Prolate-oblate shape phase transition is an interesting topic in nuclear structure, which is useful for understanding the intrinsic interactions between nucleons. Recently, the interacting boson model with SU(3) higher-order interactions was proposed, in which the prolate shape and the oblate shape are not described in a mirror symmetric way. This asymmetric description seems more realistic. The level evolutions, $B\left(E2\right)$ values, and other important indicators showing the prolate-oblate asymmetric transitions are investigated in detail, and realistic structure evolutions from ${}^{180}\mathrm{Hf}$ to ${}^{200}\mathrm{Hg}$ are compared. A key finding is that the average deformation of the prolate shape is nearly twice the one of the oblate shape. These results, together with the successful description of the $B\left(E2\right)$ anomaly in ${}^{168,170}\mathrm{Os}, {}^{172}\mathrm{Pt}$, the $\gamma$-soft properties of ${}^{196}\mathrm{Pt}, {}^{82}\mathrm{Kr}$, and the normal states of ${}^{110}\mathrm{Cd}$, support the validity of the new model.

In recent years, with the wide use of carbon beams, in order to verify the predictive ability of Monte Carlo programs to simulate nuclear reactions, researchers around the world have done many benchmark tests on simulations of outgoing fragments of ${}^{12}\mathrm{C}$ beam bombarding light target materials such as hydrogen, carbon, oxygen, and water targets. With the increase of target mass number, the fragmentation reaction will become more complex, and the applicability of the geant4 nuclear reaction models for this aspect is still unknown. In this paper, the simulation results of emitted light fragments using three hadronic reaction models embedded in the geant4 toolkit are compared with experimental measurements of Cu, W, Au, and Pb targets. The three models are G4BinaryLightIonReaction, G4QMDReaction, and $\mathrm{INCL}++$. This paper discusses the performance of these models in reproducing the energy spectra and angular distributions of the secondary light charged particles, and the results with different targets are shown.

Pairing correlations typically decrease as temperature increases, but in some nuclei, pairing is enhanced within a specific temperature range. This phenomenon, known as pairing reentrance, often occurs in nuclei with an odd number of protons and/or neutrons and is possibly due to the configurations of single-particle levels, especially those close to the Fermi energy. In this study, we examine various nuclear single-particle level configurations that can produce this effect. Our findings show that, although configurations with an odd number of nucleons cause the pairing reentrance, this effect may decrease or even disappear by decreasing the distance between levels located close to the one occupied by the odd nucleon. This reduction leads to an increase in the Pauli blocking effect, which is likely attributed to the participation of nucleons in the neighboring levels into the blocking effect, particularly when the distance between these levels and that occupied by the odd nucleon is very small. Our calculations for realistic calcium isotopes confirm the presence of this phenomenon.

The challenging task in heavy-ion collisions is unambiguously identifying the true fusion events in the deep sub-barrier region. Considering the primary challenge, we have measured fusion excitation functions for ${}^{28}\mathrm{Si}+{}^{158}\mathrm{Gd}$ reaction at energies above to deep sub-barrier region to decipher the role of multineutron transfer with positive $Q$ value and fusion hindrance in an asymmetric system. A comparison has been made with our previous measurement for ${}^{30}\mathrm{Si}+{}^{156}\mathrm{Gd}$ system where only one transfer channel with $Q>$ 0 exists and populates the same compound nucleus ${}^{186}\mathrm{Pt}^{*}$. The enhancement in fusion cross sections is observed on a reduced scale in the ${}^{28}\mathrm{Si}+{}^{158}\mathrm{Gd}$ reaction over ${}^{30}\mathrm{Si}+{}^{156}\mathrm{Gd}$ system at sub-barrier energies. The measured fusion data and extracted barrier distribution have been analyzed within the framework of coupled-channels (CC) programs, CCFULL and empirical channel coupling. Coupling to rotational excitations in projectile and target along with up to $2n$ transfer channel with positive $Q$ value is found to be promising to explain the fusion excitation functions except for the lowest energy point. However, the influence of more than two neutrons transfer is insignificant in ${}^{28}\mathrm{Si}+{}^{158}\mathrm{Gd}$ system. At the lowest energy ($\approx 14\%$ down the Coulomb barrier), a deviation from standard CC has been found, which may indicate the threshold for fusion hindrance, but additional lower-energy data are needed to prove this. The experimental threshold energy ($E_S$) for fusion hindrance is in good agreement with the empirical formula, and it is consistent with the observed pattern of $E_S$ as a function of the entrance channel parameter ($\zeta$) for other nearly symmetric and asymmetric systems.

