Background: Interaction of a heavy projectile with a heavy target produces a massive compound nucleus (CN), which deexcites through two possible modes: evaporation of light particles and fission. In order to develop a clear understanding of fusion-fission (FF) dynamics, it is important to explore the preactinide region at energies around and above the Coulomb barrier.

Purpose: The objective is to study the dynamics involved in the fusion of ${}^{12}\mathrm{C}$, a cluster structured projectile, with ${}^{181}\mathrm{Ta}$ target, at energies within 4.3–6.0 MeV/nucleon, by measuring the production cross sections of the radionuclides formed through complete/incomplete fusion (CF/ICF) and fission processes. In addition, the mass distribution of fission fragments, which is an important fission observable, is probed for a better understanding of dynamics.

Method: Tantalum foil, backed by the aluminum catcher, arranged in a stack, was bombarded by ${}^{12}\mathrm{C}$ ions of 52–73 MeV energy. The off-beam $\gamma$-ray spectrometry method was adopted to measure the activity of the residues produced in each Ta target after the end of bombardment (EOB), and cross sections were calculated. To analyze the experimental cross sections, PACE4 and EMPIRE3.2.2 reaction model codes were employed. Further, the mass distribution of fission fragments was explored to obtain mass variance information.

Results: In general, measured excitation functions of the residues produced through the evaporation of particles in ${}^{12}\mathrm{C}+{}^{181}\mathrm{Ta}$ reaction showed good agreement with the predictions of PACE4. ICF of ${}^{12}\mathrm{C}$ in ${}^{181}\mathrm{Ta}$ target with strength up to $7.7\%$ has been observed and compared with the strength deduced from previously reported data for the same system. However, no signature of precompound processes has been observed in this study. A total of 12 fission fragments within $71\le A\le 135$ mass range have been identified. Further, mass variance is rising with increasing mass asymmetry, which hints at the importance of entrance-channel parameters' role in deciding the spread of the mass distribution.

Conclusions: Good agreement of PACE4 with the excitation functions of $xn$ channel evaporation residues confirms their production through the CF mechanism. Enhancement of cross sections in the $\alpha xn$ channel is attributed to the ICF process. Further, evidence of the production of fission fragments through a compound nuclear mechanism is indicated as a broad and symmetric mass distribution, observed through the Gaussian fitting. The trend of mass variance with rising excitation energy and mass asymmetry is found to be growing.

In heavy-ion collisions at energies above the Coulomb barrier, the multiple nucleon transfer mechanism feeding double charge exchange (DCE) reactions can compete with the meson-induced DCE process once, in both cases, the same final partition is achieved. While the former is a mean field driven process, the latter is generated by second-order isovector components of the nucleon-nucleon interaction. It is particularly interesting to isolate the meson-induced DCE from measured cross sections since their matrix elements can be linked to those controlling the expected double $\beta$ decay rates. However, one needs first to isolate the meson-induced DCE contribution, which in turn means that careful scrutiny of the DCE flux from the multinucleon transfer is mandatory. This work presents theoretical results for all the multinucleon transfer routes feeding the ${}^{116}\mathrm{Cd}({}^{20}\mathrm{Ne},{}^{20}\mathrm{O}){}^{116}\mathrm{Sn}$ reaction at 306 MeV incident energy. The calculated cross sections are obtained considering the distorted wave Born approximation and coupled channel Born approximation, where the role of the couplings with inelastic states in the initial partition is discussed. Moreover, the spectroscopic amplitudes for the projectile and target overlaps are extracted by considering a large-scale shell-model calculation.

