Academia Sinica Logo

【Abstract】

Cosmic rays with energies exceeding 10 to the 20th power electron volts have been observed. However, their origin is still a mystery. The Telescope Array (TA) experiment has been conducting observations to reveal the origin of ultra-high-energy cosmic rays (UHECRs). The TA detector is located in the desert of Utah, USA and is the largest UHECR observatory in the Northern Hemisphere. It consists of an array of 507 surface particle detectors covering approximately 700 square kilometers. Three fluorescence telescope stations were constructed around the surface detector array. Here we present the recent results on the energy spectrum, mass composition, and anisotropy of arrival directions of UHECRs detected by the TA experiment, including its two extensions: One is the TA Low Energy extension (TALE) and the other is TAx4 which quadruples TA. Prospects for future UHECR observations are also discussed.