Energy-sharing asymmetries in ionization by positron impact

The triply differential cross section of molecular hydrogen for ionization by 50 eV positrons has been determined, for the first time, for both the ejected electron in coincidence with the remnant ion and for the scattered projectile. Asymmetries in the energy sharing between the two light particles in the final state are observed, with the electron spectrum being shifted to significantly lower (and the scattered positron to correspondingly higher) energies than expected. A similar shape is observed in the case of the ejected electron spectrum from a helium target at the same excess energy

Fragmentation of positronium in collision with He atoms

The absolute cross section for the fragmentation of positronium in collision with He atoms has been measured. The results are compared with available theories. The longitudinal energy distributions of positrons resulting from fragmentation have also been determined and are found to display a peak situated just below half the residual energy. This is suggestive of the occurrence of "electron loss to the continuum" in which the two residual charged particles lie in a low relative-velocity Coulomb-continuum state

Resonant scattering of positronium as a quasifree electron

In order to clarify the physics underlying the observations of the electronlike behavior of positronium (Ps) and its resonant scattering from CO2, we have measured the Ps+N2 total cross section and found it also to exhibit significant structure. Analysis of the resonances reveals that Ps is distorted in the collisions and classical trajectory Monte Carlo calculations indicate that the electron is on average closer to the target than the positron, which may in turn bind resonantly to the ensuing temporary negative ion. This description of the nature of Ps resonances agrees with long-standing theoretical predictions

Monitoraggio ambientale tramite tecnologia LoRaWAN: misurazioni sperimentali e piattaforma di data analytics

I requisiti di molte applicazioni IoT necessitano di trasmettere dati su lunghe distanze, con basso data rate e con il minor impatto possibile sul consumo energetico. Le tecnologie LPWAN (Low Power Wide Area Network) sono state progettate per complementare ed in alcuni casi sostituire le soluzioni offerte dalla reti cellulari e dalle reti di sensori a corto/medio raggio. Nonostante la pletora di standards LPWAN disponibili sul mercato, la tecnologia LoRa/LoRaWAN sta riscuotendo notevole successo grazie alle performance che riesce a garantire. L’imponente mole di dati generata dalle applicazioni IoT richiede soluzioni in grado di poter archiviare e gestire in maniera efficiente il ciclo di vita delle informazioni. L’utilizzo di piattaforme di data analytics basate su sistemi NoSQL permettono una gestione più agile dei Big Data. In questa tesi è stata progettata ed implementata un’infrastruttura per il monitoraggio ambientale tramite LoRaWAN e la relativa piattaforma di data analytics adoperata per lo studio delle metriche relative alla trasmissione radio LoRa. I risultati ottenuti dalla sperimentazione possono essere usati per fare tuning delle configurazioni per il deploy in contesti reali

Studio ed edizione del canzoniere di Guiraut de Calanso

Edizione critica del corpus lirico di Guiraut de Calans

Absolute differential positronium-formation cross sections

The first absolute experimental determinations of the differential cross-sections for the formation of ground-state positronium are presented for He, Ar, H2 and CO2 near 0○. Results are compared with available theories. The ratio of the differential and integrated cross-sections for the targets exposes the higher propensity for forward-emission of positronium formed from He and H2

High-Resolution Measurements of e+ + H2O Total Cross Section

Using a purely positron beam, the total cross section of positrons scattering from H2O has been measured for the first time with a high angular discrimination (≃1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section