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Brookhaven | Long Island, NY | USA

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The Glue that Binds Us All

RHIC, the Relativistic Heavy Ion Collider at Brookhaven Lab, found it first: a “perfect” liquid of strongly interacting quarks and gluons – a quark-gluon plasma (QGP) – produced by slamming heavy ions together at close to the speed of light. The fact that the QGP produced in these particle smashups was a liquid and not the expected gas, and that it flowed like a nearly frictionless fluid, took the physics world by surprise. These findings, now confirmed by heavy-ion experiments at the Large Hadron Collider (LHC) in Europe, have raised compelling new questions about the nature of matter and the strong force that holds the visible universe together.

Similarly, searches for the source of “missing” proton spin at RHIC have opened a deeper mystery: So far, it’s nowhere to be found.

To probe these and other puzzles, nuclear physicists would like to build a new machine: an electron-ion collider (EIC) designed to shine a very bright “light” on both protons and heavy ions to reveal their inner secrets.

“An electron-ion collider would be the brightest, highest-intensity ‘femtoscope’ to shine on the structure of matter,” said Brookhaven theoretical physicist Raju Venugopalan, referring to its ability to discern structures at the scale of femtometers – that’s 10-15 meters, a millionth of a nanometer, or a millionth of a billionth of a meter!

“Snapshots” of matter at that scale over a wide range of energies would offer deeper insight into the substructure of the nucleus, its constituents, and particularly its smallest components, the quarks and gluons and how they interact.

“Increasingly, it’s looking as if gluons and their interactions may hold the keys to many of our puzzles,” Venugopalan said. An electron-ion collider would be the ideal tool for gazing at the “glue” under conditions where scientists believe that it completely dominates the structure of neutrons, protons, and nuclei.

Spin Timeline

Evolution of physicists' understanding of proton spin: from the early view that the spins of the proton's three quarks should make up most if not all the proton's spin (left), to one in which gluons and the motion of quarks and gluons can also play significant roles (center). Current and planned investigations of the angular motion of quarks and gluons — the latter to be carried out at by an electron-ion collider (right) — may help resolve the mystery of the missing source of spin.

If an electron-ion collider becomes a reality, what the physicists learn will offer deeper insight into what holds 99 percent of the matter in the visible universe together. That’s the percentage of everything we see around us – from stars to planets to our own physical forms – that gets its mass from protons and neutrons, and thus ultimately from the quarks and gluons governed by the strong force.

“At the most fundamental level,” Venugopalan said, “we are driven by our curiosity to learn more about what we are made up of.”

Much more about the physics behind an electron-ion collider and the exciting mysteries on the horizon can be found in this feature story at Brookhaven’s website. Those of you interested in time dilation, missing spin, and super-saturated color glass condensate should check it out.

-Karen McNulty Walsh, BNL Media & Communications Office


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  • fluidic

    Karen, BIG BANG Thank you.

    RHIC indeed discovered that the state of matter quark-gluon-plasma was a perfect liquid when heavy ion smached near speed c.

    Now we are happier that LHC too is kind of confirming these results which surprised the world of physcists specially that proton spin is where?? no where to be seen.

    I was the one who for over a decade conjectured that matter is fluid / liquid like the name of my email address and made mathematical physics theories along with anonther colleague. We proved using electron in the concept of a manifold that matter is liquid with varying densities.

    Atoms have no particles in themselves and they are perfect liquid as RHIC discorverd. Particles are formed on exit or escape from atoms, exactly like my famous example of rain in clouds. There are no raindroplets in clouds, but once surrounding conditions exist, rain falls while there was no rain before. Particles are not in atoms and are formed under surrouding magnetic, electric, or other forces or fields at the speed exceeding the speed of light and get ejected as particles from the innner liquid form of matter.

    Protons and neutrons occupy he ultra density part of the atom (nucleus) and they deflet particles because of their liquid ultra high density that acts like solid matter not liquid, but in fact it it liquid.\

    Electrons likewise formed on exit but have the lowest positive density of matter. Any particle like quarks are formed likewise upon collisions of high density energy and are also liquid form. LHC and RHIC have proved that matter is liquid NOT and that matter has only a SINGLE STATE == LIQUID which nature displayed in high collisions. The liquidity that matter shows under high energy collisions is not a change of matter from solid to liquid but is a further expansion and elongation or stretching of the original liquid matter. micromatter at the quantum level DOES NOT CHANGE STATE with temperature.

    Thank you Karen and RHIC for this extremely illuminating and pointing article.
    The liquidity of matter and light-2-ultra density of same atom from lightest density at outermost to the ultra high densit at the centroidal nucleas is beginning to appear.


  • Amir Livne

    How does the geometry of electron-ion collision go? Do they collide head-to-head as in regular colliders? Or at a right angle? Is the energy of the beams similar? Is there an effort to make the electrons and the ions have equal and opposite momentum? How hard is it to control the energy of an ion beam relative to an electron beam?

  • jfb2252

    Quoting from the web site http://web.mit.edu/eicc/index.html

    The Electron-Ion Collider Collaboration consists of more than 100 physicists from over 20 laboratories and universities from around the world who are working to realize a powerful new facility in the United States with the aim of studying the particles (gluons) which bind all the observable matter in the world around us. This new facility, known as the Electron-Ion Collider (EIC), would collide intense beams of spin-polarized electrons with intense beams of both polarized nucleons and unpolarized nuclei from deuterium to uranium.


