I'm working on a story that involves planting a chunk of antimatter the size of the US capital... well, on the US capital. Unfortunately, I realized that it would probably blow up like an atom bomb the size of the Empire State Building, and would take half the solar system with it. The antimatter chunk is actually a Godzilla-esque monster. For my purposes, it's important that it be large, totally made of antimatter, and be able to not dissipate for at least a few days. So, my question... Is there a way to slow burn antimatter? Even something flimsy, like "the angle of collision wasn't head on" or "the particles were all colliding with non-matching antiparticles." I want something to appease the particle physicists. I could just flub the energy conversions (c to the power of... 0.25...) but the thought of particle physicists rolling their eyes would drive me crazy. Thank you!