We investigate hyperon polarization and its relation with the directed flow of quark-gluon plasma (QGP) in noncentral $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\text{NN}}}=27$ GeV. A modified three-dimensional Glauber model is developed and coupled to a ($3+1$)-dimensional viscous hydrodynamic evolution of the QGP. Within this framework, we obtain a satisfactory simultaneous description of the directed flow of identified particles and $\mathrm{\Lambda }$ polarization, and we show a sensitivity of polarization to both the tilted geometry and the longitudinal flow profile of the QGP. A nonmonotonic transverse momentum dependence of the $\mathrm{\Lambda }$ polarization is found in our calculation, which is absent from hydrodynamic simulation using other initialization methods, and it can be tested by future experimental data with higher precision. The relation between global polarization and the directed flow of $\mathrm{\Lambda }$ is explored as the longitudinal flow field or the medium deformation varies. Due to the common origin of these two observables, their combination may provide a more stringent constraint on the initial condition of the QGP.

Heavy-ion collisions can be well described through relativistic viscous hydrodynamics, but questions still remain when hydrodynamics is applicable because the initial state may begin very far from equilibrium. Thus, a pre-equilibrium evolution phase is used to bridge the gap between the initial state and hydrodynamics. KøMPøST is one such pre-equilibrium model that propagates the energy-momentum tensor by decomposing it into the background and fluctuations around that background, whose evolution is captured by Green's functions. We extend this formalism to include conserved charges and calculate the corresponding nonequilibrium Green's functions in the relaxation-time approximation. The ICCING algorithm initializes conserved charges in the initial state by sampling $g\to q\overline{q}$ splitting probabilities and is, thus, perfectly positioned to implement Green's functions for charge propagation. We show that this method alters the initial-state charge geometries and is applicable in central to mid-central collisions.

We revisit the short-range baryon-baryon potentials in the flavor SU(3) sector, using the constituent quark model. We employ the color Coulomb, linear confining, and color magnetic forces between two constituent quarks, and solve the three-quark Schrödinger equation using the Gaussian expansion method to evaluate the wave functions of the octet $(N,\mathrm{\Lambda },\mathrm{\Sigma },\mathrm{\Xi })$ and decuplet $(\mathrm{\Delta },{\mathrm{\Sigma }}^{*},{\mathrm{\Xi }}^{*},\mathrm{\Omega })$ baryons. We then solve the six-quark equation using the resonating group method and systematically calculate equivalent local potentials for the $S$-wave two-baryon systems which reproduce the relative wave functions of two baryons in the resonating group method. As a result, we find that the flavor antidecuplet states with total spin $J=3$, namely, $\mathrm{\Delta }\mathrm{\Delta }, \mathrm{\Delta }{\mathrm{\Sigma }}^{*}, \mathrm{\Delta }{\mathrm{\Xi }}^{*}\text{−}{\mathrm{\Sigma }}^{*}{\mathrm{\Sigma }}^{*}$, and $\mathrm{\Delta }\mathrm{\Omega }\text{−}{\mathrm{\Sigma }}^{*}{\mathrm{\Xi }}^{*}$ systems, have attractive potentials sufficient to generate dibaryon bound states as hadronic molecules. In addition, the $N\mathrm{\Omega }$ system with $J=2$ in coupled channels has a strong attraction and forms a bound state. We also make a comparison with the baryon-baryon potentials from lattice QCD simulations and try to understand the behavior of the potentials from lattice QCD simulations.

