With the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) [or SU(5)] symmetry on the rotational symmetry, the superdeformed (SD) identical bands of the odd-A nuclei in $A\sim 190$ mass region, ${\{}^{191}\mathrm{Hg}{\mathrm{}\left(2\right),}^{193}\mathrm{Hg}\mathrm{}\left(2\right)\mathrm{}\},$ ${\{}^{191}\mathrm{Hg}{\mathrm{}\left(3\right),}^{193}\mathrm{Hg}\mathrm{}\left(3\right)\mathrm{}\},$ ${\{}^{193}\mathrm{Tl}{\mathrm{}\left(3\right),}^{193}\mathrm{Tl}\mathrm{}\left(5\right)\mathrm{}\}$ and the middle-point identical bands ${\{}^{193}\mathrm{Tl}{\mathrm{}\left(1\right),}^{193}\mathrm{Tl}\mathrm{}\left(2\right)\mathrm{}\}$ are investigated. Quantitatively good results of the $E_{\gamma }$ spectra and the dynamical moments of inertia are obtained. It shows that the supersymmetry approach is powerful to describe not only the generic rotational property, but also the identical bands of SD states simultaneously.

In this work microsecond isomers in ${}^{130,132}\mathrm{Te}$ and ${}^{134}\mathrm{Xe}$ are investigated. These nuclei are produced by thermal neutron induced fission of ${}^{239}\mathrm{Pu}$ and ${}^{241}\mathrm{Pu}.$ The detection is based on time correlation between fission fragments selected by the LOHENGRIN spectrometer at ILL (Grenoble) and the $\gamma$ rays or conversion electrons from isomers. The ${10}^{+}\to 8^{+}$ isomeric transition of ${}^{132}\mathrm{Te}$ and ${}^{134}\mathrm{Xe}$ was measured for the first time and the half-life of the analogous transition in ${}^{130}\mathrm{Te}$ was remeasured. The systematic behavior of the $B\left(E2\mathrm{}\right)\mathrm{}$ values of this isomeric transition is studied in Sn, Te, Xe, and Ba isotopes close to ${}^{132}\mathrm{Sn}.$ A simple mechanism is proposed to explain the strong increase in the $B\left(E2\mathrm{}\right)\mathrm{}$ strengths from the Sn to the Te isotones.

In the simulation of intermediate energy heavy ion collisions by using isospin-dependent quantum molecular dynamics, the isospin effect on the process of multifragmentation and dissipation has been studied. It is found that the multiplicity of intermediate mass fragments $N_{\mathrm{IMF}}$ for the neutron-poor colliding system is always larger than that for the neutron-rich system, while the quadrupole of single particle momentum distribution $Q_{\mathrm{zz}}$ for the neutron-poor colliding system is smaller than that of the neutron-rich system for all projectile-target combinations studied at beam energies from about 50 to 150 MeV/nucleon. Since $Q_{\mathrm{zz}}$ depends strongly on the isospin dependence of the in-medium nucleon-nucleon cross section and weakly on symmetry potential at the above beam energies, it may serve as a good probe to extract the information on the in-medium nucleon-nucleon cross section. The correlation between the multiplicity $N_{\mathrm{IMF}}$ of intermediate mass fragments and the total number of charged particles $N_c$ has a behavior similar to $Q_{\mathrm{zz}},$ which can be used as a complementary probe to the in-medium nucleon-nucleon cross section.

Excited states of the odd-odd ${}^{62}\mathrm{Cu}$ isotope were populated and studied via the ${}^{16}\mathrm{O}$ $(65\mathrm{}\hspace{0.5em}\mathrm{MeV}{)+}^{52}\mathrm{Cr}$ reaction using a gamma detector array equipped with a charged-particle detector array for reaction channel separation. On the basis of $\gamma -\gamma$ coincidence relations and angular distribution ratios, an extended level scheme was constructed up to $E_x=10.88\mathrm{}$ MeV and $J^{\pi }{=(14\mathrm{}}^{+})ħ,$ and ${(14\mathrm{}}^{-})ħ,$ and this result was interpreted in terms of shell model calculations with a restricted basis of the $f_{5/2},$ $p_{3/2},$ $p_{1/2},$ and $g_{9/2}$ orbitals outside a ${}_{28}^{56}\mathrm{Ni}$ core.

