Particle Physics Seminar

The Telescope Array (TA) experiment consists of three fluorescence telescope stations and an
array of about 500 plastic scintillator surface detectors to explore the origin of the highest
energy cosmic rays. The construction of the TA has completed in 2007. All three fluorescence
telescope stations are fully operational since November, 2007. The surface detector array was
tuned and will be fully operational in March, 2008.
The TA experiment has three big advantages to determine the energy of the highest energy cosmic
rays: plastic scintillator detectors, HiRes telescopes, and an electron LINAC at the site. The
contradiction of the energy spectrum around the highest energy cosmic rays originated from
the difference between AGASA and HiRes results.
TA uses plastic scintillators like AGASA, which are less sensitive to hadron interaction models and composition than the water tanks
that AUGER uses. Thus the surface detector array can detemine energy scale independently of
fluorescence telescopes.
A part of the HiRes telescopes were moved to one of three fluorescence telescope stations of TA.
Thus the HiRes telescope system and the new TA telescope system can be crosschecked each other.
We constructed a compact electron beam LINAC in Japan. It will be installed at the TA site for
absolute end-to-end calibration of the fulorescence telescopes by using air showers induced by
electron beams with known total energy.