The excitation functions of reaction residues populated via the complete fusion and incomplete fusion process in the interaction of the ${}^{19}\mathrm{F}+{}^{159}\mathrm{Tb}$ system have been measured at energies $\approx 4–6$ MeV/nucleon, using off-line $\gamma$-ray spectroscopy. The analysis of data was done within the framework of statistical model code pace4 (a compound nucleus model). A significant fraction of incomplete fusion was observed in the production of reaction residues involving $\alpha$ particle(s) in the exit channels, even at energies as low as near the Coulomb barrier. The incomplete fusion strength function was deduced from the experimental excitation functions and the dependence of this strength function on various entrance channel parameters was studied. The present results show a strong dependence on the projectile $\alpha$-Q value that agrees well with the existing data. To probe the dependence of incomplete fusion on entrance channel mass asymmetry, the present work was compared with the results obtained in the interaction of ${}^{12}\mathrm{C}, {}^{16}\mathrm{O}$, and ${}^{19}\mathrm{F}$ with nearby targets available in the literature. It was observed that the mass asymmetry linearly increases for each projectile separately and turns out to be a projectile-dependent mass-asymmetry systematics. The deduced incomplete fusion strength functions in the present work are also plotted as a function of $Z_P{Z}_T$ (Coulomb effect) and compared with the existing literature. A strong dependence of the Coulomb effect on the incomplete fusion fraction was observed. It was found that the fraction of incomplete fusion linearly increases with $Z_P{Z}_T$ and was found to be more for larger $Z_P{Z}_T$ values indicating significantly important linear systematics.

A high-resolution (${}^3\mathrm{He},t$) charge-exchange experiment at an incident energy of 420 MeV has been performed on the double beta ($\beta \beta$) decay nucleus ${}^{82}\mathrm{Se}$. A detailed Gamow-Teller (${\mathrm{GT}}^{-}$) strength distribution in ${}^{82}\mathrm{Br}$ has been extracted, which provides information to the $\beta \beta$-decay nuclear matrix elements. Three strong and isolated transitions, which are to the 75, 1484 and the 2087 keV states in ${}^{82}\mathrm{Br}$, are found to dominate the low-excitation region below $\approx 2.1$ MeV. Above 2.1 MeV a sudden onset of a strong GT fragmentation is observed. The degree of fragmentation resembles a situation found in the neighboring $A=76$ system ${}^{76}\mathrm{Ge}$, whereas the observed concentration of strength in the three low-lying states is reminiscent of the heavier neighbors ${}^{96}\mathrm{Zr}$ and ${}^{100}\mathrm{Mo}$. The strong GT transition to the 75 keV $(1^{+})$ state makes ${}^{82}\mathrm{Se}$ interesting for solar neutrino detection. The ${}^{82}\mathrm{Se}({\nu }_e,e^{-}){}^{82}\mathrm{Br}$ solar neutrino capture rate in a nonoscillation scenario is therefore evaluated to $668\pm 12\text{(stat)}\pm 60\text{(sys)}$ SNU, and some of the advantages of using selenium for solar neutrino studies are discussed.

The structure of collective bands in ${}^{113}\mathrm{Sn}$, populated in the reaction ${}^{100}\mathrm{Mo}({}^{19}\mathrm{F},p5n)$ at a beam energy of 105 MeV, has been studied. A new positive-parity sequence of eight states extending up to 7764.9 keV and spin $(39/2^{+})$ has been observed. The band is explained as arising from the coupling of the odd valence neutron in the $g_{7/2}$ or the $d_{5/2}$ orbital to the deformed 2p-2h proton configuration of the neighboring even-$A$ Sn isotope. Lifetimes of six states up to an excitation energy of 9934.9 keV and spin $47/2^{-}\mathrm{belonging}$ to a $\mathrm{\Delta }I=2$ intruder band have been measured for the first time, including an upper limit for the last state, from Doppler-shift-attenuation data. A moderate average quadrupole deformation ${\beta }_2=0.22\pm 0.02$ is deduced from these results for the five states up to spin $43/2^{-}$. The transition quadrupole moments decrease with increase in rotational frequency, indicating a reduction of collectivity with spin, a feature common for terminating bands. The behavior of the kinematic and dynamic moments of inertia as a function of rotational frequency has been studied and total Routhian surface calculations have been performed in an attempt to obtain an insight into the nature of the states near termination.

