Cosmic rays have surprising amounts of antimatter. Is dark matter responsible?

[chemicalmicroscopist]

So, how is it that gravimetric chemical analysis agrees with electrochemical and mass spectrometry analyses. Each adds the analyzed mass to 100%. This should not be possible if there is a component that has gravity properties, but lacks electromagnetic properties.
What physics makes this possible? I am only a retired chemist, but this apparent contradiction needs to be addressed.

 

[Unclear Engineer]

Aren't each of those analysis techniques empirically calibrated to 100% of what is being measured? That would make them all come out to 100%. If there is something that you cannot detect, then it would not show up in the measurement or the calibration.

 

[billslugg]

If two particles have the same mass and speed, and collide from 180° different directions, their net momentum will be zero. If they anihillate and then emit a single photon, it will have a non-zero momentum. Momentum would not be conserved. Two photons allows conservation of momentum.