The experimental asymptotic normalization coefficient determined from peripheral transfer reactions is used to obtain the root-mean-square radius of the wave function for the loosely bound proton in ${}^8\mathrm{B}.$ It is shown that the asymptotic region contributes most and that matching of the interior wave function with the asymptotic part yields a nearly model-independent radius. We obtain $〈r^2{〉}^{1/2}=4.20\mathrm{}\pm 0.22\hspace{0.5em}\mathrm{fm}$ for the root-mean-square (rms) radius of the last proton, much larger than the rms radius of the ${}^7\mathrm{Be}$ core. This large value and the fact that the asymptotic part of the proton wave function contributes $85\%$ to the rms radius are good sign that ${}^8\mathrm{B}$ is a halo nucleus.

The dependence on deformation of the isovector twist mode $\left(\right[{\mathrm{rY}}^1\overrightarrow{l}{]}^{\lambda =2\mathrm{}}{t}_{+})$ is investigated. We calculate the strengths and energies in the asymptotic (oblate) limit using ${}^{12}\mathrm{C}$ as an example of a strongly deformed nucleus. We also consider the $\lambda =1\mathrm{}$ case. In a $\Delta N=0\mathrm{}$ Nilsson model the summed strength is independent of the relative $P_{3/2}$ and $P_{1/2}$ occupancy but when we allow for different frequencies ${\omega }_i$ in the x, y, and z directions there is an enhancement of this strength due to deformation. This dependence is stronger than that for the ordinary dipole mode but much weaker than that for the scissors mode. At the same time, it is observed that there are considerable changes in the spectrum and that the strength is strongly fragmented amongst these disparate levels. We further show that in this model the associated spin mode $[{\mathrm{rY}}^1\overrightarrow{s}{]}^{\lambda }{t}_{+}$ has a weaker dependence on deformation and is less fragmented than the twist mode.

Fusion excitation functions were obtained for ${}^{37}\mathrm{Cl}{+}^{70,72,73,74,76}\mathrm{Ge}$ at energies from about 6 MeV below to 7 MeV above the Coulomb barrier. The barrier parameters extracted from the data agree within 3% with those obtained from the systematics for fusion above the barrier. Low-energy enhancements are observed, whose behavior is explained within the context of simple model calculations by assigning appropriate degrees of freedom to the respective reaction partners. These degrees of freedom reflect the shape transition between spherical ${}^{70,72,73}\mathrm{Ge}$ and prolate-deformed ${}^{74,76}\mathrm{Ge},$ and show also remarkable effects of the odd-$A$ structure of ${}^{73}\mathrm{Ge}.$ The results are consistent with those of similar analysis of different data sets where the same targets were used. The possible effects of double identical-phonon states for spherical nuclei, hexadecapole deformations for deformed ones, and nucleon transfer are also examined. An analysis of the barrier distributions is made, which indicates consistency with the assumed degrees of freedom.

The nucleosynthesis of heavy neutron-deficient nuclei in a stellar photon bath at the temperatures relevant for the astrophysical $\gamma$ process was investigated. In order to derive $(\gamma ,n)$ cross sections and reaction rates, the stellar photon bath was simulated by the superposition of several bremsstrahlung spectra with different end-point energies. As a first test for this method, the $(\gamma ,n)$ reaction rates of the platinum isotopes ${}^{190}\mathrm{Pt},$ ${}^{192}\mathrm{Pt},$ and ${}^{198}\mathrm{Pt}$ were derived. The results are compared to other experimental data and theoretical calculations.

Contribution of higher order effects to the one-photon exchange approximation were studied in the first excited state of ${}^{12}\mathrm{C}$ by comparing inclusive inelastic scattering cross sections of electrons and positrons obtained at the Saclay Linear Accelerator. The data were compared to a distorted wave Born approximation (DWBA) calculation. The results indicate an effect less than 2% within $2\sigma ,$ compatible with what was observed in recent elastic scattering measurements.

A recently developed helicity basis for nucleon-nucleon $\mathrm{}\left(\mathrm{NN}\right)\mathrm{}$ scattering is applied to the deuteron bound state. Here the total spin of the deuteron is treated in such a helicity representation. For the bound state, two sets of two coupled eigenvalue equations are developed, where the amplitudes depend on two variables and one variable, respectively. Numerical illustrations based on the realistic Bonn-B $\mathrm{NN}$ potential are given. In addition, an “operator form” of the deuteron wave function is presented, and several momentum dependent spin densities are derived and shown, in which the angular dependence is given analytically.

