Search

A combined mathematical model was developed for the regional-scale dynamics of gaseous admixtures and aerosols in the atmosphere. The model incorporates the following modules: thermo-hydrodynamic equations for meso-scale atmospheric processes in the non-hydrostatic approximation; transport of gaseous admixtures and aerosols, with allowance for photochemical transformation and binary homogeneous nucleation; and kinetic processes of condensation/evaporation and coagulation. Particular emphasis is given to the mechanisms of new-particle formation through binary homogeneous nucleation of drops of sulfuric acid and water vapor. By using this model, numerical experiments were performed to investigate spatio-temporal variations in the concentrations of gaseous admixtures and aerosols, as well as the formation of fine aerosol clusters in the Lake Baikal (Russia) and Antwerp (Belgium) areas due to strong industrial emission sources. The results of the numerical experiments are analyzed.

The JYFL gas-filled recoil separator RITU, combined with Ge detector arrays and a SACRED magnetic solenoid spectrometer, has been successfully employed in recoil-decay-tagging (RDT) experiments in order to probe structures of very neutron-deficient heavy nuclei. The present contribution focuses on the light Pb region where the new data extend the systematics of shape-coexisting yrast states towards the proton dripline. Similarities between band structures and their relation to possible multi-particle multi-hole intruder excitations will be discussed.

Abstract:: Heavy 65-70Co, 68-74Ni, 70-76Cu and 74-81Ga isotopes were produced at the LISOL facility by means of 30 MeV proton-induced fission of 238U. Production rates were deduced and compared to two types of cross-section calculations: the empirical model (V. Rubchenya, private communication) and the PROFI code. Comparison with experimental data favors the latter model. Yields using different beam-target combinations and different energies are calculated and discussed.

Abstract:: Alpha-decay properties of the neutron-deficient isotope 185Pb were studied at the PSB-ISOLDE (CERN) on-line mass separator using the resonance ionisation laser ion source (RILIS). The nuclei of interest were produced in a 1.4 GeV proton-induced spallation reaction of a uranium graphite target. In contrast to previous studies, two α-decaying isomeric states were identified in 185Pb. The relative production of the isomers, monitored by their α-counting rates, could be significantly changed when a narrow-bandwidth laser at the RILIS setup was used to scan through the atomic hyperfine structure. Based on the atomic hyperfine structure measurements, along with the systematics for heavier odd-mass lead isotopes, the spin and the parity of these states were interpreted as 3/2- and 13/2+ and their nuclear magnetic moments were deduced. The α-decay energy and half-life value for the I π = 13/2+ isomer are E α = 6408(5) keV, T 1/2 = 4.3(2) s, respectively; while for the I π = 3/2- isomer ( T 1/2 = 6.3(4) s) two α-decays with E α1 = 6288(5) keV, I α1 = 56(2)% and E α2 = 6486(5) keV, I α2 = 44(2)% were observed. By observing prompt α-γ coincidences new information on the low-lying states in the daughter isotope 181Hg was obtained.

The transition rates of ΔL=0 - transitions in the lightest Po isotopes are considerably slower than the transition rates of the heavier ones, even leading to a considerable deviation in the classical Geiger-Nuttall plot. Evidence will be given that due to particle-hole excitations through the Z=82 proton shell, the groundstate of the lighter Po isotopes becomes deformed and direct - decay to the spherical groundstate of the corresponding Pb isotopes is highly retarded.