The BRAHMS collaboration has measured transverse momentum spectra of pions, kaons, protons, and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at $\sqrt{s_{\mathit{\text{NN}}}}=200$ GeV. As the collisions become more central the collective radial flow increases while the temperature of kinetic freeze-out decreases. The temperature is lower and the radial flow weaker at forward rapidity. Pion and kaon yields with transverse momenta between 1.5 and $2.5 \mathrm{GeV}/c$ are suppressed for central collisions relative to scaled $p+p$ collisions. This suppression, which increases as the collisions become more central, is consistent with jet quenching models and is also present with comparable magnitude at forward rapidity. At such rapidities, initial state effects may also be present and persistence of the meson suppression to high rapidity may reflect a combination of jet quenching and nuclear shadowing. The ratio of protons to mesons increases as the collisions become more central and is largest at forward rapidities.

Identical particle correlations at fixed multiplicity are considered by means of quantum canonical ensemble of finite systems. We calculate one-particle momentum spectra and two-particle Bose-Einstein correlation functions in the ideal gas by using a recurrence relation for the partition function. Within such a model we investigate the validity of the thermal Wick's theorem and its applicability for decomposition of the two-particle distribution function. The dependence of the Bose-Einstein correlation parameters on the average momentum of the particle pair is also investigated. Specifically, we present the analytical formulas that allow one to estimate the effect of suppressing the correlation functions in a finite canonical system. The results can be used for the femtoscopy analysis of the $A+A$ and $p+p$ collisions with selected (fixed) multiplicity.

An effective field theory of $\alpha$-cluster condensation is formulated as a spontaneously broken symmetry in quantum field theory to understand the raison d'être and the nature of the Hoyle and $\alpha$-cluster states in ${}^{12}\mathrm{C}$. The Nambu-Goldstone and Higgs mode operators in infinite systems are replaced with a pair of canonical operators whose Hamiltonian gives rise to discrete energy states in addition to the Bogoliubov–de Gennes excited states. The calculations reproduce well the experimental spectrum of the $\alpha$-cluster states. The existence of the Nambu-Goldstone-Higgs states is demonstrated and crucial. The $\gamma$-decay transitions are also obtained.

The semimagic nucleus ${}^{89}\mathrm{Y}$ has been investigated using the ${}^{82}\mathrm{Se}({}^{11}\mathrm{B},4n)$ reaction at beam energies of 48 and 52 MeV. More than 24 new transitions have been identified, leading to a considerable extension of the level structures of ${}^{89}\mathrm{Y}$. The experimental results are compared with the large-basis shell model calculations. They show that cross-shell neutron excitations play a pivotal role in high-spin level structures of ${}^{89}\mathrm{Y}$. The systematic features of neutron-core excitations in the $N=50$ isotones are also discussed.

The first measurement of the hypersatellite-satellite two-photon angular correlation function following the electron capture decay of ${}^{55}\mathrm{Fe}$ was carried out. In particular, two hybrid active pixel detectors were employed to measure the anisotropy parameter ${\beta }_2^{\mathrm{eff}}\left(\exp \right)=0.097\pm 0.053$, which closely agreed with the theoretical value ${\beta }_2^{\mathrm{eff}}\left(\mathrm{theor}\right)=0.09735$, calculated in the electric-dipole approximation. In addition, we also determined the double $K$-shell vacancy creation probability in this specific electron capture decay with improved accuracy. We found $P_{KK}=(1.388\pm 0.037)\times {10}^{-4}$, with a systematic error $\mathrm{\Delta }{P}_{KK,\text{syst}}=0.042\times {10}^{-4}$.

The thermal quasiparticle random-phase approximation is combined with the Skyrme energy density functional method (Skyrme-TQRPA) to study the response of a hot nucleus to an external perturbation. For the sample nuclei ${}^{56}\mathrm{Fe}$ and ${}^{82}\mathrm{Ge}$, the Skyrme-TQRPA is applied to analyze thermal effects on the strength function of charge-neutral Gamow–Teller transitions, which dominate neutrino-nucleus reactions at $E_{\nu }\lesssim 20$ MeV. For the relevant supernova temperatures we calculate the cross sections for inelastic neutrino scattering. We also apply the method to examine the rate of neutrino-antineutrino pair emission by hot nuclei. The cross sections and rates are compared with those obtained earlier from the TQRPA calculations based on the phenomenological quasiparticle-phonon model Hamiltonian. For inelastic neutrino scattering on ${}^{56}\mathrm{Fe}$ we also compare the Skyrme-TQRPA results to those obtained earlier from a hybrid approach that combines shell-model and RPA calculations.

