Telescope Array TAX4 Upgrade Deployment Proposal

University Of Utah, Salt Lake City UT

Investigators

Abstract

Cosmic rays are highly energetic sub-atomic particles from space that travel at velocities near the speed of light. The origin and acceleration mechanism for ultra-high energy cosmic rays, which likely come from extreme astrophysical phenomena outside our galaxy, are currently unknown. The Telescope Array (TA) is the largest cosmic ray detector in the northern hemisphere. Located outside Delta, Utah, and representing a joint US-Japanese effort, TA was designed to study the nature and origin of the highest energy particles in the Universe. This award to the University of Utah supports the US contribution to an expansion of the experiment, designated TAx4, which will significantly increase the collecting area of the observatory. With new capabilities, TAx4 will probe an apparent anisotropy, or "hotspot," observed in the northern hemisphere that may represent a local source of ultra-high energy cosmic rays. The enlarged TAx4 will also help to address differences in the results from TA in the northern hemisphere and the Pierre Auger Observatory in the southern hemisphere. This award will also support the University of Utah group's involvement in the Astrophysics Science Project Integrating Research and Education (ASPIRE) program, which engages area teachers, students, and the public through visits to schools and a web site of science lessons designed around the curricula of schools in Utah and neighboring states. The group will also host associated experiments in other fields that benefit from the TA location and infrastructure. TAx4 will enlarge TA by a factor of four. Japanese TA collaborators will build the scintillation counters of the TAx4 surface detectors. The University of Utah group is responsible for deploying the surface detectors in two areas in Millard and Juab Counties, and then building two fluorescence detectors to overlook the two TAx4 surface detector areas. The project will be implemented in phases while TA continues to operate and collect data.