Correlation functions of hadrons can be accessed in high-energy collisions of atomic nuclei, revealing information about the underlying interaction. This work complements experimental efforts to study nucleon-deuteron $Nd$—with $N=p$ (proton) or $N=n$ (neutron)—correlations with theory evaluations using different techniques. The correlation functions $C_{nd}$ and $C_{pd}$ are calculated based on a scattering wave function, extending previous benchmarks for the $Nd$ scattering matrix to this new observable. We use hyperspherical harmonics and Faddeev techniques with one of the widely used nucleon-nucleon ($NN$) interactions, the Argonne $v_{18}$ potential. Moreover, in the low-energy region we perform additional calculations in the framework of pionless effective field theory. The $pd$ correlation function is computed in the large-energy region to make contact with a recent measurement by the ALICE Collaboration. We show that the scattering wave function has the proper dynamical input to describe an initial rise and subsequent oscillations of $C_{pd}$ as a function of the energy. Effects on the observables using different $NN$ and three-nucleon potentials are evaluated with the conclusion that variations of around $2\%$ are observed. Although these effects are small, future measurements can go beyond this accuracy, allowing for new detailed studies of strong interaction in light nuclear systems. The present study supports the current efforts devoted to the measurement of correlation functions in systems dominated by the strong interactions, such as $pd, ppp, \mathrm{\Lambda }d$, and $pp\mathrm{\Lambda }$.

The formation process of the $\alpha$ cluster at the surface of nuclei is believed to unravel the structural properties of heavy nuclei, while the fully microscopic understanding of the formation probability is still extremely difficult. In this study, the $\alpha$ decay width is obtained within the cluster model plus the identical $\alpha$-core interaction potential for our previous $\alpha$-cluster structure investigation. Given that the $\alpha$ decay half-life is determined by the decay width (penetration probability) and the $\alpha$ preformation probability ($P_{\alpha }$), the relative-varying trend of $P_{\alpha }$ can be then systematically analyzed via the comparison of the ratio of experimental $\alpha$ decay half-lives in isotopic chains with that of calculated decay widths to avoid exploring the model-dependent values of preformation probabilities. The ratio of extracted $P_{\alpha }$ values, for neighboring $\alpha$ emitters, is further presented to clearly reveal the smooth pattern of the formation probabilities of the $\alpha$ cluster off the shell closure. As a comparative study, the ratio of the $P_{\alpha }$ value from the cluster formation model is listed in the valence nucleon scheme as well, showing a similar pattern to the present results.

The detailed study of the ${\beta }^{+}$/EC decay of the very neutron-deficient and alpha-unbound nucleus ${}^{115}\mathrm{Cs}$ is presented. The measurement was performed at the ISOLDE, CERN where delayed charged particles and $\gamma$ rays were detected. The observed delayed $\gamma$ rays are in agreement with the previously reported characteristics $\gamma$ rays of ${}^{115}\mathrm{Xe}$. Based on the experimental observations, the tentative ground-state spin of ${}^{115}\mathrm{Cs}$ is suggested to be $7/2^{+}$ or ${\mathrm{9/2}}^{+}$. Furthermore, the measured decay branching ratio of delayed protons exceeds the previously reported value. Additionally, new delayed $\alpha$-branching ratio and several reconstructed proton and $\alpha$-unbound excited states of ${}^{115}\mathrm{Xe}$ are being reported for the first time. The properties of proton-unbound states at excitation energies from 3.9–7.9 MeV have been obtained by fitting the delayed proton spectrum via the Bayesian method. The measured lifetimes of these proton-unbound states are in the order of zeptoseconds.

Background: Light curves are the primary observable of type-I x-ray bursts. Computational x-ray burst models must match simulations to observed light curves. Most of the error in simulated curves comes from uncertainties in $rp$ process reaction rates, which can be reduced via precision mass measurements of neutron-deficient isotopes in the $rp$ process path.

Purpose: Perform a precise atomic mass measurement of ${}^{27}\mathrm{P}$. Use this new measurement to calculate $rp$ process reaction rates and input these rates into an x-ray burst model to reduce simulated light curve uncertainty. Use the mass measurement of ${}^{27}\mathrm{P}$ to validate the isobaric multiplet mass equation (IMME) for the $A=27 T=\frac{3}{2}$ isospin quartet which ${}^{27}\mathrm{P}$ belongs to.

Method: High-precision Penning trap mass spectrometry utilizing the time-of-flight ion cyclotron resonance technique was used to determine the atomic mass of ${}^{27}\mathrm{P}$. The mesa code (Modules for Experiments in Stellar Astrophysics) was then used to simulate x-ray bursts using a one-dimensional multizone model to produce updated light curves.

