Proton antiproton 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 [Broken]

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