Photoprotoneutron Torpedo

""Fry, cover us buddy! You got the only wounded-up positron shooter!""

- Futurama

So, you're writing science fiction. Need a weapon name? All you have to do is put the name of a subatomic particle in front of a regular modern weapon. Simple! Sometimes "ion" and "plasma" are used to the same effect despite not being subatomic particles, although they may be relevant to the weapon's working in some cases. Sometimes, just "particle" is used, and sometimes, "quantum" is used despite the word by itself being utterly irrelevant to the weapon's operation (its meaning being "small(est) individual quantity").

This sometimes results in hilariously unrealistic weapon names for people with a knowledge of the properties of said particles. A "Neutrino Cannon", for example, would be a terribly pointless weapon, although its name sounds cool. This however can be averted by creating your own fictional particles with fictional properties, or by simply doing a bit of research - 'Photon Beam Cannon' for example could realistically denote a laser or any electromagnetic radiation based Energy Weapon, and 'Positron Warhead' could refer to an explosive that uses Antimatter annihilation as its energy source.

Often, if the writers bother with background material they will list such weapons as having yields in the kilo-gigaton range, making this a case of Nuclear Weapons Taboo

This is a Sub-Trope of Sci Fi Name Buzzwords. Less realistic examples often fall into Techno Babble.

Anime

 * GaoGaiGar has King J-der's finger-mounted Anti-Meson Guns.
 * In Real Life, a meson consists of one quark and one antiquark. So all mesons are also antimesons.
 * Neon Genesis Evangelion has the Positron Rifle.

Comics

 * Some Bronze Age Marvel titles occasionally featured a "meson disintegrator".

Film

 * The proton torpedoes of Star Wars count as these.
 * So does the Ion Cannon in The Empire Strikes Back.
 * Ghostbusters: Proton packs, which are "positron colliders" (or sometimes "unlicensed nuclear accelerators") that shoot particles from "neutrona wands".
 * From the checklist Alex ran down in The Last Starfighter, Gunstars are apparently armed with a particle beam and proton bolts.
 * In the novelization, Grig states the real names involve science too advanced to translate, so he uses the game terms for the sake of convenience.

Literature

 * The fairies of Artemis Fowl use neutrino charges to blow stuff up at one point.
 * One of the main LEP weapons is the Neutrino handgun series, which has variable power settings that let it gently heat substances, stun perps, or provide lethal blasts of powerful energy.
 * One character in Fantastic Voyage II by Isaac Asimov jokingly suggests that the military should start researching neutrino bombs. As he sees it, they'd have all the positive effects of weapons development -- scientific advancement, job creation, and so on -- and none of the negative effects -- such as the ability to actually kill people.
 * Some Real Life models of supernovae claim that it's outrushing neutrinos from the collapsing core that ignite the star's outer layers. So maybe it is possible to use neutrinos to kill people....
 * The "proton cannons" of The Pentagon War actually fire an electrically neutral hydrogen plasma, but "electrically neutral hydrogen plasma cannon" would take too long to say.

Live Action TV

 * Star Trek likes to name torpedo types like this despite sometimes having an actual explanation for their payloads, but mostly the names just denote the color of the torpedoes. There's the standard Photon Torpedo (Antimatter, white in the original series, blue in Star Trek the Motion Picture, red in the subsequent movies, orange in the Next Generation onwards,) the better Quantum Torpedoes (zero-point energy, blue-white.) Polaron Torpedoes(purplish red), Plasma Torpedoes (red in the original series, green in Star Trek the Next Generation)...
 * Battlestar Galactica Classic gave us "pulsar cannons." While pulsars aren't a subatomic particle, they're a type of neutron star, which does have "neutron" in its name. (The prospect of somebody shooting neutron stars at you is also pretty frightening.)
 * Tom Servo of Mystery Science Theater 3000 once had a "neutron machine pistol" during a sketch. He called it Lucille.

Tabletop Games

 * Traveller largely keeps it "realistic" (with most ships only having lasers or nuclear missiles), save for the fusion gun and the spinal mount meson cannon.

