that the recombination model is an effective hadronization mechanism in heavy-ion collisions.

Relativistic heavy-ion collisions produce femtometer-scale sources whose space-time structure can be constrained using two-particle femtoscopic correlations. Standard implementations rely on the smoothness and on-shell approximations, which effectively remove the relative momentum dependence of the particle emission function. We explore the validity of these approximations by deriving model-independent expansions that quantify the leading corrections for femtoscopy and coalescence with arbitrary sources and final-state interactions. The resulting first- and second-order correction terms can be evaluated with essentially the same numerical complexity as the usual Koonin-Pratt expressions; for angle-averaged correlations the first-order contributions vanish by symmetry. We illustrate the framework with explicit calculations in a blast-wave source model; for blast-wave parameter sets representative of pp and PbPb fits at LHC energies, the corrections are at or below the percent level for pp correlations and deuteron coalescence. These corrections are potentially subdominant compared to other effects, for example, corrections to the equal time approximation.

We investigate the forces acting on a proton vortex in superconducting neutron-star matter composed of neutrons, protons, and electrons, accounting for Fermi-liquid interactions in the neutron-proton subsystem. While the force arising from electron scattering by the vortex magnetic field is well known, we demonstrate that normal neutrons also exert a force on proton vortices due to Fermi-liquid coupling with superconducting protons. Using a kinetic approach based on Landau Fermi-liquid theory, we show that neutron quasiparticles scatter off a proton vortex through the spatially varying condensate momentum, giving rise to a longitudinal force proportional to the relative neutron-vortex velocity. In contrast with the electron contribution, this force has no transverse component and vanishes in the absence of neutron-proton Fermi-liquid interaction. Within a simple model, we analyze the main properties of this force and provide physically motivated estimates of its magnitude.

The charge-dependent nucleon-nucleon $\left(NN\right)$ interaction plays a crucial role in understanding the nuclear structure and reaction problems. In this work, we explore the charge-dependent $NN$ interaction in covariant chiral effective field theory. By incorporating the isospin-breaking contributions, we derive the charge-dependent covariant chiral $NN$ potential up to next-to-next-to-leading order. The calculated $np$ and $pp$ phase shifts are in satisfactory agreement with the PWA93 partial wave analysis. Our results contribute to a deeper understanding of isospin-breaking effects in nuclear forces and provide a solid foundation for future studies of nuclear structure and reactions within the covariant framework.

The lowest states of the ${}^{52,54}\mathrm{Cr}$ isotopes are investigated for the presence of the shape coexistence phenomenon. The ground state deformation is extracted using the covariant density functional theory with a density-dependent point-coupling X parametrization, while the properties of the excited states are described involving the Bohr-Mottelson collective Hamiltonian with a sixth order anharmonic oscillator. A coexistence between near-spherical and well-deformed shapes is found in ${}^{52}\mathrm{Cr}$, and shape fluctuations of the ground state in ${}^{54}\mathrm{Cr}$. Moreover, the presence of coexisting shapes in ${}^{52}\mathrm{Cr}$ indicates that the $4^{+}$ state at 2768 keV would fit better the ground band than the $4^{+}$ state at 2370 keV. This latter assumption, in turn, implies that ${}^{52}\mathrm{Cr}$ could be a good candidate for the manifestation of the so-called $B_{4/2}$ anomaly.

