system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why is the photon torpedo called "photon torpedo"?

Quoth *Memory Alpha*: 

> Photon torpedoes were warp-capable tactical matter/antimatter weapons commonly deployed aboard starships and starbases by various organizations. 

and 

> The weapon was armed with a photon warhead. The warhead had a detonation chamber filled with antimatter. Upon detonation the torpedo created a matter-antimatter explosion and a flood of ion radiation. 

Now, photons are not matter, nor do they have an antiparticle. It's not possible to annihilate photons in a particle/antiparticle reaction at least in our world, which means that whatever the "photon" designation of the "photon warhead" signifies, it is not the same as that antimatter payload, nor that with which the antimatter payload reacts.  "Photon" can thus not refer to the payload of the weapon, which would be properly indicated by the term "antimatter torpedo", unless photons are in any way a separate part of the payload. If they are, in what way? 

To me, it seems more plausible that a photon torpedo carries only a matter/antimatter charge (or possibly an antimatter charge that reacts with the matter of the torpedo itself), and the "photon" designation refers to the emission of photons generated during a matter/antimatter reaction, which would be conform with our world's physics. Is this the correct reading? 

Edit: 
"Ion radiation" may then be a misspelling or shorthand for "ionIZING radiation", which is what high-energy photons, such as in gamma radiation, are. Or it may refer to alpha radiation, which consists of helium cations (ions with a positive charge), for which "ion radiation" would be a term that I've never heard used before, but which would be, I suppose, technically correct, and which would be created in some unknown fashion, perhaps the matter of the torpedo itself, or thinly-stretched matter floating around space in some locations - gas clouds, dust - being ionized by the photon emission of the matter/antimatter reaction.
gpt
Your second explanation (that the "photon" comes from the result of a matter/antimatter collision, possibly using deuterium and antideuterium, as deuterium is already used as a fuel source for the ship's conventional fusion reactors) is the correct one, though that then opens up the question of "just why the heck are quantum torpedoes called 'quantum' torpedoes"?