The effect of weak binding of ${}^9\mathrm{Be}$ on complete fusion has been explored through the study of complex fragment emission in ${}^{20}\mathrm{Ne}+{}^9\mathrm{Be}$ reaction. The yields of the fragments ${}^{6,7}\mathrm{Li}$ and ${}^{7,9}\mathrm{Be}$ emitted from the excited compound nucleus ${}^{29}\mathrm{Si}^{*}$ have been compared with the respective statistical model predictions. Emission of same fragments from another close-by compound nucleus ${}^{28}\mathrm{Si}^{*}$ at similar excitation energy, formed by the fusion of two strongly bound nuclei, ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$, has been studied for comparison. It has been observed that for the system ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$, the yields of ${}^{6,7}\mathrm{Li}$ and ${}^{7,9}\mathrm{Be}$ fragments are close to the predictions of the statistical model. However, for the ${}^{20}\mathrm{Ne}+{}^9\mathrm{Be}$ system, although the experimental yield pattern follows the statistical model prediction, there is substantial reduction in yield for all detected fragments. These observations have been attributed to the suppression of complete fusion in ${}^{20}\mathrm{Ne}+{}^9\mathrm{Be}$ system due to the weak binding of ${}^9\mathrm{Be}$, a dynamical effect which is not incorporated in the conventional statistical models. It is the first time that a clear signature of the suppression of complete fusion in light systems involving weakly bound nucleus has been observed in complex fragment emission from fully equilibrated composite produced in fusion well above the barrier.

Background: The properties of the collective low-lying states of Zr isotopes which include excitation energies and $E2$ reduced transition probabilities indicate that some of these states are mainly spherical and the other are mainly deformed ones. A consideration of these data in the framework of the geometrical collective model with $\beta$, $\gamma$, and rotational degrees of freedom is necessary for ${}^{92\text{–}102}\mathrm{Zr}$.

Purpose: To investigate the properties of the low-lying collective states of ${}^{92\text{–}102}\mathrm{Zr}$ based on the five-dimensional geometrical quadrupole collective model, to obtain the collective potentials for the chain of Zr isotopes and to investigate their evolution with increase of the number of neutrons.

Method: The quadrupole-collective Bohr Hamiltonian depending on both $\beta$ and $\gamma$ shape variables with a potential having spherical and deformed minima is applied. The relative depth of two minima, height and width of the barrier, and rigidity of the potential near both minima are determined so as to achieve the best possible description of the observed properties of the low-lying collective quadrupole states of ${}^{92\text{–}102}\mathrm{Zr}$.

Results: Satisfactory agreement with the experimental data on the excitation energies and the $E2$ reduced transition probabilities is obtained. The evolution of the collective potential with increase of $A$ is described and the distributions of the wave functions of the collective states in $\beta \text{−}\gamma$ plane are found.

Conclusion: It is shown that the low-energy structure of ${}^{92\text{–}102}\mathrm{Zr}$ can be described in a satisfactory way within the geometrical collective model with the Bohr Hamiltonian. The $\beta$ dependence of the potential energy is fixed to describe the experimental data in a best possible way. The resulting potential evolves with $A$ increase from having only one spherical minimum in ${}^{92}\mathrm{Zr}$, through the potentials having both spherical and deformed minima, to the potential with one deformed minimum in ${}^{102}\mathrm{Zr}$. A $\beta$ dependence of the wave functions is presented in a set of figures illustrating their distribution over $\beta$.

