Local density fluctuations near the QCD critical point has been suggested to exhibit a power-law behavior which can be probed by an intermittency analysis on scaled factorial moment (SFM) in relativistic heavy-ion collisions. The collision energy and centrality dependence of the second-order SFMs are systematically investigated in $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}}=7.7$, 11.5, 19.6, 27, 39, 62.4, and 200 GeV within the urqmd model. We estimate the noncritical background in the measurement of intermittency and propose a cumulative variable method to effectively remove the background contributions. We further study the effect of particle detection efficiency by implementing the RHIC (STAR) experimental tracking efficiencies in the urqmd events. A cell-by-cell method is proposed for experimental application of efficiency corrections on SFM. This work can provide a guidance of background subtraction and efficiency correction for the experimental measurement of intermittency in the search of the QCD critical point in heavy-ion collisions.

A stochastic approach based on four-dimensional Langevin equations has been used to estimate the mass distributions of fission fragments, the average masses of heavy fragments, the average total kinetic energies of fragments, and the average number of neutrons emitted per fission of ${}^{236}\mathrm{Np}$ produced in the $p+{}^{235}\mathrm{U}$ reaction at $10.3\le E_p\le 30.0\mathrm{MeV}$. Three collective shape coordinates plus the projection of total spin of the compound nucleus to the symmetry axis $K$ were considered in the four-dimensional dynamical model. The effects of shell corrections and dissipation coefficient of $K {\gamma }_K$ were considered in the dynamical calculations. Comparison of the theoretical results for the mass distributions of fission fragments, the average masses of heavy fragments, and the average number of neutrons emitted per fission with the experimental data showed that the results of calculations were in good agreement with the experimental data, although the results of calculations for the average total kinetic energies of fission fragments were slightly higher than the experimental data. It was also shown that the number of fission events increased with time, and almost all of the fission events occurred dynamically until $t=4\times {10}^{-18}\mathrm{s}$ and that the number of fission events became saturated. Furthermore, it was also shown that the average masses of heavy fragments and the average total kinetic energies of fission fragments of ${}^{236}\mathrm{Np}$ decreased with increasing projectile energy.

A new formula to evaluate the nonresonant background for binary breakup is proposed by extending the Migdal-Watson (MW) formula, which was originally developed for $s$-wave breakup in charge neutral systems. The strength of the direct breakup, which is assumed by a one step transition from the initial bound state, is simulated by the complex scaling method (CSM) in binary cluster systems. The extended MW formula is applied to the direct breakup of ${}^{20}\mathrm{Ne}\to \alpha +{}^{16}\mathrm{O}$, and we have found that the formula nicely reproduces the strength of the direct breakup evaluated by CSM. We have demonstrated that new parameters introduced in the extended MW formula have a close connection to the spatial size of the initial wave packet, which is given by the product of the initial wave function and the external field. The application of the new formula to the direct breakup of ${}^{12}\mathrm{Be}$ into $\alpha +{}^8\mathrm{He}$ is also discussed.

In this paper, we investigate the kinetic freeze-out properties in relativistic heavy ion collisions at different collision energies. We present a study of standard Boltzmann-Gibbs blast-wave (BGBW) fits and Tsallis blast-wave (TBW) fits performed on the transverse momentum spectra of identified hadrons produced in $\mathrm{Au}+\mathrm{Au}$ collisions at collision energies of $\sqrt{s_{\mathrm{NN}}}=7.7$–200 GeV at the Relativistic Heavy Ion Collider (RHIC), and in $\mathrm{Pb}+\mathrm{Pb}$ collisions at collision energies of $\sqrt{s_{\mathrm{NN}}}=2.76$ and 5.02 TeV at the Large Hadron Collider (LHC). The behavior of strange and multistrange particles is also investigated. We found that the TBW model describes data better than the BGBW one overall, and the contrast is more prominent as the collision energy increases as the degree of nonequilibrium of the produced system is found to increase. From TBW fits, the kinetic freeze-out temperature at the same centrality shows a weak dependence of collision energy between 7.7 and 39 GeV, while it decreases as collision energy continues to increase up to 5.02 TeV. The radial flow is found to be consistent with zero in peripheral collisions at RHIC energies but sizable at LHC energies and central collisions at all RHIC energies. We also observed that the strange hadrons, with higher temperature and similar radial flow, approach equilibrium more quickly from peripheral to central collisions than light hadrons. The dependence of temperature and flow velocity on nonequilibrium parameter ($q-1$) is characterized by two second-order polynomials. Both $a$ and $d\xi$ from the polynomials fit, related to the influence of the system bulk viscosity, increase toward lower RHIC energies.

