Recent measurements of $\alpha$-particle induced reactions on the ${}^{64}\mathrm{Zn}$ nucleus, below and around the Coulomb barrier, are analyzed simultaneously with $\alpha$-particle emission at similar energies in proton-induced reactions on Zn isotopes. All open reaction channels, particularly the $\gamma$ decay, are calculated using consistent input parameters. Additionally, we check a previous optical-model potential for $\alpha$ particles on nuclei within the mass number range $45\le A\le 209$ [Avrigeanu et al., Phys. Rev. C 90, 044612 (2014)] and prove its correctness in the outgoing channel at least for the present case involving ${}^{64}\mathrm{Zn}$ and nearby nuclei. The reliability of this potential for incident as well as emitted low-energy $\alpha$ particles is supported by the successful reproduction of high-precision measured data, using no empirical rescaling factor of the $\gamma$ and/or particle widths.

I propose event-plane correlations as a test of collectivity in small colliding systems: In $d$-Au and ${}^3\mathrm{He}$-Au collisions, I predict a strong anticorrelation between elliptic and triangular flow, generated by the geometry of the light projectile. A significant anticorrelation is also predicted in central $p$-Pb collisions at the CERN Large Hadron Collider, which is solely generated by fluctuations. Similar, but stronger correlation patterns are predicted in correlations involving dipolar flow.

The $\beta$ decay of ${}^{31}\mathrm{Ar}$, produced by fragmentation of an ${}^{36}\mathrm{Ar}$ beam at 880 MeV/nucleon, was investigated. Identified ions of ${}^{31}\mathrm{Ar}$ were stopped in a gaseous time projection chamber with optical readout allowing us to record decay events with emission of protons. In addition to $\beta$-delayed emission of one and two protons we clearly observed the $\beta$-delayed three-proton branch. The branching ratio for this channel in ${}^{31}\mathrm{Ar}$ is found to be $0.07\pm 0.02$%.

A complete calculation of phase space factors (PSFs) for Majoron-emitting $0\nu {\beta }^{-}{\beta }^{-}$ decay modes is presented. The calculation makes use of exact Dirac wave functions with finite nuclear size and electron screening and includes lifetimes, single-electron spectra, summed electron spectra, and angular electron correlations. Combining these results with recent microscopic interacting boson model nuclear matrix elements (NMEs) we make half-life predictions for the ordinary Majoron decay (spectral index $n=1$). Furthermore, comparing theoretical predictions with the obtained experimental lower bounds for this decay mode we are able to set limits on the effective Majoron-neutrino coupling constant $\langle g_{ee}^M\rangle$.

We calculate the energy per particle of symmetric nuclear matter and pure neutron matter using the microscopic many-body Brueckner-Hartree-Fock (BHF) approach and employing the Argonne V18 (AV18) nucleon-nucleon (NN) potential supplemented with two different three-nucleon force models recently constructed to reproduce the binding energy of ${}^3\mathrm{H},{}^3\mathrm{He}$, and ${}^4\mathrm{He}$ nuclei as well as the neutron-deuteron doublet scattering length. We find that none of these new three-nucleon force models is able to reproduce simultaneously the empirical saturation point of symmetric nuclear matter and the properties of three- and four-nucleon systems.

Background: The conventional optical model is quite successful in describing the nucleon elastic scattering data from medium and heavy nuclei. However, its success in describing the light $1p$-shell nuclei is somewhat limited. The velocity-dependent optical potential resulted in a significant improvement in describing the elastic angular distributions for light nuclei in the low energy region.

Purpose: To extend the formalism of the velocity-dependent potential to higher energies, and to assess its importance in describing neutron elastic scattering data from light $1p$-shell nuclei at high energies.

Method: We fit the angular distribution data for neutron elastic scattering from ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ using (i) the velocity-dependent optical potential and (ii) the conventional optical potential. The results of the two models are then compared. At low energies, we compare our angular distribution fits with the fits of other works that exist in the literature. Furthermore, the total integrated cross sections in addition to the analyzing power are calculated using the velocity-dependent optical potential and compared to the experimental data.

Results: The velocity-dependent potential resulted in significant improvements in describing the angular distributions particularly in the large-angle scattering region and for certain energy ranges. This model is important where the experimental data show structural effects from nuclear surface deformations, which are important in light nuclei. Furthermore, the calculated total elastic cross sections and analyzing power are in good agreement with the experimental data.

