We utilize the shell model Monte Carlo method to study the structure of rare earth nuclei. This work demonstrates the first systematic full oscillator shell with intruder calculations in such heavy nuclei. Exact solutions of a pairing plus quadrupole Hamiltonian are compared with the static path approximation in several dysprosium isotopes from $A=152\mathrm{}$ to 162, including the odd mass $A=153.\mathrm{}$ Some comparisons are also made with Hartree-Fock-Bogoliubov results from Baranger and Kumar. Basic properties of these nuclei at various temperatures and spin are explored. These include energy, deformation, moments of inertia, pairing channel strengths, band crossing, and evolution of shell model occupation numbers. Exact level densities are also calculated and, in the case of ${}^{162}\mathrm{Dy},$ compared with experimental data.

Isotope shifts and hyperfine structure constants of the neutron-deficient isotopes ${}^{155}\mathrm{Yb},{\hspace{0.5em}}^{154}\mathrm{Tm}\mathrm{}(I=9\mathrm{}),{\hspace{0.5em}}^{154}\mathrm{Tm}\mathrm{}(I=2\mathrm{}),$ and ${}^{153}\mathrm{Tm}\mathrm{}(I=11/2\mathrm{})\mathrm{}$ have been measured by the resonance ionization spectroscopy in the laser ion source. The changes in mean-square charge radii $〈r^2〉$ and the electromagnetic moments $\mu$ and $Q_s$ of these isotopes have been determined. A new method for background suppression for the laser spectroscopy in the ion source of mass separator has been proposed and applied.

The process of the synthesis of superheavy elements (SHEs) is not yet understood completely. In the presented work we make an attempt to describe the cold fusion reactions of the type $X+(\mathrm{P}\mathrm{b},\mathrm{B}\mathrm{i})\to \mathrm{SHE}+1n$ at subbarrier energies. The process of the formation of SHEs is subdivided into three steps. (1) The capture of two spherical nuclei and the formation of a common shape of the two touching nuclei. Low-energy surface vibrations and transfer of few nucleons are taken into account in the first step of the reaction. (2) The formation of a spherical or near spherical compound nucleus. (3) The survival of the excited compound nucleus due to evaporation of neutrons and $\gamma$-ray emission in competition with fission. A lowering of the fission barrier was taken into account, which arises from a reduction of shell effects at increasing excitation energy of the compound nucleus. The following reactions were analyzed in detail: ${(}^{58}\mathrm{Fe},$ ${}^{64}\mathrm{Ni},$ ${}^{70}\mathrm{Zn},$ ${}^{78}\mathrm{Ge}{)+}^{207}\mathrm{Pb},$ ${(}^{50}\mathrm{Ti},$ ${}^{54}\mathrm{Cr},$ ${}^{58}\mathrm{Fe},$ ${}^{59}\mathrm{Co},$ ${}^{62,64}\mathrm{Ni},$ ${}^{65}\mathrm{Cu},$ ${}^{66,68,70}\mathrm{Zn},$ ${}^{71}\mathrm{Ga},$ ${}^{74,76,78}\mathrm{Ge},$ ${}^{75}\mathrm{As},$ ${}^{80,82}\mathrm{Se}{)+}^{208}\mathrm{Pb},$ ${(}^{58}\mathrm{Fe},$ ${}^{64}\mathrm{Ni},$ ${}^{70}\mathrm{Zn},$ ${}^{78}\mathrm{Ge}{)+}^{210}\mathrm{Pb},$ and ${(}^{50}\mathrm{Ti},$ ${}^{54}\mathrm{Cr},$ ${}^{58}\mathrm{Fe},$ ${}^{64}\mathrm{Ni},$ ${}^{70}\mathrm{Zn},$ ${}^{78}\mathrm{Ge}{)+}^{209}\mathrm{Bi}.$ The presented model describes well the available experimental cross-section data and allows for predicting cross-section values for the synthesis of so-far unknown heavier elements.

New experimental data obtained mainly at the GSI/FRS facility allow one to modify the empirical parametrization of fragmentation cross sections. It will be shown that minor modifications of the parameters lead to a much better reproduction of measured cross sections. The most significant changes refer to the description of fragmentation yields close to the projectile and of the memory effect of neutron-deficient projectiles.

We discuss the nuclear dependence of $\psi$ and ${\psi }^{\prime }$ production in hadron-nucleus interactions as a function of longitudinal momentum fraction $x_F.$ Nuclear effects such as final-state absorption, interactions with comovers, shadowing of parton distributions, energy loss, and intrinsic heavy-quark components are described separately and incorporated into the model which is then compared to the preliminary E866 data. The resulting nuclear dependence of Drell-Yan production at 800 GeV and proposed measurements of $\psi ,$ ${\psi }^{\prime },$ and Drell-Yan production at 120 GeV are also calculated.