Consequences of increasing the binding energy of the hypertriton ground state ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}(J^P={\frac{1}{2}}^{+})$ from the emulsion value $B_{\mathrm{\Lambda }}^{\mathrm{EMUL}}\left({}_{\mathrm{\Lambda }}{}^3\mathrm{H}_{\mathrm{g}.\mathrm{s}.}\right)=0.13\pm 0.05$ MeV to the STAR value $B_{\mathrm{\Lambda }}^{\mathrm{STAR}}{(}_{\mathrm{\Lambda }}^3\mathrm{H})=(0.41\pm 0.12\pm 0.11)$ MeV are studied for $s$-shell hypernuclei within a pionless effective field theory ($\cancel{\pi }$ EFT) approach at leading order, constrained by the binding energies of the $0^{+}$ and $1^{+}{}_{\mathrm{\Lambda }}{}^4\mathrm{H}$ states. The stochastic variational method is used in bound-state calculations, whereas the inverse analytic continuation in the coupling constant method is used to locate $S$-matrix poles of continuum states. It is found that the $\mathrm{\Lambda }nn\left({\frac{1}{2}}^{+}\right)$ resonance becomes broader and less likely to be observed experimentally, whereas the ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}\left({\frac{3}{2}}^{+}\right)$ spin-flip virtual state moves closer to the $\mathrm{\Lambda }d$ threshold to become a shallow bound state for specific $\mathrm{\Lambda }N$ interaction strengths. The effect of such a near-threshold ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}\left({\frac{3}{2}}^{+}\right)$ state on femtoscopic studies of $\mathrm{\Lambda }$-deuteron correlations, and its lifetime if bound, are discussed. Increasing $B_{\mathrm{\Lambda }}\left({}_{\mathrm{\Lambda }}{}^3\mathrm{H}_{\mathrm{g}.\mathrm{s}.}\right)$ moderately, up to $\approx 0.5$ MeV, hardly affects calculated values of $B_{\mathrm{\Lambda }}\left({}_{\mathrm{\Lambda }}{}^5\mathrm{He}\right)$.

The recent measurement of the mass of neutron stars (PSR J1614−2230, PSR J0348+0432, MSP J0740+6620) restricts the lower limit $\sim 2M_{\odot }$ of the maximum mass of such compact stars, making it possible for dense matter to exist in massive stars. The relativistic mean-field theory with parameter sets FSUGold including kaon condensation is used to describe the properties of neutron stars in $\beta$ equilibrium. Through careful choice of the parameter of the $\sigma$-cut $c_{\sigma }$, we are able to produce a maximum mass neutron star with kaon condensation heavier than $2M_{\odot }$, and we find that the parameter ${\mathrm{\Lambda }}_{\nu }$ of the $\rho -\omega$ interaction term in this model has a significant effect on $K^{-}$ condensation. In the case of using the $\sigma$-cut scheme, $K^{-}$ condensation occurs only when the $\rho -\omega$ interaction ${\mathrm{\Lambda }}_{\nu }$ is switched off.

The dynamics of chiral nuclei is investigated for the first time with the time-dependent and tilted axis cranking covariant density functional theories on a three-dimensional space lattice in a microscopic and self-consistent way. The experimental energies of the two pairs of the chiral doublet bands in ${}^{135}\mathrm{Nd}$ are well reproduced without any adjustable parameters beyond the well-defined density functional. A novel mechanism, i.e., chiral precession, is revealed from the microscopic dynamics of the total angular momentum in the body-fixed frame, whose harmonicity is associated with a transition from the planar into aplanar rotations with the increasing spin. This provides a fully microscopic and dynamical view to understand the chiral excitations in nuclei.

The canonical states in the relativistic continuum Hartree-Bogoliubov theory with Green's function method are obtained by diagonalizing the density matrix on a spatial mesh. Taking the giant halo nucleus ${}^{128}\mathrm{Zr}$ as an example, the obtained canonical single-particle energies and wave functions are compared in detail with the corresponding calculations with the box-discretized method. The occupation number $v_i^2$ in the canonical basis and the neutrons in continuum $N_c$ are investigated for the Zr giant halo nuclei. The dependencies on the pairing strength $V_0$ and on the different density functionals PK1 and NL-SH are also studied. It is found that the calculations with Green's function and box-discretized methods are almost consistent in describing nuclear global properties and the neutrons in continuum, meanwhile the $N_c$ of giant halo nuclei may heavily depend on the adopted pairing strength as well as the density functional.

