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Science

The LEP Collider Will Be Closed Down 100

mukund writes "The Large Electron-Positron (LEP) collider will be dismantled soon, as this article on BBC News reports. The LEP is the world's largest particle collider and is built inside a 27km long tunnel. The collider has been used to confirm the existence of the Higgs particle unsuccessfully. A new project to build another larger collider is on the way. The article says, "According to commentators, whoever finds the Higgs first will probably win a Nobel Prize.""
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The LEP Collider Will Be Closed Down

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  • by billybob2001 ( 234675 ) on Wednesday November 08, 2000 @07:00AM (#637913)
    The collider has been used to confirm the existence of the Higgs particle unsuccessfully.

    Is that like the Presidential election was used to confirm the new President unsuccessfully?

  • Question is, where do you bury something the size of that thing?
  • by Bob McCown ( 8411 ) on Wednesday November 08, 2000 @07:02AM (#637915)
    The collider has been used to confirm the existence of the Higgs particle unsuccessfully.

    Er, what does this mean? They confirmed it, or didnt they? What is the Higgs boson anyway, beyond the sketchy clues the article gives? Pointers from the physicists out there?

  • Argh, LEP is passing under my town... there will be a big hole?!
  • by Anonymous Coward
    This particular particle collider has been fraught with problems since it was built in 1982. First, it caused an enourmous scare when a small section of the control room caught on fire. Since then, it has been the number one source of 'false positive' particle detections amongst the LGACs.

    There has been talk of (and I'm posting AC because I know about it!) corruption in the construction phase - the use of a substandard emitter array has long been seen as being caused by shill bidding.

    Hopefully, the next one they build there will do better.
  • You live in Geneva? Lucky you! That place is great. Anyway, the LEP is being stopped so the LHC can be put in its place. But there will be (in fact already is) a big hole since the LHC experiments are absolutely enormous. The ATLAS cavern has to be big enough to fit a piece of apparatus 5 stories high!
  • by jbischof ( 139557 ) on Wednesday November 08, 2000 @07:08AM (#637920) Journal
    Thank GOD! now they can't create a black hole and suck us all in.


    But really, why are they closing it down?? the more the merrier.
  • "Er, what does this mean? They confirmed it, or didnt they? What is the Higgs boson anyway, beyond the sketchy clues the article gives? Pointers from the physicists out there?"

    As the article said, they 3 of the 4 collectors saw 'shadows' of the particle. Therefore, they feel justified is saying that it exists, but it hasn't been proven yet. So, they did not confirm its' existance conclusively, but did 'hint' at its' existance.

    The article goes on to state that a Higgs boson is a field that 'defines' the mass of other particles. Defines is not really the best word, but as particles pass through this field, they experience drag. The more drag, the more massive the object. The analogy isn't really good, but try to imagine a net in which everything must pass through. Now the net doesn't necessarily stop anything, but 'slows it down' depending on its mass. As I said, it's not a great analogy, an my physics friends will probably get on my case for it, but that is the best way I know how to explain it.

    Eric Gearman
    --
  • The only reason to keep the collider on line at all right now is to try and be first, so as to win the Nobel Prize. They're replacing the collider with a better one, but they're afraid that while they're under construction Fermi will beat them to the punch. I thought this was supposed to be Science for Science's sake, not Nobel's sake.
  • "According to commentators, whoever finds the Higgs first will probably win a Nobel Prize."

    I don't know what the heck the Higgs is, but I sure hope that the scientists don't think along the same lines as these commentators. The scientists should be after something "just because". Not for the Nobel Prize.

    Noble (adj) Having or showing qualities of high moral character, such as courage, generosity, or honor: a noble spirit.

    Yes, I know that it is actually named after Alfred Bernhard NobEL, but I like to think that people who get it should be nobLE.

  • These things are always closing down. How about getting something that has some near term. How about working on a fuel cell?
  • The Higgs field is what gives everything mass, so without it there would be no mass. However this is not a confirmed entity. The Higgs Boson would be a result of this field and confirm its existence. The Higgs Boson would have 0 spin 0 electric charge and a mass greater than 78 GeV. Basically the Higgs Boson is responsible for giving other particles mass.
  • If you want to find out more about the LHC, which replaces LEP, and LEP itself (and even what a Higgs boson actually is) have a look at the ATLAS educational site (ATLAS is one of the experiments being built on the LHC) here [lbl.gov]

    For those who just want a quick summary of what a Higgs boson is, jump straight to that page here [lbl.gov]

  • by Dr. Dew ( 219113 ) on Wednesday November 08, 2000 @07:15AM (#637927) Homepage

    For more background information, see links:

    Scientific American [sciam.com]

    Another description [fnal.gov]

    Oh-So-Useful Slashdot Article [slashdot.org]

    Uh, Keyboardist [higgsboson.com]

  • by mackga ( 990 ) <eatshitanddie@slashdot.org> on Wednesday November 08, 2000 @07:17AM (#637928) Homepage
    There was a great story on All Things Considered yesterday, I think, about this. The guy they interviewed explained what was going on and why very clearly. I'm not into this much, but understood the basic concepts pretty well. For those in the audience asking "What's a Higgs?", here's a link [sciam.com] to a Scientific American Article about the Higgs Boson. I tried to get to NPR's site to see if they have a link to the story, but the site is pretty hosed right now. I wonder why :)
  • I worked at the Electronics and Computing for Physics at CERN as a summer student in 1993. It is truly an impressive site, with many very talented people (e.g. I had a guy called Tim Berners-Lee show me a thing called the World-Wide Web). As one of the last things during my three month stay, I got to visit the Aleph detector. We took an elevator approx. 100 meters down into the ground (the LEP ring is underground and actually tilted slighty as not to collide with nearby mountains). These detectors are HUGE (methinks on the order of 20 meters tall), and generate quite a fierce magnetic field - most computers down there had very warped displays ^/^.

