How much energy is lost due to neutrinos in matter-antimatter reaction ?

[Hurricane93]

I read that matter-antimatter annihilation is not as useful as we thought because a large amount of energy is carried away by neutrinos. So, how much is this energy ? What is the percentage of the lost energy to the energy calculated from E=mc^2 ?

 

[mfb]

We had this discussion a while ago here. It depends on the setup, but the fraction is significant for the annihilation of nucleons.
Electron-positron annihilation gives (nearly always) photons, so there are no losses involved.

 

[Hurricane93]

After reading every single post, I still don't have a conclusion.
I just need a rough percentage. Would saying 50% be wrong ?

 

[mfb]

It is the correct order of magnitude :). Something between 20% and 80%.