Background: The ${}^{14}\mathrm{N}(n,p){}^{14}\mathrm{C}$ reaction is of interest in neutron capture therapy, where nitrogen-related dose is the main component due to low-energy neutrons, and in astrophysics, where ${}^{14}\mathrm{N}$ acts as a neutron poison in the $s$ process. Several discrepancies remain between the existing data obtained in partial energy ranges: thermal energy, keV region, and resonance region.

Purpose: We aim to measure the ${}^{14}\mathrm{N}(n,p){}^{14}\mathrm{C}$ cross section from thermal to the resonance region in a single measurement for the first time, including characterization of the first resonances, and provide calculations of Maxwellian averaged cross sections (MACS).

Method: We apply the time-of-flight technique at Experimental Area 2 (EAR-2) of the neutron time-of-flight (n_TOF) facility at CERN. ${}^{10}\mathrm{B}(\mathrm{n},\alpha ){}^7\mathrm{Li}$ and ${}^{235}\mathrm{U}(n,f)$ reactions are used as references. Two detection systems are run simultaneously, one on beam and another off beam. Resonances are described with the $R$-matrix code sammy.

Results: The cross section was measured from subthermal energy to 800 keV, resolving the first two resonances (at 492.7 and 644 keV). A thermal cross section was obtained ($1.809\pm 0.045$ b) that is lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 and JEFF-3.3 evaluations. A 1/$v$ energy dependence of the cross section was confirmed up to tens of keV neutron energy. The low energy tail of the first resonance at 492.7 keV is lower than suggested by evaluated values, while the overall resonance strength agrees with evaluations.

Conclusions: Our measurement has allowed determination of the ${}^{14}\mathrm{N}(n,p)$ cross section over a wide energy range for the first time. We have obtained cross sections with high accuracy (2.5%) from subthermal energy to 800 keV and used these data to calculate the MACS for $kT=5$ to $kT=100$ keV.

Background: The ground-state wave function of deuteron is required to obtain its structure and form factors. Currently, an accurate analytical expression for the wave function is not available.

Purpose: In this paper, we determine the deuteron's static properties, low-energy scattering parameters, and form factors using an analytical ground-state wave function.

Methods: An inverse $S$-wave potential is constructed using the Morse function as the zeroth reference potential. The scattering phase shifts (SPSs) at different laboratory energies are determined using phase function method. The model parameters are optimized using least-squares minimization by both global optimization and combinatorial data analysis techniques.

Results: The mean absolute error between experimental and obtained SPSs for the state ${}^{3}S_1$, using global optimization, is found to be 0.35. The low-energy scattering parameters match well with the expected values. The analytical ground-state deuteron wave function (DWF) is obtained by utilizing the experimental value for the quadrupole moment. Other static properties and form factors determined from the obtained DWF are found to be in close agreement with experimental ones.

Conclusions: Modeling $np$ interaction using the Morse potential has been reasonably successful in explaining all static and low-energy parameters as well as SPSs for laboratory energies up to 350 MeV. The obtained electromagnetic form factors using an analytical deuteron ground-state wave function are found to closely match with experimental data.

A quasielastic scattering study of the ${}^7\mathrm{Be}+{}^{\mathrm{nat}}\mathrm{Zr}$ system was performed at five sub- and near- Coulomb barrier energies, namely, 20.6, 22.1, 23.7, 27.3, and 28.2 MeV ($E_{\mathrm{C}.\mathrm{b}.}^{\mathrm{lab}}=24.3$ MeV). Differential angular distributions were measured in the angular ranges $\approx {20}^{\circ }$ to ${63}^{\circ }$ and ${111}^{\circ }$ to ${154}^{\circ }$ and were considered in an optical model approach, to define the energy dependence of the potential as well as to determine the total reaction cross sections. The real part of the optical potential was found to be energy independent in most of the energy range, with a weak trend of a dispersion augmentation at the lowest energy point. Total reaction cross sections were found to be compatible with phenomenological predictions, validating the choice of our potential. Fusion cross sections were also calculated, taking into account the obtained potential, and were found to compare well with experimental results of ${}^7\mathrm{Li}$ on the medium mass target of ${}^{124}\mathrm{Sn}$. The measured quasielastic scattering cross sections were reasonably well reproduced by continuum-discretized coupled-channel calculations. These calculations indicated a modest, but not negligible, coupling to the continuum effect.

