Radio-controlled xenon flashers for atmospheric monitoring at the HiRes cosmic ray observatory

Abstract

Stable, robust ultraviolet light sources for atmospheric monitoring and calibration pose a challenge for experiments that measure air fluorescence from cosmic ray air showers. One type of light source in use at the High Resolution Fly's Eye (HiRes) cosmic ray observatory features a xenon flashbulb at the focal point of a spherical mirror to produce a 1 μs pulse of collimated light that includes a strong UV component. A computer-controlled touch tone radio system provides remote operation of bulb triggering and window heating. These devices, dubbed 'flashers', feature stand-alone operation, ± 5% shot-to-shot stability, weather proof construction and are well suited for long-term field use. This paper describes the flashers, the radio control system, and a 12-unit array in operation at the HiRes cosmic ray observatory.