Pronouncing the LHC

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Now that the Large Hadron Collider is stumbling towards full operation, perhaps it's time to clarify how to parse (and interpret, and pronounce) its name. Is it the [large [hadron collider]] or the [[large hadron] collider]? Is it a device for colliding hadrons (in the way that a particle accelerator accelerates particles, and an atom smasher smashes atoms) or just a collider whose operation depends essentially on hadrons (in the way that a hydrogen bomb depends on hydrogen, and a lithium-ion battery depends on lithium ions)?) And is the main phrase stress on the last word ("collider") or on the middle word ("hadron")?

Earlier this year, in a Physics Forum thread discussing a History Channel show about the LHC, Sarah Heck asked:

Also, this may be a stupid question, but why is it called the Large Hadron Collider? Is it because the collider is large, or because it will be colliding large hadrons?

To which one of the show's producers answered:

To answer your question, it is indeed called the "Large" Hadron Collider due to the size of the machine. The "Hadrons" are your basic hydrogen protons.

That's what I always thought. Although the LHC will also eventually collide lead 208 nuclei, I'm pretty sure that its name is meant to be understood as referring to a hadron collider that is large, rather than a collider of large hadrons. (Anyhow, physicists don't refer to multi-nucleon nuclei as hadrons, do they?  Though if only proton beams were going to collide, why not call it the "large proton collider"?)

This analysis, I also thought, implies that the inner part of the name, "hadron collider", is a noun-noun compound, whose first element is a noun, whose second element is an agentive nominalization, and whose first element is construed as the object of (the verb in) its second element. This makes it exactly like "particle accelerator" or "football player" or "beer distributor". A "hadron collider" collides hadrons, just as a "particle accelerator" accelerates particles, a "football player" plays football, or a "beer distributor" distributes beer.

But recently I started to wonder. In those two-element agentive compounds, we expect the main stress to go on the first element: PARTICLE accelerator, BEER distributor, FOOTBALL player… and HADRON collider. Adding the adjective "large" in the beginning shouldn't affect the stress pattern of the following noun compound at all, any more than it does in phrases like "the first particle accelerator" or "a successful beer distributor".

Some people do pronounce it "large HADRON collider". In a PBS Nova episode on the LHC, Dave Wark (a physicist from Imperial College, London, who should know) pronounces it that way:

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But most of the time, I hear the main stress on collider, with the expected rhythmic alteration of stresses before that.

Thus from Studio 360 with Kurt Andersen, 9/19/2008:

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And from a CERNTV promotional video:

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This might mean that people are not really thinking of hadron as the object of collider, but rather as a sort of modifier. Then a "hadron collider" would not be like a "particle accelerator" — morphosyntactically speaking — but like a "hydrogen bomb" or a "stealth fighter" or a "pebble bed reactor", which have main stress on their final element.

In any event, quite a few people are thinking about this device as a way to make large hadrons collide. We see evidence of this in jocular blog posts by non-experts:

…if there’s no down side to predicting the end of the world via the collision of large hadrons (which end is delayed, though still obviously inevitable) then there’s no down side to predicting the complete and utter collapse of the world financial system …

But also, curiously, experts of various kinds tell us, apparently with a straight face, things like this ("What are large hadrons, and why should we make them collide?"):

So, in summary, large hadrons are subatomic particles much more massive than protons. We want to make them collide to answer fundamental questions about what we’re made of, and how it got to be that way.

And back in 1998, the Berkeley Lab Research Review, in an article with the cute title "Desperately Seeking SUSY", gave a subsection the title "When Large Hadrons Collide". This is a pair of classical references, not meant to imply any linguistic or physical analyses, but still.

Let me make it clear that I'm not complaining that "people are doing it wrong". It's just that the way people usually pronounce this phrase puzzles me, and I wonder — is this because they're thinking about large hadrons as a modifier of collider; or just because that's what they've heard other people say?

These questions are especially pointed ones because I find myself joining most others in saying large hadron collider. In my case, I think it's some combination of "that's what I've heard" and "I never thought about it much". Until now. In the future, I'm not sure what my excuse will be.


  1. Sili said,

    September 22, 2008 @ 7:17 am

    And here I thougt the main issue was whether it's /ɛɪ/ or /æ/.

    I don't know why it's "hadron" rather than "proton" but perhaps it's a question of keeping it general in case someone finds an effective way of producing anti-protons/mesons/strange-baryons.

