The ${}^{18}\mathrm{Ne}(\alpha ,p){}^{21}\mathrm{Na}$ reaction plays a significant role in Type-I X-ray bursts. It is a major path in the breakout from the hot-CNO cycles to the synthesis of heavier elements in the $\alpha p$- and $rp$-processes. An experiment to determine the cross section of this reaction was performed with the ANASEN active-target detector system, determining the cross section at energies between 2.5 and 4 MeV in the center-of-mass frame. The measured cross sections for reactions populating the ground state in ${}^{21}\mathrm{Na}$ are consistent with results obtained from the time-inverse reaction, but significantly lower than the previously published experimental data of direct measurements. The total cross sections are also compared with those derived from indirect methods and statistical-model calculations. This experiment establishes a new experimental data set on the excitation function of the ${}^{18}\mathrm{Ne}(\alpha ,p){}^{21}\mathrm{Na}$ reaction, revealing the significance of the excited states' contributions to the total reaction cross section and allowing us to separate the contribution of the $(\alpha ,2p)$ reaction. The impact of the measured cross section on thermal reaction rates is discussed.

The new thorium isotope ${}^{207}\mathrm{Th}$ has been produced in the $5n$ evaporation channel of the fusion reaction ${}^{36}\mathrm{Ar}+{}^{176}\mathrm{Hf}$. It was separated in flight by the gas-filled recoil separator SHANS and identified on the basis of a correlated $\alpha$-decay chain. The $\alpha$ decay of ${}^{207}\mathrm{Th}$, measured with an $\alpha$-particle energy of 8167(21) keV and a half-life of $9.7_{-4.4}^{+46.6}$ ms, is assigned to originate from ground state. By combining with existing data, we find that the $\alpha$-decay energies of nuclei with $Z>82$ and $N<126$ show a regular and distinct odd-even staggering (OES) rather than the commonly supposed smooth pattern. A theoretical analysis has been performed within relativistic Hartree-Fock-Bogoliubov and large-scale shell-model approaches. It is found that the OES originates from both pairing correlations and blocking of particular orbitals by unpaired nucleons. Of particular importance is that pairing correlations result in the OES not only through the contribution of pairing energy to binding energy, but also by configuration mixing induced by scattering nucleons to orbitals away from Fermi levels.

We investigate the importance of the three-nucleon ($3N$) force contact terms in elastic nucleon-deuteron ($Nd$) scattering by applying the $\mathrm{N}{}^4\mathrm{LO}^{+}$ chiral semilocal momentum space (SMS) regularized nucleon-nucleon chiral potential supplemented by $\mathrm{N}{}^2\mathrm{LO}$ and all subleading $\mathrm{N}{}^4\mathrm{LO}$ three-nucleon force contact terms. Strength parameters of the contact terms were obtained by least squares fitting of theoretical predictions to cross sections and analyzing power data at three energies of the impinging nucleon. Although the ${\mathrm{N}}^3\mathrm{LO}$ contributions to the $3N$ force were completely neglected, the results calculated with the contact terms multiplied by the fit strength parameters yield an improved description of the elastic $Nd$ scattering observables in a wide range of incoming nucleon energies below the pion production threshold.

Precise determination of ground-state feeding in the $\beta$ decay of fission products is an important but challenging component in modeling reactor antineutrino flux and reactor decay heat. The Modular Total Absorption Spectrometer (MTAS) is a versatile NaI(Tl) detector array that determines the true $\beta$-decay pattern free from the pandemonium effect, including precise ground-state feeding intensities. In this paper, we report MTAS results of the $\beta$ feeding intensities of ${}^{88}\mathrm{Rb}$ and ${}^{88}\mathrm{Kr}$, fission products with large cumulative yields in nuclear reactors. By comparing MTAS results with previous measurements, ${}^{88}\mathrm{Rb}$ provides a validation of MTAS's ability to determine ground-state feedings in $\beta$ decays, while the precision of ${}^{88}\mathrm{Kr}$ ground-state feeding is improved when compared with the Evaluated Nuclear Structure Data File (ENSDF). The investigation of sources that contribute to $\beta$ feeding branching uncertainties in MTAS experiments is discussed in detail. Lastly, the deconvolution of ${}^{88}\mathrm{Rb}$ decay spectra suggests that MTAS can distinguish an allowed $\beta$ spectral shape from a first forbidden unique $\beta$ spectral shape.