The momentum correlation functions of $S=-2$ baryon pairs ($p{\mathrm{\Xi }}^{-}$ and $\mathrm{\Lambda }\mathrm{\Lambda }$) produced in high-energy $pp$ and $pA$ collisions are investigated on the basis of the coupled-channels formalism. The strong interaction is described by the coupled-channels HAL QCD potential obtained by lattice QCD simulations near physical quark masses, while the hadronic source function is taken to be a static Gaussian form. The coupled-channels effect, the threshold difference, the realistic strong interaction, and the Coulomb interaction are fully taken into account for the first time in the femtoscopic analysis of baryon-baryon correlations. The characteristic features of the experimental data for the $p{\mathrm{\Xi }}^{-}$ and $\mathrm{\Lambda }\mathrm{\Lambda }$ pairs at the Large Hadron Collider are reproduced quantitatively with a suitable choice of nonfemtoscopic parameters and the source size. The agreement between theory and experiment indicates that the $N\mathrm{\Xi }$ ($\mathrm{\Lambda }\mathrm{\Lambda }$) interaction is moderately (weakly) attractive without having a quasibound (bound) state.

Background: Quasifission plays a detrimental role in the synthesis of superheavy elements. Understanding the dynamics of quasifission helps in selecting the optimum target projectile combinations for the synthesis of new superheavy elements.

Purpose: The influence of various entrance channel parameters on the quasifission dynamics was explored. Three reactions, ${}^{84}\mathrm{Kr}+{}^{198}\mathrm{Pt}$, ${}^{86}\mathrm{Kr}+{}^{198}\mathrm{Pt}$, and ${}^{86}\mathrm{Kr}+{}^{197}\mathrm{Au}$, expected to be dominated by quasifission, were studied near the Coulomb barrier energies.

Methods: The binary fission fragments from the three reactions were detected using the double arm time-of-flight spectrometer CORSET. The mass and total kinetic energy distributions, which are sensitive to the quasifission dynamics, were measured and analyzed for the three reactions.

Results: The mass and total kinetic energy distributions of all the three reactions have the characteristics that show the dominance of quasifission. For the reaction ${}^{84}\mathrm{Kr}+{}^{198}\mathrm{Pt}$, symmetric quasifission has been found to be relatively more dominant compared to ${}^{86}\mathrm{Kr}+{}^{198}\mathrm{Pt}$ reaction. The results have been compared with ${}^{48}\mathrm{Ca}$- and ${}^{52}\mathrm{Cr}$-induced reactions, populating nearby nuclei, to understand the evolution of quasifission. An analysis of the timescales in these reactions using a dynamical calculation shows that ${}^{84}\mathrm{Kr}+{}^{198}\mathrm{Pt}$ takes a longer time to reach a particular dinuclear shape compared to the other two reactions. The driving potential at the barrier radius also shows a shallower pocket for ${}^{84}\mathrm{Kr}+{}^{198}\mathrm{Pt}$ compared to ${}^{86}\mathrm{Kr}+{}^{198}\mathrm{Pt}$ and ${}^{86}\mathrm{Kr}+{}^{197}\mathrm{Au}$ reactions.

Conclusion: The entrance channel isospin difference is found to influence the quasifission dynamics. A higher entrance channel isospin difference may have a larger evolution time, thus driving the systems toward a more symmetric mass split.

