Transverse mass and rapidity distributions for charged pions, charged kaons, protons, and antiprotons are reported for square root of [sNN]=200 GeV pp and Au+Au collisions at Relativistic Heary Ion Collider (RHIC). Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.
SummaryThe interactions of Pu(N) and Pu(VI) in alkaline media with some metal hydroxides and oxides commonly found in Hanford Site tank wastes were studied. The properties of mixed hydroxide systems of Pu(IV) with various metal ions mi@), Fe(III), C o o , Al(m), Cr(m>, Zr(IV), La(IlI), and U(VI)] were investigated at variable component ratios using physicalchemical methods. The interactions of P u O with Al(lII), Fe(III), and Cr(IlI) also were studied.It was shown by infrared (IR) spectroscopy that, except for the system Pu(IV)-Ni(II), Pu(IV) interacts with all the listed metal ions and affects their interatomic bonding. The locations of IR absorption bands of the mixed hydroxides change irregularly compared with the spectra of pure components, with change in the Pu:metal mole ratio of from 1:lO to 1O:l. The changes occur both for the valent and deformation vibration bands of hydroxyl ions and water at 3600 to 3100 and 1750 to 1250 cm-' and for the vibrations of metal-oxygen (M-0) bridging bonds in the range of 1050 to 850 cm-'. In the Pu(IV)/Ni(II) system, the IR spectra are equivalent to the sum of the individual components precipitated separately from alkaline solution.The separate precipitation of h(N) hydrous oxide and Ni(OH), upon adding NaOH solution to acidic solution containing both Pu(N) and Ni(II) nitrate was confirmed by studying the dissolution rate of the resulting precipitate in 3 M HCl at 60°C. No difference in plutonium dissolution behavior was found for pure PuO,-xH,O and the products obtained by alkaline precipitation of 1: 1 mole ratio Pu(N):Ni(II) mixtures, aged for 1 hour at 70"C, over a wide range of NaOH concentrations. Similar results were obtained for the Pu(IV)-Al(III) system. Only trace amounts of aluminum were detected in pUO,.xl&O precipitates formed even in relatively dilute NaOH solutions.
SummaryThis investigation was undertaken to obtain new data on the composition and properties of . plutonium(IV) compounds formed under diverse conditions in strongly alkaline media in the presence of various anions. Such information is important to understand P u o behavior and the forms of its existence in the alkaline sludges of Hanford Site radioactive waste tanks. The knowledge then may be applied to assess plutonium disposition in the 'storage, retrieval, and treatment of Hanford Site tank wastes with respect to its criticality hazards and contribution to the transuranic waste inventory.In all studied cases, P u o precipitates from 0.2 to 10 M NaOH solutions at 10 to 200°C to form nearly amorphous compounds of general composition Pu02'xH20. Extended aging of the compounds does not produce well-crystallized phases. Aging was accelerated by coagulation at elevated temperatures, including hydrothermal conditions. The number of water molecules, x, associated with the Pu02 solid depends strongly on the PuO~.xH20 drying conditions but is not sensitive to the precipitation method (direct or reverse) or the coagulation time. For PuO~.xH20 solids prepared at 10 to 60°C and dried at 20°C in desiccators over KOH pellets (1.7 torr H20 vapor pressure) or over 25% H2SO4 (14.6 torr H20 water vapor pressure), mean values of x are 1 . 6 and 2.8, respectively. The large difference in these values confims the strongly hygroscopic properties of h02.xH20. The x values decrease with increasing temperature. ' The composition of PuO~xH20 obtained at 180 to 200°C and dried over KOH has an average x of 0.60. Thermogravimetric scans of various PuO~.xH20 samples were similar regardless of compound preparation conditions. In all cases, the mass loss occurred monotonously, in one step, in the range 50 to 250°C. All differential thermal analyses showed mildly endothermic peaks at about 110°C. This confirmed that the water in PuOrxH20 does not have discrete states but has a continuous range of bonding energy.Anhydrous P u 0 2 , produced by heating Pu02'xH20, is strongly hygroscopic. The hygroscopicity remained even after prolonged heating at 500"C, disappearing only at 800°C. The minor influence of temperature on Pu02'xH20 hygroscopicity can be explained by the rather high thermal stability of the primary crystallites. This supposition was confirmed by direct estimates of PuOrxH2O crystallite size by an X-ray powder diffraction method. It was found that PuOn.xH20 crystallite size increases only from about 2.5 to 7 nm in the range 20 to 800°C. * Infrared (IR) spectra of PuO~.xH20 solids prepared under different conditions closely resemble each other and show an intense band with maximum at 3400 cm-', three weak bands in the range 1700 to 1250 cm-', and an additional strong and generally split band between 600 and 350 cm-'. The band at 3400 cm-', arising from valent water vibrations in the PuO~.xH20 structure, is relatively wide and smooth and without shoulder. This observation confirms the assumption that water molecules have no discrete...
The molecular and crystal structures of the title compound, C4H4Cl2N2O3, were investigated by single-crystal X-ray diffraction and a Hirshfeld surface analysis. The title compound was synthesized by a new type of reaction using Mg(ReO4)2 as a new catalyst and a possible mechanism for this reaction is proposed. The six-membered ring adopts a half-chair conformation. In the crystal, hydrogen bonds connect the molecules into double layers, which are connected to each other by halogen bonds. The Hirshfeld surface analysis revealed that the most important contributions for the crystal packing are from O...H/H...O (35.8%), Cl...Cl (19.6%), Cl...H/H...Cl (17.0%), H...H (8.3%), C...O/O...C (4.3%), Cl...O/O...Cl (4.2%) and O...O (4.1%) contacts.
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