Features of a new phenomenon—so-called collinear cluster tri-partition—are analyzed from various viewpoints. First, limitations on the angular distributions which are imposed by the general principles of quantum mechanics are considered. Second, these limitations together with the experimental data published earlier are used to estimate the effect as a whole. Third, some confirmation of the large yield of the lightest component of the tri-partition arising from geochemical data is presented.

We present to our knowledge the first successful functional renormalization group (FRG)–aided density-functional theory (DFT) calculation of the equation of state (EOS) of infinite nuclear matter (NM) in (1+1) dimensions composed of spinless nucleons. We give a formulation to describe infinite matters in which the “flowing” chemical potential is introduced to control the expectation value of the particle number during the flow. The resultant saturation energy of the NM coincides with that obtained by the Monte Carlo method within a few percent. Our result demonstrates that the FRG-aided DFT can be as powerful as any other methods in quantum many-body theory.

New measurements of the neutron scattering double differential cross section of iron were carried out at the neutron time-of-flight facilities GELINA and nELBE. A neutron spectrometer consisting of an array of up to 32 liquid organic scintillators was employed, which was designed to measure the scattering differential cross section at eight scattering angles and to simultaneously determine the integral cross section via numerical quadrature. The separation of elastic from inelastic scattering was achieved by analyzing the time-of-flight-dependent light-output distributions to determine the scattered neutron energy. The method was validated by studying elastic scattering on carbon and it was proved to work well for the determination of the elastic cross section. Here, the possibility to extend it to inelastic scattering was investigated too. For these experiments a sample of natural iron was used and the results cover the incident neutron energy range from 2 to 6 MeV. Both the differential and the integral elastic cross sections were produced for ${}^{\mathrm{nat}}\mathrm{Fe}$, while for inelastic scattering, partial angular distributions for scattering from the first excited level of ${}^{56}\mathrm{Fe}$ could be determined.

The multinucleon transfer reactions in collisions of ${}^{136}\mathrm{Xe}+{}^{198}\mathrm{Pt}$ at incident energies $E_{\mathrm{lab}}=5.25$, 6.20, 7.98, 10.0, and 15.0 MeV/nucleon are investigated by using the improved quantum molecular dynamics model. It is found that 6.20 MeV/nucleon is the optimal incident energy for producing the neutron-rich heavy nuclei. About 80 unknown neutron-rich nuclei might be produced in this reaction with cross sections from ${10}^{-6}$ to ${10}^{-2}$ mb. The angular distributions of the neutron-rich isotopes are predicted.

Optical model analyses of recent ${}^8\mathrm{He}+{}^{208}\mathrm{Pb}$ elastic scattering data for incident energies of 16 and 22 MeV, together with existing data for ${}^6\mathrm{He}+{}^{208}\mathrm{Pb}$ at the same energies, reveal a significant difference in the behavior of the imaginary part of the optical potential for the two isotopes as the incident energy is reduced below the Coulomb barrier. While the strength of the ${}^6\mathrm{He}$ imaginary potential reduces as the incident energy is reduced below the barrier, as is the case for most heavy ions, that for ${}^8\mathrm{He}$ remains constant within uncertainties and may even increase. Similar behavior was observed for the ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}+{}^{208}\mathrm{Pb}$ optical potentials [Nucl. Phys. A 571, 326 (1994)], with the strength of the ${}^6\mathrm{Li}$ imaginary potential appearing to increase as the incident energy is reduced below the Coulomb barrier while that for ${}^7\mathrm{Li}$ reduces. However, the explanation for this difference in behavior put forward in that work, viz. the increased importance of breakup for ${}^6\mathrm{Li}$ as the incident energy is reduced towards the Coulomb barrier, later supported explicitly by calculations [Phys. Lett. B 427, 1 (1998)], does not hold for the He isotopes since it is the ${}^8\mathrm{He}$ optical potential that behaves in a similar fashion to that of ${}^6\mathrm{Li}$ in spite of ${}^8\mathrm{He}$ having the higher breakup threshold of the two He isotopes. We conclude that the difference is due to the influence of $3n$ and $4n$ stripping on the ${}^8\mathrm{He}$ scattering, reactions which cannot take place for ${}^6\mathrm{He}$ projectiles.