Effects of rotation and valence nucleons in molecular linear $\alpha$-chain nuclei are analyzed using a three-dimensional lattice cranking model based on covariant density functional theory. The structure of the mirror nuclei ${}^{16}\mathrm{C}$ and ${}^{16}\mathrm{Ne}$ is investigated as a function of rotational frequency. The valence nucleons, with respect to the $3\alpha$ linear chain core of ${}^{12}\mathrm{C}$, at low frequency occupy the $\pi$ molecular orbital. With increasing rotational frequency these nucleons transition from the $\pi$ orbital to the $\sigma$ molecular orbital, thus stabilizing the $3\alpha$ linear chain structure. It is predicted that the valence protons in ${}^{16}\mathrm{Ne}$ change occupation from the $\pi$ to the $\sigma$ molecular orbital at $\hslash \omega \approx 1.3$ MeV, a lower rotational frequency compared to $\hslash \omega \approx 1.7$ MeV for the valence neutrons in ${}^{16}\mathrm{C}$. The same effects of valence protons are found in ${}^{20}\mathrm{Mg}$, compared to the four valence neutrons in ${}^{20}\mathrm{O}$. The model is also used to examine the effect of alignment of valence nucleons on the relative positions and size of the three $\alpha$ clusters in the mirror nuclei ${}^{16}\mathrm{C}$ and ${}^{16}\mathrm{Ne}$.

The nature of quadrupole and octupole collectivity in ${}^{222}\mathrm{Rn}$ was investigated by determining the electric-quadrupole ($E2$) and octupole ($E3$) matrix elements using subbarrier, multistep Coulomb excitation. The radioactive ${}^{222}\mathrm{Rn}$ beam, accelerated to 4.23 MeV/u, was provided by the HIE-ISOLDE facility at CERN. Data were collected in the Miniball $\gamma$-ray spectrometer following the bombardment of two targets, ${}^{120}\mathrm{Sn}$ and ${}^{60}\mathrm{Ni}$. Transition $E2$ matrix elements within the ground-state and octupole bands were measured up to $10\hslash$ and the results were consistent with a constant intrinsic electric-quadrupole moment, $518\left(11\right)e{\mathrm{fm}}^2$. The values of the intrinsic electric-octupole moment for the $0^{+}\to 3^{-}$ and $2^{+}\to 5^{-}$ transitions were found to be respectively ${2360}_{-210}^{+300}e{\mathrm{fm}}^3$ and ${2300}_{-500}^{+300}e{\mathrm{fm}}^3$ while a smaller value, ${1200}_{-900}^{+500}e{\mathrm{fm}}^3$, was found for the $2^{+}\to 1^{-}$ transition. In addition, four excited non-yrast states were identified in this work via $\gamma \text{−}\gamma$ coincidences.

We explore the possibility to perform symmetry restoration with the variation after projection technique on a quantum computer followed by additional postprocessing. The final goal is to develop configuration interaction techniques based on many-body trial states preoptimized on a quantum computer. We show how the projection method used for symmetry restoration can prepare optimized states that could then be employed as initial states for quantum or hybrid quantum-classical algorithms. We use the quantum phase estimation and the quantum Krylov approaches for the postprocessing. The latter method combined with the quantum variation after projection leads to very fast convergence toward the ground-state energy. The possibility to access excited states energies is also discussed. Illustrations of the different techniques are made using the pairing Hamiltonian.

The shape and collectivity of ${}^{80}\mathrm{Ge}$ were investigated via a sub-barrier-energy Coulomb excitation measurement using the JANUS setup at the NSCL ReA3 facility. The ${}^{80}\mathrm{Ge}$ spectroscopic quadrupole moment $Q_s\left(2_1^{+}\right)$ of the $2_1^{+}$ state was measured for the first time, and the precision of the ${}^{80}\mathrm{Ge}$ $B(E2;0_1^{+}\to 2_1^{+})$ transition strength was increased. The experimental $Q_s\left(2_1^{+}\right)$ value indicates a large, prolate deformation for ${}^{80}\mathrm{Ge}$, which is consistent with large-scale shell-model calculations performed for comparison. These results provide important benchmarks for models that try to describe nuclear shape in neutron-rich nuclei near the magic number $N=50$.

Bulk and spectroscopic properties of ${}^4\mathrm{He}$ are studied within an equation of motion phonon method. Such a method generates a basis of $n$-phonon ($n=0,1,2,3...$) states composed of tensor products of particle-hole Tamm-Dancoff phonons and then solves the full eigenvalue problem in such a basis. The method does not rely on any approximation and is free of any contamination induced by the center of mass, in virtue of a procedure exploiting the singular value decomposition of rectangular matrices. Two potentials, both derived from the chiral effective field theory, are adopted in a self-consistent calculation performed within a space including up to three phonons. The latter basis states are treated under a simplifying assumption. A comparative analysis with the experimental data points out the different performances of the two potentials. It shows also that the calculation succeeds only partially in the description of the spectroscopic properties and suggests a recipe for further improvements.