Conclusions: The velocity-dependent potential gives rise to surface-peaked real terms in the optical model. Such terms account, at least partly, for the structural effects seen in the angular distribution data. The energy range over which the surface terms are needed is found to depend on the target nucleus. Other works that have introduced real surface terms in the optical potential are discussed.

Using the ultrarelativistic quantum molecular dynamics (UrQMD) model, we investigate azimuthal correlations in $p-\mathrm{Pb}$ collisions at $\sqrt{s_{\mathit{NN}}}=5.02\mathrm{TeV}$. Comparison with the experimental data shows that UrQMD cannot reproduce the multiplicity dependence of two- and four-particle cumulants, especially the transition from positive to negative values of $c_2\left\{4\right\}$ in high-multiplicity events, which has been taken as experimental evidence of collectivity in $p-\mathrm{Pb}$ collisions. Meanwhile, UrQMD cannot describe the differential elliptic flow $v_2\left(p_{\mathrm{T}}\right)$ of all charged hadrons at various multiplicity classes. These discrepancies show that the simulated hadronic $p-\mathrm{Pb}$ systems cannot generate enough collective flow as observed in experiment, the associated hadron emissions are largely influenced by nonflow effects. However, the characteristic $v_2\left(p_{\mathrm{T}}\right)$ mass ordering of pions, kaons, and protons is observed in UrQMD, which is the consequence of hadronic interactions and not necessarily associated with strong fluid-like expansions.

I used a simple potential model to compute energies and widths of single-particle states in ${}^{14}\mathrm{O}$ and their corresponding $T=1$ states in ${}^{14}\mathrm{N}$, using information for the parent states in ${}^{14}\mathrm{C}$ as input. Agreement is reasonable, but some discrepancies exist.

In a recent work [Phys. Rev. C 84, 044321 (2011)] M. J. Ermamatov and P. R. Fraser have studied rotational and vibrational excited states of axially symmetric nuclei within the Bohr Hamiltonian with different mass parameters. However, the energy formula that the authors have used contains some inaccuracies. So the numerical results they obtained seem to be controversial. In this paper, we revisit all calculations related to this problem and determine the appropriate formula for the energy spectrum. Moreover, in order to improve such calculations, we reconsider this problem within the framework of the deformation-dependent mass formalism. Also, unlike the work of Bonatsos et al. [Phys. Rev. C 83, 044321 (2011)], in which the mass parameter has not been considered, we will show the importance of this parameter and its effect on numerical predictions.

The evaporation residue yields from the compound nuclei ${}^{220}\mathrm{Th}$ formed in the ${}^{16}\mathrm{O}+{}^{204}\mathrm{Pb}, {}^{40}\mathrm{Ar}+{}^{180}\mathrm{Hf}, {}^{82}\mathrm{Se}+{}^{138}\mathrm{Ba}$, and ${}^{124}\mathrm{Sn}+{}^{96}\mathrm{Zr}$ reactions are analyzed to study the entrance channel effects by comparison of the capture, fusion, and evaporation residue cross sections calculated by the combined dinuclear system (DNS) and advanced statistical models. The difference between evaporation residue (ER) cross sections can be related to the stages of compound nucleus formation and/or its survival against fission. The sensitivity of both stages in the evolution of the DNS up to the evaporation residue formation to the angular momentum of DNS is studied. The difference between fusion excitation functions is explained by the hindrance to complete fusion due to the larger intrinsic fusion barrier $B_{\mathrm{fus}}^{*}$ for the transformation of the DNS into a compound nucleus and the increase of the quasifission contribution due to the decreasing of the quasifission barrier $B_{\mathrm{qf}}$ as a function of the angular momentum. The largest value of the ER residue yields in the very mass asymmetric ${}^{16}\mathrm{O}+{}^{204}\mathrm{Pb}$ reaction is related to the large fusion probability and to the relatively low threshold of the excitation energy of the compound nucleus. Due to the large threshold of the excitation energy (35 MeV) of the ${}^{40}\mathrm{Ar}+{}^{180}\mathrm{Hf}$ reaction, it produces ER yields less than the almost mass symmetric ${}^{82}\mathrm{Se}+{}^{138}\mathrm{Ba}$ reaction having the lowest threshold value (12 MeV).