The dynamical cluster-decay model (DCM) is employed to study the excitation functions and fusion evaporation residue (ER) cross sections for the production of ${}^{283}\mathrm{Cn}$ and ${}^{282}\mathrm{Cn}$ isotopes via $3n$ and $4n$ decay channels from the ${}^{286}\mathrm{Cn}^{*}$ compound nucleus. The study includes quadrupole deformation ${\beta }_{2i}$ and hot-optimum orientations ${\theta }_i$ at various ${}^{48}\mathrm{Ca}$-beam energies $E_{\mathrm{lab}}=233.3\text{–}240\mathrm{MeV}$ (equivalently, excitation energies $E^{*}=34.4\text{–}39.8\mathrm{MeV}$), supporting symmetric fission, which agrees well with the experimental data. The reaction was investigated by using a hot compact configuration. The Skyrme forces used are new forces GSkI and KDE0(v1), and the conventional force SIII. Apparently, the DCM with the pocket formula for nuclear proximity potential reproduces the measured data on fusion ER nicely within single-parameter fitting of $\mathrm{\Delta }R$, independently of the nuclear interaction potential and Skyrme force used. We have also calculated the fusion-fission cross section (${\sigma }_{ff}^{\mathrm{predicted}}$) at $E^{*}=35\mathrm{MeV}$ and ER cross sections for the experimentally unobserved neutron emission channels $1n$, $2n$, and $4n$ at different excitation energies $E^{*}$. Further, we have proposed new target-projectile (t-p) combinations for the synthesis of ${}^{286}\mathrm{Cn}$ for future experiments.

The initial state is one of the greatest uncertainties in heavy-ion collisions. A model-agnostic approach is taken in the phenomenological Trento framework which constrains parameters using Bayesian analysis. However, the color-glass condensate (CGC) effective theory predicts initial energy densities that lie outside the recent Bayesian analyses due, in part, to the assumption in Trento of event-by-event multiplicity fluctuations following a $\mathrm{\Gamma }$ distribution. We compare the Trento-preferred $\sqrt{T_A{T}_B}$ scaling to CGC-like $T_A{T}_B$ scaling coupled with log-normal fluctuations in AuAu and $d\mathrm{Au}$ collisions and find there is a significant impact on the multiplicity distributions and on the eccentricities, which may affect the extraction of viscosity in small systems.

The quark-gluon plasma produced in heavy-ion collisions is anisotropic throughout its evolution. This anisotropy changes the physics of jet-medium interaction, making it dependent on the momentum direction of the jet. In this paper we analyze transverse momentum broadening of a jet parton interacting with soft gluons in an anisotropic plasma. Our analysis equally applies to momentum broadening of quasiparticles in kinetic theory. We subtract contribution from instability modes in the deep infrared and discuss how our calculation should be complemented in that regime. The resulting anisotropic collision kernel for momentum broadening is qualitatively different from the equilibrium collision kernel and from the isotropic ansatz used in effective kinetic theory. Because of increased medium screening, there is substantially less transverse broadening at low and intermediate momenta.

We make ab initio predictions for the $A=6$ nuclear level scheme based on two- and three-nucleon interactions up to next-to-next-to-leading order in chiral effective field theory ($\chi \mathrm{EFT}$). We utilize eigenvector continuation and Bayesian methods to quantify uncertainties stemming from the many-body method, the $\chi \mathrm{EFT}$ truncation, and the low-energy constants of the nuclear interaction. The construction and validation of emulators is made possible via the development of jupiterncsm—a new $M$-scheme no-core shell model code that uses on-the-fly Hamiltonian matrix construction for efficient, single-node computations up to $N_{\text{max}}=10$ for ${}^6\mathrm{Li}$. We find a slight underbinding of ${}^6\mathrm{He}$ and ${}^6\mathrm{Li}$, although consistent with experimental data given our theoretical error bars. As a result of incorporating correlated $\chi \mathrm{EFT}$-truncation errors we find more precise predictions (smaller error bars) for separation energies: $S_d\left({}^6\mathrm{Li}\right)=0.89\pm 0.44\mathrm{MeV}, S_{2n}\left({}^6\mathrm{He}\right)=0.20\pm 0.60\mathrm{MeV}$, and for the beta decay $Q$ value: $Q_{{\beta }^{-}}\left({}^6\mathrm{He}\right)=3.71\pm 0.65\mathrm{MeV}$. We conclude that our error bars can potentially be reduced further by extending the model space used by jupiterncsm.

