Astroparticle Physics: The High Energy Tail of the Cosmic Ray Spectrum

In this article I review the main theoretical problems that are posed by the highest energy end of the observed cosmic ray spectrum, stressing the importance of establishing their composition in order to decide between proposed scenarios. I then discuss the possibilities that are opened by the detection of inclined showers with extensive air shower arrays. Recent progress in modelling magnetic deviations for these showers has allowed the analysis of inclined showers that were detected by the Haverah Park experiment. This analysis disfavours models that predict a large proportion of photons in the highest energy cosmic rays and open up new possibilities for future shower array detectors particularly those, like the Pierre Auger Observatory, using water Cherenkov detectors.Comment: Latex file, espcrc2.sty, 8 pages, 4 figures, talk given at the EuroConference on Frontiers in Particle Astrophysics and Cosmology, San Feliu de Guixols, October 200

Summary: ZeV Air Showers. Where do we Stand?

Here an attempt is made at summarizing the presentations, most of which were about the highest energy particles observed in nature. Particular attention is paid to the solutions to the Ultra High Energy Cosmic Ray particles, to the new and forthcoming data, to the new proposals for experiments and to the role of primary composition, that were amongst the most discussed subtopics.Comment: 19 pages, LaTeX, aipproc, Summary talk given at the International Workshop on Observing UHECR from space and earth, August 9-12-2000, Metepec, Puebla, Mexic

ZeV Air Showers: The View from Auger

In this article I briefly discuss the characteristics of the Auger observatories paying particular attention to the role of inclined showers, both in the search for high energy neutrino interactions deep in the atmosphere and as an alternative tool for the study of cosmic rays, particulartly their composition.Comment: Latex file, aipproc.sty and epsfig.sty, 10 pages, 5 figures, talk given at the 1st International Workshop on Radio Detection of High Energy Particles (RADHEP-2000), UCLA, November 200

Prospects for radio detection of extremely high energy cosmic rays and neutrinos in the Moon

We explore the feasibility of using the Moon as a detector of extremely high energy (>10^19 eV) cosmic rays and neutrinos. The idea is to use the existing radiotelescopes on Earth to look for short pulses of Cherenkov radiation in the GHz range emitted by showers induced just below the surface of the Moon when cosmic rays or neutrinos strike it. We estimate the energy threshold of the technique and the effective aperture and volume of the Moon for this detection. We apply our calculation to obtain the expected event rates from the observed cosmic ray flux and several representative theoretical neutrino fluxes.Comment: 11 pages, Latex, aipproc.sty and epsfig.sty. 5 ps figures. Talk presented by J. Alvarez-Muniz at the 1st International Workshop on Radio Detection of High Energy Particles (RADHEP-2000), UCLA, November 2000. Some typos corrected. Fig.4 caption extende