Charge Distribution and Local Structure and Speciation in the UO2+x and PuO2+x Binary Oxides for x <0.25.

The local structure and chemical speciation of the mixed valence, fluorite based oxides UO2+x (0.00pxp0.20) and PuO2+x PuO2+xy(OH)2y zH2O have been determined by U Pu LIII XAFS spectroscopy. The U spectra indicate (1) that the O atoms are incorporated as oxo groups at short (1.75A) U O distances consistent with U(VI) concomitant with a large range of U displacements that reduce the apparent number of U neighbors and (2) that the UO2 fraction remains intact implying that these O defects interact to form clusters and give the heterogeneous structure consistent with the diffraction patterns. The PuO2+x system, which does not show a separate phase at its x 1:4 0:25 endpoint, also displays (1) oxo groups at longer 1.9A distances consistent with Pu(V+d), (2) a multisite Pu O distribution even when x is close to zero indicative of the formation of stable species with H2O and its hydrolysis products with O2, and (3) a highly disordered, spectroscopically invisible Pu Pu component. The structure and bonding in AnO2+x are therefore more complicated than have previously been assumed and show both similarities but also distinct differences among the different elements.JRC.E.6-Actinides researc

CMS physics technical design report: Addendum on high density QCD with heavy ions

This report presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC). The collisions of lead nuclei at energies ,will probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research is to study the fundamental theory of the strong interaction - Quantum Chromodynamics (QCD) - in extreme conditions of temperature, density and parton momentum fraction (low-x). This report covers in detail the potential of CMS to carry out a series of representative Pb-Pb measurements. These include "bulk" observables, (charged hadron multiplicity, low pT inclusive hadron identified spectra and elliptic flow) which provide information on the collective properties of the system, as well as perturbative probes such as quarkonia, heavy-quarks, jets and high pT hadrons which yield "tomographic" information of the hottest and densest phases of the reaction.0info:eu-repo/semantics/publishe