Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an "Airwatch from Space'' Mission

The longitudinal development and other characteristics of the EECR induced atmospheric showers can be studied from space by detecting the fluorescence light induced in the atmospheric nitrogen. According to the Airwatch concept a single fast detector can be used for measuring both intensity and time development of the streak of fluorescence light produced by the atmospheric shower induced by an EECR. In the present communication the detection capabilities for the EECR observation from space are discussed.Comment: 3 pages (LaTeX). To appear in the Proceedings of TAUP'9

Plasma-wall interaction on boronized tiles studied via x-ray photoemission spectroscopy analysis

Tiles coming from different positions of the first wall of RFX have been analyzed via X-ray Photoemission Spectroscopy (XPS) at Istituto di fisica del plasma. The objectives are to study the erosion and deposition effects during the discharge and to look at the quality of the boron deposition. There is a good agreement between Rutherford Backscattering and XPS on identifying the metals of the first chamber deposited, as oxides, on the surface of the tiles. The different erosion rates, during the plasma discharges, and the differential sputtering rates during XPS profiling, modified their original concentrations. The high concentration of oxygen pointed out a boronization driven in presence of oxygen ga

Kinetics study of the GaP(110)/Cu interface via P L2,3VV Auger line shape and x-ray-photoemission spectroscopies

We have studied the evolution of the GaP(110)/Cu interface as prepared at room-temperature (RT) versus low-temperature (LT100 K) conditions. Electron-excited P L2,3VV and Cu M1VV Auger line shapes and x-ray-excited (h=1253.6 eV) Ga 2p3/2, Ga 3d, P 2p, Cu 2p3/2, and Cu 3p core-level emissions were followed as a function of the Cu coverage (2 up to 80). Regardless of the substrate temperature, substrate disruption is observed at 1 monolayer Cu, with P atoms participating in chemical bonds with deposited Cu. In parallel, the topmost Ga atoms are dislodged from their pristine locations and segregate in a metalliclike environment. These processes persist in the intermediate-coverage range (212 Cu) at both temperatures, being only relatively attenuated at LT. At very high Cu thicknesses, strong chemical intermixing and out-diffusion of substrate-derived species are still observed at RT, while these processes are nearly completely inhibited at LT. © 1990 The American Physical Society

Strong anisotropies in the unoccupied electronic structure of Si(111)/Cu interfaces via polarization dependent Cu L2,3XAS

The partial (s-d) density of empty states at the Cu sites of ultrathin Si(111)/Cu interfaces has been investigated by X-ray absorption spectroscopy (XAS) with linear polarized light at the Cu L2,3edges. The absorption spectra are found to strongly depend on whether the polarization vector is oriented parallel to the surface or nearly normal to it: a metallic character is shown in the former case, whereas a quasi-gap appears in the latter. These anisotropies are found to be extraordinaryly more pronounced in the case of the annealing-induced quasi-5 \uc3\u97 5 Si/Cu interface

Empty state anisotropies in ultrathin Ni/Si(111)7 × 7 and Cu/Si(111)7 × 7 interfaces

L2,3-edge resonances have been measured with synchrotron radiation on submonolayers and monolayers of Ni and Cu deposited on Si(111)7 X 7 at room temperature and after thermal annealing. In both systems the density of empty states shows large anisotropies with respect to the surface normal indicating the 2D character of the electronic structure in the chemisorbed layers and interfaces

Anisotropic empty electron-band states at the pseudo-5X5 SI(111)/CU interface

The partial (s-d) density of empty states at the Cu site in the pseudo-5 x 5 Si(111)/Cu interface has been investigated by polarization-dependent x-ray absorption spectroscopy at the Cu L2,3 edges. The absorption spectra are strongly dichroic showing a metallic edge in the interface plane and a quasigap in the perpendicular direction. The two-dimensional nature of the electron-band states at the pseudo-5 x 5 interface layer is therefore directly probed

Absorption spectroscopy at the Cu-2p edges in Cu/Si(111)7 × 7 interface

We report on a study of the empty states at the Cu/Si(111)7 \uc3\u97 7 interface via polarization-dependent CuL2,3X-ray absorption spectroscopy (XAS) as a function of the Cu coverage (0.25-5 ML). Joint analysis of the CuL3XAS line-shapes of Cu-based reference compounds allows us to interpret the high coverage spectra in terms of pseudo-stoichiometric Cu-silicides