The ${}^{56}\mathrm{Fe}(n,\gamma )$ thermal neutron capture cross section and the ${}^{57}\mathrm{Fe}$ level scheme populated by this reaction have been investigated in this work. Singles $\gamma$-ray spectra were measured with an isotopically enriched ${}^{56}\mathrm{Fe}$ target using the guided cold neutron beam at the Budapest Reactor, and $\gamma \gamma$-coincidence data were measured with a natural Fe target at the LWR-15 research reactor in Řež, Czech Republic. A detailed level scheme consisting of 448 $\gamma$ rays populating/depopulating 97 levels and the capture state in ${}^{57}\mathrm{Fe}$ has been constructed, and $\approx 99\%$ of the total transition intensity has been placed. The transition probability of the 352-keV $\gamma$ ray was determined to be $P_{\gamma }\left(352\right)=11.90\pm 0.07$ per 100 neutron captures. The ${}^{57}\mathrm{Fe}$ level scheme is substantially revised from earlier work and $\approx 33$ previously assigned levels could not be confirmed while a comparable number of new levels were added. The ${}^{57}\mathrm{Fe}\gamma$-ray cross sections were internally calibrated with respect to ${}^1\mathrm{H}$ and ${}^{32}\mathrm{S}\gamma$-ray cross section standards using iron(III) acetylacetonate $\left({\mathrm{C}}_{15}{\mathrm{H}}_{21}{\mathrm{FeO}}_6\right)$ and iron pyrite $\left({\mathrm{FeS}}_2\right)$ targets. The thermal neutron cross section for production of the 352-keV $\gamma$-ray cross section was determined to be ${\sigma }_{\gamma }\left(352\right)=0.2849\pm 0.015$ b. The total ${}^{56}\mathrm{Fe}(n,\gamma )$ thermal radiative neutron cross section is derived from the 352-keV $\gamma$-ray cross section and transition probability as ${\sigma }_0=2.394\pm 0.019$ b. A least-squares fit of the $\gamma$ rays to the level scheme gives the ${}^{57}\mathrm{Fe}$ neutron separation energy $S_n=7646.183\pm 0.018$ keV.

The evolution of level structures due to the unique parity orbitals $g_{9/2}$, $h_{11/2}$, and $i_{13/2}$ in odd-mass nuclei from Zn to Am is studied within a unified framework, by correlations between ratios of excitation energies in both odd-mass nuclei and their even-even core nuclei. These plots reveal regularities that can be understood in terms of the particle-plus-rotor model, as evolutions along its three limiting coupling schemes: weak coupling, decoupling, and strong coupling, and transitions between them. Peculiar transitions between the decoupling and strong coupling schemes are found in both $i_{13/2}$ structures of neutron-odd nuclei and $h_{11/2}$ structures of proton-odd nuclei, at neutron numbers around 90 and 70, respectively. These are correlated with the critical shape phase transitions from vibrator to rotor from the even-even nuclei in the same regions and are characterized as critical phase transitions too. This behavior is corroborated with a nonmonotonic behavior of the differential variation of the two-neutron separation energies in the same nuclear regions.

States in ${}^{209}\mathrm{Tl}$ were populated using a multinucleon transfer reaction with a ${}^{136}\mathrm{Xe}$ beam impinging on a thick ${}^{208}\mathrm{Pb}$ target at $E=785$ MeV. The beam was pulsed at 825-ns intervals in order to perform isomer decay spectroscopy. The known $J^{\pi }=17/2^{+}$ isomer in ${}^{209}\mathrm{Tl}$ was located at 1228(4) keV and measured to have a half-life of $T_{1/2}=146\left(10\right)$ ns. A second isomer with $J^{\pi }=13/2^{+}$ was found to have $T_{1/2}=14\left(5\right)$ ns. The previously suggested low-energy X and Y transitions were found to have energies 57(2) and 47(2) keV respectively, while the measurement of conversion coefficients and a new decay path make the spin assignments below the isomers experimentally firm. Correlating the delayed $\gamma$ transitions with the prompt beam flash allowed the decay of states above the isomer to be found. The longer-lived isomer represents full alignment of the simplest two-particle, one-hole configuration and illuminates the remarkably weak coupling of the proton hole to the ${}^{210}\mathrm{Pb}$ core.

