Given:
Mass of 11C, m(11C) = 11.0114 u
Mass of 11B, m(11B) = 11.0093 u
Energy liberated in the β+ decay (Q) is given by
= (11.0114 u − 11.0093 u 20.0005486 u)c2
= 0.0010028 931 MeV
= 0.9336 MeV = 933.6 keV
For maximum KE of the positron, energy of neutrino can be taken as zero.
∴ Maximum KE of the positron = 933.6 keV