Globular cluster stars exhibit star-to-star anticorrelations between oxygen and sodium in their atmospheres. An improved description of the sodium-destroying ${}^{23}\mathrm{Na}+\mathrm{p}$ reaction rates is essential to understanding these observations. We present an energy analysis of ${}^{24}\mathrm{Mg}$ states based on a new measurement of the ${}^{23}\mathrm{Na}({}^3\mathrm{He},\mathrm{d}){}^{24}\mathrm{Mg}$ reaction. A key resonance in ${}^{23}\mathrm{Na}(\mathrm{p},\gamma ){}^{24}\mathrm{Mg}$ is found to be at $E_r^{\text{c.m.}}=133\left(3\right)$ keV, 5 keV lower than previously adopted. This finding has a dramatic effect on the ${}^{23}\mathrm{Na}(\mathrm{p},\gamma ){}^{24}\mathrm{Mg}$ reaction rate, increasing it by a factor of 2 for the recommended rate. The nucleosynthesis impact of this change is investigated.

Background: Observation of asymmetric fission of ${}^{180}\mathrm{Hg}$ has led to intensive theoretical and experimental studies of fission of neutron-deficient nuclei in the lead region.

Purpose: The study of asymmetric and symmetric fission modes of ${}^{180,190}\mathrm{Hg}$ and ${}^{184,192,202}\mathrm{Pb}$ nuclei.

Methods: Mass-energy distributions of fission fragments of ${}^{180,190}\mathrm{Hg}$ and ${}^{184}\mathrm{Pb}$ formed in the ${}^{36}\mathrm{Ar}+{}^{144,154}\mathrm{Sm}$ and ${}^{40}\mathrm{Ca}+{}^{144}\mathrm{Sm}$ reactions, respectively, at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET and compared with previously measured ${}^{192,202}\mathrm{Pb}$ isotopes produced in the ${}^{48}\mathrm{Ca}+{}^{144,154}\mathrm{Sm}$ reactions. The mass distributions for ${}^{180,190}\mathrm{Hg}$ and ${}^{184,192,202}\mathrm{Pb}$ together with old data for ${}^{187}\mathrm{Ir}, {}^{195}\mathrm{Au}, {}^{198}\mathrm{Hg}, {}^{201}\mathrm{Tl}, {}^{205,207}\mathrm{Bi}, {}^{210}\mathrm{Po}$, and ${}^{213}\mathrm{At}$ [J. Nucl. Phys. 53, 1225 (1991)] have been decomposed into symmetric and asymmetric fission modes. The total kinetic-energy distributions for different fission fragment mass regions have been analyzed for ${}^{180,190}\mathrm{Hg}$ and ${}^{184}\mathrm{Pb}$.

Results: The stabilization role of proton numbers at $Z\approx 36$, 38, $Z\approx 45$, 46, and $Z=28/50$ in asymmetric fission of excited preactinide nuclei has been observed. The high ($\approx 145\text{−}\mathrm{MeV}$) and the low ($\approx 128\text{−}\mathrm{MeV}$) energy components have been found in the total kinetic-energy distributions of ${}^{180,190}\mathrm{Hg}$ fission fragments corresponding to the fragments with proton numbers near $Z\approx 46$ and $Z\approx 36$, respectively. In the case of fission of ${}^{184}\mathrm{Pb}$ only the low-energy component ($\approx 135\mathrm{MeV}$) for the fragments with masses corresponding to the proton numbers $Z\approx 36$ and 46 has been found.

Conclusions: The studied properties of asymmetric fission of ${}^{180,190}\mathrm{Hg}$ and ${}^{184,192,202}\mathrm{Pb}$ nuclei point out the existence of well deformed proton shell at $Z\approx 36$ and less deformed proton shell at $Z\approx 46$.