The fast-neutron-induced fission cross section of ${}^{242}\mathrm{Pu}$ was measured at the neutron time-of-flight facility $n$ELBE. A parallel-plate fission ionization chamber with novel, homogeneous, large-area ${}^{242}\mathrm{Pu}$ deposits on Si-wafer backings was used to determine this quantity relative to the IAEA neutron cross-section standard ${}^{235}\mathrm{U}(n,f)$ in the energy range of 0.5 to 10 MeV. The number of target nuclei was determined from the measured spontaneous fission rate of ${}^{242}\mathrm{Pu}$. This helps to reduce the influence of the fission fragment detection efficiency on the cross section. Neutron transport simulations performed with geant4, mcnp6, and fluka2011 are used to correct the cross-section data for neutron scattering. In the reported energy range the systematic uncertainty is below 2.7% and on average the statistical uncertainty is 4.9%. The determined results show an agreement within 0.67(16)% to recently published data and a good accordance to current evaluated data sets.

The cross sections for two-neutron removal from ${}^{15,16}\mathrm{C}$ on a carbon target have been measured at around 240 MeV/nucleon. The measured cross section for ${}^{15}\mathrm{C}$ is smaller than for ${}^{16}\mathrm{C}$. The trends of the cross sections for ${}^{15,16}\mathrm{C}$ are inconsistent with the previously reported experimental data, but in agreement with the theoretical predictions based on eikonal-model calculations. Based on the present results of ${}^{15,16}\mathrm{C}$ combined with the available experimental data on ${}^{17–20}\mathrm{C}$, an odd-even staggering of the two-neutron removal cross sections along the neutron-rich carbon isotopic chain from ${}^{15}\mathrm{C}$ to ${}^{20}\mathrm{C}$ is observed, and this feature is well reproduced by the theoretical calculations.

The soft-gluon approximation, which implies that radiated gluon carries away a small fraction of initial parton's energy, is a commonly used assumption in calculating radiative energy loss of high momentum partons traversing quark-gluon plasma created at the Relativistic Heavy Ion Collider and the Large Hadron Collider. While the soft-gluon approximation is convenient, different theoretical approaches have reported significant radiative energy loss of high-$p_{\perp }$ partons, thereby questioning its validity. To address this issue, we relaxed the soft-gluon approximation within Djordjevic–Gyulassy–Levai–Vitev (DGLV) formalism. The obtained analytical expressions are quite distinct from the soft-gluon case. However, numerical results for the first order in opacity fractional energy loss lead to small differences in predictions for the two cases. The difference in the predicted number of radiated gluons is also small. Moreover, the effect on these two variables has an opposite sign, which when combined results in almost overlapping suppression predictions. Therefore, our results imply that, contrary to the commonly held doubts, the soft-gluon approximation in practice works surprisingly well in DGLV formalism. Finally, we also discuss generalizing this relaxation in the dynamical QCD medium, which suggests a more general applicability of the conclusions obtained here.

Differential cross sections of ${}^2\mathrm{H}(d,d){}^2\mathrm{H}$ elastic scattering and proton transfer ${}^2\mathrm{H}(d,{}^3\mathrm{He})n$ reactions at 160 MeV beam energy have been obtained. They have been normalized relative to the existing cross-section data for the ${}^2\mathrm{H}(d,d){}^2\mathrm{H}$ elastic scattering at 180 and 130 MeV, benefitting from the negligible energy dependence of this observable at certain range of the four-momentum transfer. The experiment was performed at KVI in Groningen, the Netherlands, using the BINA detector. The elastic scattering data are compared to theoretical predictions based on the lowest-order term in the Neumann series expansion for four-nucleon transition operators. The calculations underpredict the data. The data presented in this paper can be used to validate the future theoretical findings.

The nature of the nuclear pairing condensates in heavy nuclei, specifically neutron-proton (spin-triplet), versus identical-particle (spin-singlet) pairing has been an active area of research for quite some time. In this work, we probe three candidates that should display spin-triplet, spin-singlet, and mixed-spin pairing. Using theoretical approaches such as the gradient method and symmetry-restoration techniques, we find the ground state of these nuclei in Hartree–Fock–Bogoliubov theory and compute ground state to ground state pair-transfer amplitudes to neighboring isotopes while simultaneously projecting to specific particle number and nuclear-spin values. We identify specific reactions for future experimental research that could shed light on spin-triplet and mixed-spin pairing.