Knockout reactions with heavy ion targets in inverse kinematics, as well as “quasifree” (p,2p) and (p,pn) reactions are useful tools for nuclear spectroscopy. We report calculations on ab initio many-body wave functions based on the no-core shell model to study the nucleon removal reactions in light nuclei, including beryllium, carbon, and oxygen isotopic chains, and explore the importance of using an ab initio method. Our study helps to clarify how the extraction of spectroscopic factors from the experiments depend on the details of the many-body wave functions being probed. We show that recent advances with the ab initio method can provide more insights on the spectroscopy information extracted from experiments.

The new single-channel, single-energy partial-wave analysis method based on a simultaneous use of amplitude and partial-wave analysis called AA-PWA, developed and tested on $\eta$ photoproduction in [Phys. Rev. C 102, 064609 (2020)] is applied to the $K^{+}\mathrm{\Lambda }$ photoproduction for the center-of-mass energy range of $1625\text{MeV}<W<2296\text{MeV}$. A complete set of multipoles has been created. The advantages of the method have been confirmed and a comparison with the only existing single-energy partial-wave analysis of $K^{+}\mathrm{\Lambda }$ photoproduction given in [Phys. Rev. Lett. 119, 062004 (2017), Eur. Phys. J. A 53, 242 (2017)] is presented. We confirm the size and shape of Bonn-Gatchina multipoles, but we do not confirm the unambiguous interpretation of the structure in the $M_{1-}$ multipole as a $N\left(1880\right){\frac{1}{2}}^{+}$ resonance. The decisive role of the self-consistency of the world database is emphasized.

The proton stopping behavior in proton-proton ($\mathit{pp}$) collisions at beam momentum of 20, 31, 40, 80, 158 GeV/$c$ suggests that more physics mechanisms are at play than traditionally assumed in Monte Carlo event generators. It is shown that the thermal string fragmentation model of pythia 8.303 is able to provide a good description of the observables in inelastic $\mathit{pp}$ collisions such as the rapidity and transverse momentum spectra of protons, charged pions, and charged kaons at the whole CERN SPS energies.

Nonconformal attractor behavior is studied by solving nonconformal second-order viscous hydrodynamics with respect to boost-invariant plasmas. Numerical solutions of the relative decay rate of the enthalpy density, the inverse shear and bulk Reynolds numbers all exhibit universal patterns towards an ideal fluid description at late stages, demonstrating the existence of a nonconformal hydrodynamic attractor. However, as a generic feature, the nonconformal hydrodynamic attractor emerges only at late times, which differs drastically from the behavior observed in conformal systems. The absence of the early-time attractor in nonconformal fluids is a consequence of the early-time unstable mode, which arises from a positive-valued eigenmode associated with the free-streaming dynamics. The early-time attractor can be restored in a mixture of the shear and bulk viscous corrections, in which early-time unstable modes cancel approximately. However, to support practical simulations of hydrodynamics in high-energy heavy-ion collisions, for which the early-time nonconformal attractor is approachable in all independent modes, the quadratic coupling between the bulk pressure and the expansion rate should be enhanced by at least a factor of two through the transport coefficient ${\delta }_{\mathrm{\Pi }\mathrm{\Pi }}$.

Background: An analysis of recent experimental data [J. Khuyagbaatar et al., Phys. Rev. C 104, L031303 (2021)] has established the existence of two fissioning states in ${}^{253}\mathrm{Rf}$: The ground state and a low-lying isomeric state, most likely involving the same neutron single-particle configurations as in the lighter isotone ${}^{251}\mathrm{No}$. The ratio of fission half-lives measured in ${}^{253}\mathrm{Rf}$ was used to predict the fission properties of the $1/2^{+}$ isomeric state in ${}^{251}\mathrm{No}$ and draw conclusions as to the stability against fission of even lighter Rf systems.