The optimal projectile-target combination and bombarding energy for the production of the new superheavy element (SHE) $Z=119$ are predicted within the framework of a dinuclear system (DNS) model, in which the evaporation residue cross section (ERCS) is the product of capture cross section, fusion probability, and survival probability. To this end, the effects of mass asymmetry and isospin effect of target nucleus on the ERCS are analyzed. It is found that the ERCS for the production of SHE $Z=119$ is relatively large with the ${}^{45}\mathrm{Sc}$ projectile, while the ERCS in most cases decreases slowly with increasing neutron number of the target nucleus. We hope these predictions will shed new light timely for the recent experiments on the synthesis of the $Z=119$ superheavy element.

In heavy-ion induced reactions, generally, a large number of residues are populated through different reaction channels. In some cases the same residue is populated via two different modes viz., (i) directly from a given reaction and (ii) via $\beta$ and/or electron capture decay of a nuclide (precursor). Separation of the two is required for a better understanding of reaction dynamics. The procedure existing in the literature for extracting the independent production cross section from the cumulative cross section employs the assumptions of half-life of the daughter being much larger in comparison to the half-life of the precursor $(t_{1/2}^p\ll t_{1/2}^d)$ and require the counting to be performed after large cooling times $(t_l\to \infty )$. A general and more exact expression is obtained in the present work surpassing the assumptions as well as difficulties reported earlier. Analysis of the experimental reaction data sets covering a broader range of possibilities $(t_{1/2}^p>t_{1/2}^d$; $t_{1/2}^p\approx t_{1/2}^d;$ $t_{1/2}^p<t_{1/2}^d)$ presented shows the importance of the current formulations. The advantage of the generalized expression even when the assumptions hold true is also discussed. A comparison of results obtained from the traditional method in the context of its assumptions instead of the calculations from the exact expression has been made. The results obtained with the presently derived formulations are found to give justified values of cross sections for all the cases in contrast to the traditional formulation.

With the kinetic freeze-out nucleons and antinucleons obtained from the quark combination model, we study the production of light nuclei and antinuclei in the (anti-)nucleon coalescence mechanism in relativistic heavy ion collisions. We derive analytic formulas of the momentum distributions of different light nuclei and apply them to compute transverse momentum $\left(p_T\right)$ spectra of (anti-)deuterons $(d$, $\overline{d})$ and (anti-)tritons $(t,$ $\overline{t})$ in Au-Au collisions at $\sqrt{s_{\mathrm{NN}}}=7.7, 11.5, 19.6, 27, 39, 54.4 \mathrm{GeV}$. We find that the experimental data available for these $p_T$ spectra can be well reproduced. We further study the yields and yield ratios of different light (anti-)nuclei and naturally explain their interesting behaviors as a function of the collision energy. We especially point out that the multiparticle yield ratio $tp/d^2$ should be carefully corrected from hyperon weak decays for protons to probe the production characteristics of light nuclei. All of our results show that the coalescence mechanism for (anti-)nucleons plays a dominant role for the production of light nuclei and antinuclei at the BNL Relativistic Heavy Ion Collider beam energy scan energies.

We apply our calculation of direct $J/\psi$ production in the improved color evaporation model at $\mathcal{O}\left({\alpha }_s^3\right)$ in collinear factorization to $\mathrm{Pb}+\mathrm{Pb}$ collisions. The cold nuclear matter effects of nuclear modifications of the parton densities and intrinsic transverse momentum broadening are included. We find that the polarization is independent of these effects. Our calculations are compared to the $\mathrm{Pb}+\mathrm{Pb}$ polarization parameters extracted by the ALICE Collaboration at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.

A nuclear mass survey of rare-earth isotopes has been conducted with the Canadian Penning Trap mass spectrometer using the most neutron-rich nuclei thus far extracted from the CARIBU facility. We present a collection of 12 nuclear masses determined with a precision of $\le 10$ keV/$c{}^2$ for $Z=58–63$ nuclei near $N=100$. Independently, a detailed study exploring the role of nuclear masses in the formation of the $r$-process rare-earth abundance peak has been performed. Employing a Markov chain Monte Carlo (MCMC) technique, mass predictions of lanthanide isotopes have been made which uniquely reproduce the observed solar abundances near $A=164$ under three distinct astrophysical outflow conditions. We demonstrate that the mass surface trends thus far mapped out by our measurements are most consistent with MCMC mass predictions given an $r$ process that forms the rare-earth peak during an extended $(n,\gamma )\rightleftarrows (\gamma ,n)$ equilibrium.

