[填空题]
The lifetimes listed in Table 32-2 are inzxv 8ks9vg0o; terms of proper time, measure utav)*k7eil narc.j35+t7rrd in a reference frame where thrnr)tlte5r c7j.+i3* 7 kuavae 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, on average, ignoring any collisions? $\Delta x_{\text{lab}} = $ $ \times 10^{-5}\ \text{m}$
