Polarization effects in the reaction $e^{+}+e^{-}\to \overline{d}+d$ have been investigated for the case of longitudinally polarized electron beam and arbitrary polarization of the produced deuteron, with the aim of a determination of the time-like complex deuteron electromagnetic form factors. General expressions of polarization observables are derived and numerical estimations have been carried out by means of various models of deuteron electromagnetic form factors, for kinematical conditions near threshold.

For the first time, we obtained the $g$ factor for the ground state of ${}^{23}\mathrm{Al}$ by use of a β-NMR measurement. ${}^{23}\mathrm{Al}$ has a small proton separation energy and is a potential proton-halo candidate. The obtained $g$ factor, $\left|g\right|=1.557\pm 0.088$, clearly shows the spin and parity, $J^{\pi }=5/2^{+}$, for ${}^{23}\mathrm{Al}$, which is the same as that of its mirror partner, ${}^{23}\mathrm{Ne}$. The possible nuclear structure of ${}^{23}\mathrm{Al}$ is also discussed.

We present predictions of a relatively simple model of the low-lying $0^{+}$ states in ${}^{12}\mathrm{Be}$, their predicted energy splitting in ${}^{12}\mathrm{O}$, their cross-section ratios in ${}^{10}\mathrm{Be}$($t,p$) and ${}^{14}\mathrm{C}$($p,t$) and their decay widths. Comparison is made with predictions using earlier wave functions of Barker.

Incoherent pion photoproduction on the deuteron is studied in the first resonance region. The unpolarized cross section, the beam asymmetry, and the vector and tensor target asymmetries are calculated in the framework of a diagrammatic approach. Pole diagrams and one-loop diagrams with $\mathit{NN}$ scattering in the final state are taken into account. An elementary operator for pion photoproduction on the nucleon is taken in various on-shell forms and calculated using the SAID and MAID multipole analyses. Model dependence of the obtained results is discussed in some detail. A comparison with predictions of other works is given. Although a reasonable description of many available experimental data on the unpolarized total and differential cross sections and photon asymmetry has been achieved, in some cases a significant disagreement between the theory and experiment has been found. Invoking known information on the reactions $\gamma d\to {\pi }^{0}d$ and $\gamma d\to \mathit{np}$ we predict the total photoabsorption cross section for deuterium. We find that our values strongly overestimate experimental data in the vicinity of the Δ peak.

We investigate collective multipole excitations for closed-shell nuclei from ${}^{16}\mathrm{O}$ to ${}^{208}\mathrm{Pb}$ by using correlated realistic nucleon-nucleon interactions in the framework of the random phase approximation (RPA). The dominant short-range central and tensor correlations are treated explicitly within the unitary correlation operator method (UCOM), which provides a phase-shift-equivalent correlated interaction $V_{\mathrm{UCOM}}$ adapted to simple uncorrelated Hilbert spaces. The same unitary transformation that defines the correlated interaction is used to derive correlated transition operators. Using $V_{\mathrm{UCOM}}$, we solve the Hartree-Fock (HF) problem and employ the single-particle states as a starting point for the RPA. By construction, the UCOM-RPA is fully self-consistent, i.e., the same correlated nucleon-nucleon interaction is used in calculations of the HF ground state and in the residual RPA interaction. Consequently, the spurious state associated with the center-of-mass motion is properly removed, and the sum rules are exhausted within $\pm 3\%$. The UCOM-RPA scheme results in a collective character of giant monopole, dipole, and quadrupole resonances in closed-shell nuclei across the nuclear chart. For the isoscalar giant monopole resonance, the resonance energies are in agreement with experiment, hinting at a reasonable compressibility. However, in the $1^{-}$ and $2^{+}$ channels the resonance energies are overestimated because of missing long-range correlations and three-body contributions.