The only available electroweak measurement of the ${}^{208}\mathrm{Pb}$ neutron skin $\mathrm{\Delta }{R}_{\mathrm{np}}$, performed by the PREX-II Collaboration through polarized electron-lead scattering, shows a mild tension with respect to both the theoretical nuclear-model predictions and a host of measurements. However, the dependence on the weak mixing angle should be incorporated in the calculation, since its low-energy value is experimentally poorly known. We first repeat the PREX-II analysis confirming their measurement by fixing the weak mixing angle to its standard model value. Then, we show the explicit dependence of the PREX-II measurement on the weak mixing angle, obtaining that it is fully degenerate with the neutron skin. To break this degeneracy, we exploit the weak mixing angle measurement from atomic parity violation on lead, obtaining a slightly thinner neutron skin but with about doubled uncertainties, possibly easing the PREX tension. Relying on the theoretical prediction, $\mathrm{\Delta }{R}_{\mathrm{np}}^{\mathrm{th}}\approx 0.13\text{–}0.19\mathrm{fm}$, and using it as a prior in the fit, we find a weak mixing angle value about $1.2\sigma$ smaller than the standard model prediction. Thus, we suggest a possible solution of the PREX-II tension by showing that, considering its underlying dependence on the weak mixing angle, the PREX-II neutron skin determination could be in agreement with the other available measurements and predictions if the weak mixing angle at the proper energy scale is smaller than the standard model prediction.

We use a high-resolution ${}^{32}\mathrm{S}(d,t)$ measurement to investigate the claimed existence of a 6401(3) keV state in ${}^{31}\mathrm{S}$ that may affect the ${}^{30}\mathrm{P}(p,\gamma )$ nuclear reaction rate in oxygen-neon (ONe) novae. Our data are shown to exclude the null hypothesis—that the state does not exist—with high significance. Additionally, the data also suggest the existence of a hitherto unreported state at 6648(4) keV. This state corresponds to a ${}^{30}\mathrm{P}(p,\gamma )$ resonance at 517(4) keV, located below the higher edge of the Gamow window for peak nova temperatures of about 0.4 GK.

In this work, the traditional two-variable few-body integrodifferential equations approach is reviewed. Boundary conditions are implemented in both the hyperradial and hyperangular domains. A novel procedure of including effects of higher partial waves of the interaction potential is introduced. The new approach reproduces results obtained by an exact method for boson systems. These results suggest that many-body correlations are negligibly small in systems with short-range interactions and that effect of higher partial waves are adequately accounted for by the revised hypercentral potential.

The effects of four-quasiparticle configurations and time-odd interactions are investigated in the framework of configuration-interaction projected density functional theory by taking the yrast states of ${}^{60}\mathrm{Fe}$ as examples. Based on the universal PC-PK1 density functional, the energies of the yrast states with spin up to $20\hslash$ and the available $B\left(E2\right)$ transition probabilities are well reproduced. The yrast states are predicted to be of four-quasiparticle structure above spin $I=16\hslash$. The inclusion of the time-odd interactions increases the kinetic moments of inertia and delays the appearance of the first band crossing, and, thus, improves the description of the data.

All possible chances of heavy-cluster emissions are predicted for even-even isotopes of ${}^{290–304}120$ using the modified generalized liquid drop model with a Q-value-dependent preformation factor. We have considered only those cluster emissions with half-life below the measurable limits. We have also estimated the probable heavy cluster emitted from each isotope of ${}^{290–304}120$ with half-life comparable to $\alpha$-decay half-life and the most probable cluster emission with the least half-life among all cluster-daughter combinations possible, and the predicted decays have either magic number of protons or neutrons or near to it. The highest and second highest $\alpha$-decay half-life from ${}^{290–304}120$ corresponds to ${}^{298}120$ and ${}^{304}120$, both isotopes with magic or semimagic numbers. Thus, the role of the magic number in stability is highlighted through our paper. The predicted $\alpha$ half-lives are compared with other theoretical models and are in agreement. For the first time we explore the possibility of $2\alpha$ decay from the superheavy (SH) nuclei. The agreement in theoretical $\alpha$-decay half-lives with experimental values for the isotopes in the decay chains of $Z=120$ shows the predictability of the model in the SH region, and so we predict the isotopes ${}^{290,292}120$ decays by $6\alpha$-decay chains and even-even isotopes ${}^{294–304}120$ decays by $4\alpha$-decay chains. Our predictions become particularly important as the predicted half-lives are within experimentally measurable limits and can be detected in the near future.