Results: The mass excess of ${}^{27}\mathrm{P}$ was measured to be $-670.7\left(6\right)$ keV, a 14-fold precision increase over the mass reported in the 2020 Atomic Mass Evaluation (AME2020). The ${}^{26}\mathrm{Si}(p,\gamma ){}^{27}\mathrm{P}-{}^{27}\mathrm{P}(\gamma ,p){}^{26}\mathrm{Si}$ rate equilibrium has been determined to a higher precision based on the precision mass measurement of ${}^{27}\mathrm{P}$. x-ray burst light curves were produced with the mesa code using the new reaction rates. Changes in the mass of ${}^{27}\mathrm{P}$ seem to have minimal effect on light curves, even in burster systems tailored to maximize impact.

Conclusion: The mass of ${}^{27}\mathrm{P}$ does not play a significant role in x-ray burst light curves. It is important to understand that more advanced models do not just provide more precise results, but often qualitatively different ones. This result brings us a step closer to being able to extract stellar parameters from individual x-ray burst observations. In addition, the IMME has been validated for the $A=27,T=3/2$ quartet. The normal quadratic form of the IMME using the latest data yields a reduced ${\chi }^2$ of 2.9. The cubic term required to generate an exact fit to the latest data matches theoretical attempts to predict this term.

A new model of the bremsstrahlung emission in the scattering of light nuclei is constructed with the main focus on the strict cluster formulation for nuclear processes. The analysis is performed in the frameworks of the folding approximation for $s$ nuclei. The reactions $p+{}^4\mathrm{He}, {}^2\mathrm{H}+{}^4\mathrm{He}, {}^3\mathrm{H}+{}^4\mathrm{He}$, and ${}^3\mathrm{He}+{}^4\mathrm{He}$ are considered. The properties of the emission of bremsstrahlung photons in a wide region of kinetic energies of relative motion of two nuclei from 7 to 1000 MeV are systematically studied. The influence of the oscillator length on the calculated bremsstrahlung emission spectra is discussed. Using the example of ${}^3\mathrm{H}+{}^4\mathrm{He}$, the dependence of the bremsstrahlung spectra on parameters of the nuclear component of the interaction potential is established (for the first time for light nuclei). Experimental bremsstrahlung data for the proton-deuteron scattering and proton–$\alpha$-particle scattering are described on the basis of this model.

Lifetime measurements of the ($3^{-}$), ($4^{-}$), and ($6^{-}$) intraband states in the neutron-rich, odd-odd ${}^{96}\mathrm{Rb}$ nucleus were performed at the LOHENGRIN spectrometer of Institut Laue-Langevin, using thermal-neutron-induced fission of ${}^{235}\mathrm{U}$ and fast-timing techniques with ${\mathrm{LaBr}}_3:\mathrm{Ce}$ scintillator detectors. The nanosecond isomeric nature of the ($3^{-}$) bandhead was established as well as the ${\beta }_2=0.39\left(3\right)$ deformation parameter of the band, pointing to a robust deformation in ${}^{96}\mathrm{Rb}$. Moreover, a hindered $B\left(E2\right)$ value of $3.9_{-13}^{+19}\times {10}^{-2}$ W.u. was found for the $\gamma$ decay of the deformed ($4^{-}$) state to the spherical $2^{-}$ ground state. A retardation was also found for the ($3^{-}$) $\to 2^{-}$ transition, possibly due to the shape change and giving strong support to a shape coexistence scenario in this nucleus, at the borders of the island of deformation at $N=60$. Analogies with the structure of the ${}^{98}\mathrm{Y}$ isotone are discussed.