With the $R{}^3\mathrm{B}$-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of ${}^{18}\mathrm{C}$ at a projectile energy around $425A$ MeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of ${}^{17}\mathrm{C}$ into the ground state of ${}^{18}\mathrm{C}$. Those data have been used to constrain theoretical calculations for transitions populating excited states in ${}^{18}\mathrm{C}$. This allowed to derive the astrophysical cross section ${\sigma }_{n\gamma }^{*}$ accounting for the thermal population of ${}^{17}\mathrm{C}$ target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures $T_9\le 1$ GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of ${}^{17}\mathrm{C}$ on the production of second- and third-peak elements in contrast to earlier sensitivity studies.

Fluctuations and correlations of conserved charges are sensitive observables for studying the QCD phase transition and critical point in high-energy heavy-ion collisions. We have studied the centrality and energy dependence of mixed cumulants (up to fourth order) between net baryon and net strangeness in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=7.7$, 11.5, 19.6, 27, 39, 62.4, and 200 GeV from the ultrarelativistic quantum molecular dynamics (UrQMD) model. To compare with other theoretical calculations, we normalize these mixed cumulants by various order cumulants of net-strangeness distributions. We found that the results obtained from UrQMD calculations are comparable with the results from lattice QCD at low temperature and hadron resonance gas model. The ratios of mixed cumulants ($R_{11}^{BS},R_{13}^{BS},R_{22}^{BS},R_{31}^{BS}$) from UrQMD calculations show weak centrality dependence. However, the mixed-cumulant ratios $R_{11}^{BS}$ and $R_{31}^{BS}$ show strong increase at low energy, while the $R_{13}^{BS}$ and $R_{22}^{BS}$ are similar at different energies. Furthermore, we have also studied the correlations between different hadron species and their contributions to the net-baryon and net-strangeness correlations. These model studies can provide baselines for searching for the signals of QCD phase transition and critical point in heavy-ion collisions.

We have followed up on our previous measurements of upscattering of ultracold neutrons (UCNs) from a series of gases by making measurements of total cross sections on the following gases hydrogen, ethane, methane, isobutene, $n$-butane, ethylene, water vapor, propane, neopentane, isopropyl alcohol, and ${}^3\mathrm{He}$. The values of these cross sections are important for estimating the loss rate of trapped neutrons due to residual gas and are relevant to neutron lifetime measurements using UCNs. The effects of the UCN velocity and path-length distributions were accounted for in the analysis using a Monte Carlo transport code. Results are compared to our previous measurements and with the known absorption cross section for ${}^3\mathrm{He}$ scaled to our UCN energy. We find that the total cross sections for the hydrocarbon gases are reasonably described by a function linear in the number of hydrogen atoms in the molecule.

The inclusive production of $\mathrm{\Lambda }$ hyperons in proton-proton collisions at $\sqrt{s}=3.18\mathrm{GeV}$ was measured with HADES at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. The experimental data are compared to a data-based model for individual exclusive $\mathrm{\Lambda }$ production channels in the same reaction. The contributions of intermediate resonances such as $\mathrm{\Sigma }\left(1385\right)$, ${\mathrm{\Delta }}^{++}$, or ${\text{N}}^{*}$ are considered in detail. In particular, the result of a partial-wave analysis accounts for the abundant $p{\mathrm{K}}^{+}\mathrm{\Lambda }$ final state. Model and data show a reasonable agreement at midrapidities, while a difference is found for larger rapidities. A total $\mathrm{\Lambda }$ production cross section in $p+p$ collisions at $\sqrt{s}=3.18\mathrm{GeV}$ of $\sigma (p+p\to \mathrm{\Lambda }+X)=207.3\pm 1.3{}_{-7.3}^{+6.0}(\mathrm{stat}.)\pm 8.4(\mathrm{syst}.){}_{-0.5}^{+0.4}(\mathrm{model}.)\mu \mathrm{b}$ is found.

We present results of large-scale shell-model calculations for the $A=129$ hole nuclei below ${}^{132}\mathrm{Sn}$. We discuss structures of ${}^{129}\mathrm{Sn}$, ${}^{129}\mathrm{In}$, and ${}^{129}\mathrm{Cd}$ with emphasis on the monopole effects and excitations across the neutron $N=82$ shell gap, and further predict low-lying levels for the more exotic ${}^{129}\mathrm{Ag}$. It is demonstrated that the monopole corrections in the Hamiltonian, which dynamically affect occupations of relevant orbits, can lead to interesting consequences for the shell evolution. It is found especially that the monopole terms, previously introduced to reproduce the cross-shell excitations of the $17/2^{+}$ and $21/2^{+}$ states in ${}^{131}\mathrm{In}$, shows more pronounced effects on the $A=129$ nuclei. In ${}^{129}\mathrm{In}$, the cross-shell excitations of $17/2^{+}$ and $21/2^{+}$ are pushed down significantly by the monopole terms, and in ${}^{129}\mathrm{Cd}$, the same monopole terms reverse the order of the single-hole states of $\nu d_{3/2}$ and $\nu h_{11/2}$, causing ${11/2}^{-}$ as the ground state for this nucleus. The structure of isomeric states in the $A=129$ nuclei is also discussed.

Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction products. This approach is complementary to conventional $\gamma$-ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin $I=19/2\hslash$ states in the mirror nuclei ${}^{53}\mathrm{Fe}$ and ${}^{53}\mathrm{Co}$ are measured to study angular momentum population following the projectile fragmentation of ${}^{78}\mathrm{Kr}$ at energies of $\sim 480A$ MeV on a beryllium target. The 19/2 state isomeric ratios of ${}^{53}\mathrm{Fe}$ produced from different projectiles in the literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to abrabla07 model calculations. The isomeric ratios of ${}^{53}\mathrm{Fe}$ produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss.

We investigate the clustering effects in light mass $N=Z$ and $N\ne Z$ composite systems ${}^{20}\mathrm{Ne}^{*}, {}^{28}\mathrm{Si}^{*}, {}^{40}\mathrm{Ca}^{*}$ and ${}^{21,22}\mathrm{Ne}^{*}, {}^{39}\mathrm{K}^{*}$, respectively, formed in low-energy heavy ion reactions at different excitation energies, within the collective clusterization approach of the dynamical cluster-decay model (DCM) of Gupta and collaborators based on quantum-mechanical fragmentation theory (QMFT). Considering quadrupole deformed and compact orientated nuclei, a comparative decay analysis of these systems has been undertaken for the emission of different intermediate mass fragments (IMFs) or clusters, specifically the IMFs having $Z=3$, 4, and 5 (or $Z=7$, 6, and 5 complimentary fragments from the ${}^{20}\mathrm{Ne}^{*}$ and ${}^{21,22}\mathrm{Ne}^{*}$ composite systems) which are having the experimental data available for their $Z$ distribution. Quite interestingly, the QMFT supports clustering in $N=Z$ (${}^{20}\mathrm{Ne}^{*}$ and ${}^{28}\mathrm{Si}^{*}$) and $N\ne Z$ (${}^{21}\mathrm{Ne}^{*}$ and ${}^{22}\mathrm{Ne}^{*}$) nuclear systems at excitation energies corresponding to their respective decay threshold or resonant-state energies for the $4\alpha , {}^{16}\mathrm{O}$ cluster and non-$\alpha$ cluster ${}^{14}\mathrm{C}$ (more so in ${}^{22}\mathrm{Ne}^{*}N\ne Z$ composite system), supported by the Ikeda diagrams, taking into account the proper pairing strength in the temperature-dependent liquid drop energies. Within the DCM, we notice that at higher excitation energies in addition to $x\alpha$-type (where $x$ is an integer) clusters from $N=Z$ composite systems and $xn-x\alpha$-type clusters from $N\ne Z$ composite systems, $np-x\alpha$-type clusters are relatively quite dominant, with larger preformation probability due to the decreased pairing strength at higher temperatures in the liquid drop energies. Also, the study reveals the presence of competing reaction mechanisms of compound nucleus (fusion-fission, FF) and of noncompound nucleus origin (deep inelastic orbiting, DIO) in the decay of very-light-mass composite systems ${}^{20,21,22}\mathrm{Ne}^{*}$ and ${}^{28}\mathrm{Si}^{*}$ at different excitation energies. The DIO contribution in the IMF cross section ${\sigma }_{\text{IMF}}$ is extracted for these composite systems, ${\sigma }_{\text{IMF}}$ is given as the sum of FF cross section ${\sigma }_{\text{FF}}$ and DIO cross section ${\sigma }_{\text{DIO}}$. The DCM calculated FF cross sections ${\sigma }_{\text{FF}}^{\text{DCM}}$ are in good agreement with the available experimental data.

Background: Fission process with heavier projectiles and actinide targets has contributions from processes, such as compound nucleus fission, transfer-induced fission, and noncompound nucleus fission. Mass distribution and mass-dependent anisotropy can be used to identify and delineate the contributions due to these different processes.

