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1.
L. Biasetto M. Manzolaro A. Andrighetto G. Meneghetti S. Carturan P. Zanonato P. Colombo G. Prete 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):517-521
The target is one of the key issues of isotope separation on line (ISOL) facilities. SPES, now under development at LNL-INFN,
is an innovative ISOL facility possessing a target chatacterized by seven separate uranium dicarbide thin disks. The research
on the materials development and target prototyping is discussed in the following. 相似文献
2.
Rao L Zhang Z Zanonato P Di Bernardo P Bismondo A Clark SB 《Dalton transactions (Cambridge, England : 2003)》2004,(18):2867-2872
The complexation between Th(IV) and acetate in 1.05 mol kg(-1) NaClO4 was studied at variable temperatures (10, 25, 40, 55 and 70 degrees C). The formation constants of five successive complexes, Th(Ac)j(4-j)+ where Ac = CH3COO- and j = 1-5, and the molar enthalpies of complexation were determined by potentiometry and calorimetry. Extended X-ray absorption fine structure spectroscopy (EXAFS) provided additional information on the complexes in solution. The effect of temperature on the stability of the complexes is discussed in terms of the electrostatic model. 相似文献
3.
D. Scarpa L. Biasetto S. Corradetti M. Manzolaro A. Andrighetto S. Carturan G. Prete P. Zanonato D. W. Stracener 《The European Physical Journal A - Hadrons and Nuclei》2011,47(3):32
In the framework of the R&D program for the SPES (Selective Production of Exotic Species) project of the Istituto Nazionale
di Fisica Nucleare (INFN), production yields of neutron-rich isotopes have been measured at the Holifield Radioactive Ion
Beam Facility (HRIBF, Oak Ridge National Laboratory, USA). This experiment makes use of the multi-foil SPES target prototype
composed of 7 uranium carbide discs, with excess of graphite (ratio C/U = 4 . 77 isotopes of medium mass (between 72 and 141amu), produced via proton-induced fission of uranium using a 40MeV proton
beam, have been collected and analyzed for the target heated at 2000 ° C target temperature. 相似文献
4.
Zanonato P Di Bernardo P Bismondo A Liu G Chen X Rao L 《Journal of the American Chemical Society》2004,126(17):5515-5522
The hydrolysis of uranium(VI) in tetraethylammonium perchlorate (0.10 mol dm(-3) at 25 degrees C) was studied at variable temperatures (10-85 degrees C). The hydrolysis constants (*beta(n,m)) and enthalpy of hydrolysis (Delta H(n,m)) for the reaction mUO(2)(2+) + nH(2)O = (UO(2))(m)(OH)(n)((2m-n))+) + nH(+) were determined by titration potentiometry and calorimetry. The hydrolysis constants, *beta(1,1), *beta(2,2), and *beta(5,3), increased by 2-5 orders of magnitude as the temperature was increased from 10 to 85 degrees C. The enthalpies of hydrolysis, Delta H(2,2) and Delta H(5,3), also varied: Delta H(2,2) became more endothermic while Delta H(5,3) became less endothermic as the temperature was increased. The heat capacities of hydrolysis, Delta C(p(2,2)) and Delta C(p(5,3)), were calculated to be (152 +/- 43) J K(-1) mol(-1) and -(229 +/- 34) J K(-1) mol(-1), respectively. UV/Vis absorption spectra supported the trend that hydrolysis of U(VI) was enhanced at elevated temperatures. Time-resolved laser-induced fluorescence spectroscopy provided additional information on the hydrolyzed species at different temperatures. Approximation approaches to predict the effect of temperature were tested with the data from this study. 相似文献
5.
M. Barbui A. Andrighetto C. Antonucci S. Carturan F. Cervellera S. Cevolani M. Cinausero P. Colombo A. Dainelli P. Di Bernardo F. Gramegna G. Maggioni G. Meneghetti C. Petrovich L. Piga G. Prete V. Rizzi M. Santana-Leitner M. Tonezzer P. Zanonato D. Zafiropoulos 《The European physical journal. Special topics》2007,150(1):275-276
A Direct Target for a mid-term RIB ISOL-type facility is being developed at LNL, in the framework of the R&D for the SPES
project [1]. Using a 40 MeV proton beam impinging on a UCx thick target of 2.5 g/cm3 density, a production rate of 1013 in target fissions per second is expected [2]. The crucial point, when short-lived isotopes are produced in the target, is
to build systems (target + ion source) with good release properties and high efficiency.
