The
Telescope Array project is an international collaboration involving research and educational institutions in Japan, Taiwan, China, Russia, South Korea, and the United States. The experiment is designed to observe
ultra-high-energy cosmic rayIn high-energy physics, an ultra-high-energy cosmic ray or extreme-energy cosmic ray is a cosmic ray which appears to have extreme kinetic energy, far beyond both its rest mass and energies typical of other cosmic rays...
air showers using a combination of ground array and air-fluorescence techniques. It is located in the high desert in Millard County, Utah, USA at about 1400m above sea level.
The TA observatory is a hybrid detector system consisting of both an array of 576 scintillation surface detectors which measure the distribution of charged particles at the Earth's surface, and three fluorescence stations which observe the night sky above the SD array.
The
Telescope Array project is an international collaboration involving research and educational institutions in Japan, Taiwan, China, Russia, South Korea, and the United States. The experiment is designed to observe
ultra-high-energy cosmic rayIn high-energy physics, an ultra-high-energy cosmic ray or extreme-energy cosmic ray is a cosmic ray which appears to have extreme kinetic energy, far beyond both its rest mass and energies typical of other cosmic rays...
air showers using a combination of ground array and air-fluorescence techniques. It is located in the high desert in Millard County, Utah, USA at about 1400m above sea level.
Overview
The TA observatory is a hybrid detector system consisting of both an array of 576 scintillation surface detectors which measure the distribution of charged particles at the Earth's surface, and three fluorescence stations which observe the night sky above the SD array. Each fluorescence station is also accompanied by a LIDAR system for atmospheric monitoring. The SD array is much like that of the
AGASAThe Akeno Giant Air Shower Array is a very large surface array designed to study the origin of ultra-high energy cosmic rays. It covers an area of 100 km2 and consists of 111 surface detectors and 27 muon detectors...
group, but covers an area that is nine times larger. The hybrid setup of the Telescope Array project allows for simultaneous observation of both the longitudinal development and the lateral distribution of the air showers.
At the center of the ground array is the Central Laser Facility which is used for atmospheric monitoring and calibrations.
Cosmic ray center
The Lon and Mary Watson Millard County Cosmic Ray Center was dedicated on March 20, 2006. The center is located in Delta - the seat of Millard County. The building serves as a headquarters and data processing center for the TA Project.
Surface detector
The surface detectors are evenly distributed across a 762km
2 grid array with 1.2km between each unit. Each surface detector has an assembled weight of 250kg and consists of a power supply, two layers of scintillation detectors and electronics. Power is generated by a 120W solar panel and stored in a sealed lead-acid battery. The system has the capacity to operate for one week in complete darkness. Each scintillation detector layer is made of extruded plastic scintillator that is 1.2cm thick and has an area of 3m
2. The photo multiplier tube is connected to the scintillator via 96 wave length shifting fibers.
FD station, telescope, and camera
The Telescope Array has three fluorescence detector stations. The stations are located on a triangle about 35km apart from one another. Each station has 12-14 telescopes viewing the range from 3 to 33 degrees in elevation. The three sites are named
Black Rock Mesa (BRM),
Long Ridge (LR), and
Middle Drum (MD).
Each telescope has a fluorescence light camera made up of 256 PMTs.
TALE
TALE is the Telescope Array Low Energy extension. It is designed to observe cosmic rays with energies between 3x10
16eV and 10
19eV. TALE has two fluorescence sites, one of which is located about 5km away from the Black Rock Mesa FD site, and another which is about 5km away from the Long Ridge FD site.
The TALE tower is a tower of fluorescence telescopes looking from near zenith to near horizon. These telescopes have 3m diameter mirrors to push the energy threshold of observable events as low as possible.
The TALE project also has an infill array of scintillator ground array stations spaced about 500m apart. These stations measure charged particle densities (the shower footprint) at the earth's surface for lower energy events approaching 3x10
16eV