We present the first direct measurement of the atomic mass of a superheavy nuclide. Atoms of ${}^{257}\mathrm{Db}$ ($Z=105$) were produced online at the RIKEN Nishina Center for Accelerator-Based Science using the fusion-evaporation reaction ${}^{208}\mathrm{Pb}({}^{51}\mathrm{V}$, 2n)${}^{257}\mathrm{Db}$. The gas-filled recoil ion separator GARIS-II was used to suppress both the unreacted primary beam and some transfer products, prior to delivering the energetic beam of ${}^{257}\mathrm{Db}$ ions to a helium gas-filled ion stopping cell wherein they were thermalized. Thermalized ${}^{257}\mathrm{Db}^{3+}$ ions were then transferred to a multireflection time-of-flight mass spectrograph for mass analysis. An alpha particle detector embedded in the ion time-of-flight detector allowed disambiguation of the rare ${}^{257}\mathrm{Db}^{3+}$ time-of-flight detection events from background by means of correlation with characteristic $\alpha$ decays. The extreme sensitivity of this technique allowed a precision atomic mass determination from 11 events. The mass excess was determined to be $100063{\left(231\right)}_{\text{stat}}{\left(132\right)}_{\text{sys}}\mathrm{keV}/{\mathrm{c}}^2$. Comparing to several mass models, we show the technique can be used to unambiguously determine the atomic number as $Z=105$ and should allow similar evaluations for heavier species in future work.

Possible bound nuclei beyond the two-neutron drip line in the $50\le Z\le 70$ region are investigated by using the deformed relativistic Hartree-Bogoliubov theory in continuum with density functional PC-PK1. Bound nuclei beyond the drip lines of ${}_{56}\mathrm{Ba}$, ${}_{58}\mathrm{Ce}$, ${}_{62}\mathrm{Sm}$, ${}_{64}\mathrm{Gd}$, and ${}_{66}\mathrm{Dy}$ are predicted, forming peninsulas of stability in the nuclear landscape. Near these peninsulas, several multineutron emitters are predicted. The underlying mechanism of the peninsulas of stability is investigated by studying the total energy, Fermi surface, quadrupole deformation, and the single-neutron spectrum in the canonical basis. It is found that the deformation effect is crucial for forming the peninsulas of stability, and pairing correlations are also essential in specific cases. The dependence on the deformation evolution is also discussed. The decay rates of multineutron radioactivity in Ba and Sm isotopic chains are estimated by using the direct decay model.

In this paper, we report on a study of the spectral features associated with dipole resonances in medium-mass nuclei $(E\le 12 \mathrm{MeV})$, as revealed in the framework of the spd-interacting boson model. The effect of pairing correlations on the theory follows from solutions obtained through an application of the Bethe ansatz equation. In general, calculated spectra around the critical point of the vibrational to $\gamma$-soft transitions appear to approach those of a Gaussian orthogonal ensemble, while near the rotational and vibrational limits of the theory the spectra show more regular behavior. Specifically, the results reveal that the statistical features of the spectra are sensitive to the vector boson pairing strength $c_p$ in the transition region; that is, when $c_p$ is zero, or when the system approaches one of its dynamical symmetry limits, the spectra display regular features, while for stronger $c_p$ values, or when near to the critical phase transition region, the spectral features show more chaotic behavior. Overall, our results indicate that the statistical features are governed by the interplay between dipole resonant energies, pairing correlations, and interactions between and among the single and vector boson modes of the theory. As part of this work we also found out that chaoticity occurred when results were fit to a Berry-Robnik distribution. Throughout our analyses, we used experimentally known information about both positive- and negative-parity states. Our findings suggest that dipole resonances appear to be best-described by Poisson statistics for $A\approx 32–138$ nuclei.