Results of a search for ${}^{136}\mathrm{Xe}$ double β decay with high-pressure multiwire wall-less proportional counters at the Baksan Neutrino Observatory are presented. The experimental method and the characteristics of the detectors are described. The detector background in the energy range 0.5–3.5 MeV has been reduced due to event position discrimination and pulse shape discrimination. Results of the analysis of background components for different event types and source positions are described. A new lower limit of $T_{1/2}>~0.81\times {10}^{21}\mathrm{yr}$ (90% C.L.) is found for the ${}^{136}\mathrm{Xe}$ 2νββ decay mode.

The $\beta$-decay half-life of ${}^{70}\mathrm{Kr}$ has been measured for the first time at the ISOLDE PSB Facility at CERN. Mass separated ${}^{70}\mathrm{Kr}$ ions were produced by 1 GeV proton-induced spallation reactions in a Nb foil. The measured half-life is 57(21) ms. This value is consistent with the half-life calculated assuming a pure Fermi decay, but is clearly lower than the value used in a recent rp-process reaction flow calculation. The result shows that the reaction flow via two-proton-capture of ${}^{68}\mathrm{Se}$ is 2.5 times faster than previously calculated assuming an astrophysical temperature of 1.5 GK and a density of ${10}^6{\mathrm{g}/\mathrm{c}\mathrm{m}}^3.$

We study the excitation energy of the isoscalar giant quadrupole resonance by the scaling method in the relativistic many-body framework with the momentum dependent parts of the Dirac self-energies arising from the one-pion exchange. It is shown that this momentum dependence enhances the Landau mass significantly and thus suppresses the quadrupole resonance energy while the Dirac effective mass is kept to a reasonable value.

Double differential cross sections $d^2\sigma /d\omega d\Omega$ and spin-flip probabilities $S_{\mathrm{nn}}$ have been measured for the ${}^{40}\mathrm{Ca}(\overrightarrow{p},p^{\prime })$ reaction at $E_p=319\mathrm{}$ MeV. The angular range of the experiment was $10.5°<~{\theta }_{\mathrm{lab}}<~23°$ and the range of excitation energies was $6<~\omega <~47$ MeV. These data and earlier data at smaller angles are compared to calculations employing random phase approximation nuclear structure and a distorted wave impulse approximation reaction model.

Mean lifetimes of high-spin states of ${}^{74}\mathrm{Kr}$ have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the ${}^{40}\mathrm{Ca}{(}^{40}\mathrm{Ca},$$\alpha 2p)$ reaction at a beam energy of 160 MeV with the GASP $\gamma$-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations.

First order Brueckner-Hartree calculations for the Λ single-particle energies were performed with potentials Ib and IIa from a recent fit of the Nijmegen soft core potential parameters. The method was applied to ${}_{\Lambda }^5\mathrm{He},$ ${}_{\Lambda }^{13}\mathrm{C},$ ${}_{\Lambda }^{17}\mathrm{O},$ ${}_{\Lambda }^{41}\mathrm{Ca},$ ${}_{\Lambda }^{49}\mathrm{Ca},$ ${}_{\Lambda }^{91}\mathrm{Zr},$ and ${}_{\Lambda }^{208}\mathrm{Pb}.$ Although potentials Ib and IIa have very different short range characteristics, their results differed little over the $A=5\mathrm{}$ to 209 mass range. The results for ${}_{\Lambda }^5\mathrm{He}$ and ${}_{\Lambda }^{17}\mathrm{O}{(1/2\mathrm{}}^{+}{,1/2\mathrm{}}^{-}{,3/2\mathrm{}}^{-})$ were within 0.7 MeV of the approximate calculations used in the fitting process. This shows that the inclusion of the approximate calculations in potential fits will provide reliable constraints. The $0p$-shell hypernuclei were in good agreement with experimental results, however, ${}_{\Lambda }^5\mathrm{He}$ was underbound by 0.9 and 1.0 MeV for the two potentials. It is emphasized that g-matrix procedures more suited for the heavy systems should be developed to have reliable predictions of hypernuclear saturation properties.

The influence of relativistic contributions to elastic electron deuteron scattering is studied systematically at low and intermediate momentum transfers ${(Q}^2<~30{\mathrm{fm}}^{-2}).\mathrm{}$ In a $\mathrm{}(p/M)\mathrm{}$ expansion, all leading-order relativistic $\pi$-exchange contributions consistent with the Bonn OBEPQ models are included. In addition, static heavy meson exchange currents including boost terms and lowest order $\rho \pi \gamma$ currents are considered. Sizable effects from the various relativistic two-body contributions, mainly from $\pi$ exchange, have been found in form factors, structure functions, and the tensor polarization $T_{20}.$ Furthermore, static properties, viz. magnetic dipole and charge quadrupole moments and the mean square charge radius are evaluated.