    Also, while lead nuclei aren't hadrons in themselves, they are composed of hadrons: protons and neutrons. But if that was all they could just have a called it a baryon collider.

    Perhaps they just like the puns …

  2. Bob Lieblich said,

    September 22, 2008 @ 9:22 am

    In the other direction, I frequently hear "Empire STATE Building."

  3. GAC said,

    September 22, 2008 @ 9:31 am

    I find pronunciations with main stress on "collider" just bizarre — even if I think of people reanalyzing it the way you suggest. I'm not sure what makes it, maybe I have the other analysis heavily ingrained in my brain, or maybe the "large" does something for me.

    BTW, how is the name often translated. Some research reveals that the ambiguity doesn't exist in Spanish ("Gran colisionador de hadrones" = big collider of hadrons), but appears to still happen in Chinese (大型强子对撞器 = "large-scale hadron collision device" — though I'm not sure if Chinese compounds can be analyzed in all the same ways as English ones).

    BTW, I'm not sure if the one definition of hadron is correct. Wikipedia ( defines it as "a bound state of quarks" that is "held together by the strong force, similar to how atoms are held together by the electromagnetic force." AIUI, that would include all protons and neutrons — and according to Wikipedia a few other, kinda strange creatures.

  4. GAC said,

    September 22, 2008 @ 9:33 am


    Yes, in fact, I say it that way. Maybe I just take proper names like that without analyzing them.

  5. Bryan said,

    September 22, 2008 @ 9:48 am

    It's been a few years since I was in physics grad school, but at least at the UC campuses I was at, I never heard anyone ever put stress on "collider" when talking about the LHC. It was always large HADRON collider. (Or so I recall, anyway)

    Also GAC, you are correct although there are more than "a few" hadrons besides protons and neutrons, the Particle Data Handbook lists a veritable zoo of particles. :) Hadrons may be contrasted with leptons, electrons and neutrinos and muons, which are not composed of quarks (and in fact at least at the energy scales that we can probe, do not admit any simpler substructure at all).

  6. Lazar said,

    September 22, 2008 @ 10:07 am

    I pronounce it with the main stress on "collider", but I've always correctly interpreted it as a "large collider" and I haven't paid much attention to how I stress it. So I think you can't be sure of somebody's analysis of the name just from the stress.

    @ Sili: Yeah, the first thing that came to my mind when I saw the title was how to pronounce "hadron".

    @ Bob: I pronounce it like that too, as if it were a kind of "State Building", even though on an intellectual level I know it was named after the Empire State.

  7. Skullturf Q. Beavispants said,

    September 22, 2008 @ 10:11 am

    My intuitions agree with GAC, and I agree with Mark's analysis as to why, in a sense, people "should" put the emphasis on "hadron". With constructions like "large football player" or "big beer distributor", I can't imagine placing the emphasis anywhere but on the second word. I'm surprised to learn that so many people emphasize "collider".

    BTW, I too say "Empire STATE Building", and I think it's because I just learned the term as a "whole" without thinking about the meaning of its parts.

    When I was a kid, I once made fun of one my friends for talking about a "FIFTY-cent piece" instead of a "fifty-CENT piece".

  8. Chris said,

    September 22, 2008 @ 10:14 am

    @Sili: i also thought this would be about /ɛɪ/ vs. /æ/. and i'm curious about the answer to that, too :)

    personally, i almost never stress the last word in all the phrases you've mentioned.

  9. Mark Liberman said,

    September 22, 2008 @ 10:21 am

    Compounds of the form "X Building" generally take main stress on X: the Chrysler Building, the Seagram Building, etc. This usually doesn't change when X itself is complex — in that case, the main stress generally falls on the expected main stress of X. Thus what used to be the Field Building in Chicago is now the LaSalle National Bank Building — and I assume (without ever having heard it pronounced) that the main stress ought to be on bank. I assume that the analogous thing happens to the New York Life Insurance Building, so that the main stress winds up on life, just as it does on "New York Life Insurance" by itself.

    Since New York is the Empire State — with main stress on state — it follows that the Empire State Building ought also to have main stress on state.

  10. Ks said,

    September 22, 2008 @ 10:30 am

    The cern's FAQs explain the name ( ).

    They also explain that hadron comes from the Greek 'adros' meaning 'bulky' as opposed to other particles (e.g. electrons) which are leptons from the Greek 'leptos' ('thin').

    I was wondering if that could explain the stress on collider, since 'although' large refers to the device, hadrons are by definition large.