We describe the observation of the isospin violating and charge symmetry breaking reaction $dd\to \alpha {\pi }^0$ just above threshold. Measurements using a magnetic channel (gated by two photons) of the ${}^4\mathrm{He}$ scattering angle and momentum (from time of flight) permitted reconstruction of the ${\pi }^0$ “missing mass,” the quantity used to separate distributions of ${}^4\mathrm{He}+{\pi }^0$ events from a continuum containing ${}^4\mathrm{He}+\gamma +\gamma$ and ${}^4\mathrm{He}+{\pi }^0+\gamma$ events. A review has been completed of the apparatus, relevant geant simulations, various corrections, and the $d+p$ scattering cross section used as a luminosity calibration. The new values of the total cross section for neutral pion production are $14.3\pm 2.2\left(\mathrm{stat}\right)\pm 1.6\left(\mathrm{sys}\right)$ pb at 228.5 MeV and $17.3\pm 3.4\left(\mathrm{stat}\right)\pm 2.4\left(\mathrm{sys}\right)$ pb at 231.8 MeV. The uncertainty remains dominated by statistical errors. These cross sections arise from the down-up quark mass difference and quark electromagnetic effects.

An equation of motion phonon method, developed for even nuclei and recently extended to odd systems with a valence particle, is formulated in the hole-phonon coupling scheme and applied to $A=15$ and $A=21$ isobars with a valence hole. The method derives a set of equations which yield an orthonormal basis of states composed of a hole coupled to an orthonormal basis of correlated $n$-phonon states ($n=0,1,2,\cdots$), built of constituent Tamm-Dancoff phonons, describing the excitations of a doubly magic core. The basis is then adopted to solve the full eigenvalue problem. The method is formally exact but lends itself naturally to simplifying approximations. Self-consistent calculations using a chiral Hamiltonian in a space encompassing up to two-phonon and three-phonon basis states in $A=21$ and $A=15$ nuclei, respectively, yield full spectra, moments, electromagnetic and $\beta$-decay transition strengths, and electric dipole cross sections. The analysis of the hole-phonon composition of the eigenfunctions contributes to clarify the mechanism of excitation of levels and resonances and to understand the reasons of the deviations of the theory from the experiments. Prescriptions for reducing these discrepancies are suggested.

Background: New superheavy nuclei are often identified through their characteristic $\alpha$-decay energies, which requires accurate calculations of $Q_{\alpha }$ values. While many $Q_{\alpha }$ predictions are available, little is known about their uncertainties, and this makes it difficult to carry out extrapolations to as-yet-unknown systems.

Purpose: This work aims to analyze several models, compare their predictions to available experimental data, and study their performance for the unobserved $\alpha$-decay chains of ${}^{296}120$ and ${}^{298}120$, which are of current experimental interest. Our quantified results will also serve as a benchmark for future, more sophisticated statistical studies.

Methods: We use nuclear superfluid density functional theory (DFT) with several Skyrme energy density functionals (EDFs). To estimate systematic model uncertainties, we employ uniform model averaging.

Results: We evaluated the $Q_{\alpha }$ values for even-even nuclei from Fm to $Z=120$. For well-deformed nuclei between Fm and Ds, we find excellent consistency between different model predictions, and a good agreement with experimental results. For transitional nuclei beyond Ds, intermodel differences grow, resulting in an appreciable systematic error. In particular, our models underestimate $Q_{\alpha }$ for the heaviest nucleus ${}^{294}\mathrm{Og}$.

Conclusions The robustness of DFT predictions for well-deformed superheavy nuclei supports the idea of using experimental $Q_{\alpha }$ values, together with theoretical predictions, as reasonable $(Z,A)$ indicators. Unfortunately, this identification method is not expected to work well in the region of deformed-to-spherical shape transition as one approaches $N=184$. The use of $Q_{\alpha }$ values in the identification of new superheavy nuclei will benefit greatly from progress in developing both new spectroscopic-quality EDFs and more sophisticated statistical techniques of uncertainty quantification.