A detailed investigation of the structural evolution of mercury (Hg) isotopes with mass numbers $A=174$–266 is carried out within the Skyrme Hartree-Fock-Bogoliubov (SHFB) framework using the UNEDF2 energy density functional. The study encompasses both bulk nuclear properties, such as binding energies, two-neutron separation energies, potential energy surfaces, root-mean-square radii, nuclear deformation parameters, and single-particle energy levels, as well as isospin-sensitive observables relevant to neutron-rich systems. To explore the isospin dependence, the coherent density fluctuation model (CDFM) is employed, using SHFB results as input to extract the symmetry energy and its volume and surface components. These quantities are particularly crucial for understanding the behavior of nuclei near the neutron drip line. The results reproduce the established shell closures at neutron numbers $N$ = 82 and 126 across both bulk and isospin-dependent observables. In addition, several calculated observables exhibit features consistent with a possible shell or subshell closure around $N$ = 184, although its presence remains model dependent and less robust than the traditional magic numbers. These findings suggest enhanced stability in extremely neutron-rich Hg isotopes and motivate further theoretical and experimental investigations in this region. The consistency between SHFB and CDFM predictions highlights the robustness of the combined theoretical framework in capturing both microscopic and macroscopic aspects of nuclear structure. The present work contributes to a deeper understanding of shell evolution, the role of the symmetry energy, and the stability of heavy isotopes far from the valley of stability.

The most stringent laboratory-based experimental limits on the existence of submegaelectronvolt sterile neutrinos are currently set by decay spectroscopy of radioactive ${}^7\mathrm{Be}$ embedded into superconducting sensors. The systematic uncertainties are dominated by the modeling of the electron shakeup and shakeoff spectra that are not based on state-of-the-art atomic theory and do not include electron correlations or relativistic effects. We have used the multiconfiguration Dirac-Fock formalism to obtain correlated wave functions ab initio and compute all single and double shake processes in the electron capture decay of atomic ${}^7\mathrm{Be}$. The simulations can explain some but not all of the observed spectral features, likely because the wave functions are modified by the Ta sensor material that the ${}^7\mathrm{Be}$ is embedded into. The new models also show that the $L/K$ electron capture ratio of ${}^7\mathrm{Be}$ in Ta has previously been slightly underestimated revising the previous value of 0.070(7) to a new value of 0.0756(20).

The inelastic scattering of ${}^{12}\mathrm{C}$ from ${}^{208}\mathrm{Pb}$ at an incident energy of 98 MeV exhibits a curious anomaly. While the shape of the angular distribution for populating the 4.086-MeV $2_1^{+}$ level of ${}^{208}\mathrm{Pb}$ is well reproduced by distorted wave Born approximation (DWBA) calculations, a coupling strength approximately double that of the accepted value is required. The inelastic scattering of a 270-MeV ${}^3\mathrm{He}$ beam from a ${}^{208}\mathrm{Pb}$ target exhibits similar behavior. This minor mystery has remained unsolved for the past 50 years. A solution is suggested based on the high level density of ${}^{208}\mathrm{Pb}$ in the region of 4-MeV excitation energy and the possibility that the measured $2_1^{+}$ angular distributions contain contributions from a number of unresolved levels, in particular the 4.324-MeV $4_1^{+}$. The coupling strengths for these levels, required as input for DWBA calculations, were obtained from an analysis of existing high-resolution ${}^{208}\mathrm{Pb}$($p,p^{\prime }$) scattering data, while the $2_1^{+}$ coupling strength was fixed by the adopted value of the $B\left(E2\right)$. Using these strengths a consistent description of a wide range of light-ion scattering data is obtained, in addition to the “anomalous” ${}^{12}\mathrm{C}$ and ${}^3\mathrm{He}$ data. While the individual contributions of the levels other than the $2_1^{+}$ and $4_1^{+}$ are negligible, their sum makes a significant contribution to the total angular distribution.

The electron spectra of the $\beta$ decays of ${}^{92}\mathrm{Rb}$ and ${}^{142}\mathrm{Cs}$, key contributors to the reactor antineutrino spectrum, were measured at the IGISOL facility using radioactive beams of high isotopic purity. The shapes of the measured $\beta$ spectra were compared with various $\beta$-shape models, including first-forbidden correction factors for $\mathrm{\Delta }{I}^{\pi }=0^{-}$ ground-state to ground-state transitions. Comparisons with previous experimental results are also provided. The shapes of the newly measured $\beta$ spectra are well reproduced employing feedings extracted from total absorption gamma spectroscopy measurements.