We present calculations of ground state properties of spherical, doubly closed-shell nuclei from ${}^{16}\mathrm{O}$ to ${}^{208}\mathrm{Pb}$ employing the techniques of many-body perturbation theory using a separable density-dependent monopole interaction. The model gives results in Hartree-Fock order that are of similar quality to other effective density-dependent interactions. In addition, second and third order perturbation corrections to the binding energy are calculated and are found to contribute small, but non-negligible corrections beyond the mean-field result. The perturbation series converges quickly, suggesting that this method may be used to calculate fully correlated wave functions with only second or third order perturbation theory. We discuss the quality of the results and suggest possible methods of improvement.

Within the pure Coulomb breakup mechanism, we investigate the one-neutron removal reaction of the type $A(a,b\gamma )X$ with ${}^{11}\mathrm{Be}$ and ${}^{19}\mathrm{C}$ projectiles on a heavy target nucleus ${}^{208}\mathrm{Pb}$ at the beam energy of 60 MeV/nucleon. Our intention is to examine the prospect of using these reactions to study the structure of neutron-rich nuclei. Integrated partial cross sections and momentum distributions for the ground as well as excited bound states of core nuclei are calculated within the finite-range distorted-wave Born approximation as well as within the adiabatic model of the Coulomb breakup. Our results are compared with those obtained in the studies of the reactions on a light target where the breakup proceeds via the pure nuclear mechanism. We find that the transitions to excited states of the core are quite weak in the Coulomb dominated process as compared to the pure nuclear breakup.

The normalization of the overlap between the ${}^6\mathrm{He}$ and ${}^4\mathrm{He}$ wave functions, which enters into the cross sections of the ${p(}^6\mathrm{He}{,}^4\mathrm{He})t$ and ${}^4\mathrm{He}{(}^6\mathrm{He}{,}^4\mathrm{He}{)}^6\mathrm{He}$ reactions, has been calculated in the translation-invariant shell model. It has been shown that when both antisymmetrization between individual nucleons and the center-of-mass motion are treated properly, the distorted-wave Born approximation (DWBA) cross sections of the ${p(}^6\mathrm{He}{,}^4\mathrm{He})t$ and ${}^4\mathrm{He}{(}^6\mathrm{He}{,}^4\mathrm{He}{)}^6\mathrm{He}$ reactions increase by the factor of 25/16 and ${\mathrm{}(25/16)\mathrm{}}^2,$ respectively, as compared to those calculated in models considering the ${}^4\mathrm{He}$ core of ${}^6\mathrm{He}$ as structureless. The DWBA analysis of the available experimental data on these reactions has been performed using the shell model normalization obtained. It has been shown that at current level of knowledge of the reaction mechanisms and the input parameters associated with them, the shell model normalization does not contradict the experimental data.

A stochastic approach to fission dynamics based on three-dimensional Langevin equations was applied to calculate fission fragment mass-energy distribution from a number of excited compound nuclei formed in reactions induced by heavy ions. Evaporation of prescission light particles along Langevin fission trajectories from the ground state of the compound nucleus to its scission has been taken into account using a Monte Carlo simulation technique. Inclusion of the third collective coordinate in Langevin dynamics leads to a considerable increase of the variance of the mass and the kinetic-energy distributions of fission fragments as compared with two-dimensional Langevin calculations. A liquid-drop model with finite range of nuclear forces and a modified one-body mechanism for nuclear dissipation have been used in the calculations. The results of the calculations are compared with the available experimental data. The calculations performed using the three-dimensional Langevin dynamics reproduce sufficiently well all the parameters of the two-dimensional fission fragment mass-energy distribution and their dependence on various parameters of the compound nucleus. The mean prescission neutron multiplicities are also reproduced with good accuracy. In order to reproduce simultaneously the measured prescission neutron multiplicities and the variance of the fission fragment mass-energy distribution, the reduction coefficient of the contribution from a wall formula has to be decreased at least by half of the one-body dissipation strength $(0.25\mathrm{}<~k_s<~0.5).$

We present the final results from Experiment 864 of a search for charged and neutral strange quark matter produced in interactions of 11.5 $\mathrm{GeV}/c$ per nucleon Au beams with Pt or Pb targets. Searches were made for strange quark matter with $A>~5.$ Approximately $3\times {10}^{10}$ 10% most central collisions were sampled and no strangelet states with $A<~100$ were observed. We find 90% confidence level upper limits of approximately ${10}^{-8}$ per central collision for both charged and neutral strangelets. These limits are for strangelets with proper lifetimes greater than 50 ns. Also limits for $H^0-d$ and pineut production are given. The above limits are compared with the predictions of various models. The yields of light nuclei from coalescence are measured and a penalty factor for the addition of one nucleon to the coalescing nucleus is determined. This is useful in gauging the significance of our upper limits and also in planning future searches for strange quark matter.