We discuss anharmonicity of the multi–octupole-phonon states in ${}^{208}\mathrm{Pb}$ based on a covariant density functional theory by fully taking into account the interplay between the quadrupole and the octupole degrees of freedom. Our results indicate the existence of a large anharmonicity in the transition strengths, even though the excitation energies are similar to those in the harmonic limit. We also show that the quadrupole-shape fluctuation significantly enhances the fragmentation of the two–octupole-phonon states in ${}^{208}\mathrm{Pb}$. Using those transition strengths as inputs to coupled-channels calculations, we then discuss the fusion reaction of ${}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}$ at energies around the Coulomb barrier. We show that the anharmonicity of the octupole vibrational excitation considerably improves previous coupled-channels calculations in the harmonic-oscillator limit, significantly reducing the height of the main peak in the fusion barrier distribution.

Background: The intense current experimental interest in studying the structure of the deuteron and using it to enable accurate studies of neutron structure motivate us to examine the four-dimensional space-time nature of the nuclear wave function and the various approximations used to reduce it to an object that depends only on three spatial variables.

Purpose: The aim is to determine if the ability to understand and analyze measured experimental cross sections is compromised by making the reduction from four to three dimensions.

Method: Simple, exactly calculable, covariant models of a bound-state wave-state wave function (a scalar boson made of two constituent-scalar bosons) with parameters chosen to represent a deuteron are used to investigate the accuracy of using different approximations to the nuclear wave function to compute the quasielastic scattering cross section. Four different versions of the wave function are defined (light-front-spectator, light-front, light-front with scaling, and nonrelativistic) and used to compute the cross sections as a function of how far off the mass shell (how virtual) is the struck constituent.

Results: We show that making an exact calculation of the quasielastic scattering cross section involves using the light-front-spectator wave function. All of the other approaches fail to reproduce the model exact calculation if the value of Bjorken $x$ differs from unity. The model is extended to consider an essential effect of spin to show that constituent nucleons cannot be treated as being on their mass shell even when taking the matrix element of a “good” current.

Conclusions: Developing realistic light-front-spectator wave functions to meet the needs of current and planned experiments is a worthwhile activity.

Large-scale shell-model calculations are carried out in the model space including neutron-hole orbitals $2p_{1/2},1f_{5/2},2p_{3/2},0i_{13/2},1f_{7/2}$, and $0h_{9/2}$ to study the structure and electromagnetic properties of neutron-deficient Pb isotopes. An optimized effective interaction is used. Good agreement between full shell-model calculations and experimental data is obtained for the spherical states in isotopes ${}^{194-206}\mathrm{Pb}$. The lighter isotopes are calculated with an importance-truncation approach constructed based on the monopole Hamiltonian. The full shell-model results also agree well with our generalized seniority and nucleon-pair-approximation truncation calculations. The deviations between theory and experiment concerning the excitation energies and electromagnetic properties of low-lying $0^{+}$ and $2^{+}$ excited states and isomeric states may provide a constraint on our understanding of nuclear deformation and intruder configuration in this region.

We investigate the isoscalar and isovector $E1$ response of neutron-rich nuclei, within a semiclassical transport model employing effective interactions for the nuclear mean field. In particular, we adopt the recently introduced SAMi-J Skyrme interactions, whose parameters are specifically tuned to improve the description of spin-isospin properties of nuclei. Our analysis evidences a relevant degree of isoscalar-isovector mixing of the collective excitations developing in neutron-rich systems. Focusing on the low-lying strength emerging in the isovector response, we show that this energy region essentially corresponds to the excitation of isoscalar-like modes, which also contribute to the isovector response owing to their mixed character. Considering effective interactions which mostly differ in the isovector channels, we observe that these mixing effects increase with the slope $L$ of the symmetry energy at saturation density, leading to a larger strength in the low-energy region of the isovector response. This result appears connected to the increase, with $L$, of the neutron-proton asymmetry at the surface of the considered nuclei, i.e., to the neutron skin thickness.

A numerical method to solve time-dependent Hartree-Fock-Bogoliubov equations by using a hybrid basis of two-dimensional harmonic oscillator eigenfunctions and a one-dimensional Lagrange mesh with the Gogny effective interaction is applied to head-on collisions of superfluid ${}^{20}\mathrm{O}$ nuclei. Taking the energies around the barrier top, the trajectories, pairing energies, and numbers of transferred nucleons are displayed. Their dependence on the relative gauge angle at the initial time is studied.

We study the effect of charged secondaries coming from resonance decay on the net-baryon, net-charge, and net-strangeness fluctuations in high-energy heavy-ion collisions within the hadron resonance gas (HRG) model. We emphasize the importance of including weak decays along with other resonance decays in the HRG, while comparing with the experimental observables. The effect of kinematic cuts on resonances and primordial particles on the conserved number fluctuations are also studied. The HRG model calculations with the inclusion of resonance decays and kinematical cuts are compared with the recent experimental data from STAR and PHENIX experiments. We find good agreement between our model calculations and the experimental measurements for both net-proton and net-charge distributions.

