Energy Spectrum of Ultra-High-Energy Cosmic Rays Measured by The Telescope Array

Abstract

The Telescope Array (TA) is a hybrid cosmic ray detector using air fluorescence detectors (FDs) and an array of surface detectors (SDs) which covers $700 \, {\rm km^2}$ in Utah. The TA Low-energy Extension (TALE) also consists of FDs with larger elevation angles and an infill SD array with 400 m spacing, which extends the observable energy range down to 4 PeV. In this contribution we present the spectrum from the TA SD, which has the largest statistics, the FD monocular spectrum, the FD-SD hybrid spectrum, and the lower energy spectrum obtained by TALE. We discuss the declination dependence of the energy spectrum in the northern sky.