Nuclear deexcitation lines are regularly observed in the $\gamma$-ray emission spectra of strong solar flares. The most prominent lines are produced by interactions of protons and $\alpha$ particles, accelerated up to hundreds of MeV, with abundant nuclei of the solar atmosphere. Analysis and interpretation of these lines, which carry valuable information on the solar flare properties, need cross-section data for the $\gamma$-ray line emission in these interactions for a wide particle energy range. To this purpose, we measured the $\gamma$-ray emission in interactions of $\alpha$-particle beams of $E_{\alpha }=50\text{–}90$ MeV with target foils of C, Mg, Si, and Fe at the center for proton therapy of the Helmholtz-Zentrum Berlin. Setups of three high-purity Ge detectors and one $\mathrm{La}{\mathrm{Br}}_3$:Ce detector have been employed to detect the $\gamma$ rays in two experiment campaigns. Relatively large distances of the detectors from the target and pulsed beams with sub-ns-wide pulses allowed the separation of beam-induced prompt $\gamma$-ray emission from the targets from other $\gamma$ rays and neutron-induced background. $\gamma$-ray production cross sections for about 60 deexcitation lines from excited target nuclei or reaction products have been determined. For the strongest deexcitation lines from the major target isotopes, ${}^{12}\mathrm{C}$, ${}^{24}\mathrm{Mg}$, ${}^{28}\mathrm{Si}$, ${}^{56}\mathrm{Fe}$, there are now measured cross-section data from reaction threshold to $E_{\alpha }=90$ MeV that can be directly used for astrophysical applications like solar flares. Comparison of the results with a cross-section compilation for strong $\gamma$-ray lines in solar flare emissions and the predictions of the talys nuclear reaction code were done. They underline the importance of cross-section determinations at accelerator laboratories for the establishment of an accurate cross-section data base in a wide projectile energy range.

We have presented the systematics of fusion evaporation with deformation and entrance channel parameters based on 107 experiments in the pre-actinide, actinide, and superheavy region. The experimental evaporation residue cross sections were successfully reproduced by advanced statistical model (ASM) and dinuclear system model (DNS) models. Among the studied entrance channel parameters, the Coulomb interaction parameter $z$ and mean fissility ${\chi }_m$ influence effectively the fusion reactions. Deformation effects are also included. It can also be concluded that the fusion of two spherical nuclei yields the largest ${\sigma }_{\text{ER}}$. The highest ${\sigma }_{\text{ER}}$ that can obtained is dictated by the properties of the entrance channel parameters such as Coulomb interaction parameter and mean fissility parameter. By studying these systematics, we have established an entrance channel and deformation parameter dependent empirical formula for maximum evaporation residue cross sections. The presented formula is useful in determining evaporation residue cross sections of the heavy ion fusion reaction to synthesize heavy and superheavy nuclei.

The ${}^{26}\mathrm{Al}(n,p){}^{26}\mathrm{Mg}$ reaction is the key reaction impacting on the abundances of the cosmic $\gamma$-ray emitter ${}^{26}\mathrm{Al}$ produced in massive stars and impacts on the potential pollution of the early solar system with ${}^{26}\mathrm{Al}$ by asymptotic giant branch stars. We performed a measurement of the ${}^{26}\mathrm{Al}(n,p){}^{26}\mathrm{Mg}$ cross section at the high-flux beam line EAR-2 at the n_TOF facility (CERN). We report resonance strengths for eleven resonances, nine being measured for the first time, while there is only one previous measurement for the other two. Our resonance strengths are significantly lower than the only previous values available. Our cross-section data range to 150 keV neutron energy, which is sufficient for a reliable determination of astrophysical reactivities up to 0.5 GK stellar temperature.

Deexcitation $\gamma$ rays associated with an isomeric state of ${}^{186}\mathrm{Ta}$ were investigated. The isomers were produced in multinucleon transfer reactions between a ${}^{136}\mathrm{Xe}$ beam and a natural W target and were collected and separated by the KEK Isotope Separation System. Two $\gamma$ transitions with energies of 161.1(2) and 186.8(1) keV associated with an isomeric decay were observed for the first time. The half-life of the isomeric state of the neutral atom ${}^{186\mathrm{m}}\mathrm{Ta}$ was deduced as 17(2) s. Based on the comparison with the previous measurements of the isomeric state using the Experimental Storage Ring at GSI Darmstadt and the coupling of angular momenta of individual particle orbitals in odd-odd nuclei, a decay scheme of ${}^{186\mathrm{m}}\mathrm{Ta}$ was proposed.