A method is presented to include quantum corrections into the calculation of two-pion correlations for the case where particles originate from resonance decays. The technique uses classical information regarding the space-time points at which resonances are created. By evaluating a simple thermal model, the method is compared to semiclassical techniques that assume exponential decaying resonances moving along classical trajectories. Significant improvements are noted when the resonance widths are broad as compared to the temperature.

The quark mean field model, which describes the nucleon using the constituent quark model, is applied to investigate the properties of finite nuclei. The couplings of the scalar and vector mesons with quarks are made density dependent through direct coupling to the scalar field so as to reproduce the relativistic Brueckner-Hartree-Fock results of nuclear matter. The present model provides satisfactory results on the properties of spherical nuclei, and predicts an increasing size of the nucleon as well as a reduction of the nucleon mass in the nuclear environment.

The $6_1^{+}$ and $6_2^{+}$ in ${}^{48}\mathrm{Ti}$ form a nearly degenerate doublet. In single-j shell calculation with the matrix elements from experiment the $6_1^{+}$ changes sign under the interchange of protons and neutron holes (odd signature) while the $6_2^{+}$ does not (even signature). As a consequence the calculated $B\left(E2\mathrm{}\right)\mathrm{}$ $6_1^{+}\to 4_1^{+}$ is much stronger than the $6_2^{+}\to 4_1^{+}$ and the Gamow-Teller matrix element to the $6_2^{+}$ states vanishes. When using some popular interaction, e.g., FPD 6 in single-j shell the ordering of the even signature and odd signature states gets reversed, so that the Gamow-Teller matrix element to the $6_1^{+}$ state vanishes and the $6_2^{+}\to 4_1^{+}$ $E2\mathrm{}$ transition is the strong one. When configuration mixing is introduced, the $E2\mathrm{}$ transition $6_2^{+}\to 4_1^{+}$ persists in being large. However the Gamow-Teller strengths reverse, with the large matrix element to the $6_1^{+}$ state in agreement with experiment. Static properties $\mu$ and Q for the two $6^{+}$ states are also considered. The experimental $B\left(E2\mathrm{}\right)\mathrm{}\mathrm{’}\mathrm{s}$ from the $6^{+}$ states to the $4_1^{+}$ state are not well known.

Excited states in ${}^{126}\mathrm{Ce}$ have been observed with the GAMMASPHERE γ-ray detector array, used in conjunction with the MICROBALL charged-particle detector. The reaction ${}^{64}\mathrm{Zn}{(}^{64}\mathrm{Zn},\mathrm{xpn}\alpha )$ (beam energy 260 MeV) was used to populate a wide range of nuclei in the neutron-deficient region with $A\approx 120.$ ${}^{126}\mathrm{Ce}$ was populated via the $2p$ evaporation channel. The three previously observed bands have been extended to higher spins and some other structures have been identified. The yrast band shows evidence of a delayed neutron alignment occurring at a rotational frequency ω≈0.5 MeV/ħ as observed in the neighboring odd-A nucleus ${}^{127}\mathrm{Pr}.$ One of the two excited bands shows evidence for a similar crossing at a slightly lower frequency and also exhibits a sudden gain in alignment at ω=0.57 MeV/ħ. The third band may involve the coupling of a γ-vibrational state. All three rotational bands are discussed in terms of standard and extended cranked shell model calculations.

The collective rotational-vibrational spectrum of a giant trinuclear molecule is computed for the case when the clusters which are composing this exotic nuclear system are spherical. Special attention is paid to the case of a triangular configuration which corresponds to an absolute minimum in the total ternary potential and in our view is a good candidate for a molecular configuration. Although the coupling between different included collective degrees of freedom looks rather complicated it is shown that by expanding the Hamiltonian operator around the equilibrium values and retaining only the first term a satisfactory approximation in building the molecular spectrum is obtained. For the sake of completeness we compare the above-mentioned molecular spectrum with that obtained in the case of the linear molecule. We consider as an application the splitting ${}^{132}\mathrm{Sn}+\alpha {+}^{116}\mathrm{Pd}$ which occurs in the alpha-accompanied ternary cold fission of ${}^{252}\mathrm{Cf}.$