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Science

200GeV Collisions at RHIC 47

Posted by michael from the no-blackholes-yet dept.
PHENIX Experiment writes: "Brookhaven Labs has produced for the first time, collisions of gold nuclei at a center of mass energy of 200GeV/nucleon. This is a new energy regime for the high energy nuclear physics relativistic heavy ion program which is now getting underway. We have put together a bunch of nice photos of event displays for some nice central collisions, the collisions where the two nuclei hit head on. Over the next 6 months or so, we are looking to collect on the order of a petabyte of data which will then be analyzed using our VA Linux farm operated by the RHIC Computing Facility."
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200GeV Collisions at RHIC More

200GeV Collisions at RHIC

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  • The figure is 200 GeV/nucleon. Since a gold nucleus has about 250 nucleons this is about 50 TeV/nucleus.

    This sort of accelerator explores a different physical regime from something thje LHC or the Tevatron, which use single higher-energy particles. It
  • By colliding particles at every-increasing energies we can split them into their contituent sub-particles. The sub-particls require lots of energy to be "dissociated" from their parent particles. As new particles are discovered, or their existence is confirmed, new theories are made as to whether they have smaller constituent particles. To see them, if they exist, requires more energy, ie faster collisions.... and so on.
    By finding these sub-particles we can figure out how the particles in the "particle zoo" behave, why energy and matter appear as they do, and how the universe formed etc.
  • We have lots of tin cans in orbit that do work properly. Possibly an orbital particle detector doesn't have to be a manned spacestation. On the other hand it is a real challenge to build such a thing on earth so it will probably be nigh impossible to build in space.
  • the Earth is a 'type-13' civilization. Type 13 civilizations destroy themselves by turning their planet into degenerate matter looking for the Higgs boson.
  • Mmm...should be looking for lithium flares, then. :)
  • s/atoms/protons/g
  • Emmm...
    you're looking for real-life benefits from particle physics?

    As someone who has worked in both particle physics and medicine I can point out:

    *) development of accelerators for cancer radiotherapy, used routinely in hospitals every day

    *) advanced dedicated accelerators for novel cancer therapy, like pion therapy and boron neutron capture therapy

    *) synchrotron light sources, used for biomedical and semiconductor materials research

    *) detectors developed for Positron Emission Tomography scanners

    *) development of high field superconducting magnets, as used both in particle detectors and MRI scanners

    I think that's a good few examples!
  • ....in joke for fans of Stephen Baxter's Xeelee Novels....
  • Isn't this the facility that was supposed to create a black hole and destroy the earth? Here's the report [bnl.gov] that Brookhaven had to research to quiet the fears of the folks concerned about the RHIC's disaster potential.
  • That's right, folks, if this collider can't find a Higgs, that means SUSY is just plain Wrong

    In a word, no. These energies were reached a long time ago, but the lack of a Higgs is not surprising. Remember that the Higgs is never produced alone, and that other particles produced need energy too. You need a center of mass energy on the order of a few TeV before you look for the Higgs.

  • Were all still here! Congratulations, Brookhaven, you didnt destroy the Universe, or create a mini black hole that swallowed the earth, or a new big bang or anything like that. I know you guys are still working on it, but youll kill us all eventually ;-)
  • It doesnt really matter how much mass you have, or gravity to make a black hole, what matters is how compressed that mass is. IIRC, if the earths mass were contained in something the size of a pinhead, it would become a black hole with an event horizon the size of a marble. As you accelerate an object, its mass increases, but its size does not. Accelerate a pinhead so that its mass became that of the earth, and you would have a black hole with the earths mass, wether or not it would be stable if slowed down is another matter, but it would become a black hole for awhile.
  • I'm sure the Insurance Institute for Highway Safety (IIHS [hwysafety.org]) will do off-set collisions and rank at least 50% of the nuclei as "Poor"...

    That was a lame joke. Oh well.

  • This is wrong.

    1. Be precise. I guess when you say SUSY you mean MSSM (Minimal Supersymmetric StandardModell).

    2. There are enough free parameters in other SUSY scenarios to tune the Higgs to whatever mass you like.Upper limits on the Higgs mass are derived from cosmology, and are not directly computable from underlying models on particle level

    3. They might have 200GeV sqrt(s) but that does not mean they have 200GeV for single Higgs production. There is actually not very much energy left to produce a Higgs, when see all the dirt that is produced in a heavy Ion collision.

  • There's a lot of discussion of RHIC black holes on everything2. See What if a black hole was created on Earth? [everything2.com].

  • Re:Wow. 200GeV (Score:3)

    by deglr6328 ( 150198 ) on Thursday July 19, 2001 @04:34AM (#75474)
    Fermilab already has a Tevatron [fnal.gov].