Background: In stellar environments, carbon is produced exclusively via the $3\alpha$ process, where three $\alpha$ particles fuse to form ${}^{12}\mathrm{C}$ in the excited Hoyle state, which can then decay to the ground state. The rate of carbon production in stars depends on the radiative width of the Hoyle state. While not directly measurable, the radiative width can be deduced by combining three separately measured quantities, one of which is the $E0$ decay branching ratio. The $E0$ branching ratio can be measured by exciting the Hoyle state in the ${}^{12}\mathrm{C}(p,p^{\prime })$ reaction and measuring the pair decay of both the Hoyle state and the first $2^{+}$ state of ${}^{12}\mathrm{C}$.

Purpose: We aim to reduce the uncertainties in the carbon production rate in the universe by measuring a set of proton angular distributions for the population of the Hoyle state $\left(0_2^{+}\right)$ and $2_1^{+}$ state in ${}^{12}\mathrm{C}$ in ${}^{12}\mathrm{C}(p,p^{\prime })$ reactions between 10.20 and 10.70 MeV, used in the determination of the $E0$ branching ratio of the Hoyle state.

Method: Proton angular distributions populating the ground, first $2^{+}$, and the Hoyle states in ${}^{12}\mathrm{C}$ were measured in ${}^{12}\mathrm{C}(p,p^{\prime })$ reactions with a silicon detector array covering ${22}^{\circ }<\theta <{158}^{\circ }$ in 14 small energy steps between 10.20 and 10.70 MeV with a thin $(60\mu \mathrm{g}$/${\mathrm{cm}}^2)$ ${}^{\mathrm{nat}}\mathrm{C}$ target.

Results: Total cross sections for each state were extracted and the population ratio between the $2_1^{+}$ and Hoyle state determined at each energy step. By appropriately averaging these cross sections and taking xtheir ratio, the equivalent population ratio can be extracted applicable for any thick ${}^{12}\mathrm{C}$ target that may be used in pair-conversion measurements. This equivalent ratio agreed with a direct measurement performed with a thick target.

Conclusions: We present a general data set of high-precision ${}^{12}\mathrm{C}(p,p^{\prime })$ cross sections that make uncertainties resulting from the population of the $2_1^{+}$ and $0_2^{+}$ states by proton inelastic scattering negligible for any future measurements of the $E0$ branching ratio in ${}^{12}\mathrm{C}$. Implications for future measurements are discussed, as well as possible applications of this data set for investigating cluster structures in ${}^{13}\mathrm{N}$.

We calculate the electric dipole moments (EDMs) of three-nucleon systems at leading order in pionless effective field theory. The one-body contributions that arise from permanent proton and neutron EDMs and the two-body contributions that arise from charge-parity-odd nucleon-nucleon interactions are taken into account. Neglecting the Coulomb interaction, we consider the triton and ${}^3\mathrm{He}$, and also investigate them in the Wigner-SU(4) symmetric limit. We also calculate the electric dipole form factor and find numerically that the momentum dependence of the electric dipole form factor in the Wigner limit is, up to an overall constant (and numerical accuracy), the same as the momentum dependence of the charge form factor. Finally, we study the cutoff dependence of these observables and find that they are properly renormalized.

A modified generalized liquid drop model with the proximity 77 parametrization is used for studying the alpha decay of superheavy nuclei in the range $104\le Z\le 118$. The spontaneous fission (SF) half-lives are computed using a new formula which depends on the shells effect ($E_{\mathrm{shell}}$) and the mass inertia ($I_{\mathrm{rigid}}$). The modes of decay are predicted by comparing $T_{1/2}^{\alpha }$ with $T_{1/2}^{\mathrm{SF}}$ and are compared with the experimental observations. These studies may induce further investigations in the superheavy region.

Background: Knockout reactions with proton targets provide an invaluable tool to access the properties of two-neutron halo nuclei. Recently, experimental results for the average opening angle as a function of the intrinsic neutron momentum in ${}^{11}\mathrm{Li}$ have shown a localization of dineutron correlations on the nucleus surface.

Purpose: Study the model dependence and the effect of distortion and absorption on the opening angle distributions to assess the reliability of this observable to extract properties of Borromean two-neutron halo nuclei.

