Gli ovini nella monetazione greco-romana tra culto ed economia

Short account of the central position of sheep in the Greek and Roman coinage, particularly rams in the language and in the pre-coinage forms as aspect of religiosity and element of sacrifices, with some examples taken from the archaic, classical and Hellenistic Greek coinage, through Roman Republican denarii to Roman Imperial and Provincial issues (as Cyrene or Antinous)

Spin Hall and Edelstein effects in metallic films: from 2D to 3D

A normal metallic film sandwiched between two insulators may have strong spin-orbit coupling near the metal-insulator interfaces, even if spin-orbit coupling is negligible in the bulk of the film. In this paper we study two technologically important and deeply interconnected effects that arise from interfacial spin-orbit coupling in metallic films. The first is the spin Hall effect, whereby a charge current in the plane of the film is partially converted into an orthogonal spin current in the same plane. The second is the Edelstein effect, in which a charge current produces an in-plane, transverse spin polarization. At variance with strictly two-dimensional Rashba systems, we find that the spin Hall conductivity has a finite value even if spin-orbit interaction with impurities is neglected and "vertex corrections" are properly taken into account. Even more remarkably, such finite value becomes "universal" in a certain configuration. This is a direct consequence of the spatial dependence of spin-orbit coupling on the third dimension, perpendicular to the film plane. The non-vanishing spin Hall conductivity has a profound influence on the Edelstein effect, which we show to consist of two terms, the first with the standard form valid in a strictly two-dimensional Rashba system, and a second arising from the presence of the third dimension. Whereas the standard term is proportional to the momentum relaxation time, the new one scales with the spin relaxation time. Our results, although derived in a specific model, should be valid rather generally, whenever a spatially dependent Rashba spin-orbit coupling is present and the electron motion is not strictly two-dimensional.Comment: 23 pages, 3 figure

ATLAS RPC offline monitoring and data quality assessment

In this work several aspects of ATLAS RPC offline monitoring and data quality assessment are illustrated with cosmics data selected by RPC trigger. These correspond to trigger selection, front-end mapping, detection efficiency and occupancy, which are studied in terms of low level quantities such as: RPC off-line hits and standalone tracks. The tools and techniques presented are also extended to the forthcoming LHC p-p beam collisions.Comment: Poster section at ICHEP08, Philadelphia, USA, July 2008. 3 pages, LaTeX, 3 eps figure

Spacetime geometries and light trapping in travelling refractive index perturbations

In the framework of transformation optics, we show that the propagation of a locally superluminal refractive index perturbation (RIP) in a Kerr medium can be described, in the eikonal approximation, by means of a stationary metric, which we prove to be of Gordon type. Under suitable hypotheses on the RIP, we obtain a stationary but not static metric, which is characterized by an ergosphere and by a peculiar behaviour of the geodesics, which are studied numerically, also accounting for material dispersion. Finally, the equation to be satisfied by an event horizon is also displayed and briefly discussed.Comment: 14 pages, 7 figure

Spin polarizations and spin Hall currents in a two-dimensional electron gas with magnetic impurities

We consider a two-dimensional electron gas in the presence of Rashba spin-orbit coupling, and study the effects of magnetic s-wave impurities and long-range non-magnetic disorder on the spin-charge dynamics of the system. We focus on voltage induced spin polarizations and their relation to spin Hall currents. Our results are obtained using the quasiclassical Green function technique, and hold in the full range of the disorder parameter $\alpha p_F\tau$.Comment: 5 pages, 2 figures. References added, minor stylistic modification

Analogue Gravity and ultrashort laser pulse filamentation

Ultrashort laser pulse filaments in dispersive nonlinear Kerr media induce a moving refractive index perturbation which modifies the space-time geometry as seen by co-propagating light rays. We study the analogue geometry induced by the filament and show that one of the most evident features of filamentation, namely conical emission, may be precisely reconstructed from the geodesics. We highlight the existence of favorable conditions for the study of analogue black hole kinematics and Hawking type radiation.Comment: 4 pages, revised versio

ATLAS RPC Quality Assurance results at INFN Lecce

The main results of the quality assurance tests performed on the Resistive Plate Chamber used by the ATLAS experiment at LHC as muon trigger chambers are reported and discussed. Since July 2004, about 270 RPC units has been certified at INFN Lecce site and delivered to CERN, for being integrated in the final muon station of the ATLAS barrel region. We show the key RPC characteristics which qualify the performance of this detector technology as muon trigger chamber in the harsh LHC enviroments. These are dark current, chamber efficiency, noise rate, gas volume tomography, and gas leakage.Comment: Comments: 6 pages, 1 table, 9 figures Proceedings of XXV Physics in Collision-Prague, Czech Republic, 6-9 July 200

Neutron Energy Spectrum Measurements with a Compact Liquid Scintillation Detector on EAST

A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and gamma-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI (Tl) gamma-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.Comment: 19 pages,10 figures, 1 tabl