We report on the first direct mass measurements of the ${}^{118,119}\mathrm{Cd}$ and ${}^{117–119}\mathrm{In}$ isotopes performed at the Ion Guide Isotope Separator On-Line facility using the JYFLTRAP double Penning trap mass spectrometer. The masses of ${}^{117}\mathrm{In}$ and ${}^{118}\mathrm{Cd}$ isotopes are in agreement with the literature, while ${}^{118,119}\mathrm{In}$ and ${}^{119}\mathrm{Cd}$ differ from literature by 49, 13, and 85 keV (6.1, 1.9, and 2.1 standard deviations), respectively. The excitation energy of the ${}^{118}\mathrm{In}$ first isomeric state, $E_x=40.3\left(25\right)$ keV, was determined for the first time. The updated mass values removed the fluctuations observed in the two-neutron separation energies and led to a smoother linear decrease of both isotopic chains. The $log\left(ft\right)$ value for the ${}^{118}\mathrm{Cd}$ decay was also found to increase from 3.93(6) to 4.089(8). The reported results indicate an absence of significant structural changes around $N=70$.

Background: Nuclear fission is influenced by shell effects. Fission modes are a strong signature of the compound nucleus formation in heavy ion induced reactions. The evolution of the relative strengths of the fission modes with excitation energy is a matter of intense interest.

Purpose: We investigate the signatures of fission modes in ${}^{238}\mathrm{Np}$ populated by the ${}^6\mathrm{Li}+{}^{232}\mathrm{Th}$ reaction through the mass–total kinetic energy distribution.

Method: The mass–total kinetic energy distributions of fission fragments of the reaction ${}^6\mathrm{Li}+{}^{232}\mathrm{Th}$ are measured at four laboratory energies, $E_{\text{lab}}=28.5$, 40, 45, and 62.5 MeV. Mass–total kinetic energy distributions of ${}^6\mathrm{Li}+{}^{232}\mathrm{Th}$ are described by the multimodal random neck rupture model.

Results: Channel probabilities of different fission modes are obtained obtained through a two-dimensional fitting procedure. The contribution of the standard 1 (S1) mode is found to become $\approx 2\%$ at $E_{\text{lab}}=40$ MeV. The heavy fragments of S1 and standard 2 (S2) modes are found to be associated with $Z\approx 52$ and $Z\approx 55$ shells, respectively. The slope of the asymmetric to symmetric fission yields ratio with the excitation energy of ${}^6\mathrm{Li}+{}^{232}\mathrm{Th}$ is found to be similar to that of ${}^{18}\mathrm{O}+{}^{208}\mathrm{Pb}$ (previously reported).

Conclusions: The analysis of mass–total kinetic energy distribution data reveals the presence of fission modes in ${}^6\mathrm{Li}+{}^{232}\mathrm{Th}$. The average kinetic energy release in fission obtained from Viola systematic matches well with the one of the of S2 mode. The liquid-drop-like broad symmetric (SL) mode is found to peak at a lower energy than predicted by Viola systematic. This is associated with the decrease of the total kinetic energy in the asymmetric fission mode due to the fading out of shell effects with increasing excitation energy.