Purpose: Mass distribution in ${}^{28}\mathrm{Si}+{}^{232}\mathrm{Th}$ has been studied at beam energies of 180 and 158 MeV to investigate the nature of mass distribution arising from complete and incomplete momentum-transfer fission events. Mass-dependent angular anisotropy has been measured at 166 MeV to investigate the dominant noncompound nucleus process contributing to the fission.

Method: Mass distribution and mass resolved angular distribution of fission products were measured by the recoil catcher method followed by off-line $\gamma$-ray spectrometry.

Results: Mass distributions for full momentum-transfer fission processes were found to be symmetric, and those for transfer-induced fission were found to be asymmetric at both beam energies. The relative contribution from transfer-induced fission was found to be higher at lower beam energy. The anisotropy of the fission product angular distribution was found to increase with decreasing mass asymmetry.

Conclusions: The mass distribution indicates that, apart from the full momentum-transfer fission process, there is a significant contribution due to transfer-induced fission. The mass dependence of angular anisotropy indicated that preequilibrium fission is the dominant noncompound nucleus process in the present reaction system at near barrier energy $(E_{\mathrm{c}.\mathrm{m}.}/V_{\mathrm{C}}=1.06)$.

Background: $\alpha$-nucleus potentials play an essential role in the calculation of $\alpha$-induced reaction cross sections at low energies in the statistical model. Uncertainties of these calculations are related to ambiguities in the adjustment of the potential parameters to experimental elastic scattering angular distributions (typically at higher energies) and to the energy dependence of the effective $\alpha$-nucleus potentials.

Purpose: The present work studies cross sections of $\alpha$-induced reactions for ${}^{64}\mathrm{Zn}$ at low energies and their dependence on the chosen input parameters of the statistical model calculations. The new experimental data from the recent Atomki experiments allow for a ${\chi }^2$-based estimate of the uncertainties of calculated cross sections at very low energies.

Method: Recently measured data for the ($\alpha ,\gamma$), ($\alpha ,n$), and ($\alpha ,p$) reactions on ${}^{64}\mathrm{Zn}$ are compared to calculations in the statistical model. A survey of the parameter space of the widely used computer code talys is given, and the properties of the obtained ${\chi }^2$ landscape are discussed.

Results: The best fit to the experimental data at low energies shows ${\chi }^2/F\approx 7.7$ per data point, which corresponds to an average deviation of about 30% between the best fit and the experimental data. Several combinations of the various ingredients of the statistical model are able to reach a reasonably small ${\chi }^2/F$, not exceeding the best-fit result by more than a factor of 2.

Conclusions: The present experimental data for ${}^{64}\mathrm{Zn}$ in combination with the statistical model calculations allow us to constrain the astrophysical reaction rate within about a factor of 2. However, the significant excess of ${\chi }^2/F$ of the best fit from unity demands further improvement of the statistical model calculations and, in particular, the $\alpha$-nucleus potential.

The low-lying, low-spin levels of ${}^{76}\mathrm{Ge}$ were studied with the $\left(n,n^{\prime }\gamma \right)$ reaction. Gamma-ray excitation function measurements were performed at incident neutron energies from 1.6 to 3.7 MeV, and $\gamma$-ray angular distributions were measured at neutron energies of 3.0 and 3.5 MeV. From these measurements, level spins, level lifetimes, $\gamma$-ray intensities, and multipole mixing ratios were determined. No evidence for a number of previously placed levels was found. Below 3.3 MeV, many new levels were identified, and the level scheme was re-evaluated. The $B\left(E2\right)$ values support low-lying band structure. The $2^{+}$ mixed-symmetry state has been identified for the first time. A comparison of the level characteristics with large-scale shell model calculations yielded excellent agreement.

We show that the rotation axis of a triaxial nucleus may flip from the intermediate axis ($\gamma =-{30}^{\circ }$) to the smallest axis ($\gamma =+{30}^{\circ }$) due to the polarization by an aligned $T=0np$ pair. The example we discuss is the triaxial $N=Z$ nucleus ${}^{64}\mathrm{Ge}$ where the isoscalar $\pi \left(g_{9/2}\right)\otimes \nu \left(g_{9/2}\right)$ pair aligns to $i^{\pi }=9^{+}$ in ${}^{66}\mathrm{As}$ and flips the rotation from $\gamma \approx -{30}^{\circ }$ to $\gamma \approx {30}^{\circ }$. Calculations are performed in the spherical shell model as well as in the cranked Nilsson-Strutinsky model, supporting the suggested scenario. The role of the $np$ interaction in forming the $np$ pair is discussed in both models.