  11. linda seebach said,

    September 22, 2008 @ 10:51 am

    In New York, the main stress in Empire State is on "Empire," as it is with the other state tags I can recall offhand. California is the GOLDEN state. On the other hand it's the Golden State FREEWAY.

  12. Mateo Crawford said,

    September 22, 2008 @ 10:52 am

    I say large hadron collider, and, preferring print news and not having had an out-loud conversation about it with anyone, am surprised that that's not only the only way people say it, but not even the commonest way. I also say stealth fighter, hydrogen bomb and pebble-bed reactor, so this probably has less to do with my awareness of the size of the collider vs. the size of the hadrons and more to do with an idiosyncrasy I had never twigged to before.

  13. Robert F said,

    September 22, 2008 @ 10:55 am

    I think adros isn't the right transcription. It should be hadros. Possibly the transcriber didn't know about rough vs smooth breathings?

  14. Alex said,

    September 22, 2008 @ 11:06 am

    @GAC: in Russian, there seems to be no ambiguity (it's the "large hadron-y collider").

    Anyway, I'm English, and I say "large HADRON collider". I knew what hadrons where before hearing about the LHC, though, which could have affected it.

    I also, though, say "HYDROGEN bomb" and "STEALTH fighter". I've certainly never noticed this as unusual down in the south of England.

  15. Christopher Stone said,

    September 22, 2008 @ 11:11 am

    @Ks: I doubt that explanation is really the culprit behind the different pronunciations, as I'm guessing most people (even the ones who put emphasis on 'collider') don't have much knowledge about either the relative sizes of subatomic particles or the etymology of their names.

  16. Mark P said,

    September 22, 2008 @ 11:20 am

    I agree with Linda S. I emphasize Empire in Empire State, as well as Peach in Peach State.

  17. Mateo Crawford said,

    September 22, 2008 @ 11:21 am

    not only the only way people say it

    This whole phrase was doomed the moment I started typing it. I meant 'not only not the only way people say it', which is awful.

  18. Bobbie said,

    September 22, 2008 @ 11:21 am

    Sounds like it could be called the Great Big Collider for Subatomic Particles. Does this mean that there is or was an Itsy-Bitsy Teeny-Weeny Collider? Why is emphasis being placed on the size of the collider rather than what it does?

  19. John Cowan said,

    September 22, 2008 @ 11:26 am

    (I'm going to use % before the word bearing the phrasal stress, rather than SHOUTING with CAPS or paraphrasing.)

    Since New York is the Empire State — with main stress on state

    But that's where the oddity around "Empire State Building" comes in: at least for me, it's the "%Empire State", like the "%Garden State", the "%Old Dominion" (as distinct from "an old %dominion"), the "%Mississippi River", and the "%Flatiron Building" — but the "Empire %State Building", with stress shift. (But "Penn %Station", "Grand Central %Station", the latter being a compound of "Grand %Central" and "Station" as far as stress is concerned, though its etymological structure is "Grand [[[[New York] Central] Railroad] Station]".)

    But then again, I say "%hydrogen bomb", "%stealth fighter", "%pebble bed reactor" (a second-level compound of "%pebble bed" and "reactor"), making no distinction from "%particle accelerator", "%football player", "%beer distributor". "Hydrogen %bomb" sounds very weird to me; I'd expect it only in a contrastive stress situation like "not a hydrogen %engine, a hydrogen %bomb".

    And definitely "large %hadron collider".

  20. Theo said,

    September 22, 2008 @ 11:55 am

    Important in understanding the etymology of LHC's name is that it's replacing LEP, the Large Electron-Positron Collider. There it's even more clear that "large" modifies "collider", not "electron-positron".

  21. Brett said,

    September 22, 2008 @ 12:19 pm

    I don't think I stress any of the words in "large hadron collider" when I say them. The phrase has no natural rhythm; it's awkward. The reason is that I feel like I'm being affected when I say "large hadron collider," rather than "LHC."

  22. Yonatan Zunger said,

    September 22, 2008 @ 1:07 pm

    As a fairly recently ex-high energy physicist, I can offer that it's definitely the collider which is large; while some large hadrons are going to be collided in the future (lead nuclei and so on) that's not the primary goal of the LHC. The reason it wasn't named "large proton collider" is that architecturally, it's designed to be able to accelerate any sort of hadron; it could accept lead nuclei, protons, antiprotons, or a fairly wide bestiary of other things. (As opposed to a lepton collider, like the one at SLAC near Stanford, which normally sends electrons and positrons down the pipe)

    I normally put the stress on "hadron," but I've definitely heard stress on "collider" in speech; I think that what's happened is that people who refer to this object every day are often thinking more about the fact that it's a collider than about anything else, and so all of "large hadron" is conceptually being treated more like a proper name than like an actual English description of the object. On the other hand, most people who are dealing with it day-to-day just say "LHC" most of the time.