The population of isomeric states in the prompt decay of fission fragments—so-called isomeric yield ratios (IYRs)—is known to be sensitive to the angular momentum $J$ that the fragment emerged with, and may therefore contain valuable information on the mechanism behind the fission process. In this work, we investigate how changes in the fissioning system impact the measured IYRs of fission fragments to learn more about what parameters affect angular momentum generation. To enable this, a new technique for measuring IYRs is first demonstrated. It is based on the time of arrival of discrete $\gamma$ rays, and has the advantage that it enables the study of the IYR as a function of properties of the partner nucleus. This technique is used to extract the IYR of ${}^{134}\mathrm{Te}$, strongly populated in actinide fission, from the three different fissioning systems: ${}^{232}\mathrm{Th}(n,\mathrm{f}), {}^{238}\mathrm{U}(n,\mathrm{f})$, at two different neutron energies, as well as ${}^{252}\mathrm{Cf}$(sf). The impacts of changing the fissioning system, the compound nuclear excitation energy, the minimum $J$ of the binary partner, and the number of neutrons emitted on the IYR of ${}^{134}\mathrm{Te}$ are determined. The decay code talys is used in combination with the fission simulation code freya to calculate the primary fragment angular momentum from the IYR. We find that the IYR of ${}^{134}\mathrm{Te}$ has a slope of $0.004\pm 0.002$ with increase in compound nucleus (CN) mass. When investigating the impact on the IYR of increased CN excitation energy, we find no change with an energy increase similar to the difference between thermal and fast fission. By varying the mass of the partner fragment emerging with ${}^{134}\mathrm{Te}$, it is revealed that the IYR of ${}^{134}\mathrm{Te}$ is independent of the total amount of prompt neutrons emitted from the fragment pair. This indicates that neutrons carry minimal angular momentum away from the fission fragments. Comparisons with the freya$+$talys simulations reveal that the average angular momentum in ${}^{134}\mathrm{Te}$ following ${}^{238}\mathrm{U}(n,\mathrm{f})$ is $6.0\hslash$. This is not consistent with the value deduced from recent cgmf calculations. Finally, the IYR sensitivity to the angular momentum of the primary fragment is discussed. These results are not only important to help understanding the underlying mechanism in nuclear fission, but can also be used to constrain and benchmark fission models, and are relevant to the $\gamma$-ray heating problem of reactors.

Correlations of two or more particles have been an essential tool for understanding the hydrodynamic behavior of the quark-gluon plasma created in ultrarelativistic nuclear collisions. In this paper, we extend that framework to introduce a mathematical construction of multiparticle correlators that utilize correlations between arbitrary numbers of particles of interest (e.g., particles selected for their strangeness, heavy flavor, and conserved charges) and inclusive reference particles to estimate the azimuthal anisotropies of rare probes. To estimate the fluctuations and correlations in the azimuthal anisotropies of these particle of interest, we use these correlators in a system of cumulants, raw moments, and central moments. Finally, we introduce two classes of observables that can compare the fluctuations in the azimuthal anisotropies of particles of interest with reference particles at each order.

The double-differential production cross sections $d^2\sigma /d\mathrm{\Omega }dE$ for hydrogen isotopes and charged pions in the reaction of $p+{}^{93}\mathrm{Nb}$ at 3.5 GeV proton beam energy have been measured by the high-acceptance dielectron spectrometer (HADES). Thanks to the high acceptance of HADES at forward emission angles and the use of its magnetic field, the measured energy range of hydrogen isotopes could be significantly extended in comparison with the relatively scarce experimental data available in the literature. The data provide information about the development of the intranuclear cascade in the proton-nucleus collisions. They can as well be utilized to study the rate of energy or momentum dissipation in the nuclear systems and the mechanism of elementary and composite particle production in excited nuclear matter at normal density. Data of this type are important also for technological and medical applications. Our results are compared with models developed to describe the processes relevant to nuclear spallation (incl$++$) or oriented to probe either the elementary hadronic processes in nuclear matter or the behavior of compressed nuclear matter (gibuu).

