Online Event Reconstruction of Data Taken by the High Resolution Fly's Eye Cosmic Ray Detector

Abstract

The High Resolution Fly's Eye Detector (HiRes) has been observing high-energy (10 17 eV and greater) cosmic rays since the summer of 1997. Cosmic rays are made up predominately of positively charged particles that, when interacting with the earth's atmosphere, collide with other particles and create extensive air showers (EAS). To detect cosmic rays, HiRes uses several arrays of mirrors and photo-multiplier tubes to collect light from the moonless night sky. The HiRes detector is one of the only sites in the world to use a fluorescence technique to measure such cosmic rays. The goals of the Fly's Eye project are to recreate high-energy cosmic ray events to find possible sources and to gain a better understanding of their behavior. My work with the HiRes detector consisted primarily of creating an online event reconstruction program to be implemented at the detector site. By the end of the summer we installed a new computer at the site and began taking preliminary data. The program (called OMA) is an amalgamation of several existing programs and sub-routines used at the University of Utah to analyze data.