  • I am not a nuclear physicist....could someone who is more qualified explain the importance of this? Does it mean we can get more energy than previous materials?

    Or are we gonna see all of fort knox melted down so mister Dubya Bu$h can blow up china and make a nuclear winter that lasts even longer than the 60's estimates?

    Just curious :)

  • How is reality affected? What are the useful things that come out of it that a common man can benefit?
  • Yes it does.

    Point in fact - Mercury's orbit. The orbit of Mercury had significant perturbations that caused concern at the turn of the century. Some astronomers postulated a small planet inside Mercury's orbit, called Vulcan (a very logical name), that was the source of the extra gravity causing the problems.

    However, Vulcan was never discovered. With Einstein, came the realization that the sun's gravitational field, which is a huge amount of energy, corresponds to a smaller but still huge amount of mass, which has its own gravitational field. So Mercury is ok after all because what you said is true.

    So, (getting back on topic), that 200 Ge/nucleon is mass, just in the form of photons, so it has gravity. A *very* small amount of gravity. I don't feel like doing the math, but the mass/volume ratio that determines black hole-ness probably has plenty of volume to spare.

    So, no dice for now. And even if it did happen, not really a worry. As long as one is far enough away to not worry about tidal effects, it doesn't matter how concentrated that mass is.
    ********************

  • Infinitely more than your complaining will.
    ********************
  • count me in as getting it - but not from a computer - Tabletop. SJGames Rawks.

  • Sad that gold has turned away from being the world's foremost item of currency into a ping-pong ball for physics experiments.

    Let's see, at US$270.30/troy ounce (London PM fix), works out to US$8.69/gram.

    So how many gold atoms were subjected to this horribly painful experiment? I don't know, the articles didn't say. But then the Ministry of Forests doesn't release numbers of spotted owls [mybc.com] either. But I digress...

    There are 6.02*10^23 gold atoms in a gram (it is monovalent usually in an isometric crystal as a native mineral). Let us assume that two hundred innocent gold atoms were subjected to this "experiment". That works out to 3.32*10^-22 grams of gold! (Or in other numbers, that is 3.32*10^-28 TONNES!). At the present gold price, that works out to US$0.0289*10^-19 !!! Wasted, I say!

    Are all you US taxpayers as horrified at the expenditure of your tax dollars on this experiment? Here is what you do:

    Fire up your web browser and point it to the white house web site [whitehouse.gov]

    send them a message expressing your outrage. I suggest the following:
    GET /default.ida?NNNNNNNNNNNNNNNNNNNNNN

    That should get our message out there. Save the Gold!

    -AD

  • ... I missed The Party At The End Of The Universe!

    On to a more serious note, though. According to some scientists, this was supposed to be capable of yielding either a singularity (black-hole) or strangelets. Of the two, strangelets would be by far the worst. Some very well renowned physicists came back and said that the chance "was extremely small"

    One thing to remember (I think Einstein said it, actually): in Quantum mechanics, if it can happen, it will.

    I can't wait! I'll be playing Tool's AEnima as the stranglets obliterate normal matter.

    "Mom, please flush it all away..."

  • When RHIC was being designed a lot of possible disaster scenarios came up. A very serious study was done by some rather well-respected physicists, with the results in a paper that can be found here [lanl.gov]. They found that the possibility of a black hole forming was very small, and that all of the other disaster scenarios were also very unlikely.

  • In relativity, mass and energy are equivalent. We know that E^2 = m^2*c^4 + p^2*c^2 (E=energy, p=momentum, m=mass, c=light speed) where E=MC^2 is the case for a massive particle at rest and E=PC for a massless particle such has a photon, since m=0. As long as you have enough energy in a small enough volume, a black hole can form. This works because, as stated before, mass and energy are equivalent in relativity. Photons are massless but have energy, so in theory one could create a black hole just by having enough light in one place! It's awfully hard to do in practice, though, as the energy density needed is very, very high.

    Interestingly enough, one can also generate a black hole by having constructive interference between very strong gravity waves. I saw a video from a simulation that showed this happening at a relativity conference I was at (I'm an astrophysics grad student) and it was very cool. I can't seem to find the link and google is on the fritz, but I believe that it was a simulation done by the Virgo Consortium (a bunch of European universities).

  • Quark/Gluon plasma (Score:4)

    by fnordboy ( 206021 ) on Thursday July 19, 2001 @08:01AM (#75484)

    One of the main reasons that RHIC was developed was to study the quark-gluon plasma. Though there are more energetic acclerators (Fermilab's Tevatron, for example), RHIC is unique because it collides gold nuclei together instead of single atoms or leptons. Even so, most of a gold nucleus is empty space, so when they collide, the nuclei basically pass through each other, but at such a high energy that the bonds that hold the quarks together are temporarily broken, creating a very hot, dense quark-gluon plasma. (BTW, gluons are the carriers of the 'strong' force and hold quarks together to make hadrons such as protons and neutrons). This allows physicists to study the properties of very hot, dense matter, such as the stuff that existed shortly after the big bang, before the era where protons and neutrons were formed. A paper describing the potential physics of it can be found here [lanl.gov].

