10. Show that the threshold in kinetic energy at which an accelerated proton beam will begin to produce proton antiproton pair (using stationary proton target) in the reaction p+pp+p+p+p, is 6mc where m, is the rest mass of proton/antiproton. 11. A stationary nucleus of mass M is in an excited state of excitation energy Eo. It emits a photon in a transition which takes it to the ground state. Show that the frequency of the photon is (1 1 Hint: rest mass of the atom in the ground state is M = - (M-0) V = Eo h Eo 2 Mc and its momentum is hv