    It was by the way the first place, I ever saw scientific notation used for numberz: A Swiss physicist was giving a briefing on the Large Hadron Collider (the new collider with superconducting magnets, they are going to place in the ring), and at that time estimated the cost around 1 x 10^9 Swiss Francs...
  • That's true but

    a) scientists are still human ... if you've been looking for something for 10 years it's a bit upsetting if someone else gets it, and more importantly

    b) science is funded by governments who tend to want concrete achievements to brag about (before they give you money for your swanky new experiment). Finding the Higgs boson would fit nicely.

    It isn't just egomaniac physicists behind this race, but instead physicists desperate for cash trying to satisfy their funding bodies.

  • Small powerfull particles exist in all the universes at the same time, forces (ie gravity) spread out among all dimensions (and universes) and thats why gravity is so week, the Higgs Boson would have to travel from universe to universe to make this true, which is what they think, all those wheelchair bound voice simulated physicists
  • Where can I get the parts they take out and how fast will it microwave popcorn?
  • ...and move it to London. Then again, I don't think they really need another "collider" line ;-)
  • Picture this: you get assigned to a project where an electron and a positron collide into each other at sub-light speeds. That's sort of a throwback to the days where you used to take Matchbox cars and ram them into each other at 25 mph.

    Except this time, the apparatus to accelerate the particles is many miles long. Who says that size doesn't matter here?

  • by GoNINzo ( 32266 ) <(GoNINzo) (at) (yahoo.com)> on Wednesday November 08, 2000 @07:33AM (#637935) Journal
    The shutdown of LEP is actually a good thing... With the shutdown of the LEP, the construction of the LHC [web.cern.ch] be started on. This collider will allow energies in the TeV range, with is 10 times the LEP [web.cern.ch] or Fermilab Tevatron [fnal.gov]. If they had delayed in the building of this, the Relativisitic Heavy Ion Collider (RHIC) [bnl.gov] might beat them to the higher energy ranges. Plus, you never know when funding might be cut, etc.

    Let a lower powered accelerator attempt to find the Higgs, I STILL don't believe it will be discovered, because it's been stated over and over 'we just need a little more power to find the Higgs boson!'. The problem is that all of these vast teams are lead by one or two scientists, who desperately want the Nobel Prize. Hence, good science is sometimes ignored in favor of the limelight... I'm just glad 'good physics' prevailed this time around.

    I had hoped to talk about this on BottomQuark [bottomquark.com] but lost all my research midway through the discussion [bottomquark.com]. whoops. `8r) I wonder if there is such a thing as an amateur partical physics person....

    --
    Gonzo Granzeau

  • by The Iconoclast ( 24795 ) on Wednesday November 08, 2000 @07:33AM (#637936)
    The Large Electron Positron (LEP) Collider is being shutdown to make room for the LHC (Large Hadron Collider). The LEP smashed electrons and positrons together (hence the name). The LHC will smach protons and anti-protons together. Protons and anti-protons are a thousand times more massive than electrons and positrons. Therefore, since mass and energy are equivalent (E=mc**2), the LHC will be able to reach energies many orders of magnitude higher than the LEP. The LEP is being shutdown because the LHC will use the same tunnel at CERN in the Alps that the LEP used (as a cost saving measure).
  • by mingux ( 243286 ) on Wednesday November 08, 2000 @07:34AM (#637937)

    All these people seem to be complaining about scientists chasing the Nobel prize, implying that that's a bad thing to be taking into consideration, etc.

    I mean, if you worked for several years at a company developing some sort of important software , wouldn't you be sort of pissed off if someone else came out with essentially the same product during an unforeseen server outage on your company's side?

    The nobel prize is to a scientist as writing some piece of software like Napster or Linux is to a programmer - it provides:

    • Lifelong job security.
    • Instant name recognition.
    • And most important of all, CONTINUED FUNDING FROM THE GOVERNMENT.

    It's "proof" that they accomplished something. Without said proof, even if you are very, very close, no one is going to give you any more money (at least not politicians - remember, sonny boy, these fancy partickal excellorators come out of my taxpayers pockets, and they ain't done one dang thing but ask for more money! Look at what happened to the Princeton Plasma Physics lab [pppl.gov] - they were close to actually getting a positive energy return on a fusion reactor (closer than anyone else), but since they weren't actually getting one, they lost their funding and their accelerator just sits there. I've talked to some of the physicists, and believe me, they are bitter about it.

  • by avsed ( 168886 ) on Wednesday November 08, 2000 @07:37AM (#637938) Homepage Journal

    Why is the Higgs so important?

    Apart from being the last of the Standard Model particles to be discovered, it is also (via the so-called) Higgs Mechanism responsible for the generation of mass.

    What?

    Well, just as the photon is the "carrier" of the electromagnetic field, the carrier (incidently, all such carrier particles are bosons - that is, have integer "spin") of the mass field is the Higgs Boson, and will be seen as evidence for either the Standard Model of Particle Physics, or (depending upon its properties, or indeed, existence!) for other competing models. As one might well imagine, the mass generation process is very interesting to Physicists, and Higgs discovery would certainly be worthy of a Nobel prize.

    As to the closure of LEP - LEP has done some startling physics and has been an extremely successful endevour however you look at it (for a start, without CERN we would not have the World Wide Web!) The collaborative model of smaller states coming together to afford large scientific projects was the predessesor to the ISS, and even a couple of the US High Energy Physics experiments (such as the experiment I'm involved with, BaBar [stanford.edu] are going the same route.

    Finally, don't forget that Physics is still a human endevour, and us Physicists need a pat on the back sometimes too!

    - Dan

    PS: Ed, get back to work!

