Isn't the annihilation supposed to cause an explosion? It releases lots of energy proportional to the mass, yes, but one proton + one anti-proton annihilating

Isn't the annihilation supposed to cause an explosion? It releases lots of energy proportional to the mass, yes, but one proton + one anti-proton annihilating at a time, it's a very small explosion. And they only had 38 anti-protons. I believe that one of the the articles quotes one of the Physicists saying that it "wouldn't even warm up a cup of coffee" Edit here you go: Prof Rob Thompson, head of physics and astronomy at the University of Calgary, one of the 42 Alpha investigators, said: 'This is a major discovery. ... We've been able to trap about 38 atoms, which is an incredibly small amount, nothing like what we would need to power Star Trek's Starship Enterprise or even to heat a cup of coffee.'