Editing High Resolution Fly's Eye Cosmic Ray Detector (section)

{{Short description|Ultra-high-energy cosmic ray observatory in Utah, United States}}
The '''High Resolution Fly's Eye''' or '''HiRes''' detector was an [[ultra-high-energy cosmic ray]] observatory that operated in the [[West Desert]] of Utah from 1981 until April&nbsp;2006. HiRes (HiRes-I, HiRes-II, and HiRes prototype) used the "atmospheric fluorescence" technique that was pioneered by the Utah group first in tests at the [[Volcano Ranch experiment]] and then with the original Fly's Eye experiment. The experiment first ran as the HiRes prototype in a tower configuration operating in conjunction with the CASA (Chicago Air Shower Array) and MIA (Michigan Muon Array).  The prototype was later reconfigured to view 360 degrees in azimuth. HiRes-II followed later and was located on a hilltop about 13km away.  HiRes-I and HiRes-II operated in stereo. In 1991 it discovered the [[Oh-My-God Particle]].