The nuclear liquid-gas phase transition of the system in ideal thermal equilibrium is studied with antisymmetrized molecular dynamics. The time evolution of a many-nucleon system confined in a container is solved for a long time to get a microcanonical ensemble of a given energy and volume. The temperature and the pressure are extracted from this ensemble and the caloric curves are constructed. The present work is the first time that a microscopic dynamical model which describes nuclear multifragmentation reactions well is directly applied to get the nuclear caloric curve. The obtained constant pressure caloric curves clearly show the characteristic feature of the liquid-gas phase transition, namely negative heat capacity (backbending), which is expected for the phase transition in finite systems.

The fragment mass analyzer at the ATLAS facility has been used to unambiguously identify the mass number associated with different decay modes of the nobelium isotopes produced via ${}^{204}\mathrm{Pb}$$($${}^{48}\mathrm{Ca}$$,\mathit{xn})$${}^{252-x}\mathrm{No}$ reactions. Isotopically pure ($>99.7$%) ${}^{204}\mathrm{Pb}$ targets were used to reduce background from more favored reactions on heavier lead isotopes. Two spontaneous fission half-lives ($t_{1/2}=3.7_{-0.8}^{+1.1}$ and ${43}_{-15}^{+22}$ μs) were deduced from a total of 158 fission events. Both decays originate from ${}^{250}\mathrm{No}$ rather than from neighboring isotopes as previously suggested. The longer activity most likely corresponds to a $K$ isomer in this nucleus. No conclusive evidence for an α branch was observed, resulting in upper limits of 2.1% for the shorter lifetime and 3.4% for the longer activity.

We extend the Brueckner-Hartree-Fock (BHF) approach to include the three-body force (TBF) rearrangement contribution in calculating the neutron and proton single particle (s.p.) properties in isospin asymmetric nuclear matter. We investigate the TBF rearrangement effect on the momentum-dependence of neutron and proton s.p. potentials, the isospin splitting and especially its density dependence of the neutron and proton effective masses, and the isospin symmetry potential in neutron-rich nuclear matter by adopting the realistic Argonne $V_{18}$ two-body nucleon-nucleon interaction supplemented with a microscopic TBF. We find that at low densities, the TBF rearrangement effect is fairly weak, whereas the TBF induces a significant rearrangement effect on the s.p. properties at high densities and large momenta. The TBF rearrangement contribution to s.p. potential is shown to be repulsive, and it reduces considerably the attraction of the BHF s.p. potential. The repulsion from the TBF rearrangement turns out to be strongly momentum dependent at high densities and high momenta. As a consequence, it enhances remarkably the momentum dependence of the proton and neutron s.p. potentials and reduces the neutron and proton effective masses. At low densities, the TBF rearrangement effect on symmetry potential is almost negligible, while at high densities, it enlarges sizably the symmetry potential. At high enough densities, it may even change the high-momentum behavior of symmetry potential. In both cases, with and without including the TBF rearrangement contribution, the predicted neutron effective mass is larger than the proton one in neutron-rich matter within the BHF framework; i.e., the predicted isospin splitting of the proton and neutron effective masses in neutron-rich matter is such that $m_n^{*}\ge m_p^{*}$, in agreement with the recent Dirac-BHF predictions. The TBF rearrangement contribution reduces remarkably the magnitude of the proton-neutron effective mass splitting at high densities. At high enough densities, inclusion of the TBF rearrangement contribution even suppresses almost completely the effective mass splitting.

We discuss the emission of high momentum lepton pairs ($p_T>4$ GeV) in central Au+Au collisions at RHIC ($\sqrt{s_{\mathit{NN}}}=200$ GeV) and Pb+Pb collisions at the LHC ($\sqrt{s_{\mathit{NN}}}=5500$ GeV). Yields of dileptons produced through interactions of jets with thermal partons have been calculated, with next-to-leading order corrections through hard thermal loop (HTL) resummation. They are compared to thermal dilepton emission and the Drell-Yan process. A complete leading order treatment of jet energy loss has been included. Jet-plasma interactions are found to dominate over thermal dilepton emission for all values of the invariant mass $M$. Drell-Yan is the dominant source of high momentum lepton pairs for $M>3$ GeV at RHIC, after the background from heavy quark decays is subtracted. At LHC, the range $M<7$ GeV is dominated by jet-plasma interactions. Effects from jet energy loss on jet-plasma interactions turn out to be weak, but non-negligible, reducing the yield of low-mass dileptons by about $30\%$.