I have applied a simple two-state mixing model to matrix elements for $0\leftrightarrow 2$ transitions in ${}^{98,100}\mathrm{Mo}$. Because the situation regarding the second and third $2^{+}$ states is unclear, I have performed three separate fits for each nucleus. Results indicate that ${}^{100}\mathrm{Mo}$ is somewhat more collective than ${}^{98}\mathrm{Mo}$, and that basis-state band $g$ is significantly more deformed than band $e$.

A unified theoretical model reproducing charge radii of known atomic nuclei plays an essential role in making extrapolations for unknown nuclei. Recently developed new ansatz which phenomenologically takes into account the neutron-proton short-range correlations ($np$-SRCs) can describe the discontinuity properties and odd-even staggering (OES) effect of charge radii along isotopic chains remarkably well. In this work, we further review the modified root-mean-square (rms) charge radii formula in the framework of relativistic mean field (RMF) theory. The charge radii are calculated along various isotopic chains that include the nuclei featuring the $N=50$ and 82 magic shells. Our results suggest that RMF with and without considering a correction term give an almost similar trend of nuclear size for some isotopic chains with open proton shell, especially the abrupt increases across the strong neutron closed shells and the OES behaviors. This reflects that the $np$-SRCs have almost no influence for some nuclei due to the strong coupling between different levels around Fermi surface. The weakening OES behavior of nuclear charge radii is observed generally at completely filled neutron shells and this may be proposed as a signature of magic indicator.

An extension to our previous method to deduce the neutron radii of neutron-rich nuclei is presented. This method requires measuring the reaction cross sections of both the neutron-rich nucleus and its stable isotope at the same energy per nucleon on a carbon target. Using this method and the available experimental data, the neutron radii of ${}^{21–29}\mathrm{F}, {}^{21–32}\mathrm{Ne}, {}^{24–35}\mathrm{Na}, {}^{25–38}\mathrm{Mg}$, and ${}^{45–51}\mathrm{Ca}$ isotopes have been deduced. The neutron skin of these isotopes (in the mass region $A=21–51$) exhibited a linear relationship with the isospin $(N-Z)/A$ at a slope equal to $3.216\pm 0.11$ fm. This tends to be much larger than that previously reported for nuclei in the mass region $A=40–238$ at $0.9\pm 0.15$ fm.

The nuclear matter parameters (NMPs), those underlie in the construction of the equation of state (EoS) of neutron star matter, are not directly accessible. A Bayesian approach is applied to reconstruct the posterior distributions of NMPs from the EoS of neutron star matter. The constraints on lower-order parameters as imposed by the finite nuclei observables are incorporated through appropriately chosen prior distributions. The calculations are performed with two sets of pseudo data on the EoS whose true models are known. The median values of second- or higher-order NMPs show sizable deviations from their true values, and associated uncertainties are also larger. The sources of these uncertainties are identified as (i) the correlations among various NMPs and (ii) leeway in the EoS of symmetric nuclear matter, symmetry energy, and neutron-proton asymmetry which propagates into the posterior distributions of the NMPs.

In the present paper, we report the results from the study of excited states in the ${}^{72}\mathrm{Se}$ nucleus using the ${}^{50}\mathrm{Cr}({}^{28}\mathrm{Si}, \alpha 2p){}^{72}\mathrm{Se}$ fusion evaporation reaction at a beam energy of 90 MeV. The deexciting $\gamma$ rays were detected using the Indian National Gamma Array (INGA). A total of ten new $\gamma$-ray transitions have been identified using the $\gamma \text{−}\gamma$ coincidence technique. The $K^{\pi }=0_2^{+}$ band based on an isomeric state has been extended up to a (${10}^{+}$) state at 5.473 MeV excitation energy, and four new interconnecting transitions have been placed between this band and yrast band. Further, the enhanced interconnecting $E1$ transitions between positive- and negative-parity bands suggest the existence of octupole correlations in this nucleus. The characteristics of the observed bands in the experiment have been interpreted in terms of the total Routhian surface (TRS) calculations.

