9321949 Sokolsky This grant supports research with the Fly's Eye detector and prototype improved High Resolution (HiRes) versions of that device to study cosmic-rays at the very highest energies yet observed or expected to be observed on earth. A 14-mirror prototype Hi Res array has been in operation since March, 1993 at one site and a 4-mirror array at another, 13 km distant, has been in operation since the beginning of 1994 at the Dugway proving grounds in Utah. Together, the two arrays allow stereo reconstruction of shower directions. Events are also detected in coincidence with CASA/MIA ground array and with Fly's Eye II 3.4km distant. The Utah group in collaboration with physicists from Columbia University, the University of Illinois, and the University of Adelaide, Australia seek to determine the energy distribution of cosmic-ray primaries and their composition. The overarching goal of these studies is to identify sources and understand the natural accelerating mechanisms that produce particle energies much greater than any achieved with accelerators. ***