Correlations driven by the constraints of local charge conservation have been shown to provide insight into the chemical evolution and diffusivity of the high-temperature matter created in ultrarelativistic heavy ion collisions. Two-particle correlations driven by final-state interactions have allowed the extraction of critical femtoscopic space-time information about the expansion and dissolution of the same collisions. Whereas correlations from final-state interactions mainly appear at small relative momenta, a few tens of MeV/$c$, charge-balance correlations extend over a range of hundreds of MeV/$c$. In nearly all previous analyses, this separation of scales is used to focus solely on one class or the other. The purpose of this study is to quantitatively understand the degree to which correlations from final-state interactions distort the interpretation of charge-balance correlations and vice versa.

Heavy quarks are valuable probes of the electromagnetic field and the initial condition of the quark-gluon plasma (QGP) matter produced in high-energy nuclear collisions. Within an improved Langevin model that is coupled to a ($3+1$)-dimensional viscous hydrodynamic model, we explore the origin of the directed flow coefficient ($v_1$) of heavy mesons and their decay leptons, and its splitting ($\mathrm{\Delta }{v}_1$) between opposite charges. We find that while the rapidity dependence of the heavy flavor $v_1$ is mainly driven by the tilted energy density profile of the QGP with respect to the longitudinal direction at energies available at the BNL Relativistic Heavy Ion Collider (RHIC), it is dominated by the electromagnetic field at energies available at the CERN Large Hadron Collider (LHC). The $\mathrm{\Delta }{v}_1$ serves as a novel probe of the spacetime evolution profile of the electromagnetic field. Our results of $D$ mesons and their decay electrons are consistent with the available data at RHIC and LHC, and our predictions on the heavy flavor decay muons can be further tested by future measurements.

Motivated by the recent observation of anomalous electron-positron angular correlations in the decay of the 18.15-MeV $1^{+}$ excited states in ${}^8\mathrm{Be}$, we reexamine in detail the standard model expectations for these angular correlations. The 18.15-MeV state is above particle threshold, and several multipoles can contribute to its $e^{+}{e}^{-}$ decay. We present the general theoretical expressions for $e^{+}{e}^{-}$ angular distributions for nuclear decay by $C0,C1,C2,M1,E1$, and $E2$ multipoles, and we examine their relative contribution to the $e^{+}{e}^{-}$ decay of ${}^8\mathrm{Be}$ at 18.15 MeV. We find that this resonance is dominated by $M1$ and $E1$ decay, and that the ratio of $M1$ to $E1$ strength is a strong function of energy. This is in contrast to the original analysis of the $e^{+}{e}^{-}$ angular distributions, where the $M1/E1$ ratio was assumed to be a constant over the energy region $E_p=0.8–1.2$ MeV. We find that the existence of a “bump” in the measured angular distribution is strongly dependent on the assumed $M1/E1$ ratio, with the present analysis finding the measured large-angle contributions to the $e^{+}{e}^{-}$ angular distribution to be lower than expectation. Thus, in the current analysis we find no evidence for axion decay in the 18.15-MeV resonance region of ${}^8\mathrm{Be}$.

The fusion probability for the production of superheavy nuclei in cold fusion reactions was investigated and compared with recent experimental results for ${}^{48}\mathrm{Ca}, {}^{50}\mathrm{Ti}$, and ${}^{54}\mathrm{Cr}$ incident on a ${}^{208}\mathrm{Pb}$ target. Calculations were performed within the fusion-by-diffusion model (FbD) using the new nuclear data tables by Jachimowicz et al. [At. Data Nucl. Data Tables 138, 101393 (2021)]. It is shown that the experimental data could be well explained within the framework of the FbD model. The saturation of the fusion probability at bombarding energies above the interaction barrier is reproduced. It emerges naturally from the physical effect of the suppression of contributions of higher partial waves in fusion reactions. The role of the difference in values of the rotational energies in the fusion saddle point and contact (sticking) configuration of the projectile-target system is discussed.

In an effort to elucidate the rich band structures observed in odd-neutron systems, the triaxial projected shell model approach is extended to include three-quasineutron and five-quasiparticle configurations. This extension makes it possible to investigate the high-spin states up to and including the second band crossing. Detailed investigation has been performed for odd-mass Xe isotopes with the extended basis, and it is shown that the character of the band crossing along the yrast line changes with shell filling of the $1h_{11/2}$ orbital. Further, it is observed that the three-quasiparticle state that crosses the ground-state configuration, leading to the normal band crossing phenomenon along the yrast line, first crosses the $\gamma$ band based on the ground-state configuration at an earlier spin value. This crossing feature explains the occurrence of the signature inversion observed in the $\gamma$ bands for some of the studied isotopes.