  • I'm working at Fermi in production of the RunII CDF detector (as an engineer, not a physicist) and from what I hear, taking LEP down means we are nearly assured of the Higgs before LHC comes up - unless it is truely impossible at Tevatron's size, which seems unlikely, currently. Things here seem to be going quite well, imo.

    To give a (very) rough explanation of the Higgs: when you smash things together with very high energies, you get a huge explosion (huge, considering it was started by one proton and one antiproton) and all sorts of fragments are produced.

    However, we have to measure these fragments using very odd means, because it is mostly impossible to directly measure most of these things... you can only measure the effects they have on the relatively normal stuff we can build a detector out of. (if you build it out of these things, the detector would vanish in much less than a second...) So the more "normal" fragments are relatively easier to measure, because they interact more with the more normal detector.

    In recent high energy physics history there has been a string of these things, Higgs is the next.

    Someone said they first saw sci notation in 93, and I'm amazed. I'd heard in Junior High earlier than that... or did you mean something else.

    Btw, Fermi has a significant linux community. Also, (from a bad memory and this isn't my department but) they have to filter the incoming data in realtime, keeping only the most interesting 1/millionth of it - and that data alone is a couple CDs/second worth of data. Lots o' bandwidth there...
  • Well, dont forget that the guys running the LEP invented the web, some ten years ago...
  • by tbo ( 35008 ) on Wednesday November 08, 2000 @07:49AM (#637941) Journal
    Here's an email that's been circulating through the physics department at my university. It does a pretty good job of explaining what's up with LEP, and why it would be nice to keep it going for just a little while longer. The short of it is that they think they've found Higgs, but need a bit more data to be sure.

    Anyway, here's the email:
    -------------------

    Hi,

    Since we've been getting a lot of enquiries about the reports of a Higgs
    Boson 'discovered' at LEP, I thought I'd give you more info.

    There are 4 experimental groups taking data at the LEP electron-positron
    collider. On Friday Nov.3, the each of the 4 experimental groups
    presented our analyses to the LEPC (LEP Experimental Committee) i.e. the
    Research Board, at CERN. And one analysis combining the results of all 4
    expts was also presented.

    The LEP experiments were all scheduled to stop data taking on Nov.1, after
    over 11 years of experimental data taking -- probing & testing of the
    Standard Model to unprecedented precision. Stopping and dismantling LEP is
    necessary before the installation of the LHC accelerator and detectors may
    begin, as LHC uses the LEP tunnels. (LHC is the Large Hadron proton-proton
    Collider, which has discovering the Higgs Boson as a centerpiece of its
    physics program)

    LEP reached the highest energies ever this year, with 208.2 GeV as the
    highest energy reach possible, (limited by the number of RF cavities) but
    the accelerator is so unstable at this energy that less than 4% of this
    year's data was taken up there. The bulk of this year's data was in the
    205-207 GeV range.

    Every experiment sees "Higgs candidates". These are events which look like
    e+ e- --> Higgs ZBoson, with each the Higgs and ZBoson subsequently
    decaying. For 3 of the 4 of the expts, the "candidates" seen are
    absolutely and entirely consistent with what's expected from known
    Standard Model processes i.e. background. ( 2 Z's, 2 W's, and other
    processes which can look very similar to ZH)

    3 of the 4 LEP groups have completed analyses which result in upper limits
    on Standard Model Higgs masses. 1 (ALEPH) reports a 115 GeV Higgs with a
    significance equivalent to a 3.4 sigma excess over background
    expectations. When all 4 expts combine our data, this diminishes to a 2.9
    sigma effect for a 115 GeV SM Higgs boson.

    Our UBC group is a part of the OPAL experiment, one of the four expts.
    OPAL rules out a Standard Model Higgs boson at masses under 208GeV at 95%
    confidence level. Our OPAL bottom line can be seen in a talk by Arnulf
    Quadt of OPAL, at the LEPC presentations:
    http://www.physics.ubc.ca/~janis/arnulf.ps If we are to interpret our
    results in terms of a Higgs Boson at 115 GeV, we have a 1.3 sigma excess
    over background processes at this mass. We have a 2.6 sigma effect at 107
    GeV. You give us a mass, we can tell you if we see an excess above, or
    depletion below the background expectations. (the 2.6sigma at 207 GeV is
    the largest deviation from expected background at high energies)

    The combined 4 experiments talk at LEPC by Peter Igo-Kemenes, incidently
    also an OPAL collaborator, (emailed to you by Douglas) may be seen at
    http://lephiggs.web.cern.ch/LEPHIGGS/talks/pik_l epc_nov3_2000.ps

    You can see the ALEPH LEPC talk at:
    http://alephwww.cern.ch/ALPUB/seminar/lepc_nov00 .pdf

    Judge it for yourself. I'd say we are in an interesting situation and it
    woudl be shame to stop the LEP program now with these interesting hints
    from ALEPH. With another year of data taking at LEP (and hence a year
    delay in the LHC) we would be able to confirm or refute the existence of a
    115 GeV Higgs at a honking 5 sigma level... what we usually refere to as
    the "discovery level" It would be very exciting if we could indisputably
    discover the Higgs Boson. But I would say we do not have a Higgs Boson at
    this time.

    CERN has not issued any press releases on this matter (as of Saturday
    evening). Only the LA Times has. Even NY Times has not.
  • Rather than building a larger accelerator, might I suggest the "Where's Higgs?' problem could be solved by a modified Beowulf cluster of "Where's Wally?" books?
  • I see an opportunity here... if we can just adjust the thing to handle really big bags of refuse - think of all the landfills that could be replaced if we could squish the bejeezees out of all our trash and stick it in a big tunnel!

    That would rule!



    Not that I would ever be sarcastic or anything...