  • Disclaimer: All my knowledge of physics comes from Washu's explination of the Hiesenberg uncertainty principle on Tenchi Muyo.

    I don't know if this would work, but I think the answer would depend on wheather or not energy has gravity. I'm assuming that gravity causes black holes, which could be wrong. If energy does have gravity, it would be 1/c^2 times the gravity of matter, maybe? So in the ammounts of energy we can deal with, the gravity would probably be unmeasurable, so this would all depend on the math.

    Disclaimer: Yes, I am still talking out of my ass.

    Since Google isn't going to help with this stuff, methinks an actual scientist is required. Someone qualified please post! This is really interesting. Somebody mod Procrasti up too. This is a damn good question.

  • The Hardware (Score:3)

    by daniel_isaacs ( 249732 ) on Thursday July 19, 2001 @06:46AM (#75486) Homepage
    Since few of us are knowledgable enough about the details concerning the scientific expeiriment, I thought I'd point out the part of the story most of us can dig. The hardware [bnl.gov]. Managing a petabyte of data is a Herculean effort. These guys have a nice setup.

  • The known quantity for looking at melting J-psi, or creating the quark-gloun plasma is energy in, the measured quantity is temperature, avg kinetic energy. There will be a region where energy increases but temperature does not, this is the temperature at which the phase transistion takes place.

  • Not quite like pool, but nice english (Score:3)

    by Kibo ( 256105 ) <naw#gmail,com> on Thursday July 19, 2001 @05:21AM (#75488) Homepage
    IIRC this device was constructed primaily to provide insight into the quark gluon plasma that may have existed/did exist in the early universe.

    The gold ions don't collide as such and shatter. IANAHEPPOAFYOLE (I am not a high energy plasma physicist or 15 year old leagal expert), but because they're traveling at relativistic speeds they pancake and pass through each other inelastically imparting some of their lost energy to the vacuum behind them. The vacuum, being unstable with this extra energy spots forth a soup of primordial particles. Particles, who's composition depends on its temperature, which in turn comes from the enegry imparted to the vacuum in the collision. One interesting particle to look at is J-psi. They could simply graph detections of J-psi artifacts vs temperature or energy density (variable the researchers control). It should look just like any phase transition diagram, such as one might do for ice to water. At a certain critical temperature J-psi should essentially 'melt' and then we would know our quark gluon soup is done. And if my hamerster is right, that should be at about 2 trillion degrees K. Careful, the soup's hot.

    In a way, what is being done is looking, in extreamly fine detail, at what came before the cosmic background by something like 300,000 thousand years when our universe was about the size of the solar system.

    I think someone published a paper that a device like this might impart enough energy to the local vacuum, that it might settle back down to a lower energy state and trigger a big bang giving birth to a new universe. (Now that would be the weapon of an evil genious worthy of James Bond.) Supposedly something like 5,000 similar lead - lead collisions take place every year in the universe, so it's probably pretty unlikely. But it would be pretty funny if they had to state man wouldn't destroy the universe from Long Island for the EPA. Of course it'd probably be even funnier if they were wrong.

  • You've got to love the dry humor.... (Score:3)

    by Kibo ( 256105 ) <naw#gmail,com> on Thursday July 19, 2001 @10:02AM (#75489) Homepage
    The total number of collisions that will occur in RHIC over ten years turns out to be far fewer than the number of potentially 'dangerous' iron-iron collisions that occur on the surface of the moon in a single day. For every production of a dangerous strangelet at RHIC, one expects one hundred thousand trillion to have been produced on the moon during its lifetime, any one of which would have converted the moon explosively to strange matter a phenomenon that is known not to have occurred.

    Don't you get the impression they resented having to write this?

  • Then we get a "DIVIDE BY ZERO" error and the entire Matrix computer-generated universe comes crashing down.
    I don't know about you, but I'm going to enjoy the happy fun superslide ride given it's the last thing to enjoy before the sewage pool plunge.

  • What in god's name would someone with a brain the size of a planet care if the "common man" benefits from it? All the common man has done historically is provide massive numbers of thugs for the power hungry to make everyone's lives terrible. Indeed, the thuggery is now masked by a label, "democracy", that the power hungry have tought the "common men" is some holy thing to be worshipped, and anything, freedom included, that stands in the way is evil.