The $\gamma$-ray strength function and the nuclear level density of ${}^{167}\mathrm{Ho}$ have been extracted using the Oslo method from a ${}^{164}\mathrm{Dy}(\alpha ,p\gamma ){}^{167}\mathrm{Ho}$ experiment carried out at the Oslo Cyclotron Laboratory. The level density displays a shape that is compatible with the constant temperature model in the quasicontinuum, while the strength function shows structures indicating the presence of both a scissors resonance and a pygmy dipole resonance. Using our present results as well as data from a previous ${}^{163}\mathrm{Dy}(\alpha ,p\gamma ){}^{166}\mathrm{Ho}$ experiment, the ${}^{165}\mathrm{Ho}(n,\gamma )$ and ${}^{166}\mathrm{Ho}(n,\gamma )$ eellian-averaged cross section (MACS) uncertainties have been constrained. The possible influence of the low-lying, long-lived 6 keV isomer ${}^{166}\mathrm{Ho}$ in the $s$ process is investigated in the context of a $2M_{\odot }, [\text{Fe}/\text{H}]=-0.5$ asymptotic giant branch star. We show that the newly obtained ${}^{165}\mathrm{Ho}(n,\gamma )$ MACS affects the final ${}^{165}\mathrm{Ho}$ abundance, while the ${}^{166}\mathrm{Ho}(n,\gamma )$ MACS only impacts the enrichment of ${}^{166,167}\mathrm{Er}$ to a limited degree due to the relatively rapid $\beta$ decay of the thermalized ${}^{166}\mathrm{Ho}$ at typical $s$-process temperatures.

Neutron multiplicities, folding angle distribution, mass distribution, and mass-energy distribution are measured for the compound nucleus ${}^{210}\mathrm{Po}$ populated through the ${}^{12}\mathrm{C}+{}^{198}\mathrm{Pt}$ reaction at an excitation energy of 61.6 MeV. The measured neutron multiplicities are compared with the statistical model code joanne2 to extract total fission time for the ${}^{210}\mathrm{Po}$ compound nucleus. The total fission time $\left({\tau }_{\mathrm{tot}}\right)$ obtained for this system is $(10\pm 5)\times {10}^{-21}$ s at 49 MeV and increases to $(23\pm 5)\times {10}^{-21}$ at 61.8 MeV excitation energy indicating that dissipation increases with excitation energy. A comparison with ${\tau }_{\mathrm{tot}}$ of the ${}^{18}\mathrm{O}+{}^{192}\mathrm{Os}$ reaction populating the same compound nucleus indicates the influence of entrance channel mass asymmetry on the fission time. Dynamical model calculations have been performed to understand the fusion dynamics for these reactions and it is observed that the formation time of the compound nucleus increases as we go from the asymmetric to the symmetric entrance channels. Also, these calculations predict that 93% of the total angular momentum lead to the formation of a fully equilibrated compound nucleus for the ${}^{12}\mathrm{C}+{}^{198}\mathrm{Pt}$ reaction whereas this percentage decreases to 84%, for the ${}^{18}\mathrm{O}+{}^{192}\mathrm{Os}$ reaction indicating a higher percentage of noncompound nuclear processes in the latter case.

We simultaneously measured the ${}^4\mathrm{He}(\gamma , n){}^3\mathrm{He}$ and ${}^4\mathrm{He}(\gamma , p){}^3\mathrm{H}$ reactions in the energy range around the giant dipole resonance. A quasi-monoenergetic photon beam produced via the laser Compton scattering technique was irradiated on the active-target time-projection chamber filled with helium gas, and trajectories of charged decay particles emitted from ${}^4\mathrm{He}$ were measured. Our data suggest that the ${}^4\mathrm{He}(\gamma , n){}^3\mathrm{He}$ and ${}^4\mathrm{He}(\gamma , p){}^3\mathrm{H}$ cross sections peak around 26 MeV. This result contradicts the previous experimental data reported by Shima et al. [Phys. Rev. C 72, 044004 (2005)] but is consistent with other experimental results.

In-beam $\gamma$-ray spectroscopy of ${}^{131}\mathrm{Xe}$ was carried out to study the structure of the intruder $\nu h_{11/2}$ band. Excited states were populated via an $\alpha$-induced fusion-evaporation reaction at $E_{\alpha }=38\mathrm{MeV}$. Inspection of $\gamma \gamma$-coincidence data resulted in the identification of a new rotational sequence. Based on the systematics of excitation energy, assigned spin-parity, decay pattern, and the electromagnetic character of the interband $\mathrm{\Delta }I=1 \gamma$ transitions, this sequence is proposed as the unfavored signature partner of the $\nu h_{11/2}$ band. The structure of this band is further illuminated in the light of the triaxial particle rotor model (TPRM). The possibility of wobbling excitation in $N=77$ Xe-Ba-Ce isotones was explored in a systematic manner.