  • That is the key to "warp speed" if we can create anti-gravity then we can create wormholes, and if we ever figure out how to determine where we create our wormholes then we can travel light years away by taking a short path throught the wormhole.
  • The Higgs boson actually has very little to do with the mass of your average matter. If you were to take your average atomic nucleus, the amount of that mass which is due to the Higgs boson is negligible, most of it is due to gluons.
  • Does the Higgs boson's "spin" affect the mass assigned to a given object that passes through it. In other words, would altering the spin of a Higgs boson cause it to behave differently? By this I mean applying a different mass to objects under its "influence?"

    I ask this because if physicists can determine how mass is "applied" to an object, couldn't we then change the characteristics of an object by affecting the way it's mass is determined? By altering a group of these paritcles so that an object in that space has its mass reduced or increased based upon the way the Higgs bosons have been altered?

    That could solve alot of problems.

    Regards.
  • Since they are using my tax dollars to do this, do I get to share in the Nobel prize if they win?
  • Physicsists are spending all these Billions of dollars (and Euros) to win this Nobel prize, they will be sorely disappointed when they find out that the prize is only about a million bucks.
  • by SilverSun ( 114725 ) on Wednesday November 08, 2000 @08:17AM (#637949) Homepage

    For some more (but brief) information about the Higgs boson read here [teachers.cern.ch]

    Some comments:

    The collider has been used to confirm the existence of the Higgs particle unsuccessfully.

    Maybe some of you wonder why these guys can't tell if they found the Higgs particle or not. Let me try to explain. It's all about statistics. Imagine you have two dices, one has the numbers from one to six on it. The other one you just know it has the numbers one to five and the last number can be any of 1 to 6, there might be e.g. another 2 or something. let's call this dice 'signal dice'. Unfortunately they look exactly the same and you can only read the number on top.

    The Higgs is like the number 6 on the second dice.

    ok. roll the dices. you get 3 and 5. Now you know there is at least a 3 or a 5 on the signal dice. Noone cares. again: 1 and 6. Wow.. do we have something? You don't know because you cannot tell which dice shows the 6.

    The trick: if you roll a hundert times, you expect 100 * 2 (dices) / 6 = 33.3 times the number 6 if the 'signal dice' has a 6 and only 100 * 1 / 6 = 16 times 6 if the signal dice has no 6.

    You see, a single (or a few) rolles don't help. Even if you see the 6, it might be the other dice. Unfortunately they cut the power to LEP so they cannot keep on rolling.

    Actually only Aleph has 3.5 sigma excess in one channel Z*->H Z (H -> b + anti b), so that means pretty much nothing and they don't really trust their Monte Carlo (which provides the second dice :). That means they see something, but just have not enough data to really confirm the existence. NOrmally you do that with at leat 5 sigma.

    According to commentators, whoever finds the Higgs first will probably win a Nobel Prize.
    Well, todays HEP collaborations are very large. Especially when it commes to LHC experiments. There is no single 'person' that is by any means able to actually 'find' the Higgs. My best guess is that, given the Higgs particle will ever be found, Peter Higgs himself might get the Nobel Prize.
  • Infortunately all reasonable theories predict the spin of the Higgs to be zero. That means you cannot alter it as you can with the spin of an electron (fermion) or vector boson. no chance to alter mass.
  • In order to create wormholes, as any sci-fi fan knows, are essential for long distance travel, you need anti-gravity. Once we confirm the existance of Higgs Boson, will we be able to creat the anti-Higgs Boson. Looks like the first step in the right direction for interplanetary travel.
  • Soooo.... Someone's going to spend millions (billions even?) to build a particle accelerator so they can make a different kind of particle to win the nobel prize so they can...
    Make back their initial investment?
    ---
  • Why close it down? We can use it to test our web site for /. tidal wave collision, to make sure our site really can handle that kind of load.

  • Umm, as a professional physicist you should be a little more careful when you go around saying things like "the higgs is responsible for the generation of mass". The fact is for most stable matter the Higgs has relatively little to do with mass. The mass of a proton is less than 10% due to the Higgs mechanism, if memory serves, with most being due to strong interactions.
  • I can't believe you guys resisted using "So Long and Thanks for all the Fission" as your byline... :) (And yes, I know, it's not fission, but the line is worth bending it IMHO, heh)
  • It refers to an interesting sci-fi book, which I can't remember the title of. Aliens (Giant ants or something) where going to invade our universe after detecting a Supercolider experiment. The main character then traveled back in time to prevent the construction of the SSC.
  • Perhaps an analogy of ballistic gelatin and a bullet would work better. A very small, high-speed bullet will often penetrate much deeper into the gelatin than a larger round, simply due to friction. The same thing happens in the Higgs' boson field, where the more massive an object, the greater the drag, and the more it is slowed.

    OK, so that's not a perfect version, either, and my gun-toting friends will probably get on my case for it, but that is the best way *I* know how to explain it.
  • It isn't strictly a government thing. There are American scientists working on experiments at CERN in Switzerland, in Japan (I can't remember the name of the center), and at Fermilab in Illinois.

    There are also plenty of people of other nationalities working side by side with them.

    Big sciense is done internationally.

    The interesting thing is that when the results are published, the paper will have two hundred or so names on it. This includes graduate students that helped build the detectors years ago and are no longer on the project.

    But if the discovery is done at Fermilab, a different set of two hundred names will be on the paper.
  • Care to tell me why? What's wrong with the French? Or Paris, for that matter? Aside from the price you pay for a glass of beer that is, of course.
  • That's "Where's Waldo?", or more properly - "Where's Taco?"
    --
  • I had a Higgs boson too. I found it at a garage sale for only $1.50. Then I got married. My wife threw it away, along with my old comic books and porn collection.
  • When I was in graduate school. They took us on a tour of Stanford Linear Accelerator.
    They had the same problem of wanting to store all the data for all the transducers in the detector.
    But they could only store it if they triggered on
    one in a million events (roughly).
    So they used a lot of electronics to generate the trigger signal (think at least one 50ft trailer filled with relay racks).
    Of course, this was around 1986 or so.
    At that time, they used a VAX 11/780 to store the data onto digital tapes (the 9 track 6250bpi variety). They also used Fujitsu IBM mainframe clones things.
    And they used a lot of FORTRAN.

