In-beam study of105In and103In

The effects on pair density fluctuations in superfluid nuclei, associated with the projection on good particle number, are studied. The model, which is based on standard particle number projection techniques, is developed for the case of one and two-body density fluctuations in spherical superfluid nuclei. The results, for the case of some even mass isotopes of Sn, show that pair density fluctuations and the derivative of the one body density almost coincide in a number projected BCS treatment of pairing correlations.     

Calculated ground-state properties of heavy nuclei

Ground-state distortions and single-particle corrections are calculated fornuclei with $\text{Z ≧ 68}\text{and}\text{N ≧ 106}$ by use of the macroscopic-microscopic method as developed by Strutinsky. The microscopic part is calculated primarily by use of the folded Yukawa single-particle potential. Its parameters are redetermined to fit a actinide data. The modified oscillator potential is also used in some of the studies. Two methods for calculating the macroscopic energy are investigated. One is the droplet model of Myers and Swiatecki, and other is a modified liquid-drop model in which the surface-energy term is modified to take into account the finite range of the nuclear force. Single-particle level diagrams for the folded Yukawa potential are also presented. They are plotted as functions of the distortion parameters ?, ?₄ and ?₆. Theoretical and experimental single-particle levels at the ground state for actinide nuclei are also compared.     

The beta-decay energies of103In and104In

The β⁺ spectra of neutron-deficient nuclei with mass numbers 103 and 104 have been measured, using a semiconductor beta spectrometer. The nuclei were produced by on-line mass separation of reaction products formed by bombarding an enriched Mo target with Ne ions. Values for Q_EC have been deduced. The decay energies are in agreement with systematics. The decay of¹⁰⁴In shows remarkably strong feeding to levels above 5 MeV. In addition, Q_EC values for₁₀₃Cd,₁₀₃Ag,₁₀₄Ag and_104mAg have been determined.     

Decay properties of baryonia

Decay properties of baryonia are discussed and widths are estimated for L = 1 states. All presently known candidates for baryonia are shown to have properties consistent with those expected. Several novel characteristics which are to be anticipated are pointed out.     

Nuclear ground-state properties in a relativistic Meson-Field theory

We investigate the ability of a relativistic Mean-Field theory to reproduce nuclear ground state properties by an exhaustive fit to experimental data. We find that the bulk properties of nuclei from¹⁶O to²⁰⁸Pb can be adjusted very well. There remain problems with level density and fluctuations in the charge density similar as in fits using the conventional Skyrme Hartree-Fock model.     

Decay properties of76m Br

The remeasured half-life of^76m Br was found to be 1.31±0.02s.γ-ray and conversion electron measurements gave for two cascading transition energy values 57.11±0.02 and 45.48±0.02 keV with multipolaritiesM2 and M1, respectively. The 4⁺ isomeric state at 102.59±0.04 keV is placed in the⁷⁶Br level scheme. The intensity of the cross-over transition is less than 0.8% of isomeric decays.     

Model simulations of ground-state and finite-temperature properties of disordered magnetic nanostructures

The properties of two-dimensional ensembles of magnetic nanoparticles that interact by magnetic dipole coupling are investigated. The low-temperature magnetic arrangements, the average binding energy E _dip due to dipolar interactions, and its scaling behavior with respect to the particle density C are calculated for different types of structural disorder and particle-size distributions. Many different metastable magnetic states are obtained, which exhibit strong noncollinearities and are reminiscent of a spin-glass behavior. For a given C, |E _dip| increases with increasing disorder of the particle positions. For random distributions at low particle densities C0.2, E _dip is dominated by the contributions of short interparticle distances. Thus, it scales as | E _dip| C with an unusually small exponent = 0.85–1. The straightforward scaling of the dipole interaction, 3/2, is obtained only for C0.5 or for nearly periodic ensembles. The finite temperature behavior of these disordered interacting nanomagnets is explored. The specific heat and magnetic susceptibility are calculated by performing Monte Carlo simulations. The onset of long-range magnetic order is discussed. In addition we determine hysteresis loops at finite temperatures and compare the results for different degrees of disorder.     

Decay properties of139mSm and139Eu

The structure of¹³⁹Sm is investigated through the decay properties of^139mSm and¹³⁹Eu. The decay of^139mSm is measured to have a half-life of (10.7±0.6) s. Gamma-ray and internal conversion electron measurements lead to the construction of a decay pattern comprising seven transitions among five states. The decay of¹³⁹Eu with a measured half-life of (17.9± 0.6) s is studied with beta decay spectroscopy techniques. A decay scheme consisting fourteen states in¹³⁹Sm is proposed. Using deducedft values and transition multipolarities,J ^ρ assignments are made. Nuclear systematics of the odd-A, N=77 and 76 are discussed.     

The ground-state structure and physical properties of RuC: first-principles calculations

We have extensively explored the ground-state structure of RuC using the particle swarm optimization algorithm for crystal structural prediction. A hexagonal R-3m structure has been proposed as the best candidate, which is energetically more favorable than the previously proposed zinc blend structure. The R-3m-RuC possesses alternative stacking of double hexagonal close-packed Ru atom layers and C atom layers, and it is dynamically stable evidenced by the calculation of phonon dispersion. The calculated large bulk modulus, shear modulus, and elastic constant C 44 reveal that it is an ultra-incompressible and hard material. The evidence of strong covalent bonding of Ru-C, which plays an important role to form a hard material, is manifested by the partial densities of states analysis.     

Decay properties of neutron deficient Kr isotopes

The decay properties of the neutron deficient isotopes^73–77Kr and^73–76Br have been studied at the ISOLDE facility at CERN. The total decay energiesQ, as determined fromβ ⁺ singles orβ ⁺ -γ coincidence measurements, are compared with mass formulae.     

Self-consistent calculation of the optical potential and ground-state properties of nuclear matter

On the basis of the Green-function formalism, we performed a self-consistent calculation of the self-energy ∑(k, ω) of a particle interacting with the infinite nuclear medium. The function ∑(k, ω) was mapped out in the energy-momentum plane, and the single-particle energy ω(k), momentum distribution ?(k) and the “on-shell” part of the self-energy, ∑(k, ω(k)), were defined, from which all physical properties followed. In particular we investigated the ground-state properties of nuclear matter in two Λ-approximations of the T-matrix. In one, the intermediate two-particle propagator, Λ₀₀, represented free-particle propagation; in the other, called Λ₁₁, intermediate states included both interacting particles and holes. Pauli principle effects were included in both approximations. The second approximation was expected to be conserving because it included a large part of the rearrangement effects which, we found, contributed ～6 MeV per particle to the average energy and ～28 MeV to the singleparticle energy at zero momentum. The Hugenholtz-van Hove theorem was nearly satisfied, with only 1 MeV separating the chemical potential from the average energy. We also studied, in the Λ₀₀-approximation, the optical potential for the scattering of a particle by a large nucleus; it was directly related to the “on-shell” part of the self-energy. It was found that, below 100 MeV, the real part varied as (?90 + 0.584E) [MeV], and the imaginary part as (2.4 + 0.009 E) [MeV].