The Nab experiment at Oak Ridge National Laboratory, USA, aims to measure the beta-antineutrino angular correlation following neutron $\beta$ decay to an anticipated precision of approximately 0.1%. The proton momentum is reconstructed through proton time-of-flight measurements, and potential systematic biases in the timing reconstruction due to detector effects must be controlled at the nanosecond level. We present a thorough and detailed semiconductor and quasiparticle transport simulation effort to provide precise pulse shapes, and report on relevant systematic effects and potential measurement schemes.

In nuclear reaction experiments, the measured decay energy spectra can give insights into the shell structure of decaying systems. However, extracting the underlying physics from the measurements is challenging due to detector resolution and acceptance effects. The Richardson-Lucy (RL) algorithm, a deblurring method that is commonly used in optics and has proven to be a successful technique for restoring images, was applied to our experimental nuclear physics data. The only inputs to the method are the observed energy spectrum and the detector's response matrix also known as the transfer matrix. We demonstrate that the technique can help access information about the shell structure of particle-unbound systems from the measured decay energy spectrum that is not immediately accessible via traditional approaches such as $\chi$-square fitting. For a similar purpose, we developed a machine learning model that uses a deep neural network (DNN) classifier to identify resonance states from the measured decay energy spectrum. We tested the performance of both methods on simulated data and experimental measurements. Then, we applied both algorithms to the decay energy spectrum of ${}^{26}\mathrm{O}\to {}^{24}\mathrm{O}+n+n$ measured via invariant mass spectroscopy. The resonance states restored using the RL algorithm to deblur the measured decay energy spectrum agree with those found by the DNN classifier. Both deblurring and DNN approaches suggest that the raw decay energy spectrum of ${}^{26}\mathrm{O}$ exhibits three peaks at approximately 0.15 MeV, 1.50 MeV, and 5.00 MeV, with half-widths of 0.29 MeV, 0.80 MeV, and 1.85 MeV, respectively.

The $\gamma$-gated proton spectra measured in the reactions ${}^{64}\mathrm{Ni}({}^9\mathrm{Be},\mathrm{p}2\mathrm{n}){}^{70}\mathrm{Ga}$ and ${}^{64}\mathrm{Ni}({}^9\mathrm{Be},\mathrm{pn}){}^{71}\mathrm{Ga}$, have been utilized to probe the collective enhancement in nuclear level density (NLD) of two oblate deformed nuclei ${}^{71}\mathrm{Ga}$ and ${}^{72}\mathrm{Ga}$. It is seen that the $\gamma$-gated proton spectrum are reasonably explained by using the large value of the inverse level density parameter ($k=11.2$ MeV) in the NLD prescription of the Fermi gas model. The large value of $k$ indicates rotational enhancement, which is consistent with the earlier results in other mass regions. Furthermore, a rotational enhancement factor has been included in the NLD and used in the statistical model calculation keeping the systematic value of $=8.6$ MeV. It explains the $\gamma$-gated proton spectrum nicely, which indicates the presence of collective enhancement in the NLD. The extracted enhancement factors are found to be $8.0+/-2.0$ and $5.5+/-1.0$ and vanish at around 15, 18 MeV excitation energies for ${}^{71}\mathrm{Ga}, {}^{72}\mathrm{Ga}$, respectively. Present observations are consistent with the previous results obtained by Pandit et al. [Phys. Rev. C 97, 041301(R) (2018)] and Mohanto et al. [Phys. Rev. C 100, 011602(R) (2019)].

Recent measurement of the fusion excitation function for ${}^{17}\mathrm{O}+{}^{12}\mathrm{C}$ reported the significant suppression of the fusion cross section at $E_{\mathrm{c}.\mathrm{m}.}\approx 14$ MeV. This suppression was hypothesized to signal the existence of a ${}^{16}\mathrm{O}+n+{}^{12}\mathrm{C}$ molecular configuration. Using the active-target detector MuSIC@Indiana provided an effective means of reexamining the fusion excitation function for ${}^{17}\mathrm{O}+{}^{12}\mathrm{C}$. The accuracy of this thick-target measurement is strengthened through comparison with the thin-target measurement of the excitation function for ${}^{17}\mathrm{F}+{}^{12}\mathrm{C}$. The result provides important information about the dependence of the average fusion cross section for the oxygen isotopic chain on neutron excess.