The spins and parities of low-lying states in ${}^{72}\mathrm{Br}$ populated in the $\beta$ decay of ${}^{72}\mathrm{Kr}$ have been studied via conversion electron spectroscopy. The measurements were carried out at ISOLDE using a miniorange spectrometer with Si(Li) and HPGe detectors for electrons and $\gamma$ ray detection. Results of the conversion coefficients corresponding to transitions deexciting 12 levels in ${}^{72}\mathrm{Br}$ are reported. The multipolarities of the transitions are deduced and the spins and parities of the levels involved are discussed. From the multipolarities of the most intense transitions to the ground state, the spin and parity of the ${}^{72}\mathrm{Br}$ ground state have been definitely established as $1^{+}$. The spin of the 101.2-keV isomeric state is determined to be $3^{-}$. The level scheme is compared with mean-field and shell-model calculations and oblate deformation for the ${}^{72}\mathrm{Br}$ ground state is deduced. No $E0$ transitions have been found in ${}^{72}\mathrm{Br}$. $E0$ transitions in the neighboring isobaric nuclei, ${}^{72}\mathrm{Se}$ and ${}^{72}\mathrm{Ge}$, have also been studied.

The present study explores the limitations of the surrogate reaction method for determining the $(n,p)$ cross sections for the target nuclei in the mass region $A\approx 50$ for the neutron energies 1–20 MeV. In the past few years there have been several experimental attempts for determining the $(n,p)$ and $(n,xp)$ cross sections using the surrogate reaction method. But this method has not been benchmarked with the experimentally well-known $(n,p)$ cross sections. The surrogate reaction method with Weisskopf-Ewing approximation may help in providing good constraints for the cross-section data, but this approximation has not been validated yet for $(n,p)$ reactions. In this paper, we have examined the validity of the Weisskopf-Ewing approximation for the $(n,p)$ reactions and also check the sensitivity of the surrogate reaction results with respect to the compound nucleus spin distribution. We have simulated the cross sections obtained through the surrogate reaction method for $n+{}^{48}\mathrm{Ti}, n+{}^{53}\mathrm{Cr}, n+{}^{56}\mathrm{Fe}$, and $n+{}^{59}\mathrm{Co}$ reactions for the different schematic spin distributions of the compound nucleus and studied the effect of assuming the validity of the Weisskopf-Ewing approximation. It has been observed that the proton decay probabilities of the compound nucleus for the $(n,p)$ channel are strongly spin dependent, therefore the Weisskopf-Ewing approximation is violated. We have also observed that the cross sections obtained using the Weisskopf-Ewing approximation show clear dependence on the spin distribution of the compound nucleus. It has also been observed that, due to the large pre-equilibrium contributions in the $(n,p)$ reactions at higher neutron energies, the use of the surrogate reaction method for the neutron energies greater than $\approx 15$ MeV may not be suitable. It is concluded that the surrogate reaction method relying solely on the Weisskopf-Ewing approximation is not sufficient for determining the $(n,p)$ cross sections for the target nuclei in mass range $A\approx 50$ and further development and exploration of the surrogate technique is required.

We use one- and two-level $R$-matrix approximations to analyze data on the cross section for this reaction at center-of-mass energies below 215 keV. We critically examine the data sets using a Bayesian statistical model that allows for both common-mode and additional point-to-point uncertainties. We use Markov chain Monte Carlo sampling to evaluate this $R$-matrix-plus-statistical model and find two-level $R$-matrix results that are stable with respect to variations in the channel radii. The $S$ factor at 40 keV evaluates to 25.36(19) MeV b (68% credibility interval). We discuss our Bayesian analysis in detail and provide guidance for future applications of Bayesian methods to $R$-matrix analyses. We also discuss possible paths to further reduction of the $S$-factor uncertainty.