  23. mgh said,

    September 22, 2008 @ 3:16 pm

    In molecular biology, one sometimes uses single-stranded salmon sperm DNA, leading a colleague to remark he had never seen a single-stranded salmon.

  24. Stuart said,

    September 22, 2008 @ 4:16 pm

    I've never heard it stressed on "Collider", and have always parsed it as a large collider of hadrons. The frequent references on the CERN site and the wikipedia article to earlier, less large colliders may have helped in this. I am also one of those who say "Empire STATE Building", as are most of my fellow Aotearoans.

  25. Ian Tindale said,

    September 22, 2008 @ 5:20 pm

    You've got another couple of months – it's just been shut down:

  26. Greg Morrow said,

    September 22, 2008 @ 11:15 pm

    Sili, et al.:

    "hadron" has an /æ/ like "cat". Quite possibly the Brits pronounce it differently, but they're generally wrong on that sort of thing. (A work colleague from London today briefly didn't understand me when I referred to EP-sih-lon; he pronounces it ep-SAI-lon. I wonder how the Greeks pronounce it.)

    Also, Fermilab has been colliding protons and anti-protons for some years now. Anti-protons are fairly easy to make in quantity; you just slam a nice intense tuned beam of something (off-hand guess: electrons) into a target. There will be some anti-protons in the yield, and selecting them by mass and charge with magnets is trivial. They're stable, so once you've got 'em, as long as you keep 'em in an evacuated beam pipe, they'll stick around while you boost them and collimate them and compress them into a nice packet.

  27. Rod Whiteley said,

    September 23, 2008 @ 5:03 am

    This Brit pronounces both hadron and epsilon the same way as you do.

    AskOxford agrees. For hadron: It gives two versions of epsilon, but neither matches your colleague's (and I have never heard anyone use the second of them):

    The first Greek pronunciation site I found agrees with you and me:

  28. Marc Naimark said,

    September 23, 2008 @ 7:08 am

    In French, "grand collisionneur de hadrons".

  29. Nick Lamb said,

    September 23, 2008 @ 8:18 am

    A physicist would definitely call a nucleus a hadron if it was appropriate, in the same way that a biologist might call a human a primate if that was appropriate in context. Hadron is a concise description for the category of things that the LHC can smash into one another, even though a hadron could also be some things (solo neutrons for examples) which it can't accelerate. It's similar to calling a new research facility the "New primate centre" when in fact it studies monkeys, chimps, gorillas and lemurs, but not humans or aye-ayes. Of course the emphasis would go on "Primate" in that phrase as it does on "Hadron" here.

  30. Aaron Davies said,

    September 23, 2008 @ 9:21 am

    Re "Grand Central Station" and "Empire State Building", I'm again reminded of the amazingly elegant hyphen in the name of the New-York Historical Society.

  31. Ken Brown said,

    September 23, 2008 @ 10:58 am

    Greg Morrow: ""hadron" has an /æ/ like "cat". Quite possibly the Brits pronounce it differently, but they're generally wrong on that sort of thing. (A work colleague from London today briefly didn't understand me when I referred to EP-sih-lon; he pronounces it ep-SAI-lon."

    This Brit uses the cat vowel in "hadron" and so does everyone else he knows. I don't think I've every heard HAY-dron but if I did I would probably think it was American! I also assumed that Americans say ep-SAI-lon and we say EP-si-lon.

    No idea what the real Greek is, either modern or ancient.

  32. Greg Morrow said,

    September 23, 2008 @ 2:28 pm

    Ken: Perhaps my informant is unusual, then! I'll have to ask some of the other Brits in the office, though they're mostly north England, and that may make a difference.

    *I'm US south midlands, though I was trained in physics in a midwestern (and hence near-SAE) environment.

  33. Greg Morrow said,

    September 23, 2008 @ 2:39 pm

    Nick: I am reluctant to call anything other than a hydrogen nucleus (i.e. a single proton) a hadron. Larger nuclei are made up of hadrons, but are not themselves hadrons; it doesn't count as a single particle. A troop of chimpanzees is made up of primates but is not itself a primate, if you will.

