This award will support collaborative research between Drs. Thomas K. Gaisser and Todor Stanev, Bartol Research Institute and Dr. A.M. Hillas, University of Leeds, U.K. Drs. Gaisser and Stanev will travel to Leeds to work on a data analysis of the South Pole Air Shower Experiment (SPASE), which is an ongoing joint experiment of the two institutions. The purpose of the experiment is to inspect the arrival direction of detected air showers and to search for point sources of ultra-high energy gamma-rays. The search for extraterrestrial sources of ultra-high energy gamma-rays is an extremely interesting astrophysical problem, related to the acceleration of the cosmic rays in the Galaxy and to processes and models of X-ray binary systems. The South Pole location provides a unique opportunity for uninterrupted observations of the southern sky, which is expected to be rich in sources. In addition, SPASE is ideally situated to look for ultra-high energy gamma-rays from the new Supernova, SN 1987a. The discovery of such a signal would be of great importance for understanding acceleration processes and evolution of young supernovae. The detector that will be used for the experiment is very similar to the array now deployed by the Leeds group in England to look for signals from Northern Hemisphere sources. Close coordination of data acquisition and comparison of two independent analyses of the data are essential for success of the experiment. This research brings together three of the leading experts in the analysis of air shower experiments.