We propose that the scalar $\kappa (800)$ meson may play an important role in $K^{*}$ photoproduction. In the reactions of $\gamma p\to K^{*+}\Lambda$ and $\gamma p\to K^{*0}{\Sigma }^{+}$, we consider the production mechanisms including $t$-channel $K^{*},K,\kappa$ exchanges, $s$-channel $N,\Delta$ diagrams, and $u$-channel $\Lambda ,\Sigma ,{\Sigma }^{*}$ diagrams within the tree level approximation, and find that the κ-meson exchange may contribute significantly to $K^{*}\Sigma$ photoproduction, while it is rather supplementary in $K^{*}\Lambda$ photoproduction. We demonstrate how the observables of $K^{*}$ photoproduction can be used to constrain the κ meson properties. In particular, the parity asymmetry can separate the κ meson contribution in $K^{*}$ photoproduction.

We use a semiclassical approximation to investigate the effects of color transparency on pion electroproduction reactions. The resulting reduced nuclear interactions produce significant, but not dominating, differences with the results of conventional distorted-wave, Glauber-type treatments at kinematics accessible to Jefferson Laboratory. Nuclear effects that could mimic the influence of color transparency are also discussed.

Macroscopic-microscopic methods are applied in the high-spin regime to calculate the nuclear binding energy (“mass”) as a function of proton number, neutron number, and angular momentum. Masses at high spin are calculated using the cranked Nilsson-Strutinsky model together with two different liquid drop models, the Lublin-Strasbourg drop model and the finite range liquid drop model. When comparisons are made with experimental data, a similar agreement between theory and experiment is obtained as for ground-state masses.

A model to describe fission on light actinides, which takes into account transmission through a triple-humped fission barrier with absorption, is proposed. The fission probability derived in the WKB approximation within an optical model for fission has been incorporated into the statistical model of nuclear reactions. The complex resonant structure in the first-chance neutron-induced fission cross sections of ${}^{232}\mathrm{Th}$ and ${}^{231}\mathrm{Pa}$ nuclei has been reproduced by the proposed model. Consistent sets of parameters describing the triple-humped fission barriers of ${}^{233}\mathrm{Th}$ and ${}^{232}\mathrm{Pa}$ have been obtained. The results confirm the attribution of the gross resonant structure in the fission probability of these light actinides to partially damped vibrational states in the second well and undamped vibrational states in the third well of the corresponding fission barriers.

Isotopic cross sections of all projectile residues with $Z$ above 23 produced in collisions induced by ${}^{238}\mathrm{U}$ at $1A$ GeV on deuterium have been measured. The isotopic distributions reflect the role of evaporation and fission in the formation process of these nuclei. The comparison of the measured cross sections with Monte Carlo deexcitation codes including an analytical description of the dynamics of fission shows the sensitivity of the data to nuclear dissipation. Moreover, the large excitation-energy range covered in this experiment together with the high accuracy of the measured cross sections allowed to clearly separate and quantify the role of transient and quasistationary dissipative effects in the fission-decay width.

