[填空题]
The lifetimes listed ina uz;t9g*xcid /9gix ) Table 32-2 aj(iqt;:dv yc)re in terms of proper time, measured in a reference frame where the particle is at rest. If a tau lepton is created with a kinetic energy of 450 MeV, how long would its track be as measured in the lab, o (yt ;qv)dc:jin average, ignoring any collisions? $\Delta x_{\text{lab}} = $ $ \times 10^{-5}\ \text{m}$
