How Does Proton-Antiproton Annihilation Energy Compare at Rest and at 2 GeV?

[DaveSmith]

According to fermilab link
http://www.fnal.gov/pub/inquiring/questions/antimatter1.html

Proton antiproton annihilation at rest releases 1.8 GeV energy, but compare this to annihilation at 2 GeV,

http://en.wikipedia.org/wiki/Proton_antiproton_annihilation#Proton-antiproton_annihilation_at_2.C2.A0GeV

The energy released if we add the kinetic energy of the photons would come close to the same amount of energy observed at rest, shouldn't it be more? where am i wrong?

 

[kaksmet]

Believe that you just made the mistake of thinking about the 2GeV as kinetic energy. The 2 GeV is the total center of mass energy, which includes the masses of the proton and antiproton. And indeed, the 2GeV is larger than the rest energy of 1.8GeV.

hope I could help
Chao