Telescope Array Experiment:Status and Prospects
Pierre SokolskyUniversity of Utah
Cosmic Ray Spectrum
5σ Observation of the GZK Suppression (mono)
HiRes/Auger spectra comparison
Auger confirms all spectral features of HiRes spectrum
UHECR Status and Issues
• GZK cutoff exists – HiRes and PAO observe at 5-6 sigma level
• Anisotropy ( sources ) remain unclear- 2-3 sigma correlation in South with AGN’s (PAO), no correlations in North (HiRes).
• Composition – light (proton) favored by HiRes. Light-heavy-light(?) favored by PAO
• >>> A lot more work is required• >>> Unravelling galactic/extragalactic transition
Motivation for TA
• AGASA and HiRes give conflicting results on GZK. Why?
• Increase SD by 10 x. Coincident event observation with FD.
• Keep AGASA and HiRes energy scales • Hybrid events > calibrate SD• SD 10 x higher statistics than HiRes
Motivation for TALE
• Sources of cosmic rays above knee (1015 eV) are unknown.
• What is the Emax of the galactic accelerator?• Connect energy scale established by GZK to all
the other structures in the cr spectrum ( ankle, second knee etc.)
• Study the composition change from galactic to extragalactic cosmic rays.
TALE Proposal under consideration by PASAG
Thank You!
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