    I could see why Linux would be very popular in Physics today.
    Once they capture the data, they have to plot it.
    They could use GNUPlot now. I was in Physics
    just before Unix and X-Windows moved in.
    I believe the transition was driven by the RISC
    processors gaining ground from the CISC (like the
    VAX instruction set).
    They had something like GNUPlot called TopDrawer.

    Physicists have such big computing needs that they
    will use anything they can get their hands on.
    So Linux and FreeBSD have great potential.
    They are also used to sharing their source code.
  • He is a particle physicist, and thinks of matter in terms of gauge bosons and fundamental fermions. So the Higgs is pretty much the thing.
  • by Anonymous Coward
    you are the fool if you think they do it for the money. It's all about the chicks!
  • I second.

    That damn thing (the LEP) is easily the most complex/huge/impressive thing I've ever seen. The accelerator was running when I was there (12/98) so I was not able to tour the tunnel but surface of the CERN site conveyed the proper impression. Driving the length of the tunnel on the surface would necessitate several stops Swiss/French customs crossing the border while inside the tunnel was granted a special treaty exemption. You couldn't throw a rock without hitting a Nobel winner. Toss a second rock and hit a Nobel laureate from a different country than the first.

    Btw, TBL's first WWW host, a NeXT box, was still running in a display case near the Swiss cafeteria. If the CERN staff didn't need to empty the tunnel for the LHC installation you can be sure it (the LEP) would be running as long a it could produce data.
  • "According to commentators, whoever finds the Higgs first will probably win a Nobel Prize."

    Actually, they got the Nobel prize, but instead of getting it for finding the Higgs it was for inventing the Tachyon Tardyon Collider. See Robert Sawyer's Flash Forward.

  • Assuming discoveries are made, and funding is provided, what does the motivation matter? Isn't it the end result that matters the most?
  • The LHC will smach protons and anti-protons together.

    One minor correction: LHC is a proton-proton collider, not a proton-anti-proton machine. pp machines are cheaper to build and run than p-pbar machines, and for the energies of the LHC (14TeV Center of Mass), they have almost the same reach for finding new phenomena. This is mostly because at such high energies, protons and anti-protons both are "mostly" gluons (meaning glue, not quarks, carries most of the energy). So, LHC is basically a gluon-gluon collider. Otherwise, I agree with everything you said.

  • Most people don't know a gauge boson or top quark from Adam so it is misleading to tell them the Higgs is the origin of mass. Also it leaves open the question of how the Higgs itself gets its mass.
  • GENEVA, 8 NOVEMBER. With evidence for and against the existence of the Higgs particle too close to call, exit polls of bleary-eyed unshaven scientists emerging from their counting houses shows a deeply divided physics community. "With so few events, it is critical that the data analysis be done correctly," said one physicist who wished to remain anonymous. I will not concede that Fermi National Laboratory in the United States will win the race for the Higgs until our events are recounted and all absentee events have arrived from the French portion of the accelerator. Early media accounts of the discovery of the Higgs were retracted and then un-retracted in the most closely contested experiment since Carlo Rubbia discovered alternating neutral currents. Science reporters are stocking up on coffee, as the Higgs watch promises to drag on through the night.
  • If the CERN staff didn?t need to empty the tunnel for the LHC installation you can be sure it (the LEP) would be running as long a it could produce data.

    In fact, LEP may live again! The magnets, RF cavities, and other stuff (but not the detectors, I don't believe, although I could be wrong), will be put into storage, on the chance that CERN decides to convert the LHC to an electron-proton machine at some point in the distant future (much like HERA at DESY in Germany), after its planned program is completed.

  • The flip side of course is that the construction contracts for LHC contain large penalty clauses for delays caused by CERN. A year of data collection would pretty much wipe out the LHC budget completely, just paying for the delays. Compared with the miniscule chance of actually confirming the Higgs - remember, from the note, that there is only one detector (ALEPH) out of four with a potentially notable excess in one channel. From the perspective of many of my colleagues (theoretical particle physicists), there is little chance (given the lack of supporting evidence in other channels and detectors, and the history of such "potential discovery" announcements) that this is actually the real thing.

    Just a passing note for those that never learned or don't remember this stuff, random fluctuations to the 1 sigma level would occur in 1/3 of all experiments set up and performed exactly the same way; and 2 sigma is about a 5% chance of random fluctuation. And that is assuming perfect knowledge of all the uncertainties, which is never the case. The number of "well established" three-or-more sigma "discoveries" that have evaporated in the face of more data is well in excess of what you would expect from chance. Bottom line for a physicist (and I don't remember where I first saw this):

    • 1 sigma: write a Letter
    • 2 sigma: write a Paper
    • 3 sigma: bet your graduate student's career on it.
    • 5 sigma: bet your career
  • by krlynch ( 158571 ) on Wednesday November 08, 2000 @11:04AM (#637973) Homepage

    Here are the current Center of Mass frame energies of the colliders:

    • LEP: 200GeV electron-positron
    • Tevatron: 1.8TeV proton-antiproton (starting next year, they go to 2TeV)
    • LHC: 14TeV proton-proton machine (2005ish?). Later, they might also do many-TeV lead-lead collisions
    • RHIC: don't remember the energy, but they do gold-gold collisions, I believe.