Background: Ab initio many-body methods have been developed over the past ten years to address mid-mass nuclei. In their best current level of implementation, their accuracy is of the order of a few percent error on the ground-state correlation energy. Recently implemented variants of these methods are operating a breakthrough in the description of medium-mass open-shell nuclei at a polynomial computational cost while putting state-of-the-art models of internucleon interactions to the test.

Purpose: As progress in the design of internucleon interactions is made, and as questions one wishes to answer are refined in connection with increasingly available experimental data, further efforts must be made to tailor many-body methods that can reach an even higher precision for an even larger number of observable quantum states or nuclei. The objective of the present work is to contribute to such a quest by designing and testing a new many-body scheme.

Methods: We formulate a truncated configuration-interaction method that consists of diagonalizing the Hamiltonian in a highly truncated subspace of the total $N$-body Hilbert space. The reduced Hilbert space is generated via the particle-number projected BCS state along with projected seniority-zero two- and four-quasiparticle excitations. Furthermore, the extent by which the underlying BCS state breaks $\text{U}\left(1\right)$ symmetry is optimized in the presence of the projected two- and four-quasiparticle excitations. This constitutes an extension of the so-called restricted variation after projection method in use within the frame of multireference energy density functional calculations. The quality of the newly designed method is tested against exact solutions of the so-called attractive pairing Hamiltonian problem.

Results: By construction, the method reproduces exact results for $N=2$ and $N=4$. For $N=(8,16,20)$, the error in the ground-state correlation energy is less than (0.006%, 0.1%, 0.15%) across the entire range of internucleon coupling defining the pairing Hamiltonian and driving the normal-to-superfluid quantum phase transition. The presently proposed method offers the advantage of automatic access to the low-lying spectroscopy, which it does with high accuracy.

Conclusions: The numerical cost of the newly designed variational method is polynomial ($N^6$) in system size. This method achieves unprecedented accuracy for the ground-state correlation energy, effective pairing gap, and one-body entropy as well as for the excitation energy of low-lying states of the attractive pairing Hamiltonian. This constitutes a sufficiently strong motivation to envision its application to realistic nuclear Hamiltonians in view of providing a complementary, accurate, and versatile ab initio description of mid-mass open-shell nuclei in the future.

Background: The radioactive ${}^{220}\mathrm{Th}^{*}$ compound nucleus (CN) is of interest since the evaporation residue (ER) cross sections are available for various entrance channels ${}^{16}\mathrm{O}+{}^{204}\mathrm{Pb}$, ${}^{40}\mathrm{Ar}+{}^{180}\mathrm{Hf}$, ${}^{48}\mathrm{Ca}+{}^{172}\mathrm{Yb}$, and ${}^{82}\mathrm{Se}+{}^{138}\mathrm{Ba}$ at near barrier energies. Within the dynamical cluster-decay model (DCM), the radioactive CNs ${}^{215}\mathrm{Fr}^{*}$, ${}^{242}\mathrm{Pu}^{*}$, ${}^{246}\mathrm{Bk}^{*}$, and ${}^{254}\mathrm{Fm}^{*}$ are studied where the main decay mode is fission, with very small predicted ER cross section. ${}^{220}\mathrm{Th}^{*}$ provides a first case with experimentally observed ER cross section instead of fission.

Purpose: To look for the optimum “hot-compact” target-projectile (t-p) combinations for the synthesis of “cold” ${}^{220}\mathrm{Th}^{*}$ and then its decay. For best fitting of the measured ER cross sections, with quasifission (qf) content, if any, the fusion-fission (ff) component is predicted. The magic-shell structure and entrance channel mass-asymmetry effects are analyzed, and the behavior of CN formation and survival probabilities $P_{\mathrm{CN}}$ and $P_{\mathrm{surv}}$ is studied.

Methods: The quantum-mechanical fragmentation theory (QMFT) is used to predict the possible cold t-p combinations for synthesizing ${}^{220}\mathrm{Th}^{*}$, and the QMFT-based DCM is used to analyze its decay channels for the experimentally studied entrance channels. The only parameter of the model, the neck length $\mathrm{\Delta }R$, varies smoothly with the excitation energy $E^{*}$ of CN and is used to best fit the ER data and predict qf and ff cross sections.