In our previous work [Phys. Rev. C 98, 045209 (2018)], the available differential cross-section data for $\gamma p\to K^{*+}{\mathrm{\Sigma }}^0$ and $\gamma p\to K^{*0}{\mathrm{\Sigma }}^{+}$ have been analyzed within an effective Lagrangian approach. It was found that one needs to introduce the $s$-channel $\mathrm{\Delta }\left(1905\right){5/2}^{+}$ resonance exchange besides the $t$-channel $K, \kappa$, and $K^{*}$ exchanges, the $s$-channel $N$ and $\mathrm{\Delta }$ exchanges, the $u$-channel $\mathrm{\Lambda }, \mathrm{\Sigma }$, and ${\mathrm{\Sigma }}^{*}$ exchanges, and the generalized contact term in constructing the reaction amplitudes to describe the data. In the present work, we reanalyze the available data for $\gamma p\to K^{*+}{\mathrm{\Sigma }}^0$ and $\gamma p\to K^{*0}{\mathrm{\Sigma }}^{+}$ by considering the contributions from the $N\left(2080\right){3/2}^{-}$ and $N\left(2270\right)3/2^{-}$ molecules instead of any nucleon resonances in the $s$ channel, where the $N\left(2080\right)3/2^{-}$ was proposed to be a $K^{*}\mathrm{\Sigma }$ molecule as the strange partner of the $P_c^{+}\left(4457\right)$ hadronic molecular state, and the $N\left(2270\right)3/2^{-}$ was assumed to be a $K^{*}{\mathrm{\Sigma }}^{*}$ molecule as the strange partner of the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{*}$ bound states that are predicated as members in the same heavy-quark spin symmetry multiplet as the $P_c$ states. It turns out that all the available cross-section data can be well reproduced, indicating that the molecular structures of the possible $N\left(2080\right){3/2}^{-}$ and $N\left(2270\right)3/2^{-}$ states are compatible with the available data for $K^{*}\mathrm{\Sigma }$ photoproduction reactions. Further analysis shows that for both $\gamma p\to K^{*+}{\mathrm{\Sigma }}^0$ and $\gamma p\to K^{*0}{\mathrm{\Sigma }}^{+}$ reactions, the $N\left(2080\right){3/2}^{-}$ exchange provides dominant contributions to the cross sections in the near-threshold energy region, and significant contributions from the $N\left(2270\right)3/2^{-}$ exchange to the cross sections in the higher energy region are also found. Predictions of the beam asymmetry $\mathrm{\Sigma }$, target asymmetry $T$, and recoil baryon asymmetry $P$ are presented and compared with those from our previous work. Measurements of the data on these observables are called on to further constrain the reaction mechanisms of $K^{*}\mathrm{\Sigma }$ photoproduction reactions and to verify the molecular scenario of the $N\left(2080\right){3/2}^{-}$ and $N\left(2270\right)3/2^{-}$ states.

The astrophysical $S$ factor and reaction rates of the direct capture process ${}^6\mathrm{Li}(p,\gamma ){}^7\mathrm{Be}$ are estimated within a two-body single-channel potential model approach. Nuclear potentials of the Gaussian form in the ${}^{2}P_{3/2}$ and ${}^{2}P_{1/2}$ waves are adjusted to reproduce the binding energies and the empirical values of the asymptotic normalization coefficients (ANC) for the ${}^7\mathrm{Be}(3/2^{-})$ ground and ${}^7\mathrm{Be}(1/2^{-})$ excited bound states, respectively. The parameters of the potential in the most important ${}^{2}S_{1/2}$ scattering channel were fitted to reproduce the empirical phase shifts from the literature and the low-energy astrophysical $S$ factor of the LUNA Collaboration. The obtained results for the astrophysical $S$ factor and the reaction rates are in very good agreement with available experimental data sets. The numerical estimates reproduce not only the absolute values, but also the energy dependence of the $S$ factor and the temperature dependence of the reaction rates of the LUNA Collaboration. The estimated ${}^7\mathrm{Li}/\mathrm{H}$ primordial abundance ratio of $(4.67\pm 0.04)\times {10}^{-10}$ is consistent with recent big bang nucleosynthesis result of $(4.72\pm 0.72)\times {10}^{-10}$ after the Planck telescope observation.

Earlier, the screening condition in neutron star core has been formulated as equality of velocities of superconducting protons and the electrons ${\mathbf{v}}_p={\mathbf{u}}_e$ at wave numbers $q\ll {\lambda }^{-1}$ ($\lambda$ is the London penetration depth) and has been used to derive the force exerted by the electrons on a moving flux tube. By calculating the current-current response, I find that ${\mathbf{v}}_p\ne {\mathbf{u}}_e$ for $l^{-1}<q\ll {\lambda }^{-1}$ ($l$ is the electron mean-free path). I show that at typical realistic parameters the electric field induced by a moving (relative to the electrons) flux tube is not screened by the electron currents. The implication is that the existing picture of the momentum exchange between the electrons and the flux tubes must be reassessed.

