•Heavy metals partitioning between consecutive stages of ESP has been compared for different coals.•The concentration of heavy metals in fly ashes from Polish coals is at a level similar to mean ...values from other coals.•The concentration of heavy metals increased in fly ash from the consecutive fields of ESP.•The concentration of heavy metals correlates with decreasing mean size of precipitated particles.•Heavy metals are mainly retained in the finest particles of fly ash due to their deposition on the particle surface.
The paper presents experimental studies of heavy metals partitioning in fly ash particles after combustion of various types of coal (lignite, sub-bituminous, bituminous, and anthracite) between different fields of electrostatic precipitator. The concentration of the following heavy metals has been measured: Ba, Sr, Zn, Cu, Ni, Cr, As, Co, Pb. The results show that the concentration of heavy metals is higher in small particles (<1μm) than in larger ones that correlates with consecutive fields of electrostatic precipitator. This relation is independent of the type of combusted coal, although differences in the values of concentrations of individual elements exist. Better knowledge on heavy metal partitioning in the combustion-precipitation system is needed for the development of emission control devices of higher efficiency, such as electrostatic agglomerators or hybrid filters, particularly for PM1 particles. The results of these investigations can also be helpful in the designing of novel physical and chemical processes for recovery selected trace elements from fly ash, for their further utilization.
The first 2+ and 3- states of the doubly magic nucleus 132Sn are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the ...highly efficient MINIBALL array. The 132Sn ions are accelerated to an energy of 5.49 MeV / nucleon and impinged on a 206Pb target. Deexciting γ rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0g.s.+→21+, 0g.s.+→31-, and 21+→31- in 132Sn. The results on these states provide crucial information on cross-shell configurations which are determined within large-scale shell-model and Monte Carlo shell-model calculations as well as from random-phase approximation and relativistic random-phase approximation. The locally enhanced B(E2;0g.s.+→21+) strength is consistent with the microscopic description of the structure of the respective states within all theoretical approaches. The presented results of experiment and theory can be considered to be the first direct verification of the sphericity and double magicity of 132Sn.
There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity ...in radium isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator.
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A bismuth-germanate (BGO) escape-suppression shield for the high-purity germanium triple-cluster detector of the MINIBALL
γ
-ray spectrometer was designed and built. Monte Carlo simulations with ...the simulation code GEANT4 were performed to guide the construction and to determine the detector geometry of the new BGO shield. After the first measurements concerning mechanical properties of the BGO housing and the performance of the photomultiplier tubes at the Institut de Physique Nucléaire, Orsay, the prototype BGO escape-suppression shield was combined with a MINIBALL triple-cluster detector at the Institut für Kernphysik, Cologne. A dedicated electronics and digital data-acquisition system was put into operation in order to determine timing properties of the combined coincidence measurement and to measure values for the energy resolution of the BGO detectors, for the BGO low-energy threshold, and for the crucial peak-to-total ratio (P/T). The measured P/T value for a standard
60
Co
γ
-ray source compares well with expectations and will allow to proceed with the amendment of the MINIBALL triple-cluster detectors with an escape-suppression shield for improved in-beam
γ
-ray spectroscopy especially at the new HIE-ISOLDE accelerator for radioactive ion beams at CERN.
The first 2^{+} and 3^{-} states of the doubly magic nucleus ^{132}Sn are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with ...the highly efficient MINIBALL array. The ^{132}Sn ions are accelerated to an energy of 5.49 MeV/nucleon and impinged on a ^{206}Pb target. Deexciting γ rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0_{g.s.}^{+}→2_{1}^{+}, 0_{g.s.}^{+}→3_{1}^{-}, and 2_{1}^{+}→3_{1}^{-} in ^{132}Sn. The results on these states provide crucial information on cross-shell configurations which are determined within large-scale shell-model and Monte Carlo shell-model calculations as well as from random-phase approximation and relativistic random-phase approximation. The locally enhanced B(E2;0_{g.s.}^{+}→2_{1}^{+}) strength is consistent with the microscopic description of the structure of the respective states within all theoretical approaches. The presented results of experiment and theory can be considered to be the first direct verification of the sphericity and double magicity of ^{132}Sn.
Low-lying states in the isotope Xe130 were populated in a Coulomb-excitation experiment performed at CERN's HIE-ISOLDE facility. The magnitudes and relative signs of seven E2 matrix elements and one ...M1 matrix element coupling five low-lying states in Xe130 were determined using the semiclassical coupled-channel Coulomb-excitation least-squares search code gosia. The diagonal E2 matrix elements of both the 21+ and 41+ states were extracted for the first time. The reduced transition strengths are in line with those obtained from previous measurements. Experimental results were compared with the general Bohr Hamiltonian with the microscopic input from mean-field theory utilizing universal nuclear energy density functional (UNEDF0), shell-model calculations using the GCN50:82 and SN100PN interactions, and simple phenomenological models (Davydov-Filippov and γ-soft). The extracted shape parameters indicate triaxial-prolate deformation in the ground-state band. In general, good agreement between theoretical predictions and experimental values was found, while neither phenomenological model was found to provide an adequate description of Xe130.
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