9.在三棱锥P−ABCP-ABCP−ABC中,已知PA⊥PA\botPA⊥底面ABCABCABC,CA=CB=PA=2CA=CB=PA=2CA=CB=PA=2,AC⊥BCAC\bot BCAC⊥BC,则三棱锥P−ABCP-ABCP−ABC外接球的体积为((( )))