Monday, October 15, 2012
12:00pm (110 INSCC)
Title: Ultra High Energy Cosmic Ray Energy Spectrum and Composition using Hybrid Analysis with Telescope Array
Cosmic radiation was discovered in 1912. This year, the 100th anniversary of the discovery, marks not only the major progress that has been made in understanding these particles, but also the remaining questions about them. Questions about their sources, acceleration mechanisms, propagation and composition are still unanswered. There are only two experiments currently running which have the ability to study cosmic rays in the Ultra High Energy (E > 1018 eV) regime.
The Telescope Array studies Ultra High Energy Cosmic Rays (UHECRs) using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated by a primary cosmic ray particle, while scintillator detectors measure the lateral distribution of secondary particles that hit the ground. The Middle Drum (MD) fluorescence telescope consists of 14 refurbished telescopes from the High Resolution Fly's Eye (HiRes) experiment, providing a direct link back to the HiRes experiment and data. The surface array is comprised of 507 Scintillator Detectors (SD) of a similar design as was used by the Akeno Giant Air Shower Array
(AGASA), providing a link to that experiment as well. Using events observed by both types of detectors improves the geometrical reconstruction of the showers significantly. This provides a more accurate reconstruction of the energy of the primary particle and makes it possible to make a measurement of the cosmic ray chemical composition. The spectral and composition measurements made by this hybrid detector will be presented.