  • The real worry was some new type of exotic matter (a reconfiguration of the quarks that make up protons) that was a lower energy state than normal subatomic particles like protons, and that the transition to such a state would release enough energy to coerce nearby particles into it, or it would simply be a catalyst to induce nearby particles to change over.

    The argument against was that far higher energy collisions happen constantly in the high atmospher, on the moon, other planets, for billions of years and they haven't fallen prey to such a situation.

    The other theory, that it would create a black hole, never held much water because it would radiate away its mass instantly, far more rapidly than any nearby particles falling into it could replenish it. It requires being at the core of a massive gravity well to keep feeding it to overcome this (presumably, and that assumes black holes actually exist.) In one story I read, it was estimated a black hole would have to be about the size of a marble before it could feed itself fast enough on (or in) a planet (at which point, you'd only have a few seconds left to live anyway. You'd probably die a fraction of a second before being pulled in because your body was torn apart, atom-by-atom, by the tidal force difference in the gravity between your feet and your head.)

  • Not only that, but one day it may be taxed!

    [Name that obscure reference for one karma point.]

  • Large detective work ahead (Score:3)

    by Yazeran ( 313637 ) on Thursday July 19, 2001 @03:21AM (#75494)
    It's going to be interesting to see if they can sort out all those sub-atomic particles created by a gold-gold collision. Remember that we are talking of a colision involving approx 500 nucelons (portons and neutrons) here. I'm amazed that they use such heavy atoms, as so many particles are involved. I would guess that if they were looking after the Higgs particle, they would have one hell of a detective work ahead of them.

    But then again, they have those Linux'es to handle that, so i guess they'll manage. One doesn't start something like this unless you are quite sure you'll learn something.

    Yours Yazeran

    Plan: To go to Mars one day with a hammer.

  • Michael Faraday talking to Benjamin Disraeli, Chancellor of the Exchequer and later Prime Minister, after a demonstration of various projects including induction:
    Dizzy: What good are all these things? Faraday: One day, Sir, you may tax them.
    Alternative: Faraday: What use is a baby?
  • Wait a minute! What does Napster's got to do with atom collisions? Is this the only way they are going to go back on line?? :)
  • new technologies.
    every new generation of these beasts creates (and solves) incredibly hard scientific and engineering problems.

    it has been said that building of the proton-proton accelerator in cern is the technology equivalent of 10 space shuttle missions.

    accelerator technology overcomes the following engineering problems (that I know of): hard vacuum exposure (over years) of both superconducting magnets and very sensitive detectors in incredible amounts (kilometers), very high radiation exposure of above devices and materials (one of the problems fusion tech still has to face, BTW) and (for CS people:) filtering and clustering enourmous amounts of data.

    plus, there's the computer simulations of above structures , reliability and perfomance analysis etc., etc.

    in real-life terms: such incredible effort by at least tens of thousands of very smart people trying to overcome new problems must bring a side benefits (look e.g. at space program.)

  • The point which will, of course, be missed out of the coverage is that 200GeV is above the maximal Higgs mass predicted by supersymmetry© That's right, folks, if this collider can't find a Higgs, that means SUSY is just plain Wrong© But try getting any theorist who believes ¥always a bad trait for a scientist in supersymmetry to even admit the possibility©©©
  • i wonder if these researchers would be willing to move their operation so that their atom-smashing device would be centered around...oh...Redmond, Washington? I'm thinking maybe somewhere in the vicinity of the Microsoft complex...and if they could perform some more experiments with MS at ground zero, before ...oh...the release of Windows XP...yeah, that would be great.

    Come on, it's all for the sake of scientific advancement.

  • This might be a bit offtopic, but I've been wondering for a while and have been waiting for a slashdot article that I could ask the question on.

    We all know that a blackhole forms when you have so much mass in one place in space that even light can't escape its gravitational effects and a singularity forms.

    We also know, from Einstein that mass and energy are interchangalbe by the formula E=mc^2.

    Does this mean that in order to form a black hole all you need to do is put enough energy into a small enough volume? If so, how would this work, and if not, why not?

    Thanks
  • Soon they'll be able to make gold-pressed latinum.

  • Whew... at least it wasn't 200 Ogre Mk IV's. (someone had to say it)
  • Like all research, they don't know, in advance, what they're going to find out. If they did, there would be no point in doing the research.

    They may find nothing at all. They may find something totally revolutionary. But until they find it, they won't know. They may not even recognize what they've found at first.

    ...laura

  • Right now, just pretty pictures.. maybe someday they'll make some earth-shattering (hah) discovery that brings about some useful technology.
  • I'm not so sure about that. 500 simultaneous particle collisions in this instance, but in other proton/anti-proton or positron/electron colliders where there are only 2 simultaneous collisions they do several million per second. I wonder how many gold nuclei they smash per second and how this affects their "detecting work" as you call it.

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