Background: Positron decays of proton-rich nuclides exhibit large $Q$ values, producing complex cascades which frequently involve various radiations, including protons and $\gamma$ rays. Often, only one of the two is measured in a single experiment, limiting the accuracy and completeness of the decay scheme. An example is ${}^{31}\mathrm{Cl}$, for which protons and $\gamma$ rays have been measured separately in detail but never with substantial sensitivity to proton-$\gamma$ coincidences.

Purpose: Provide detailed measurements of ${}^{31}\mathrm{Cl} \beta$-delayed proton decay including $\beta \text{−}p\text{−}\gamma$ sequences, extract spectroscopic information on ${}^{31}\mathrm{S}$ excited states as well as their ${\beta }^{+}$ feedings, and compare to shell-model calculations.

Methods: A fast fragmented beam of ${}^{31}\mathrm{Cl}$ provided by the National Superconducting Cyclotron Laboratory was deposited in the Gaseous Detector with Germanium Tagging (GADGET) system. GADGET's gas-filled Proton Detector was used to detect $\beta$-delayed protons, and the Segmented Germanium Array was used to detect $\beta$-delayed $\gamma$ rays.

Results: As many as 20 previously unobserved $\beta$-delayed proton transitions have been discovered in the present data, most of which populate excited states of ${}^{30}\mathrm{P}$. The first detailed ${}^{31}\mathrm{Cl}$($\beta p\gamma ){}^{30}\mathrm{P}$ decay scheme is presented, including updated $\beta$-delayed proton-decay energies and intensities, as well as several new ${}^{31}\mathrm{S}$ levels. Improved agreement is found with theoretical calculations of the Gamow-Teller strengths $B\left(\text{GT}\right)$ for ${}^{31}\mathrm{S}$ excitation energies $7.5<E_x<9.5$ MeV.

Conclusions: The present work demonstrates that the ability to detect $\beta$-delayed protons and $\gamma$ rays in coincidence is essential to construct accurate positron decay schemes for comparison to theoretical nuclear structure calculations. In some respects, this phenomenon for $\beta$-delayed protons resembles the pandemonium effect originally introduced for $\beta$-delayed $\gamma$ rays.

A microscopic energy term is introduced into the $\alpha$-decay energy correlation formula and further extended to half-life predictions, substantially improving the predictive accuracy of both quantities, particularly in regions near nuclear shell closures. For 96 reference-target pairs, the root-mean-square deviation (RMSD) of the predicted $\alpha$-decay energies decreases from 0.052 to 0.018 MeV upon inclusion of the correction. Building upon the Royer systematics, we develop an improved neighboring-nuclei $\alpha$-decay half-life law (the NR formula) by incorporating the microscopic energy term. For 170 even-even nuclei, the RMSD of predicted ${log}_{10}{T}_{1/2}$ values decreases from 0.324 to 0.186, representing a 43% improvement over the original Royer formula.

The electric dipole polarizability ${\alpha }_D$ and the neutron-skin thickness $\mathrm{\Delta }{R}_{np}$ of ${}^{208}\mathrm{Pb}$ are two powerful and clean probes for constraining the symmetry energy at subsaturation densities. Within the framework of the antisymmetrized molecular dynamics (AMD) model, the width of the strength function and its dynamical origins are understood, and the ${\alpha }_D$ and $\mathrm{\Delta }{R}_{np}$ data favor effective interaction parameter sets with $S_0\approx 32–34$ MeV and $L=64–87$ MeV. In addition, our calculations show that the sensitive densities of ${\alpha }_D$ and $\mathrm{\Delta }{R}_{np}$ range from $0.2{\rho }_0$ to $0.57{\rho }_0$, and the corresponding values of the symmetry energy at the lower and upper ends of this sensitive density region are $S\left(0.2{\rho }_0\right)=10.18\pm 1.10$ MeV and $S\left(0.57{\rho }_0\right)=22.31\pm 1.32$ MeV.