The relativistic mean-field model, augmented with three types of center-of-mass corrections and two types of rotational corrections, is employed to investigate the ground-state properties of helium, beryllium, and carbon isotopes. The efficacy of the mean-field approach in describing the binding energies, quadrupole deformations, root-mean-square charge radii, root-mean-square matter radii, and neutron skins of these light nuclei is evaluated. By averaging the binding energies obtained from six selected effective interactions, a mass-dependent behavior of the mean-field approximation is elucidated. The findings from radii reveal that, unlike in heavy nuclei, the exchange terms of the center-of-mass correction play an indispensable role in accurately describing the radii of light nuclei. The mean-field approximation, when augmented with center-of-mass and rotational corrections, effectively reproduces the energies and radii of light nuclei. However, due to the absence of many-body correlations between valence neutrons, the mean-field approximation falls short in describing the deformations and shell evolutions of the helium and beryllium isotopic chains.

Background: Isomeric yield ratios are an important observable in nuclear fission as they can guide model development by providing insight into the angular momentum generation. Furthermore, isomeric yield ratios are important in applications for nuclear energy, as well as in the study of the $r$ process in stellar nucleosynthesis, and in the antineutrino mixing angle from reactor spectra. In nuclear data evaluations, the Madland-England model is commonly used to estimate isomeric yield ratios that have not been measured.

Purpose: To measure isomeric yield ratios in 25-MeV proton-induced fission of ${}^{238}\mathrm{U}$, and to compare the result with the values obtained from the Madland-England model and the fission model code gef. Furthermore, to evaluate whether the predictions of gef can be improved by coupling it to the nuclear reaction code talys.

Methods: Isomeric yield ratios in 25-MeV proton-induced fission of ${}^{238}\mathrm{U}$ have been measured at the Ion Guide Isotope Separate On-Line facility. The excited state and the ground state were separated by mass using the phase-imaging ion-cyclotron-resonance technique in the double Penning trap JYFLTRAP. The number of counts of each state was extracted from the phase-images using a Bayesian Gaussian mixture model and, after corrections for detector efficiency and decay, the isomeric yield ratios were derived. The experimental values have been compared with the calculated results from the Madland-England model and the gef code. Furthermore, gef has been combined with the nuclear reaction code talys, in order to take advantage of the latter codes' implementation of the Hauser-Feshbach formalism, and the results have been compared with the experimental values.

Results: From the measurements, 19 new isomeric yield ratios in 25-MeV proton-induced fission of ${}^{238}\mathrm{U}$ are reported and are, together with another 12 isomeric yield ratios (IYRs) from a previous campaign, compared with the model calculations. It is shown that, though the models manage to capture some of the features observed, there is room for improvement.

Conclusions: As predicted by the Madland-England model, a strong correlation between the measured IYRs and the spins of the long-lived states of the fission products is confirmed. However, the IYRs also vary between nuclides with the same spin-parity of the two states, and systematic trends in the IYRs of close-lying isotopes and isotones with similar nuclear configurations are observed. From the comparison of the experimental data with the prediction of gef it is concluded that more data from proton-induced fission are needed to optimize the internal parameters of gef. Furthermore, using a combination of gef and talys in most cases results in an underestimation of the yield ratios. This might be explained by an underestimation of the angular momentum on the initial fission fragments by gef. Altogether, these results highlight the possibility to use measurements of IYRs to improve model predictions and to study the angular momentum generation in nuclear fission.

The excitation functions of evaporation residues in $xn, pxn$, and $\alpha xn$ channels for the reactions leading to the compound nucleus with $Z=80–90$ are studied within the dinuclear system model. The stationary solution of master equation is applied to calculate the formation-decay probabilities of dinuclear systems. The results show that the maxima of excitation functions in $xn, pxn$, and $\alpha xn$ channels are comparable for the reactions leading to compound nuclei from Hg to Th. This means that the charged particles emission along with neutron emission influence the survival probability of compound nucleus in these reactions. Neutron deficiency of compound nucleus leads to favor both charged particle emission and fission.