Telescope Array extension

The Telescope Array (TA) consists of an array of surface detectors (SD) covering 700 km2 in area and three fluorescence detector (FD) stations and explores the origin of ultra-high-energy cosmic rays. We found evidence for a cosmic-ray hotspot, which is the sky area of emitting more highest-energy cosmic rays than other area. To confirm what the origin of the hotspot is, we proposed the TAx4, which would quadruple the TA. From around 1015.5 eV to 1018 eV, we expect the transition from galactic cosmic rays to extra-galactic cosmic rays. The TALE (TA Low-Energy extension) FD has been fully operational and the TALE SDs have been operating partially. We confirmed two breaks at 1016.3 eV and 1017.3 eV in the energy spectrum measured with the TALE FD, and we proposed to construct remaining TALE SDs to improve the resolution of the shower maximum depth (Xmax) measured with the TALE FD for composition identification. Both five-year proposals for TAx4 SD and TALE SD were funded independently in the spring of 2015. Here we present the status of these projects including NICHE (Non-Imaging CHErenkov detector array) that aims at energy extension down to 1015 eV (Knee region).