[填空题]
What minimum kinetic energy must two neutrons vg 9) ltl9vhm0d-3myeeach have if they :qajmz .q 6cc se, s:5suutepcj0u5d2n8 a3z0are traveling at the same speed toward.u8z:5,qnc0sm :teusj cp3d0jc q a2 a5ezu6s each other, collide, and produce a $\pi^0$ pair in addition to themselves? (See Table 32-2.) MeV