Purpose: This paper focuses again on the fission properties of ${}^{253}\mathrm{Rf}$ and their impact on the stability of other neutron-deficient isotopes, using new and improved data collected from two experiments performed at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia.

Methods: ${}^{253}\mathrm{Rf}$ and ${}^{251}\mathrm{No}$ nuclei were produced in fusion-evaporation reactions between ${}^{50}\mathrm{Ti}$ and ${}^{48}\mathrm{Ca}$ ions and the atoms of isotopically enriched ${}^{204}\mathrm{Pb}$ targets. The nuclei of interest were separated from the background of other reaction products and implanted into a Si detector where their characteristic radioactive decays were observed through position and time correlations between detected signals.

Results: Two fission activities with half-lives of $52.8\left(4.4\right)\mu \mathrm{s}$ and 9.9(1.2) ms were measured in the case of ${}^{253}\mathrm{Rf}$, confirming the results of J. Kkuyagbaatar et al. A third state, at much higher excitation energy, was also observed through the detection of its electromagnetic decay to the $52.8\text{−}\mu \mathrm{s}$ state. This observation leads to the opposite quantum-configuration assignments for the fissioning states as compared to the ones established by Khuyagbaatar et al., namely, that the higher-spin state has the shortest fission half-life. This inversion of the ratio of fission hindrances between the low- and high-spin states is corroborated in the isotone ${}^{251}\mathrm{No}$ by the nonobservation of any substantial fission branch from the low-spin isomer.

Conclusions: In going from ${}^{251}\mathrm{No}$ to ${}^{253}\mathrm{Rf}$, the fission half-life of a specific quantum state is found to decrease by close to seven orders of magnitude. Large reductions of more than five and six orders of magnitude are also found between the fission half-lives of the ground states of ${}^{252}\mathrm{No}$ and ${}^{254}\mathrm{Rf}$ and between those of ${}^{254}\mathrm{No}$ and ${}^{256}\mathrm{Rf}$, respectively, pointing to a similar rate of decrease inthe fission barrier as one removes neutrons from both systems. Following this trend to the $N=148$ isotones, our results suggest that the fission half-life of the ground state of the next even-even Rf isotope ${}^{252}\mathrm{Rf}$ will be extremely short, possibly at the limit of existence of an atom.

The existing formalism used to compute the operator overlaps necessary to carry out generator coordinate method calculations using a set of Hartree-Fock-Bogoliubov wave functions is generalized to the case where each of the HFB states are expanded in different arbitrary bases spanning different subspaces of the Hilbert space.

We report on the discovery of new analytical solutions of the equations of relativistic ideal hydrodynamics. In this solution, the fluid expands in the longitudinal direction and contains a plateau structure that extends over a finite range in rapidity and can be either symmetric or asymmetric in that variable. We further calculate the corresponding pseudorapidity distribution of hadron yields, and find decent agreement with experimental measurements in high-energy Pb $+$ Pb, Au $+$ Au, $p +$ Pb, and $d +$ Au collisions.

An alternative interpretation of the recently reported low-lying excited bands in $\gamma$-soft odd-mass nuclei as wobbling bands is presented in terms of the interacting boson-fermion model. The model Hamiltonian is determined based on the mean-field calculations with the nuclear energy density functionals. The predicted mixing ratios of the $\mathrm{\Delta }I=1$ electric quadrupole to magnetic dipole transition rates between yrast bands and those yrare bands previously interpreted as wobbling bands in ${}^{135}\mathrm{Pr}, {}^{133}\mathrm{La}, {}^{127}\mathrm{Xe}$, and ${}^{105}\mathrm{Pd}$ are consistently smaller in magnitude than the experimental values on which the wobbling interpretation is based. These calculated mixing ratios indicate predominant magnetic character in agreement with the new experimental data. The earlier wobbling assignments are severely questioned.