Relativistic collision of isobaric systems is found to be valuable in differentiating the nucleon distributions for nuclei with the same mass number. In recent contrasting experiments of ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ versus ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ collisions at $\sqrt{s_{NN}}=200\text{GeV}$, the ratios of multiplicity distribution, elliptic flow, triangular flow, and radial flow are precisely measured and found to be significantly different from unity, indicating the difference in the shapes of the isobar pair. In this work, we investigate the feasibility of nuclear structure reconstruction from heavy-ion collision observables. We perform a Bayesian inference with employing the Monte Carlo Glauber model as an estimator of the mapping from nuclear structure to the final state observables and to provide the mock data for reconstruction. By varying combination of observables included in the mock data, we find it plausible to infer Woods-Saxon parameters from the observables. We also observe that the single-system multiplicity distribution for the isobar system, rather than its ratio, is crucial to simultaneously determine the nuclear structure for the isobar system.

Due to their weak final state interactions, the $\varphi$ meson and $\mathrm{\Omega }$ baryon provide unique probes of the properties of the quark-gluon plasma (QGP) formed in relativistic heavy-ion collisions. Using the quark recombination model with the quark phase-space information parametrized in a viscous blast wave, we study the transverse-momentum spectra and elliptic flows of $\varphi$ and $\mathrm{\Omega }$ in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200$ GeV and $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV. The viscous blast wave includes nonequilibrium deformations of thermal distributions due to shear and bulk stresses and thus carries information on the specific shear viscosity $\eta /s$ and the specific bulk viscosity $\zeta /s$ of the QGP. We perform a model-to-data comparison with Bayesian inference and simultaneously obtain $\eta /s=(2.{08}_{-1.09}^{+1.10})/4\pi$ and $\zeta /s=0.{06}_{-0.04}^{+0.04}$ at $90\%$ C.L. for the baryon-free QGP at crossover temperature of about 160 MeV. Our work provides a unique approach to simultaneously determine the $\eta /s$ and $\zeta /s$ of the QGP at hadronization.

Fusion reactions induced by the weakly bound nucleus ${}^6\mathrm{Li}$ with targets ${}^{28}\mathrm{Si}, {}^{64}\mathrm{Ni}, {}^{144}\mathrm{Sm}$, and ${}^{209}\mathrm{Bi}$ at energies around the Coulomb barrier are investigated within a three-body model where ${}^6\mathrm{Li}$ is described with an $\alpha +d$ cluster model. The total fusion (TF) cross sections are calculated with the continuum-discretized coupled-channels (CDCC) method and the complete fusion (CF) cross sections are extracted through the sum-rule model. The calculations demonstrate that (i) for the TF cross-section calculations, the continuum states up to 40 MeV are found to be necessary, which corresponds to the inclusion of closed channels for light and medium mass targets, such as ${}^{28}\mathrm{Si}, {}^{59}\mathrm{Co}$, and ${}^{144}\mathrm{Sm}$; (ii) the converged CDCC results for TF cross section at energies above the Coulomb barrier are almost the same as single-channel results in which the continuum coupling effect is neglected; and (iii) the continuum coupling strongly influences partial-wave fusion cross sections and the closed channels play a significant role in the improvement of the description of the CF cross sections at energies below the Coulomb barrier for the ${}^6\mathrm{Li}+{}^{28}\mathrm{Si}, {}^{59}\mathrm{Co}$, and ${}^{144}\mathrm{Sm}$ systems.

We postulate that nonperturbative quantum chromodynamics (QCD) effects occurring during parton fragmentation can result in collective effects of a multiparton system, reminiscent of those observed in high-energy hadronic or nuclear interactions with large final-state particle multiplicity. Proton-proton collisions at the CERN Large Hadron Collider showed surprising signatures of a strongly interacting, thermalized quark-gluon plasma, which was thought only to form in collisions of large nuclear systems. Another puzzle observed earlier in $e^{+}{e}^{-}$ collisions is that production yields of various hadron species appear to follow a thermal-like distribution with a common temperature. We propose searches for thermal and collective properties resulting from parton fragmentation processes using high multiplicity jets in high-energy elementary collisions. Several novel observables are studied using the pythia 8 Monte Carlo event generator. Experimental observation of such collectivity will offer a new view of nonperturbative QCD dynamics of multiparton systems at the smallest scales. Absence of any collective effects may offer new insights into the role of quantum entanglement in the observed thermal behavior of particle production in high energy collisions.