If a quantum-mechanical Hamiltonian has an infinite symmetric tridiagonal (Jacobi) matrix form in some discrete Hilbert-space basis representation, then its Green’s operator can be constructed in terms of a continued fraction. As an illustrative example we discuss the Coulomb Green’s operator in a Coulomb-Sturmian basis representation. Based on this representation, a quantum-mechanical approximation method for solving Lippmann-Schwinger integral equations can be established, which is equally applicable for bound-, resonant- and scattering-state problems with free and Coulombic asymptotics as well. The performance of this technique is illustrated with a detailed investigation of a nuclear potential describing the interaction of two $\alpha$ particles.

The total photofission cross sections for the actinide nuclei ${}^{232}\mathrm{Th},$ ${}^{233}\mathrm{U},$ ${}^{235}\mathrm{U},$ ${}^{238}\mathrm{U},$ and ${}^{237}\mathrm{Np}$ have been measured from 68 to 264 MeV using tagged photons at the Saskatchewan Accelerator Laboratory. The fission fragments were detected using parallel-plate avalanche detectors. The results show that the fission probability for ${}^{238}\mathrm{U}$ is 20% lower than that for ${}^{237}\mathrm{Np}$ and 40% higher than that for ${}^{232}\mathrm{Th}.$ Less significant differences were also found among the individual uranium isotopes. These results contradict the assumption that the fission probability for ${}^{238}\mathrm{U}$ is approximately equal to unity in this energy range. It has also been observed that the fission probability as a function of energy for all these isotopes is constant, with the exception of that for ${}^{232}\mathrm{Th},$ which increases with energy, although it seems to be reaching a saturation value. Comparison between the total photofission cross section for ${}^{237}\mathrm{Np}$ and the photoabsorption cross sections for lighter nuclei shows a behavior consistent with a broadening of the $\Delta$ resonance with increasing atomic mass.

This paper is concerned with the use of a microscopic optical potential in the description of the final state interaction of a breakup neutron from a halo projectile such as ${}^{11}\mathrm{Be}$ on two light targets ${}^9\mathrm{Be}$ and ${}^{28}\mathrm{Si}.$ Both the breakup from the projectile ground state and from core excited states is considered. We calculate and compare two interesting observables to existing experimental data. One is the total breakup cross section due to diffraction and stripping. Nice agreement with experimental data is obtained. The other is the ejectile energy spectrum corresponding to neutron stripping for a ${}^{28}\mathrm{Si}$ target, which was measured experimentally. We show that some part of the tail towards ejectile low energies is due to the contribution from core excited states which have initial angular momentum $l_i>0,$ binding energies of several MeV and as a consequence wide final energy spectra.

In standard potential-model descriptions of the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction the ${}^7\mathrm{Be}+p$ spectroscopic factors $\mathcal{S}$ appear in the cross section. We argue that the microscopic substructure effects which are represented by $\mathcal{S}$ are short-ranged and cannot affect the asymptotic normalization of the wave function. We believe that the standard way of describing reactions in a potential model may be incorrect and the low-energy cross section should not depend on $\mathcal{S}$ in the case of external capture reactions, like ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}.$

We compute the populations of isotopes of boron, carbon, and nitrogen measured experimentally in intermediate energy heavy ion collisions. A two-component soluble statistical model is used to find the initial populations of different nuclei at a finite temperature. These initial populations are both in particle stable and particle unstable states. The particle unstable states then decay. The final populations after these decays are computed and compared with experimental data.

Cluster decay of ${}^{242}\mathrm{Cm}$ with emission of ${}^{34}\mathrm{Si}$ particles was measured using track-recording phosphate glass detectors. The corresponding partial half-life is $(1.4+0.5/-0.3)\times {10}^{23}\mathrm{s}.$ The branching ratio relative to α decay is $1.0\times {10}^{-16}$ and the one relative to spontaneous fission is $1.6\times {10}^{-9}.$ A comparison of experimental results with the predictions of different theoretical models and semiempirical systematics is presented.

The dissipative corrections to the hydrodynamic equations describing the evolution of energy-momentum tensor and parton densities are derived in a simple way using the scaling approximation for the expanding quark gluon plasma at finite baryon density. This procedure has been extended to study the process of chemical equilibration using a set of rate equations appropriate for a viscous quark gluon plasma. It is found that in the presence of dissipation, the temperature of the plasma evolves slower, whereas the quark and gluon fugacities evolve faster than their counterparts in the ideal case without viscosity.