Statistical errors in ground state observables and single-particle properties of spherical even-even nuclei and their propagation to the limits of nuclear landscape have been investigated in covariant density functional theory (CDFT) for the first time. In this study we consider only covariant energy density functionals with nonlinear density dependency. Statistical errors for binding energies and neutron skins significantly increase on approaching the two-neutron drip line. On the contrary, such a trend does not exist for statistical errors in charge radii and two-neutron separation energies. The absolute and relative energies of the single-particle states in the vicinity of the Fermi level are characterized by low statistical errors [$\sigma \left(e_i\right)\sim 0.1$ MeV]. Statistical errors in the predictions of spin-orbit splittings are rather small. Statistical errors in physical observables are substantially smaller than related systematic uncertainties. Thus, at the present level of the development of theory, theoretical uncertainties at nuclear limits are dominated by systematic ones. Statistical errors in the description of physical observables related to the ground state and single-particle degrees of freedom are typically substantially lower in CDFT as compared with Skyrme density functional theory. The correlations between the model parameters are studied in detail. The parametric correlations are especially pronounced for the $g_2$ and $g_3$ parameters which are responsible for the density dependence of the model. The accounting of this fact potentially allows us to reduce the number of free parameters of the nonlinear meson coupling model from 6 to 5.

The quadratic form of the isobaric multiplet mass equation (IMME), which was originally suggested by Wigner and has been generally regarded as valid, is seriously questioned by recent high-precision nuclear mass measurements. The usual resolution to this problem is to add empirically the cubic and quartic $T_z$ terms to characterize the deviations from the IMME, but finding the origin of these terms remains an unsolved difficulty. Based on a strategy beyond Wigner's first-order perturbation, we derive explicitly the cubic and quartic $T_z$ terms. These terms are shown to be generated by the effective charge-symmetry-breaking and charge-independence-breaking interactions in the nuclear medium combined with the Coulomb polarization effect. Calculations for the $sd$ and lower $fp$ shells explore a systematic emergence of the cubic $T_z$ term, suggesting a general deviation from the original IMME. Intriguingly, the magnitude of the deviation exhibits an oscillation-like behavior with mass number, modulated by the shell effect.

Xenon detectors are used in the search for dark matter and neutrinoless double-beta decay ($0\nu \beta \beta )$. As the next-generation detectors reach masses in the ton scale, neutrinos from astrophysical sources are soon predicted to become background in such detectors. Theoretical predictions of neutrino scattering cross sections and information of nuclear structure effects therein are crucial in accounting for the background. We perform calculations for differential and total cross sections of charged-current neutrino scattering off the most abundant xenon isotopes. The nuclear-structure calculations are made in the proton-neutron quasiparticle random-phase approximation and the microscopic quasiparticle phonon model for even-mass and odd-mass nuclei, respectively. We compute total cross sections as a function of the neutrino energy, and also give estimates of total averaged cross sections for ${}^8\mathrm{B}$ solar neutrinos and supernova neutrinos using realistic energy distributions.

Excited states of the ${}^{61}\mathrm{Ni}$ ($Z=28,N=33$) nucleus have been probed using heavy-ion-induced fusion evaporation reaction and an array of Compton suppressed germanium (clover) detectors as detection system for the emitted $\gamma$ rays. Seventeen new transitions have been identified and placement of six transitions have been modified with respect to the previous measurements, following which the level scheme of the nucleus has been extended up to an excitation energy $E_x\approx 7$  MeV and spin $\approx 10\hslash$. Higher excitations involving the $g_{9/2}$ orbital in the $fpg$ model space have been established. The experimental results on the level structure of the nucleus have been interpreted in the light of large basis shell model calculations that lead to an understanding of the single particle configurations underlying the level structure of the nucleus. The comparison can be suggestive of further refinements in the shell model interactions for better overlap of the theoretical results with the experimental data.

Nuclei are nearly transparent to each other when they collide at high energy, but the collisions do produce high-energy density matter in the central rapidity region where most experimental measurements are made. What happens to the receding nuclear fireballs? We calculate the energy loss of the nuclei using the color glass condensate model. We then use a simple space-time picture of the collision to calculate the baryon and energy densities of the receding fireballs. For central collisions of large nuclei at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider we find baryon densities more than ten times that of normal nuclear matter. These results provide initial conditions for subsequent hydrodynamic evolution and could test the equation of state at very high baryon densities.