Photocathodes: the state of the art and some news

Abstract The present cesium telluride cathodes have the capability to provide, for months, trains of picosecond pulses carrying a charge equal/higher than 10 nanocoulomb, for a total charge higher than the microcoulomb. However, they are very delicate. A possible way to increase their robustness is by covering them with a protective film of nanostructured carbon. Ferroelectric ceramics, as possible new robust photocathodes, showed an interesting level of emission with 532 nm–25 ps laser pulses

Time domain add-drop multiplexing scheme enhanced using a saw-tooth pulse shaper

We experimentally demonstrate the use of saw-tooth optical pulses, which are shaped using a fiber Bragg grating, to achieve robust and high performance time-domain add-drop multiplexing in a scheme based on cross-phase (XPM) modulation in an optical fiber, with subsequent offset filtering. As compared to the use of more conventional pulse shapes, such as Gaussian pulses of a similar pulse width, the purpose-shaped saw-tooth pulses allow higher extinction ratios for the add and drop windows and significant improvements in the receiver sensitivity for the dropped and added channels

Muon production and accumulation from positrons on target

In this paper we investigate the production of a muon beam by positrons on target. We describe the characteristics of the muon beam as produced by different target configurations. We present an optics for the muon accumulator ring, discussing how it fulfils the large energy acceptance requirement and the high order chromaticity correction at the target, as well as other parameters relevant to enhance the muon bunch quality. We discuss the muon beam dynamics through the ring for the configuration of the single-pass LEMMA scheme, and the optimization study performed with the goals of maximizing the muon bunch population and minimizing its emittance

Apparent superluminal advancement of a single photon far beyond its coherence length

We present experimental results relative to superluminal propagation based on a single photon traversing an optical system, called 4f-system, which acts singularly on the photon's spectral component phases. A single photon is created by a CW laser light down{conversion process. The introduction of a linear spectral phase function will lead to the shift of the photon peak far beyond the coherence length of the photon itself (an apparent superluminal propagation of the photon). Superluminal group velocity detection is done by interferometric measurement of the temporal shifted photon with its correlated untouched reference. The observed superluminal photon propagation complies with causality. The operation of the optical system allows to enlighten the origin of the apparent superluminal photon velocity. The experiment foresees a superluminal effect with single photon wavepackets.Comment: 11 pages, 2 figure

Confronto dei contenuti formativi delle scuole di specializzazione dell'area di sanità pubblica: le basi razionali per una proposta di core curriculum per il percorso formativo universitario ex art. 38, D.Lgs 81/2008

E' un confronto dei contenuti formativi delle scuole di specializzazione dell'area di sanità pubblica secondo il nuovo ordinamento al fine della proposta di core curriculum per il percorso formativo universitario ex art. 38, D.Lgs 81/2008 per specializzati in Igiene e Medicina legale, che conseguire i requisiti formativi per la nomina di Medico competente. Nel confronto si ravvisano carenze formative per quanto riguarda il contenuto di valutazione del rischio e prevenzione per gli specializzandi in Medicina legale, mentre carente è il contenuto in approfondimento clinico-diagnostico per gli specializzandi in Igiene. Si propone uno scheda di formazione annuale di percorso universitario

Comprehensive Analysis of Graphene Geometric Diodes: Role of Geometrical Asymmetry and Electrostatic Effects

A self-consistent Monte Carlo/3-D Poisson simulator has been developed to analyze the current asymmetry in graphene geometric diodes. The model couples ballistic transport in the graphene layer with 3-D electrostatics in the graphene and oxide substrate. Results are given in terms of transmission coefficients and currents at the two terminals of the diode. We prove that while the current asymmetry is mainly induced by ballistic transport in the asymmetric structure, the electrostatics plays a relevant role that tends to substantially counterbalance the geometrical effect