Joint Astrophysics Colloquium

For over 30 years the origin of the ultra high energy (>10²⁰ eV) cosmic rays has been the subject of great debate. It is extremely difficult for acceleration (or 'bottom-up') models to explain the observed isotropy of these cosmic rays. Recently many `top-down' models have been proposed to solve this problem. In such models the UHE cosmic rays are the decay products of super-massive relic particles produced in the early universe.

The Haverah Park array operated for nearly 20 years and collected a wealth of data on the UHE cosmic radiation. The construction of the Pierre Auger Observatory (which uses detectors similar to those of Haverah Park) has motivated a re-examination of these data. The results of the re-analysis of Haverah Park data have proved extremely interesting. In particular they have allowed us to put severe constraints on top-down models of UHE cosmic ray origin.

Thursday, October 11th 2001, 12:00
Ernest Rutherford Physics Building, room 305