Method: A quasifree sudden model is used to describe the knockout process, where absorption effects are modeled by the eikonal $S$ matrix between the proton target and the core of the Borromean nucleus. Final states in momentum space are built within a three-body model for the projectile, which enables the description of momenta and opening angle distributions.

Results: A strong dependence on absorption effects is found for the opening angle at large intrinsic momenta, while the region of lower momenta is mostly insensitive to them. Reasonable agreement with the available data is obtained for ${}^{11}\mathrm{Li}$ at low momenta with weights for $s$ and $p$ waves different from those previously reported, showing a model dependence in their extraction. For ${}^{19}\mathrm{B}$, test calculations show marked sensitivity to small $p$-wave components.

Conclusions: The opening angle for $(p,pn)$ knockout reactions on Borromean nuclei at small intrinsic momenta is a reliable observable mostly sensitive to the structure of the Borromean nucleus. For larger momenta, the reaction mechanism leads to a larger distortion of the distribution. In the case of nuclei with small components of opposite parity to the dominant ones, this observable can be used to explore them. The relation between dineutron in coordinate space and opening angle in momentum space is found to be model dependent.

Background: Isotopes of $Z=107\text{–}118$ have been synthesized using cold fusion at GSI, Darmstadt, and hot fusion reactions at JINR, Dubna. Recently theoretical models have predicted $Z=120$ with $N=184$ as an island of stability in the superheavy valley. Hence it is crucial and exciting to predict theoretically the possible combination of projectiles and targets for the synthesis of $Z=120$, which can be informative for upcoming experiments.

Purpose: Present theoretical investigations aim to explore the fusion characteristics of various isotopes of $Z=120$ within the relativistic mean-field formalism. We predict the most suitable projectile-target combination for the synthesis of element $Z=120$. The increase in fusion cross section of nuclei in the superheavy island directly signals the nuclear shell effects. Besides these, the analysis will be crucial and relevant for future experiments to synthesize superheavy nuclei.

Methods: The microscopic nucleon-nucleon R3Y interaction and the density distributions for targets and projectiles are calculated using a relativistic mean-field formalism with the ${\mathrm{NL3}}^{*}$ parameter set. These densities and R3Y nucleon-nucleon (NN) interaction are then used to calculate the nuclear interaction potential using the double folding approach. Seventeen different projectile-target combinations that allow a high $N$/$Z$ ratio are considered in the present analysis to calculate the capture and/or fusion cross sections of various isotopes of $Z=120$ within the $\ell$-summed Wong formula.

Results: The nuclear density distributions for the interacting projectile and target nuclei are obtained from relativistic mean-field Lagrangian for the ${\mathrm{NL3}}^{*}$ parameter set. The nucleus-nucleus interaction potential is estimated for seventeen possible projectile-target combinations using the mean-field density and the R3Y NN potential via a double folding approach. The fusion barriers are obtained by adding the Coulomb potential to the nucleus-nucleus interaction potential. Finally, the fusion and/or capture cross section is calculated for all the systems within the $\ell$-summed Wong formula. Further, the equivalent surface diffusion parameter is estimated to correlate the surface properties of interacting nuclei with the fusion cross section.

Conclusions: The four Ti-based reactions with the heaviest available target ${}^{\mathrm{x}}\mathrm{Cf}$, namely, ${}^{46}\mathrm{Ti}+{}^{248}\mathrm{Cf}$, ${}^{46}\mathrm{Ti}+{}^{249}\mathrm{Cf}$, ${}^{50}\mathrm{Ti}+{}^{249}\mathrm{Cf}$, and ${}^{50}\mathrm{Ti}+{}^{252}\mathrm{Cf}$, and also ${}^{54}\mathrm{Cr}+{}^{250}\mathrm{Cm}$ are found to have the most suitable target-projectile combinations for the synthesis of various isotopes $Z=120$. We also notice that ${}^{48}\mathrm{Ca}$ beams merely provide the required number of protons to synthesize the element with $Z=120$. We established a correlation among the surface properties of interacting nuclei with the fusion characteristics in terms of the equivalent surface diffusion parameter.