    What is likely to happen, is that LEP data will be able to rule out a Standard Model Higgs boson up to about 110GeV in mass, or "discover" a slightly lighter Higgs (where "discover" means a very particular thing, not just seeing a few events), while the Tevatron (I think) will be able to rule out a Higgs up to something like 140GeV and discover one up to 130GeV (these may be wrong, but they're in the right ballpark). LHC will be able to discover any Higgs up to about a TeV (with the exception of a small range right around where the limits are at now). So, if the Higgs is lighter than about 140GeV, it will be discovered by the Tevatron long before LHC turns on. RHIC, however, is not the right type of machine to study these phenomena, and so is not really a concern for LEP in the Nobel search :-)

    On the other hand, RHIC may be the machine to confirm the existence of the quark-gluon plasma at high nuclear density. There is tantalizing evidence from the SppS (I think) collider at CERN, but not confirmation. If RHIC isn't big enough, LHC should be (in lead-lead mode). So the race is on there too.

    The next few years will be extremely exciting on the experimental front (Higgs physics, supersymmetry/technicolor discovery, CP violation physics, neutrino oscillations). It's a great time to be a physicist :-)

  • did anyone else read this article as saying: According to the Slashdot Model of particle physics...

    it has been too long a day...

    -l

  • If this interests you at all, i suggest reading Flashforward by Robert J. Sawyer (my personal second favourite Sci-Fi author, next to Douglas Adams and Isaac Asimov)

    Its a piece of fiction about the discovery of the higgs boson.

    --
  • In the voice of Galactis=
    "I think a particle accelerator would make a nice conversation piece for my apartment. I can put it next to my Saturn V rocket or maybe use it for a doorstop, my door is always knocking over my Easter Island heads. I really should do something about that..."
  • Has the canton Geneva is in given women the vote yet?
    (It's a republic where the different Cantons have their own internal political systems, which includes deciding whether the female of the species can have the vote.)
    So not everyone is lucky to live in Switzerland...

    FatPhil
  • From the SA page:
    "
    ... and the weak nuclear force, which governs beta decay--a form of natural radioactivity-- ...
    "
    You know it's "popular science" when they come up with phrases like "natural radioactivity".
    What's an unnatural radioactivity then?

    Having said that I remember bugger all about Higgs fields, so thanks for the links, I'll put up with the "popular" nature in the interest of learning.

    FatPhil
    Phil
  • I know this is OT, but how many sigmas did the Cold Fusion positives accumulate before they were all down-modded?

    It's nice to compare relative "scientific" "certainties".

    You'd never hear mathmos say "My theorem's truer than yours"...
    Oh, sorry, actually you would!!!

    FatPhil
  • I was working at FermiLab when the transition from VMS to UNIX (and from F77 to C) occured.

    Boy did I hear a lot of bitching.

    But yes, FNAL was one of the biggest first users of RedHat (aka fRedHat).

  • A rather English slant, but I found it quite fun!

    http://hepwww.ph.qmw.ac.uk/epp/higgs3.html

    (i.e. from High Energy Physics at the University of London, for those interested)

    There are 5 descriptions, indexed at
    http://hepwww.ph.qmw.ac.uk/epp/higgs.html

    But I think that number 3 is the best!

    FatPhil
  • All the forces in the universe (excepting, for the moment, gravity) can be considered as waves or particles according to quantum theory.

    The Higgs boson is the manifestation of Gravity.

    In contrast to what someone said about the Higgs boson NOT being responsible for the mass (saying someone else is wrong) then THEY are wrong... (see Er... thread) the gluons are manifestations of the strong force, which holds nuclei together, and as such contribute to the energy (you could say the rest mass energy, the ubiquitous E=mc2), but not strictly, in terms of definitions, the gravitational mass (maybe not the inertial mass, these may be different, but in terms of gravity, it is the gravitational mass that matters).

    Now what gets me (an astrophysicist, not a particles buff. I hate particles), is that Einstein (and others) went on at length about the SEP, or the Strong Equivalence Principle. You know when you are in free fall, everything falling with you in your frame goes at the same speed etc. and behaves like there is no gravity? Well this is application of the SEP. So what happens to the Higgs in this case? Does it disappear? But you can't just annihilate particles simply because you are travelling at some different speed - they should still exist in any frame! Surely? I have been puzzling about this for ages - can someone help?

    [Prepared to sacrifice karma by going slightly off topic for an answer]

  • Umm, actually the particle that mediates gravity is called the GRAVITON and has nothing at all to do with the Higgs. Get a clue.
  • Actually, my post is correct. Without a Higgs, stable matter would weigh almost the same as it does with the Higgs. Atomic physics and chemestry would be changed because it depends on the mass of the electron, but that's a different story.
  • According to commentators, whoever finds the Higgs first will probably win a Nobel Prize.

    That sounds really weird to me? Will you qualify for a Nobel prize, just beacause you are proving someone else's theory to be practically correct?

    Give the prize to the guy who in the first place came up with the idea about these Higgs thingies...

    Another thing... I've also heard that contrary to popular belief, you won't get a Nobel prize for one amazing discovery alone, unless it is really brilliant. You kind of have to earn them through "long and faithful service". When you after many years as an outstanding scientist present a fine theory, you may get a noble prize.

    I might have heard wrong though.

    --

    "I'm surfin the dead zone
  • With regards to your other question, the answer has to do with the definition of the vacuum in an accelerating reference frame. Recall the GRAVITON is a massless bosonic particle and can be popped out of the vacuum at will. Any good text on quantum gravity should explain it.
  • they have to filter the incoming data in realtime, keeping only the most interesting 1/millionth of it - and that data alone is a couple CDs/second worth of data. Lots o' bandwidth there...

    Engineers at TRIUMF [triumf.ca], Canada's national particle research facility, have been using in-house data acquisition cards to do the job. Their FastBus cards are an interesting experiment in home electronics, and they hope to put them into production for any use where large amounts of data need to be processed quickly.