First-order and higher-order interferences effects on the total, Coulomb, and nuclear breakup cross sections in the ${}^{15}\mathrm{C}+{}^{208}\mathrm{Pb}$ and ${}^{11}\mathrm{Be}+{}^{208}\mathrm{Pb}$ reactions are studied at 68 $\mathrm{MeV}/\mathrm{u}$ incident energy. A partial-wave analysis is first performed, and shows that the differential total breakup cross sections are dominated by the $p$ waves. However, considered alone, they largely underestimate the data, hence the importance of the other partial-wave contributions. It is also shown that the first-order interference reduces by more than $60\%$ the total breakup cross sections, by less than $3\%$ the Coulomb breakup cross sections, and by more than $85\%$ the nuclear breakup cross sections, for both reactions. On the other hand, the higher-order interferences are found to reduce by less than $9\%$ the total breakup cross section, less than $1\%$ the Coulomb breakup cross section, and less than $7\%$ the nuclear breakup cross section for the ${}^{15}\mathrm{C}+{}^{208}\mathrm{Pb}$ reaction. For the ${}^{11}\mathrm{Be}+{}^{208}\mathrm{Pb}$ reaction however, the higher-order interference reduces by less than $7\%$ the total breakup cross section, by less than $1\%$ the Coulomb breakup cross section, and by less than $4\%$ the nuclear breakup cross section. It is finally shown that even at first order, the incoherent sum of the nuclear breakup cross sections is more important than the incoherent sum of the Coulomb breakup cross sections for the two reactions.

We propose a practical folding model to describe ${}^3\mathrm{He}$ elastic scattering. In the model, ${}^3\mathrm{He}$ optical potentials are constructed by making the folding procedure twice. First the nucleon-target potential is evaluated by folding the Melbourne $g$ matrix with the target density and localizing the nonlocal folding potential with the Brieva-Rook method, and second the resulting local nucleon-target potential is folded with the ${}^3\mathrm{He}$ density. This double single-folding model well describes ${}^3\mathrm{He}$ elastic scattering from ${}^{58}\mathrm{Ni}$ and ${}^{208}\mathrm{Pb}$ targets in a wide incident-energy range from 30 to 150 MeV/nucleon with no adjustable parameter. Spin-orbit force effects on differential cross sections are found to be appreciable only at higher incident energies such as 150 MeV/nucleon. Three-nucleon breakup effects of ${}^3\mathrm{He}$ are investigated with the continuum discretized coupled-channels method and are found to be appreciable only at lower incident energies around 40 MeV/nucleon. Effects of knock-on exchange processes are also analyzed.

Background: A quantitative understanding of neutrino interactions with nuclei is needed for precision era neutrino long baseline experiments (MINOS, NOvA, DUNE) which all use nuclear targets. Pion production is the dominant reaction channel at the energies of these experiments.

Purpose: Investigate the influence of nuclear effects on neutrino-induced pion production cross sections and compare predictions for pion-production with available data.

Method: The Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) model is used for the description of all incoherent channels in neutrino-nucleus reactions.

Results: Differential cross sections for charged and neutral pion production for the $\mathrm{MINER}\nu \mathrm{A}$ neutrino and antineutrino flux are calculated. An estimate for the coherent cross section is obtained from a comparison of data with theoretical results for incoherent cross sections. The invariant mass ($W$) distribution of the $\mathrm{\Delta }$ resonances produced is analyzed.

Conclusions: Final state interactions affect the pion kinetic energy spectra significantly. The data for charged pion production at $\mathrm{MINER}\nu \mathrm{A}$ are compatible with the results of calculations using elementary data taken from an old Argonne National Laboratory experiment. Remaining differences for charged pion production can be attributed to coherent production; the data for antineutrino induced neutral pion production, where no coherent contribution is present, are reproduced quite well. The analysis of $W$ distributions shows that sharp cuts on experimentally reconstructed invariant masses lead to shape distortions of the true $W$ distributions for nuclear targets.

Background: Heavy-ion fusion reactions involving heavy nuclei at energies around the Coulomb barrier exhibit fusion hindrance, where the probability of compound nucleus formation is strongly hindered compared with that in light- and medium-mass systems. The origin of this fusion hindrance has not been well understood from a microscopic point of view.

Purpose: I analyze the fusion dynamics in heavy systems by a microscopic reaction model in order to understand the origin of the fusion hindrance.

