The average total spins of fission fragments were measured in ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O},$ and ${}^{19}{\mathrm{F}+}^{232}\mathrm{Th}$ reactions at near and above barrier energies for fragment emission angles parallel and perpendicular to the beam direction. The fragment spins for perpendicular emissions are observed to be higher compared to that for forward-backward emissions indicating the importance of the tilting mode ($K$ degree) of spin excitations in the fission process. The observed angle dependence of fragment spin could be explained within the statistical model, only if one assumes that the collective modes (other than the tilting mode) also depend on the emission angle of the fragments. It is shown that in this way, the results on both the fragment angular distributions and fragment spins can be explained consistently using the same $K$ distribution at the fission saddle point.

The shears mechanism, underlying the rotational-like behavior observed in the $M1\mathrm{}$ bands in neutron-deficient Pb isotopes, is interpreted as a consequence of a residual interaction between the proton and neutron blades. By deriving the angle θ between the proton and neutron spin vectors $j_{\pi }$ and $j_{\nu }$ in the ${}^{198,199}\mathrm{Pb}$ bands, it is shown that the main ingredient of this effective force can be described by a $P_2\left(\theta \right)$ term with a strength of 400–600 keV. Such an interaction can be mediated through the core by particle-vibration coupling, and qualitative agreement with experimental estimates may indicate the possible role of this coupling in the appearance of shears bands.

The energy deposition associated with inelastic α particle scattering on ${}^{209}\mathrm{Bi}$ at 240 MeV has been determined using the TAMU neutron ball. A comparison of the reconstructed average excitation energies with the beam energy losses demonstrates that only part of the missing beam energy is usually deposited as thermal excitation in the target nucleus. Requiring an additional coincidence with a light charged particle or fission fragment leads to selection of a significant higher average excitation energy.

Relating the pseudospin symmetry back to the Dirac equation through the framework of relativistic Hartree-Bogoliubov (RHB) theory, the pseudospin approximation in real nuclei is discussed. From the Dirac equation, the mechanism behind the pseudospin symmetry was studied and the pseudospin symmetry is shown to be connected with the competition between the centrifugal barrier (CB) and the pseudospin orbital potential (PSOP), which is mainly decided by the derivative of the difference between the scalar and vector potentials. With the scalar and vector potentials derived from a self-consistent relativistic Hartree-Bogoliubov calculation, the pseudospin symmetry and its energy dependence in real nuclei is discussed.

We study phase transitions of small two-dimensional Lennard-Jones drops via microcanonical molecular dynamics in a broad energy range. We found that the caloric curve can be extended to high energies to comprehend high evaporation rates and highly nonequilibrium phenomena such as multifragmentation. Multifragmentation appears as a constant temperature region in the caloric curve like the solid-liquid phase transition.

We illustrate how effective field theories work in nuclear physics by using an effective Lagrangian in which all other degrees of freedom than the nucleonic one have been integrated out to calculate the low-energy properties of two-nucleon systems, viz., the deuteron properties, the $\mathrm{np}$ ${}^1{S}_0$ scattering amplitude, and the $M1\mathrm{}$ transition amplitude entering into the radiative $\mathrm{np}$ capture process. Exploiting a finite cutoff regularization procedure, we find all the two-nucleon low-energy properties to be accurately described with little cutoff dependence, in consistency with the general philosophy of effective field theories.

We report on results of the effective theory method applied to neutron-deuteron scattering. We extend previous results in the $J=3/2\mathrm{}$ channel to nonzero energies and find very good agreement with the experiment without any parameter fitting.

High spin states in ${}^{104}\mathrm{Sn}$ were identified in the reaction ${}^{58}\mathrm{Ni}{(}^{50}\mathrm{Cr}$, $2p2n)$ at 200 and 205 MeV beam energies. The $\gamma$-ray energies, intensities, multipolarities, and lifetimes of high spin states were measured with the GASP spectrometer array in combination with a plunger apparatus by means of the recoil distance Doppler shift method. The deduced level scheme and transition probabilities are compared to the results of large-scale shell model calculations using three independent two-body interactions. The agreement of the level energies is satisfactory, except for a cascade of dipole transitions at high spins. The general good agreement found for $E2\mathrm{}$ transition strengths implies a large effective neutron polarization charge. The shell-model calculations do not account for the measured enhanced $E3\mathrm{}$ transitions for which a core excited octupole phonon admixture is indicated.