The ALICE Collaboration has recently measured the correlations between amplitudes of anisotropic flow in different Fourier harmonics, referred to as symmetric cumulants. We derive approximate relations between symmetric cumulants involving $v_4$ and $v_5$ and the event-plane correlations measured by the ATLAS Collaboration. The validity of these relations is tested using event-by-event hydrodynamic calculations. The corresponding results are in better agreement with the ALICE data than existing hydrodynamic predictions. We make quantitative predictions for three symmetric cumulants which have not yet been measured.

The neck dynamics in Fermi-energy heavy-ion collisions, to probe the nuclear symmetry energy in the domain of subsaturation densities, is investigated within an isospin-dependent transport model. The single and double ratios of neutrons to protons from free nucleons and light clusters (complex particles) in the isotopic reactions are analyzed systematically. Isospin effects of particles produced from the neck fragmentations are explored. It is found that the ratios of the energetic isospin particles strongly depend on the stiffness of the nuclear symmetry energy and the effects increase with softening of the symmetry energy, which would be a nice probe for extracting the symmetry energy below the normal density in experiments. A flat structure appears at the tail spectra from the double ratio distributions. The neutron to proton ratio of light intermediate-mass fragments with charge number $Z\le 8$ is related to the density dependence of the symmetry energy with less sensitivity in comparison to the isospin ratios of nucleons and light particles.

A systematic search for extremely deformed structures in the $N\approx Z$ nuclei of the $A\approx 40$ mass region has been performed for the first time in the framework of covariant density functional theory. At spin zero such structures are located at high excitation energies, which prevents their experimental observation. The rotation acts as a tool to bring these exotic shapes to the yrast line or its vicinity so that their observation could become possible with future generation of $\gamma$-tracking (or similar) detectors such as GRETA and AGATA. The major physical observables of such structures (such as transition quadrupole moments, as well as kinematic and dynamic moments of inertia), the underlying single-particle structure and the spins at which they become yrast or near yrast, are defined. The search for the fingerprints of clusterization and molecular structures is performed and the configurations with such features are discussed. The best candidates for observation of extremely deformed structures are identified. For several nuclei in this study (such as ${}^{36}\mathrm{Ar}$), the addition of several spin units above the currently measured maximum spin of $16\hslash$ will inevitably trigger the transition to hyper- and megadeformed nuclear shapes.

The multipolarity of the main transition leading to the ground state in ${}^{210}\mathrm{Bi}$ was investigated using the angular correlations of $\gamma$ rays. The analyzed $\gamma$-coincidence data were obtained from the ${}^{209}\mathrm{Bi}\left(n,\gamma \right){}^{210}\mathrm{Bi}$ experiment performed at Institut Laue-Langevin Grenoble at the PF1B cold-neutron facility. The EXILL (EXOGAM at the ILL) multidetector array, consisting of 16 high-purity germanium detectors, was used to detect $\gamma$ transitions. The mixing ratio of the 320-keV $\gamma$ ray was defined by minimizing a multivariable ${\chi }_{\mathrm{\Sigma }}^2$ function constructed from the coefficients of angular correlation functions for seven pairs of strong transitions in ${}^{210}\mathrm{Bi}$. As a result, the almost pure $M1$ multipolarity of the 320-keV $\gamma$ ray was obtained, with an $E2$ admixture of less than 0.6% only (95% confidence limit). Based on this multipolarity the neutron-capture cross section leading to the ground state in ${}^{210}\mathrm{Bi}$, that decays in turn to radiotoxic ${}^{210}\mathrm{Po}$, was determined to be within the limits 21.3(9) and 21.5(9) mb. This result is important for nuclear reactor applications.

Optical potentials provide critical input for calculations on a wide variety of nuclear reactions, in particular, for neutrino-nucleus reactions, which are of great interest in the light of the new neutrino oscillation experiments. We present the global relativistic folding optical potential (GRFOP) fits to elastic proton scattering data from ${}^{12}\mathrm{C}$ nucleus at energies between 20 and 1040 MeV. We estimate observables, such as the differential cross section, the analyzing power, and the spin rotation parameter, in elastic proton scattering within the relativistic impulse approximation. The new GRFOP potential is employed within the relativistic Green's function model for inclusive quasielastic electron scattering and for (anti)neutrino-nucleus scattering at MiniBooNE kinematics.