Method: I employ the time-dependent Hartree-Fock (TDHF) theory as a microscopic reaction model. I extract the nucleus-nucleus potential and energy dissipation by the method combining TDHF dynamics of the entrance channel of fusion reactions with a one-dimensional Newton equation including a dissipation term. Then, I analyze the origin of the fusion hindrance using the properties of the extracted potential and energy dissipation.

Results: I obtain finite extra-push energies for heavy systems from TDHF simulations, which agree with experimental observations. Extracted nucleus-nucleus potentials show monotonic increase as the relative distance of two nuclei decreases, which induces the disappearance of an ordinary barrier structure of the nucleus-nucleus potential. This property is different from those in light- and medium-mass systems and from density-constraint TDHF calculations. Extracted friction coefficients show sizable energy dependence and universal value of their magnitude, which are rather similar to those in light- and medium-mass systems. Using these properties, I analyze the origin of the fusion hindrance and find that contribution of the increase in potential to the extra-push energy is larger than that of the accumulated dissipation energy in most systems studied in this article.

Conclusions: I find that the nucleus-nucleus potentials extracted in heavy systems show a specific property, which is not observed in light- and medium-mass systems. By the analysis of the origin of the fusion hindrance, I conclude that, as the system becomes heavier, the dynamical increase in nucleus-nucleus potential at small relative distances plays a more important role than the dissipation during the fusion reaction for understanding the origin of the fusion hindrance.

We describe low-lying collective excitations of atomic nuclei with the multireference covariant density functional theory and combine them with coupled-channels calculations for heavy-ion fusion reactions at energies around the Coulomb barrier. To this end, we use the calculated transition strengths among several collective states as inputs to the coupled-channels calculations. This approach provides a natural way to describe anharmonic multiphonon excitations, as well as a deviation of rotational excitations from a simple rigid rotor. We apply this method to subbarrier fusion reactions of ${}^{58}\mathrm{Ni}+{}^{58}\mathrm{Ni},{}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$, and ${}^{40}\mathrm{Ca}+{}^{58}\mathrm{Ni}$ systems. We find that the effect of anharmonicity tends to smear the fusion barrier distributions, better reproducing the experimental data compared to the calculations in the harmonic oscillator limit.

The hybrid model hydjet++, which considers soft and hard processes, is employed for the analysis of dihadron angular correlations measured in Pb+Pb collisions at center-of-mass energy $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. The model allows the study of both individual and mutual influence of lower flow harmonics, $v_2$ and $v_3$, on higher harmonics and dihadron angular correlations. It is shown that the typical structure called a ridge in dihadron angular correlations in a broad pseudorapidity range could appear just as the interplay of $v_2$ and $v_3$. Central, semi-central, and semi-peripheral collisions were investigated. Comparison of model results with the experimental data on dihadron angular correlations is presented for different centralities and transverse momenta $p_T$.

Pairing correlations in nuclei play a decisive role in determining nuclear drip lines, binding energies, and many collective properties. In this work a new configuration-space Monte Carlo (CSMC) method for treating nuclear pairing correlations is developed, implemented, and demonstrated. In CSMC the Hamiltonian matrix is stochastically generated in Krylov subspace, resulting in the Monte Carlo version of Lanczos-like diagonalization. The advantages of this approach over other techniques are discussed; the absence of the fermionic sign problem, probabilistic interpretation of quantum-mechanical amplitudes, and ability to handle truly large-scale problems with defined precision and error control are noteworthy merits of CSMC. The features of our CSMC approach are shown using models and realistic examples. Special attention is given to difficult limits: situations with nonconstant pairing strengths, cases with nearly degenerate excited states, limits when pairing correlations in finite systems are weak, and problems when the relevant configuration space is large.