Spectra of $\alpha$ particles were measured for ${}^{12,13}\mathrm{C} + {}^{93}\mathrm{Nb}$ systems at several angles for a bombarding energy of 65 MeV to investigate various reaction mechanisms like direct break up and cluster transfer responsible for $\alpha$ production. The $\alpha$ spectra were analyzed in detail to determine the effect of $1n$ transfer on an $\alpha$-production cross section in particular. After accounting for contributions from direct breakup and Be transfer, there is a clear signature of the $\alpha$ particles produced through the break-up process following neutron transfer in the case of a ${}^{13}\mathrm{C}$ induced reaction. This is an interesting result being reported for the strongly bound projectile.

The angular dependence of the differential cross sections for the ${}^{13}\mathrm{C}{\left(\alpha ,n_0\right)}^{16}\mathrm{O}$ reaction was measured in the energy range 2.0–6.2 MeV using the time-of-flight method for separating neutrons corresponding to the ground state of the residual nucleus. The integrated total cross sections were derived from the measured data and the cross sections for the ${}^{16}\mathrm{O}{\left(n,{\alpha }_0\right)}^{13}\mathrm{C}$ reaction were determined using the reciprocity theorem. The cross sections obtained for the reaction ${}^{16}\mathrm{O}{\left(n,{\alpha }_0\right)}^{13}\mathrm{C}$ support the evaluation given in the ENDF/B-VIII.0 library.

We performed Penning trap mass measurements for ${}^{61}\mathrm{Zn}$ at the National Superconducting Cyclotron Laboratory and NuShellX calculations of the ${}^{61}\mathrm{Zn}$ and ${}^{62}\mathrm{Ga}$ structure using the GXPF1A Hamiltonian to obtain improved estimates of the ${}^{61}\mathrm{Zn}(p,\gamma ){}^{62}\mathrm{Ga}$ and ${}^{60}\mathrm{Cu}(p,\gamma ){}^{61}\mathrm{Zn}$ reaction rates. Surveying astrophysical conditions for type-I x-ray bursts with the code mesa, implementing our improved reaction rates, and taking into account updated nuclear masses for ${}^{61}\mathrm{V}$ and ${}^{61}\mathrm{Cr}$ from the recent literature, we refine the neutrino luminosity from the important mass number $A=61$ urca cooling source in accreted neutron-star crusts. This improves our understanding of the thermal barrier between deep heating in the crust and the shallow depths where extra heat is needed to explain x-ray superbursts, as well as the expected signature of crust urca neutrino emission in light curves of cooling transients.

The first results on the ${\sigma }_{L{T}^{\prime }}$ structure function in exclusive ${\pi }^{0}p$ electroproduction at invariant masses of the final state of $1.5\text{GeV}<W<1.8\text{GeV}$ and in the range of photon virtualities $0.4{\mathrm{GeV}}^2<Q^2<1.0{\mathrm{GeV}}^2$ were obtained from data on beam spin asymmetries and differential cross sections measured with the CLAS detector at Jefferson Lab. The Legendre moments determined from the ${\sigma }_{L{T}^{\prime }}$ structure function have demonstrated sensitivity to the contributions from the nucleon resonances in the second and third resonance regions. These new data on the beam spin asymmetries in ${\pi }^{0}p$ electroproduction extend the opportunities for the extraction of the nucleon resonance electro-excitation amplitudes in the mass range above 1.6 GeV.

We investigate the quartet correlations in four-component fermionic systems at the thermodynamic limit within a variational many-body theory. The Bardeen-Cooper-Schrieffer (BCS)–type variational wave function is extended to the systems with the coexistence of pair and quartet correlations at zero temperature. Special attention is paid to the application of the present framework to an $\alpha$-particle condensation in symmetric nuclear matter, where the coexistence of deuteron and $\alpha$ condensations is anticipated. We also discuss how physical properties, such as quasiparticle dispersion, can be modified by the pair and quartet correlations and show a hierarchical structure of in-medium cluster formations in infinite nuclear matter. The present results may also contribute to the interdisciplinary understanding of fermionic condensations beyond the BCS paradigm in many-body systems.