[填空题]
The Tevatron accelerator i8.jensvd) :l cc1u2d at Fermilab (Illinois) isb( h54,i,pmdnv 0mru -mru0zj designed to carry an 11-mA beumji-uz b,pmv 4 d50r(nm r0,ham of protons traveling at very nearly the speed of light ($ 3.0\times10^{8 }\;m/s$) around a ring 6300 m in circumference. How many protons are stored in the beam? $ \times10^{12 }\;protons$
