The status of ultra high energy cosmic ray measurements and prospects for the future

by Alan WATSON (Leeds University)

Tuesday 18 Mar 2003, 16:30 → 17:30 Europe/Zurich

500/1-001 - Main Auditorium (CERN)

There is on-going interest in ultra high-energy cosmic rays. This, in part, is because of the prediction, made in 1966, that cosmic rays above about 5 x 10¹⁹ eV would be severely attenuated if their sources lay at cosmological distances. This prediction has become known as the Greisen-Zatsepin-Kuzmin (GZK) cut-off, but the question of its existence, or otherwise, is still unanswered. I will review the experimental evidence and argue that, although more statistics are certainly needed, there is good evidence that trans-GZK events do exist. There is much speculation about the origin of such events. I will show that there is strong experimental evidence against most of the events above 10¹⁹ eV being photons and hence that an explanation of their origin in terms of super-heavy relic particles from the early Universe is unlikely. A major increase in statistics is needed and requires new experiments. I will review the status of the southern Pierre Auger Observatory, which is being constructed over an area of 3000 km² in Argentina. I will demonstrate its potential by discussing some events from the first data currently being collected. Prospects for the detection of high-energy neutrinos will also be outlined. Additionally, I will discuss the prospects for the HiRes fluorescence detector, and describe progress on EUSO.

Organiser(s): Jasper Kirkby / EP Division

Note: * Tea & coffee will be served at 16.00 hrs.