Shooting a particle with its isotope!

There is a uniformly charged disc of surface charge density $\sigma$ and of radius 1m . H=10m height below the disc is a gun which is continuously emitting a charged particle and its isotope in the vertically upward direction. The particles are charged through same potential before being emitted. The charge of particle is $q=8*10^{-19}C$ . The difference of potential energies of particle and the isotope at the centre of the disc is $10^{-23}J$ . Also the velocity of particle at the centre of the disc is 0. The ratio of masses of particle and isotope is $\frac{3}{2}$ . Find the total energy of isotope at the centre of the disc.

Given: $\frac { \sigma }{ { \varepsilon }_{ 0 } } ={ 10 }^{ -4 }N/C$

The answer is of the form: $A.10^{-B}$ , where A and B are positive integers.

Find A+B.