Results: The hot-compact and “cold-elongated” fragmentation paths show dissimilar results, whose comparisons with measured fission yields result in t-p combinations, the cold reaction valleys. For the decay process, the fixed $\mathrm{\Delta }R$ fit the measured ER cross section nicely, but not the individual decay-channel cross sections, which require the presence of qf effects, less so for asymmetric t-p combinations, and large (predicted) ff cross section.

Conclusions: The calculated yields for hot-compact fragmentation path compared favorably with the observed asymmetric fission-mass distribution, resulting in mostly the same t-p reactions as are used in experiments. The best fitted $\mathrm{\Delta }R$ are found to be independent of the entrance channels, despite their very different cross sections, in conformity with our earlier works. The entrance-channel effects lead to the largest decay cross section for the most asymmetric and doubly magic t-p combination, the magicity taking over asymmetry for both the total ER and channel cross section. Furthermore, the variation of both $P_{\mathrm{CN}}$ and $P_{\mathrm{surv}}$ with $E^{*}$ fit in with the known systematic of other radioactive CN studied so far, thereby giving credence to our DCM analysis of ${}^{220}\mathrm{Th}^{*}$.

We present the first predictions for sub-threshold open charm and charmonium production in nuclear collisions. The production mechanism is driven by multistep scatterings of nucleons and their resonance states, accumulating sufficient energy for the production of $J/\mathrm{\Psi }$, ${\mathrm{\Lambda }}_c+\overline{D}$, and $D+\overline{D}$. Our results are of particular importance for the CBM experiment at FAIR, as they indicate that already at the SIS100 accelerator one can expect a significant number of charmed hadrons to be produced. This opens new possibilities to explore charm dynamics and the formation of charmed nuclei.

The freeze-out conditions in proton-proton collisions at $\sqrt{s_{\mathrm{NN}}}=200$, 900, and 7000 GeV have been extracted by fits to the mean hadron yields at midrapidity within the framework of the statistical model of an ideal gas of hadrons and resonances in the grand canonical ensemble. The variation of the extracted freeze-out thermal parameters and the goodness of the fits with $\sqrt{s_{NN}}$ are discussed. We find the extracted temperature and baryon chemical potential of the freeze-out surface to be similar in $p+p$ and heavy-ion collisions. On the other hand, the thermal behavior of the strange hadrons is qualitatively different in $p+p$ as compared to $A+A$ collisions. We find an additional parameter accounting for nonequilibrium strangeness production is essential for describing the $p+p$ data. This is in contrast to $A+A$ where the nonequilibrium framework could be successfully replaced by a sequential and complete equilibrium model with an early freeze-out of the strange hadrons.

Using event-by-event hydrodynamic calculations, we find that the fluctuations of the elliptic flow $\left(v_2\right)$ in the reaction plane have a negative skew. We compare the skewness of $v_2$ fluctuations to that of initial eccentricity fluctuations. We show that skewness is the main effect lifting the degeneracy between higher-order cumulants, with negative skew corresponding to the hierarchy $v_2\left\{4\right\}>v_2\left\{6\right\}$ observed in Pb+Pb collisions at the CERN Large Hadron Collider. We describe how the skewness can be measured experimentally and show that hydrodynamics naturally reproduces its magnitude and centrality dependence.

The competition between $\alpha$ and $\beta$ decays is investigated for neutron-deficient Pa, U, Np, and Pu isotopes. ${\beta }^{+}$/electron-capture (EC) decay rates are calculated within the deformed quasiparticle random-phase approximation with realistic nucleon-nucleon $\left(NN\right)$ interactions. Contributions from allowed Gamow-Teller and Fermi transitions as well as first-forbidden transitions are considered. $\alpha$-decay calculations are performed within the generalized density-dependent cluster model. Effects of differences between neutron and proton distributions and nuclear deformation are taken into account. In the calculations, Reid-93 $NN$ interactions are used for ${\beta }^{+}/\mathrm{EC}$ decays, while Michigan three-range Yukawa effective interactions, based on the $G$-matrix elements of Reid $NN$ potentials, are used for $\alpha$ decay. The calculated $\beta$-decay half-lives show good agreement with the experimental data over a range of magnitude from ${10}^2$ to ${10}^5$ s. The resulting total half-lives including $\alpha$ and $\beta$ contributions are found to be in good agreement with the experimental data, together with the $\alpha /\beta$-decay branching ratios.