The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to γ-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV γ-rays and a signal was detected at the 5.5 σ level. We also obtained the energy spectrum of γ-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ(E)/dE = (4.61 ± 0.90) x 10-12(E/3 TeV)-2.62 ± 0.17cm-2 s-1 TeV-1. This is the first observation of γ-ray signals from point sources with a conventional air shower array using scintillation detectors.
|号||2 PART 2|
|出版ステータス||Published - 1999 11月 10|
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