The nuclear structure of ${}^{17}\mathrm{Ne}$ has been studied by the ${}^{20}{\mathrm{N}\mathrm{e}(}^3{\mathrm{H}\mathrm{e},}^6{\mathrm{H}\mathrm{e})}^{17}\mathrm{Ne}$ reaction at 70 MeV. Thirteen levels were identified in ${}^{17}\mathrm{Ne},$ and angular distributions have been measured for the first time for this reaction. Based on the observed transferred angular momentum dependence of the angular distributions, a spin-parity assignment has been made for several states in ${}^{17}\mathrm{Ne}.$ With the inclusion of the data on ${}^{17}\mathrm{Ne},$ $T=\frac{3}{2}$ quartet analog states have been completed for six levels in the $A=17\mathrm{}$ isobar system. The level shifts in these $A=17\mathrm{}$ nuclei are analyzed in terms of the isobaric multiplet mass equation (IMME). The results of such an analysis show a slight linear dependence of the $b$ and $c$ coefficients of the equation on the excitation energy. The coefficients for the positive parity states seem to follow a different systematics than the negative parity states, suggesting that these parity-dependent level shifts are reflecting the structure change. These coefficients of the IMME are discussed.

Excited states in ${}^{112}\mathrm{Sb}$ have been observed with the Stony Brook array of six Compton-suppressed HPGe detectors and the ${}^{103}\mathrm{Rh}{(}^{12}\mathrm{C},3n)$ reaction at 60 MeV using a thick target. New excited states which decay solely towards the ${\tau }_m=773\mathrm{}$ ns, $I^{\pi }{=8\mathrm{}}^{-}$ isomer have been identified using time-correlated spectroscopy. The previously known level scheme has also been extended and corrected. In total, five rotational bands are observed, consisting of the two previously known strongly coupled bands based upon one-particle–one-hole (1p-1h) proton excitations across the $Z=50\mathrm{}$ shell gap and three newly observed decoupled bands based upon 2p-2h proton excitations. The 1p-1h bands are interpreted as deformed rotors, although there is a possibility that a shears mechanism like that observed in the lead region may also play a role. Results from a thin-target measurement using the Eurogam-II spectrometer and the ${}^{90}\mathrm{Zr}{(}^{31}\mathrm{P},2\mathrm{}\alpha n)$ reaction at 150 MeV are also presented. These data have been used to extend the decoupled bands up to $I\sim 40ħ$, a spin regime where the bands exhibit the features of smooth band termination. The combined results from the two experiments have enabled two of the bands to be connected by discrete $\gamma$-ray transitions to the low-spin level scheme, thereby determining their spins and parities. This allows for a definitive comparison with the results of cranked Nilsson-Strutinsky calculations and excellent agreement is obtained. Further confirmation of the terminating band configuration assignments is obtained from an analysis of the relative alignment properties of pairs of bands in the chain ${}^{110–112}\mathrm{Sb}$.

A superdeformed (SD) quasicontinuum in ${}^{132}\mathrm{Ce}$ is experimentally characterized from rotational ridges in $\gamma -\gamma$ correlation matrices. Evidence for a partial feeding of the SD yrast rotational band through highly deformed states is given. The evolution of the rotational transition strength as a function of the angular frequency is shown. A weak rotational damping is inferred.

A thick natural lead target has been bombarded with a 600 MeV ${}^{18}\mathrm{O}$ beam. With the use of an online gas-thermochromatographic device the mercury isotopes produced as target residues were rapidly separated and collected. A special coincident measurement technique increased the sensitivity to detecting ${\beta }^{-}$-delayed $\gamma$ rays, resulting in the observation of six neutron-rich mercury isotopes ${}^{203,205–209}\mathrm{Hg}$. Here ${}^{209}\mathrm{Hg}$ was created through an exotic $-2p+3n$ multinucleon transfer process and was identified for the first time. The half-life of ${}^{209}\mathrm{Hg}$ has been determined to be ${35}_{-6}^{+9\mathrm{}}$ s, and four $\gamma$ rays following its ${\beta }^{-}$ decays have been assigned. The measured thick-target average production cross sections of ${}^{203,205-209}\mathrm{Hg}$ were analyzed together with the known cross section data related to the $-2p\pm \mathrm{xn}$ exit channels. It has been found that the independent cross sections from various reactions induced by lighter heavy-ion projectiles below ${}^{40}\mathrm{Ar}$, display a regular $Q_{\mathrm{gg}}$ dependence, suggesting that the heavy neutron-rich target residues were produced mainly in quasielastic and deep inelastic multinucleon transfer processes. The half-life of ${}^{208}\mathrm{Hg}$ has been determined to be ${41}_{-4}^{+5\mathrm{}}$ min.