Video Games

 * Numerous weapons in Escape Velocity. Neutron turrets are superior to proton turrets, which are superior to laser turrets.
 * Mostly ditched in Nova, which just calls most of its guns "blasters" (except for the railguns and chainguns). It does have an "ion cannon", but explains that it really does shoot ions -- charged helium atoms, to be precise. However, the Auroran "Fusion Pulse Cannon" stands out as a Dubious Science Alert.
 * The MagiMechTech MechaMechs in Kingdom of Loathing use photoprotoneutron torpedoes.
 * In Supreme Commander, the Aeon Illuminate has strategic bombers which drop 'quark bombs'.
 * Transformers: War for Cybertron has 'Neutron Assault Rifles'.
 * From the Wing Commander series:
 * Neutron guns, Ion cannons, Particle guns, and Tachyon guns.
 * Privateer gives us Proton Torpedoes, which are really just very powerful dumbfire missiles that are otherwise unrelated to the regular torpedoes of the rest of the series.
 * The Backstory for "Hawk" includes his family being wiped out in the "proton bombing" of his homeworld.
 * Half Life has the Tau Cannon (aka the Gauss Gun) and the Gluon Gun (aka the Egon).
 * The gigantic Wave Motion Guns of Free Space are typically called "beams", both in-game and out, but their technical name is "Photon Beam Cannon". There's also the Meson Bomb, a superpowerful explosive that completely vaporizes anything within three kilometers. One fan-made campaign threw it all into a blender and hodge-podged together a beam cannon using a meson bomb's energy reaction as a power source.
 * The Marvel vs. Capcom series brings us Iron Man's PROTON CANNON.
 * Galactic Civilizations 2 is rife with these.
 * Command & Conquer has the GDI's Ion Cannon in the Tiberium games and the USA's very similar Particle Cannon in Generals, and the Allies have the Proton Collider in Command & Conquer: Red Alert 3.
 * Mechwarrior and its related games featured the weapon known as the PPC, which stands for 'particle projector cannon', derived from the tabletop source material. It is often compared to man-made lightning, but the fiction suggests the weapon fires beams of charged particles. A large percentage of the time, it is rendered as a blue stream of energy with some lead time. The version in the Mechwarrior 2 trilogy fires what the guides term 'plasma balls'.
 * Amusingly enough for the page description, game developers Silicon Knights created a top down turn-based-strategy/action hybrid game called Cyber Empires which featured the Neutrino Cannon as its most powerful energy weapon.
 * Starsiege and its predecessors, the Earthsiege series, featured the PBW, for particle beam weapon, which is described as an 'electromagnetic shotgun.' Bearing in mind that the weapon fires a single discrete beam, this raises some questions about how exactly the weapon operates.
 * Another example from the series is the electron flux whip, or ELF, which is called the 'lightning bolt on a leash.' It is often rendered as a continuous arc of blue or yellow electricity with a short range, or occasionally as a slow, single arc that twists awkwardly through the air to damage the target's shields or armor.
 * Mass Effect has the Reapers' Wave Motion Guns, which are not beams but are actually "magnetohydrodynamic cannons"... subverted, as this is actually a perfectly accurate descriptor of the weapon: it fires a stream of molten metal at relativistic speeds.
 * Several weapons in the X Universe series fit this. Ion Disruptor, Ion Pulse Generator, Ion Cannon, Ion Shard Railgun, and Photon Pulse Cannon. Oh, and the Kha'ak use kyon emitters, which fire a fictitious particle. The names are normally fairly justified by Flavor Text.
 * Several of the energy weapons mounted on Protoss vehicles in Starcraft qualify. Corsairs use a Neutron Flare, Scouts mount dual photon blasters, and Arbiters and Dragoons carry phase disruptor cannons.

Web Original

 * Kingdom of Loathing has these as random drops from the MagiMechTech MechaMech.

Western Animation

 * In a parody of this, positron shooters are apparently standard issue for DOOP soldiers in Futurama. They play Pop Goes The Weasel as they're wound up.