  • This doesn't make sense. A proton is about 1800 times more massive than an electron. The collider can impart a specific amount of energy to a particle. Shouldn't this simply mean that the proton is traveling at a lower velocity than the electron and hence has the same energy (momentum?).
  • How We Lost the Moon, A True Story by Frank W. Allen, by Paul J. McAuley, is another perhaps slightly more far fetched short story dealing with particle accelerator experiments. Some nice black hole moments ;)

    It's in Best SF 13, a nice collection by all accounts. Amazon.co.uk listing [amazon.co.uk]

  • Right... I just had a physicist from CERN explain this to me...

    The synchrotron radiation from a charged particle (like a proton or electron) is proportional to the gamma-factor (the time-dilation factor if you like) to the fourth power. This means when you do all the maths that the LHC can reach energies of approximately 2000^4 times greater than the LEP.

    This is because the limiting factor is not exactly the energy pumped in but the energy that is radiated away, if you see what I mean...

    Its not brilliantly clear because I've been drinking rather heavily tonight, but basically the larger mass of the proton means it has a lower time-dilation factor for the same energy and so loses less energy as it goes round the collider.

    I know I've trivialised it a fair bit, but this is the best way I can see to explain it in what are loosely called laymans' terms.

    Its not the energy that the collider can provide... but the energy that the particle loses that limits the ability of us to build bigger colliders.

  • Well that depends upon how much I need to qualify: In the Standard model, the Higgs mechanism is postulated to be responsible for mass generation - the (non-virtual) Higgs boson as a particle has little to do with it (and indeed may not even exist in the region predicted by the SM). Nevertheless, the mass field is generated by the Higgs mechanism - the colour (color) field is generated by strong interactions and the two are quite seperate in the Standard Model Langrangian. The behaviour of quarks inside the proton leads to some interesting physics, but I don't see how it has anything to do with mass generation.
  • Strong interactions have a lot to do with chiral symmetry breaking, which is more relevent to the proton mass than the Higgs mechanism is. Even within the confines of the Standard model the standard answer is a bit of a cheat because the mass of the Higgs boson itself is stuck in by hand.
  • by G-funk ( 22712 )
    Now this isn't one of those "give the money to hungry african kids" posts, I'm asking a genuine question:

    Why do we need this crap, will finding a Higgs-Boson (or whatever) further mankind in any way? What are they hoping to actually achieve with all this? Anybody know of any real applications for this other than "because it's there"?


    --Gfunk
  • Give the prize to the guy who in the first place came up with the idea about these Higgs thingies...
    that would be Scottish physicst Peter Higgs, who came up with it in 1964 :-)
  • by Anonymous Coward on Wednesday November 08, 2000 @04:16PM (#637995)
    Hiya,

    Not a usual poster on slashdot, but it seems that few/none of the other Higgs searchers at LEP are sticking their necks up. For the benefit of non-Higgs searchers in particle physics, and for those willing to wade through some details, here's a Higgs searcher's perspective on the story.

    Unfortunately, the majority of the information presented on this has been to the public session of what is essentially an internal meeting of LEP. What the experiments (and the LEP Higgs group) have shown in their brief presentations are summaries of much more detailed work which is of course still ongoing (data taking only finished a few days ago).

    The comments that I've seen in this forum from physicists are coming from what could be termed either the general community, or the competition. They reasonably point out that brief status reports of ongoing analyses have not convinced *them* that the Higgs is there, but unfortunately this was the structure of the forum in which the results were presented. Another interpretation is that we didn't properly anticipate confusion about issues that seemed obvious to the experts.

    One common misinterpretation seems to be that LEP observes only 3-4 Higgs candidates, which is actually very false. This is just the number of events collected that really 'stood up' as extremely signal-like. In fact, hundreds of possible Higgs candidates were collected, and they are each given a rating on a "signal-like" scale. If you skim off the top few, you get four events, three from Aleph and one from L3. Up until very recently, Delphi also had one, but it dropped down on the signal scale after reanalysis.

    As you drop down on the scale, to the point where you'd expect half of your events to be background and half to be signal, you expect 7 from background, and observe 14. The weight distribution agrees across the board with the signal distribution. These are divided among all four experiments and all search topologies. In fact, the sample was divided in several different ways for consistency checking purposes, and they all came out looking exactly like a Higgs signal. It gave us goosebumps to see the results of these tests.

    If there's no signal, we've had a one in a thousand blip. There is a standard for discovery which requires that to be a bit less than one in a million. We are confident that, if it's real, we'd be able to reach that one in a million, and if it's not, that the effect would dry up. The whole point is that this is an exciting observation which we'd like to verify that is at the edge of our sensitivity. To do that properly would take six months of extra running, which all of the LEP experiments requested. The whole point is that it's not yet conclusive. The CERN management has been weighing questions of cost of running (in dollars and delay of future projects) vs chance that we did just get a freaky blip in the background, and has unfortunately decided not to take the risk. People will have the next 6-7 years to wonder if what we saw was real or not before it can be tested again.

    At the moment, the most complete information is at the Physics Co-ordinator's Page [alephwww.cern.ch].

    A collection of all of the presentations at the public sessions of the LEPC meetings can be found here [delphiwww.cern.ch].

    Cheers,
    Pete McNamara
  • Ok, common question, doesn't seem to be many answers yet.

    Why is it stopping soon? Because it is being replaced, and as we delay stopping it, the longer it takes to set the new proton anti proton collider up.
    Then why is it still going? Because we want to find the particle as quickly as possible. We have hints that we have found it, as the collider was running greater than maximum power, but we need more events to be sure. Sure, we can leave it to Fermilab to possibly find it (I dont know the power of any of the colliders), but is it not better to find it as early as possible? If we find it now, maybe we can better optimise the new collider?