Mass and mass resolved angular distribution of the fission products have been measured in the ${}^{20}\mathrm{Ne}+{}^{181}\mathrm{Ta}$ reaction at $E_{\mathrm{lab}}=150$ and 180 MeV using recoil catcher technique followed by off-line $\gamma$-ray spectrometry. Recoil range distribution (RRD) of the evaporation residues (ERs) have been measured at $E_{\mathrm{lab}}=180$ MeV. Due to high angular momentum of the fissioning nucleus, variances of the mass distribution in the present system have been found to be higher than those in similar systems involving comparatively less angular momentum. Significant contribution from noncompound nucleus processes such as deep inelastic collisions (DIC) and incomplete fusion reaction (ICF) is expected in the present system due to high angular momentum. The code HICOL predicts that the noncompound nucleus process would result in fission like events. In the present study, experimental fission cross sections are in reasonably good agreement with the calculation of statistical model code PACE2. Measurement of the ER cross section indicates significant contribution from the ICF reaction. The recoil range distributions of the ERs could resolve the complete fusion (CF) and ICF channels and were used to obtain ICF cross section. The experimentally measured ICF cross section accounts for almost entire cross section between $l_{\mathrm{crit}}$ and $l_{\max }$, indicating ICF reaction to be the dominant non-compound nucleus process at beam energies of the present study. DIC products could not be detected at both the beam energies. At these beam energies, the entrance channel pocket configuration for many collision trajectories is expected to be more elongated compared to the unconditional saddle point and, therefore, significant contribution form noncompound nucleus fission (i.e., fission without passing through the unconditional saddle point) is expected. However, the experimental anisotropies of fission products could be reproduced by the statistical theory calculation after considering the change in the saddle point shape with angular momentum of the fissioning nucleus. No correlation between the angular anisotropy and mass asymmetry of the fission products was observed in the present study.

Cold-fusion reactions are investigated with the goal of synthesizing ${}^{276}$114, ${}^{286}$114, and ${}^{290}$114 elements. Potential energy surfaces are calculated as the result of dynamic minimization with independent deformations of the target and projectile, small semiaxis of the projectile, and distance between centers as degrees of freedom. An advanced binary macroscopic-microscopic method is used to obtain the deformation energy, and the Werner-Wheeler approximation yields the mass tensor. The charge asymmetry is varied for the same mass asymmetry channel belonging to an energy valley. The highest penetrability values are obtained for cold-fusion channels within ${}^{116,118}\mathrm{Cd}$ projectiles leading to ${}^{276}$114; ${}^{142}\mathrm{Ba}$ projectile for ${}^{286}$114; and ${}^{104}\mathrm{Kr}$, ${}^{108}\mathrm{Sr}$, and ${}^{112}\mathrm{Zr}$ leading to ${}^{290}$114.

In extracting deformation parameters from multipole moments for deformed nuclei, one commonly uses the formulas which are based on a sharp-cut density distribution. We discuss a possible ambiguity for this procedure and clarify the role of diffuseness parameter of the density distribution. For this purpose, we use a deformed Woods-Saxon density as well as a density distribution obtained from the self-consistent relativistic mean-field (RMF) model. We show that the formula using a root-mean-square radius instead of a sharp-cut radius requires a large correction due to a finite surface diffuseness parameter even for stable nuclei. An implication to neutron-rich nuclei is also discussed.

The angular momentum dependence of the giant dipole resonance width, reported in the literature for nuclei in different mass regions, was compared with a recent comprehensive calculation under the thermal shape fluctuation model. The proper values of the angular momenta to be used in these comparisons are shown to be less than the ones quoted in the literature. There is a disagreement of the experimental results with the model prediction for some nuclei at high spins.

The ${}^{55}\mathrm{Mn}$$(d,n){}^{56}\mathrm{Fe}$ differential cross section is measured at $E_d=7$ MeV. The ${}^{56}\mathrm{Fe}$ level density obtained from neutron evaporation spectra is compared to the level density extracted from the ${}^{57}\mathrm{Fe}$$({}^3\mathrm{He}$, $\alpha \gamma ){}^{56}\mathrm{Fe}$ reaction by the Oslo-type technique. Good agreement is found between the level densities determined by the two methods. With the level density function obtained from the neutron evaporation spectra, the ${}^{56}\mathrm{Fe}$ γ-strength function is also determined from the first-generation γ matrix of the Oslo experiment. The good agreement between the past and present results for the γ-strength function supports the validity of both methods and is consistent with the low-energy enhancement of the γ strength below $~4$ MeV that was first discovered by the Oslo method in iron and molybdenum isotopes.