| Description |
The Telescope Array (TA), deployed in central Utah, is the largest cosmic ray detector in the Northern hemisphere. It was initially designed to study Ultra-High Energy Cosmic Rays (UHECRs) with energies above 1019 eV. TA has added an extension known as the Telescope Array Low Energy Extension (TALE) to lower the experiment's energy threshold. The extension includes the addition of high elevation angle telescopes to one of the existing TA telescope stations (Middle Drum), giving it a field of view of 3-59◦ in elevation and 114◦ in azimuth. This enables the site to see more of the shower development for nearby, lower energy events and allows us to study cosmic rays in 1015.3-1018.3 eV energy range. The observatory now consists of 48 telescopes at three sites overlooking an array of 610 scintillation counters. I have used the data collected between 1 June 2014 and 31 January 2015 to make a monocular measurement of the cosmic ray energy spectrum. I have combined the fluorescence data from the original high energy TA telescopes with that of the TALE low energy extension telescopes, focusing in the energy range of 1017.2 - 1019.0 eV. This is a joint measurement using two sets of telescopes. I have found the energy spectrum has a spectral slope of -3.3±0.06 in this energy range. This is in good agreement with measurements made using other TA techniques as well as other external experiments in this energy range. |