    BTW - for those who keep saying the physicists just want to keep their job as long as possible, all of them are staying on to work on and for the new collider.

    And this is for science's sake, just a nobel prize would be neat - it is not like in medicine, however, where the nobel prize is the be-all and end-all of life as we know it.

    Discalimer, I have not much information on this subject - IANAPPY (I am not a particle physicist yet)
  • I didn't actually know that - what about the selection rules? Where does the charge and spin go, etc?
  • Actually, eveyone around here seemes to use PAW (Physics analysis workstation), http://wwwinfo.cern.ch/asd/cernlib/version.html

    Pretty neat for graphing, but the language is a kind of macro kind or fortran language which just *sucks*! Works for linux, unix etc, and tar.gz file is only 50MBs or so, if I remember correctly.

    As for your comment about source code - yeah we generally are all for openness - remember the WWW? And Science is generally (except for medicine, where they like to patent genes, for fscks sake) all about sharing knowledge :)
  • It's pretty common for government to screw over particle physicists. It happened here in British Columbia with the TRIUMF cyclotron (which is the largest of its kind in the world, I believe). There was a proposed upgrade called the KAON facility, and the government had agreed to match private donations to fund its construction.

    A few weeks from the funding deadline, the fundraisers had raised almost all the necessary funds, and had a donor lined up and ready to give the remaining amount, when the government backed out, claiming that they hadn't made the deadline (even though it hadn't passed yet, and they were going to have sufficient funds). While TRIUMF is still in use, it can't reach the energies needed for most particle physics research nowadays, so it's been relegated to other tasks (materials science, muon spin rotation experiments, medical research...)

    The Superconducting SuperCollider that got cancelled in the US is another example of government backing out of important research...

    Nobody realizes that basic scientific research nearly always pays off in the long run, in spades... Everyone is too obsessed with the short term. Where would our CD players, our computers, our satellites, and our microwaves be without basic scientific research in fundamental physics?
  • Apart from being the last of the Standard Model particles to be discovered, it is also (via the so-called) Higgs Mechanism responsible for the generation of mass (my emphasis).

    Does that mean that the anti-Higgs (if such a thing is supposed to exist) can be labeled an "anti-obesity drug" :-)

  • Everyone who doesn't care how the universe works, go stand in the corner with G-funk.

    -Legion

  • Also it leaves open the question of how the Higgs itself gets its mass.

    No. It doesn't. The Higgs itself gets it's mass via the same Higgs mechanism. What actually is wrong is that the Higgs boson is responsible for the masses. Right is: The Higgs-Field (not the boson) is responsible for the mass (of fundamentals).

  • Everyone knows time travel requires a vessel that is larger on the inside than outside. If its exterior resembles a British police call box with a flashing light, so much the better.
  • Sort of

    The interaction of massive particles with the Higgs field is what gives particles inertial mass. The force of gravity i.e. weight of the particle is given by the particles interaction with whatever curved spacetime exists at that scale, which is unknown, as the effects of GR gravity below a scale of ~1mm hasn't been measured, and these particles are smaller than 10^-12 mm
  • The higgs field gives the particles inertial mass, not gravitational mass. The effects of gravity on this scale just aren't known at all, as measurements only go down to scales of ~1mm whereas these particles are 10^-12mm in "size" (which doesn't have much meaning in quantum mechanics).
  • Also there are penalty clauses in the contracts with the construction company. It is too damn expensive to pay off these contractors to wait around while you take another years worth of data. Or so stated my particles lecturer who works on Opal there.
  • So, if the Higgs is lighter than about 140GeV, it will be discovered by the Tevatron long before LHC turns on.

    Not really. The detectors operating at the Tevatron, CDF and D0, will need roughly five years of operation to collect the luminosity necessary for Higgs discovery, and still could only find a Higgs below 120 GeV with 3 sigma confidence level. In five years, LHC is scheduled to start operations.

    Combined CDF and D0 limits after roughly five years of operation (integrated luminosity 10 fb^-1) would allow for a 3 sigma evidence below 120 GeV or 5 sigma discovery below 100 GeV. The latter is already excluded by LEP.

    So chances for a Higgs discovery at Tevatron are not too good, really. It's possible, though not very likely.

    Cheers, patrick
  • The BBC news site has a link to a streamed audio report on the Higgs particle. It may or may not be useful or interesting. I can't really tell you as I don't have a sound card. But it's linked to from their sci/tech news page [bbc.co.uk].
  • No. Work's dull. Anyway I'm not the one writing up a thesis.
  • The computer you are using, the technology that allows us to probe our DNA (x-ray diffraction etc.), to watch our minds work (PET, MRI etc.) ALL come from fundamental physics research and at every stage people have asked "what's it for." We (physicists) do research because it's interesting. *You* however should approve because the more we know about the universe, the more we can do.
  • 1. The Higgs does not get its mass purely from the Higgs mechanism. To make the Standard Model work, a quadratic Higgs mass term has to be stuck in the lagrangian by hand. It's a kludge. Ask a real physicist, he will admit it. 2. Yes, it is responsible for the mass of _fundamental_ fermions and gauge bosons, if the Standard Model is correct, but when physicists are talking to the public they rarely mention that the masses of _fundamental_ particles have very little to do with the masses of actual stable particles such as protons and neutrons which exist outside the laboratory. My initial claim that the proton would have almost the same mass without the Higgs mechanism has not been refuted, because it is true.
  • Did I say "I don't care how the universe works" or "if there's no practical use we shouldn't be doing it"???

    I think not.

    All I asked was if there was something in particular they were trying to achieve, you need to calm down buddy.

    Gfunk


    --Gfunk

The explanation requiring the fewest assumptions is the most likely to be correct. -- William of Occam

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