The minimum kinetic energy needed by an alpha particle to cause the nuclear reaction N + He H + O in a laboratory frame is n (in MeV). Assume that N is at rest in the 16 laboratory frame. The masses of N, He, H and O N, He, H and O can be taken to be 16.006 u, 4.003 u, 1.008 u and 19.003 u, respectively, where 1 u = 930 MeVc2. The value of n is