  The Tibet experiment, operating at Yangbajing (4,300 m above sea level), is
the lowest energy air shower array and the new high density array constructed
in 1996 has sensitivity to $\gamma$-ray air showers at energies as low as 3
TeV. With this new array, the Crab Nebula was observed in multi-TeV
$\gamma$-rays and a signal was detected at the 5.5 $\sigma$ level. We also
obtained the energy spectrum of $\gamma$-rays in the energy region above 3 TeV
which partially overlaps those observed with imaging atmospheric Cherenkov
telescopes. This is the first observation of $\gamma$-ray signals from point
sources with a conventional air shower array using scintillation detectors.

Astrophysics