[填空题]
What minimum kinetic enewv i5vxjs 0*e3j1bl u i8vgx/5rgy must two neutrons each have if they are traveling auc9-ghnel-i7qw.68 gvhd8 s yt the samed lih6 c89-8hsv.q gwyu-g7ne speed toward each other, collide, and produce a $\pi^0$ pair in addition to themselves? (See Table 32-2.) MeV