Monte Carlo simulations were performed using the GEANT4 toolkit [3] and the RIBO code [4] in order to optimize our target
geometry and to estimate the average release time. 相似文献
6.
7.
S. Corradetti L. Biasetto M. Manzolaro D. Scarpa A. Andrighetto S. Carturan G. Prete P. Zanonato D. W. Stracener 《The European Physical Journal A - Hadrons and Nuclei》2011,47(10):119
The temperature dependence of neutron-rich isotope yields was studied within the framework of the HRIBF-SPES Radioactive Ion
Beams (RIB) project. On-line release measurements of fission fragments from a uranium carbide target at $\ensuremath 1600 {}^{\circ}\mathrm{C}$\ensuremath 1600 {}^{\circ}\mathrm{C} , 1800 °C\ensuremath 1800 {}^{\circ}\mathrm{C} and 2000 °C\ensuremath 2000 {}^{\circ}\mathrm{C} were performed at ORNL (USA). The fission reactions were induced by a 40MeV proton beam accelerated into a uranium carbide
target coupled to a plasma ion source. The experiments allowed for tests of performance of the SPES multi-foil target prototype
loaded with seven UC2/graphite discs (ratio C/U = 4 with density about 4g/cm3. 相似文献
8.
Linfeng Rao Guoxin Tian Thandankorai G. Srinivasan PierLuigi Zanonato Plinio Di Bernardo 《Journal of solution chemistry》2010,39(12):1888-1897
Spectrophotometric titrations were performed to identify the Np(V)/acetate complex and determine the equilibrium constants
at various temperatures (T=283 to 343 K) and at the ionic strength 1.05 mol⋅kg−1. The enthalpies of complexation at the corresponding temperatures were determined by microcalorimetric titrations. Results
show that the complexation of Np(V) with acetate is weak but strengthens as the temperature increases. The complexation reaction
is endothermic and entropy driven. The enhancement of complexation at higher temperatures is primarily due to the increasingly
larger entropy gain when the solvent molecules are released from the highly-ordered solvation spheres of NpO2+\mathrm{NpO}_{2}^{+} and acetate to the bulk solvent where the degree of disorder is higher at higher temperatures. 相似文献
9.
10.
Zanonato PL Di Bernardo P Grenthe I 《Dalton transactions (Cambridge, England : 2003)》2012,41(12):3380-3386
The composition and equilibrium constants of the complexes formed in the binary U(VI)-hydroxide and the ternary U(VI)-hydroxide-peroxide systems have been studied using potentiometric and spectrophotometric data at 25 °C in a 0.100 M tetramethylammonium nitrate medium. The data for the binary U(VI) hydroxide complexes were in good agreement with previous studies. In the ternary system two complexes were identified, [UO(2)(OH)(O(2))](-) and [(UO(2))(2)(OH)(O(2))(2)](-). Under our experimental conditions the former is predominant over a broad p[H(+)] region from 9.5 to 11.5, while the second is found in significant amounts at p[H(+)] < 10.5. The formation of the ternary peroxide complexes results in a strong increase in the molar absorptivity of the test solutions. The absorption spectrum for [(UO(2))(2)(OH)(O(2))(2)](-) was resolved into two components with peaks at 353 and 308 nm with molar absorptivity of 16200 and 20300 M(-1) cm(-1), respectively, suggesting that the electronic transitions are dipole allowed. The molar absorptivity of [(UO(2))(OH)(O(2))](-) at the same wave lengths are significantly lower, but still about one to two orders of magnitude larger than the values for UO(2)(2+)(aq) and the binary uranyl(VI) hydroxide complexes. It is of interest to note that [(UO(2))(OH)(O(2))](-) might be the building block in cluster compounds such as [UO(2)(OH)(O(2))](60)(60-) studied by Burns et al. (P. C. Burns, K. A. Kubatko, G. Sigmon, B. J. Fryer, J. E. Gagnon, M. R. Antonio and L. Soderholm, Angew. Chem. 2005, 117, 2173-2177). Speciation calculations using the known equilibrium constants for the U(vi) hydroxide and peroxide complexes show that the latter are important in alkaline solutions even at very low total concentrations of peroxide, suggesting that they may be involved when the uranium minerals Studtite and meta-Studtite are formed by α-radiolysis of water. Radiolysis will be much larger in repositories for spent nuclear fuel where hydrogen peroxide might contribute both to the corrosion of the fuel and to transport of uranium in a ground water system. 相似文献