    The simple definition is that a hadron is a particle that's made up of quarks. This is all mesons (pions, kaons, etc. ad infinitum) and all baryons (proton, neutron, etc. ad infinitum), and contrasts with the leptons (electrons, muons, tau-particles, and neutrinos), and the force-mediating particles (photon, graviton, W, Z, gluon, Higgs).

  34. Neal Whitman said,

    September 23, 2008 @ 9:38 pm

    This reminds me of my confusion when my wife told me that she had "baby BUTT legs."

  35. Wes V said,

    September 23, 2008 @ 11:34 pm

    Two points:

    First: There are small colliders. The original colliders were desktop sized things with a much smaller energy than the current monsters (some were even small enough to fit in your hand). So 'Large' could very well apply to the size of the collider.

    Second: The hadrons being collided at the LHC can technically be called 'large'. There are a couple ways to measure the size of the particles being accelerated. Cross Section and Mass. Cross Section isn't very good for 'size' since it's not quite like the cross section you'd imagine in the macroscopic world.

    Mass follows E=mc^2. As the energy of the particle increases, it's mass increases. One way to increase it's energy is to give it Kinetic energy by makin it go real fast.

    Therefore, since the hadrons in the LHC are going to be at energies much higher than those in any other accelerator, the masses will be much higher. So 'Large' could apply to the 'size' of the hadrons.

    **I think that every time I spelled hadron I had to retype it to put the 'd' and 'r' in the right order. you should do a google scholar search for "physics hardon"**

  36. Paul said,

    September 24, 2008 @ 4:57 am

    Greg: I'm British and from the north of England. When I'd read the word "hadron" (without hearing it spoken) I had assumed the first syllable was [heɪd], though I've now more or less revised my pronunciation to [hæd], having heard a lot of physicists pronounce it that way on the radio. I wonder whether you might be on to something for at least some northern English speakers since my best guess as to why my idiosyncratic pronunciation didn't tally with what seems to be generally accepted pronunciation amongst people who actually use that word in their daily work is that I was pronouncing it by analogy with "Hadrian" (which starts [heɪd]), a Roman emperor who was responsible for a well-known wall which runs through the town where I was born and is a prominent tourist attraction in Northumberland and Cumbria. Before a month or so ago I'd hardly ever heard the word "hadron" but I must have heard "Hadrian" thousands of times.

  37. Jason said,

    September 24, 2008 @ 1:32 pm

    Non-physicist scientists (myself included) I've spoken to on the East and West Coasts of the U.S. have the cat vowel for "hadron". Somewhat tangentially, I had never heard "ep-SIGH-lon" until I went to Britain–so I guess my experience is somewhat the opposite of Ken Brown's.

    With regard to the Empire State Building, my poorly-substantiated hypothesis is that there are just too many unstressed syllables following the initial EM–the phrase dribbles away if you try to say "EM-pire state building". Stressing "building" sounds funny when compared with other three-word buildings such as the Met LIFE Building or the World TRADE Center.

  38. Elinore said,

    September 24, 2008 @ 4:39 pm

    This reminds me of the "chiNESE food" discussion archived here:

  39. Sili said,

    February 23, 2009 @ 2:10 pm

    I'm sure it's bad form to comment on old posts (at least they don't get 'bumbed' in this format), but this doesn't warrant an email even if it made me smile:

    David Morgan-Mar plays around with the scope of the adjective (in the annotation.

    He recently had another languageflavoured poll, too.

  40. David Bradley said,

    March 26, 2009 @ 5:00 am

    As a Brit, the stress is actually on the "I" in collider, as in large hadron coll-I-der. It's definitely a large machine for colliding hadrons. Hadrons being pronounced so that the "had" rhymes with the end of hanging chad, not "had" as in hades. Moreover, its a typographical minefield for journalists who also cover men's health who have to be constantly on the ball or knocking on wood to avoid the d-r switch…

  41. Ross Presser said,

    September 5, 2011 @ 8:43 pm

    I don't have any official standing, but I disagree in principle. A nucleus is not a single hadron any more than sugar is a single atom or the US Congress is a single primate. A hadron is a single particle composed of two or more quarks. And unless they intend to collect, generate, and then collide hadrons other than protons and antiprotons — i.e., other baryons like Sigmas or Xis, or tetraquarks like 2004's DsJ(2632), then the machine is and will remain the large HADRON collider.

    If they do collide nuclei down the line, then it will be the large HADRON AND NUCLEUS collider. It still won't be a LARGE HADRON collider.

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