Telescope Array Operations and Data Analysis by the University of Utah Cosmic Ray Group

University Of Utah, Salt Lake City UT

Investigators

Abstract

The Telescope Array (TA) is the largest detector for ultrahigh energy cosmic rays in the northern hemisphere. The nature of cosmic rays sources and the mechanism that accelerate cosmic rays to ultrahigh energies are among the most interesting open questions in astrophysics. The primary objectives of the TA experiment are to measure the energy and spatial distributions, and the chemical composition of the highest energy cosmic rays in order to address these outstanding questions. The University of Utah is the host institution for TA, and the cosmic ray physics group plays critical roles in the design, integration, deployment, operation, and management of TA. These include: (a) Facility and detector maintenance; (b) Provision of staff for observing shifts; (c) Data handling; (d) Simulation and analysis; (e) Maintaining compliance with Bureau of Land Management regulations. With this award the University of Utah group will continue the operation of the TA experiment for three more years. The TA facilities host a number of auxiliary projects and provide testbeds for detector characterization. The Astrophysics Science Project Integrating Research and Education (ASPIRE) is the project's major outreach activity. ASPIRE has created engaging interactive science lessons and labs on the Internet. ASPIRE also provides direct outreach to area teachers, students, and the public. The TA experiment comprises a Surface Detector array of 507 scintillation counters deployed over 730 square kilometers in the western Utah desert. Three Fluorescence Detector stations look inward over the air space above the Surface Detector from the edge of the array. The four years of data collected between 2013 and 2017 will double the total exposure of TA. The specific physics objectives of continued operation will be to (a) seek evidence for Large Scale Structure correlation and for clustering of arrival directions of ultrahigh energy cosmic rays in the new independent data set, testing the signals uncovered in the first five years; (b) make precise measurement of the spectrum in the region of the GZK cut-off in order to differentiate between competing models for the high energy spectral break, and (c) complete the measurement of composition at the highest energies, including the analysis of the width and shape of the shower maximum depth distributions with statistical precision comparable to the Pierre Auger Observatory result. In addition, TA is adding a low energy extension (TALE). TALE observations will share personnel and facilities with TA, and will make hybrid measurement of the energy spectrum and composition of cosmic rays in the energy region where the galactic to extragalactic transition is suspected to occur.