Alessandro D. de Angelis

CONSTRAINTS ON LARGE-SCALE MAGNETIC FIELDS FROM THE AUGER RESULTS

A recent article from the Pierre Auger Collaboration links the direction of charged cosmic rays to possible extragalactic sites of emission. The correlation of the direction of such particles with the direction of the emitter allows constraining the value of large-scale magnetic fields B. Assuming for B a coherence length λ in the range between 1 Mpc and 10 Mpc, we find values of B between 0.3 and 0.9 nG.

Domenico Pacini and the discovery of cosmic rays

The discovery of cosmic rays, a milestone in science, comprised scientists in Europe and in the New World and took place during a period characterised by nationalism and lack of communication. Many scientists that took part in this research a century ago were intrigued by the penetrating radiation and tried to understand the origin of it. Several important contributions to the discovery of the origin of cosmic rays have been forgotten and in particular that of Domenico Pacini, who in June 1911 demonstrated by studying the decrease of radioactivity with an electroscope immersed in water that cosmic rays could not come from the crust of the Earth. Several historical, political and personal facts might have contributed to the substantial disappearance of Pacini from the history of science.

Interconnections effects in multiparticle production from WW events at LEP

Abstract Interactions between the products of the hadronic decays of different Ws in WW pair events can occur at several stages: from the colour rearrangement between the quarks coming from the primary branching, to the gluon exchange during the parton cascade, to the mixing of identical pions due to Bose-Einstein correlations. Besides the intrinsic interest of their study related to the understanding of the multiparticle production mechanisms, these phenomena can affect the ultimate accuracy in the W mass measurement by LEP 2. The status of the experimental analysis on interconnection effects between W pairs hadronically decaying is reviewed in this paper.

Neural networks for offline analysis in high-energy physics

Feed-Forward Neural Networks are nowadays a standard tool in the toolbox of high energy physicists. This talk summarizes the fields of application in ofl1line analysis, and discusses some open problems.