We present a detailed formalism of the microscopic particle-rotor model for hypernuclear low-lying states based on a covariant density functional theory. In this method, the hypernuclear states are constructed by coupling a hyperon to low-lying states of the core nucleus, which are described by the generator coordinate method (GCM) with the particle number and angular momentum projections. We apply this method to study in detail the low-lying spectrum of ${}_{\mathrm{\Lambda }}{}^{13}\mathrm{C}$ and ${}_{\mathrm{\Lambda }}{}^{21}\mathrm{Ne}$ hypernuclei. We also briefly discuss the structure of ${}_{\mathrm{\Lambda }}{}^{155}\mathrm{Sm}$ as an example of heavy deformed hypernuclei. It is shown that the low-lying excitation spectra with positive-parity states of the hypernuclei, which are dominated by $\mathrm{\Lambda }$ hyperon in the $s$ orbital coupled to the core states, are similar to that for the corresponding core states, while the electric quadrupole transition strength, $B\left(E2\right)$, from the $2_1^{+}$ state to the ground state is reduced according to the mass number of the hypernuclei. Our study indicates that the energy splitting between the first $1/2^{-}$ and $3/2^{-}$ hypernuclear states is generally small for all the hypernuclei which we study. However, their configurations depend much on the properties of a core nucleus, in particular on the sign of deformation parameter. That is, the first $1/2^{-}$ and $3/2^{-}$ states in ${}_{\mathrm{\Lambda }}^{13}\mathrm{C}$ are dominated by a single configuration with $\mathrm{\Lambda }$ particle in the $p$-wave orbits and thus provide good candidates for a study of the $\mathrm{\Lambda }$ spin-orbit splitting. On the other hand, those states in the other hypernuclei exhibit a large configuration mixing and thus their energy difference cannot be interpreted as the spin-orbit splitting for the $p$ orbits.

Background: Mass-asymmetric fission has been observed in low energy fission of ${}^{180}\mathrm{Hg}$. Calculations predicted the persistence of asymmetric fission in this region even at excitation energies of 30–40 MeV.

Purpose: To investigate fission mass distributions by populating different isotopes of Hg using heavy ion fusion reactions.

Methods: Fission fragment mass-angle distributions have been measured for two reactions, ${}^{40}\mathrm{Ca}+{}^{142}\mathrm{Nd}$ and ${}^{13}\mathrm{C}+{}^{182}\mathrm{W}$, populating ${}^{182}\mathrm{Hg}$ and ${}^{195}\mathrm{Hg}$, respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Measurements were made at beam energies around the capture barrier for the two reactions and mass ratio distributions were obtained using the kinematic reconstruction method.

Results: Asymmetric fission has been observed following the population of ${}^{182}\mathrm{Hg}$ at an excitation energy of 22.8 MeV above the saddle point. A symmetric peaked mass ratio distribution was observed for ${}^{195}\mathrm{Hg}$ nuclei at a similar excitation energy above the saddle point.

Conclusions: Mass-asymmetric fission has been observed in neutron deficient Hg nuclei populated via heavy ion fusion for the first time. The results are consistent with observations from beta-delayed fission measurements and provide a proof-of-principle for expanding experimental studies of the influence of shell effects on the fission processes.

We report measurements of the primary charged-particle pseudorapidity density and transverse momentum distributions in $p-\mathrm{Pb}$ collisions at $\sqrt{s_{\mathit{NN}}}=5.02\mathrm{TeV}$ and investigate their correlation with experimental observables sensitive to the centrality of the collision. Centrality classes are defined by using different event-activity estimators, i.e., charged-particle multiplicities measured in three different pseudorapidity regions as well as the energy measured at beam rapidity (zero degree). The procedures to determine the centrality, quantified by the number of participants $\left(N_{\mathrm{part}}\right)$ or the number of nucleon-nucleon binary collisions $\left(N_{\mathrm{coll}}\right)$ are described. We show that, in contrast to Pb-Pb collisions, in $p-\mathrm{Pb}$ collisions large multiplicity fluctuations together with the small range of participants available generate a dynamical bias in centrality classes based on particle multiplicity. We propose to use the zero-degree energy, which we expect not to introduce a dynamical bias, as an alternative event-centrality estimator. Based on zero-degree energy-centrality classes, the $N_{\mathrm{part}}$ dependence of particle production is studied. Under the assumption that the multiplicity measured in the Pb-going rapidity region scales with the number of Pb participants, an approximate independence of the multiplicity per participating nucleon measured at mid-rapidity of the number of participating nucleons is observed. Furthermore, at high-$p_{\mathrm{T}}$ the $p-\mathrm{Pb}$ spectra are found to be consistent with the $pp$ spectra scaled by $N_{\mathrm{coll}}$ for all centrality classes. Our results represent valuable input for the study of the event-activity dependence of hard probes in $p-\mathrm{Pb}$ collisions and, hence, help to establish baselines for the interpretation of the Pb-Pb data.