The BGO calorimeter of the Canadian $8\pi$ $\gamma$-ray spectrometer was used to select the weak $2p$ channel in Ni-Ni fusion reactions, populating proton-rich ${}^{114}\mathrm{Xe}$ and ${}^{116}\mathrm{Xe}.\mathrm{}$ Lifetimes were measured for transitions within the low-lying positive and negative parity bands in ${}^{114,116}\mathrm{Xe}.\mathrm{}$ Measured $B\left(E2\mathrm{}\right)\mathrm{}$ values within the positive parity band were compared to calculations with algebraic models. Measured $B\left(E2\mathrm{}\right)\mathrm{}$ values within the negative parity band in ${}^{114}\mathrm{Xe}$ suggest a change in structure relative to that of the same band in the heavier xenon isotopes.

Isovector $E1\mathrm{}$ giant resonances in nonmagic nuclei are calculated by using a method which takes into account the single-particle continuum in the framework of a continuum quasiparticle random-phase approximation. A special procedure is formulated which gives the spurious dipole state at zero energy. The calculations are performed in a stable nonmagic tin isotope as well as unstable magic and nonmagic tin isotopes. The role of the single-particle continuum and the spurious dipole state is discussed. It turned out that the first ingredient has a noticeable influence on the resonance form.

Low-lying positive-parity rotational bands have been recently found in odd-$A$ nuclei of the $\mathrm{pf}$ shell. Their occurrence can be explained as due to the coupling of a hole in the ${1d}_{3/2}$ orbit to the more deformed even-even $\mathrm{pf}$-shell configurations. Shell model calculations in the full $\mathrm{pf}$ shell plus one hole in the ${1d}_{3/2}$ orbit for ${}^{47}\mathrm{V}\mathrm{-}{(1d}_{3/2}{\otimes }^{48}\mathrm{Cr})$—and for ${}^{45}\mathrm{Sc}\mathrm{-}{(1d}_{3/2}{\otimes }^{46}\mathrm{Ti})$—support this interpretation. Very good agreement with the available experimental results is obtained.

From the data on dipole excitations obtained in photon scattering experiments we extract and tabulate the mean values of the excitation energy of the $1^{+}$ scissors mode in nuclei of the mass region $130<A<\mathrm{}200.\mathrm{}$ The centers of gravity of the observed $M1\mathrm{}$ strength distributions are always close to 3 MeV including several moderately deformed transitional nuclei. In particular, the data exhibit a weak dependence of the scissors mode energy on the deformation parameter. Including roughly the deformation dependence of pairing effects we could modify an earlier estimate based on a schematic random phase approximation and get a simple formula which yields qualitative agreement with the data.

Within the framework of the interacting boson model (IBM-2) we analyze $F$-vector $\gamma$ transitions in $\gamma$-soft nuclei for which the O(6) dynamical symmetry of the IBM provides an analytical description. For certain parameter combinations, the IBM-2 Hamiltonian is invariant with respect to the $d$-parity operation which changes the sign of each $d$ boson. This symmetry of the Hamiltonian is responsible for the existence of the $d$-parity quantum number which leads to selection rules for electromagnetic transitions. The breaking of the $d$-parity symmetry can be studied in mixed $E2/M1\mathrm{}$ transitions, and especially the $E2/M1\mathrm{}$ mixing ratio of the $1_1^{+}\to 2_1^{+}$ $\gamma$ transition turns out to be a sensitive measure of IBM-2 parameters for $\gamma$-soft nuclei.

Finite size effects in the equilibrium phase space density distribution function are taken into account for calculations of the relaxation of collective motion in finite nuclei. Memory effects in the collision integral and the diffusivity and the quantum oscillations of the equilibrium distribution function in momentum space are considered. It is shown that a smooth diffuse (Fermi-type) equilibrium distribution function leads to a spurious contribution to the relaxation time. The residual quantum oscillations of the equilibrium distribution function eliminates the spurious contribution. It ensures the disappearance of the gain and loss terms in the collision integral in the ground state of the system and strongly reduces the internal collisional width of the isoscalar giant quadrupole resonances.

A strength function technique valid for a separable Hamiltonian which allows for the coupling between electric and magnetic channels is developed in the framework of proton-neutron random-phase approximation and applied to deformed nuclei. The signature formalism is adopted in view of future applications of the method to fast rotating nuclei. For illustrative purposes the technique is exploited for the computation of the distribution of the magnetic quadrupole strength in axially deformed nuclei, where the coupling with the electric dipole giant resonance is induced by the deformation.

A new set of Skyrme parameters is obtained from a fit to the binding energies, rms charge radii, and single-particle energies of both normal and exotic spherical nuclei. Nuclear matter and neutron matter properties are used to put constraints on the parameters which are not well determined from the nuclear data. Special problems with the Nolen-Schiffer anomaly and the spin-orbit interaction are discussed.