    There are competing US designs, one to add an electron accelerator to BNL and one to add an ion complex to Jefferson Lab. Both are discussed on the MIT site. There is also a design to add an electron accelerator to LHC, LHeC. There’s a conference on it today and tomorrow, see http://www.ep.ph.bham.ac.uk/exp/LHeC/

    BNL is doing the most PR because budgets may force DOE to close down one of its three large nuclear physics facilities: RHIC, CEBAF and FRIB. LHC has sufficiently high luminosity in heavy ion collisions to get much more data in 4-6 weeks late this year than RHIC can in the 20 weeks tentatively scheduled for FY13/14. CEBAF is being upgraded, doubling its energy, and over two-thirds of the upgrade funds have been spent. FRIB is just getting started. So BNL is rightly nervous about the future of RHIC. IMHO, of course.

  • Steven Vigdor, head of nuclear and particle physics at Brookhaven Lab, responds: The machines under discussion are designed as asymmetric colliders, in which the electron beam and the ion beam are not matched in momentum or energy. For example, in the eRHIC design, an electron beam of 5-10 GeV would, in the first stage of the facility, be brought into collision with already existing polarized proton beams up to 250 GeV or heavy ion beams up to 100 GeV/nucleon. The electron energy could be raised via subsequent upgrades. The collisions are close to head-on. But each design introduces a small crossing angle, with the addition of so-called “crab cavities” that rotate the beam bunch with respect to the momentum direction sufficiently to ensure maximum overlap of the electron and ion bunches to enhance collision rates. The ion and electron beam energies could be controlled independently, as needed to accomplish different parts of the science program.

  • Steven Vigdor, head of nuclear and particle physics at Brookhaven Lab, responds:

    The author is correct that there is worldwide interest in electron-ion colliders. The article on Quantum Diaries and the BNL website was intended to provide insight into the science interest for a broader public. None of the machine designs under consideration will be cheap, but they likely differ in cost by significant factors. Cost-effectiveness is likely to be a major consideration in any decision about which, if any, of the designs to build.

    The author states that BNL is nervous about the future of RHIC. Given the mismatch between the ambitious projects being discussed within the nuclear physics community and the administration and congressional budget guidance, anyone within the field who is not nervous about the future is likely not paying close attention. There are enormous consequences for nuclear physics research in the U.S. at stake in ongoing discussions in the Nuclear Science Advisory Committee.

    In contrast with what the author implies, LHC is not planning on running heavy ion collisions late this year, but is planning a proton-lead collision program instead. That run will be followed by a long shutdown of LHC lasting about 18 months. LHC heavy-ion luminosities are not nearly as high as RHIC’s. In part, this is because RHIC has just completed an upgrade that increased its heavy-ion collision luminosity by an order of magnitude. Perhaps the author is unaware of this because the upgrade was completed for only about $10M. The upgrade is already in effect during RHIC’s ongoing 2012 run, where it has worked beautifully. The RHIC run plan for the next two years is not for 20 weeks combined, as the author suggests. Depending on the outcome of ongoing Congressional budget discussions, RHIC will operate for 15-20 weeks in 2013. The length of the independent 2014 run will be determined once FY14 budgets are known. In any case, the RHIC and LHC heavy-ion programs are complementary: both are needed to explore the properties of the “perfect liquid” quark-gluon plasma as a function of temperature, and RHIC has unique reach to explore the QCD phase diagram.

  • jfb2252

    The LHeC conceptual design report, all 633 pages of it, went up on arxiv June 14. If you want orders of magnitude more info on electron-ion colliders, download it. While at much higher center of mass energy than either of the US designs, design luminosity is lower by 1.5 orders of magnitude.


  • fluidic

    Professor Steven, Head of Nuclear and Particle Physics at Brookhaven:

    You gave an outstanding clear picture of the LHC + RHIC heavy-ion programs as being “complementary”! quite concise description of the situation! Their mission is to unlock or I always call it unveil the true face of the nature of quark-gluon-plasma and its perfect liquid state. With your guidance as well as guidance from several others, scientists from both RHIC+LHC with their combined efforts will soon unveil that all matter is ONLY in quark-gluon-plasma state of perfect liquid. NO other states exist for matter except perfect liquidity. The difference between matter at the quantum level is ONLY how dense the liquid particle or liquid quark is? and how differences in density between matter’s “always perfect liquidity” state within the same atom itself, is what makes matter behave at the quantum level different that its behavior at the macrolevel (quantum level variations of matter densities within matter holds matter together).

    Particles are perfect liquid matter each characterized by certain density which makes it intrinsic always appearing with the same mass the same charge, same color etc. Nucleons as particles for example have ultra high density which make them behave like solids to our detectors because their ultra high density deflects objects.

    Anyway, thank you for your special clearance on objectives anc views of RHIC and LHC


  • Fluidic,
    May I first say I agree with you fluid principle and have thought this for some time. I do however have a few comments to make about your rain cloud analogy and its lack of particles, there may be no rain droplets but the water vapour is made of molecules / atoms which are your component parts. So as all fluids and by the same token gasses (which obey fluid dynamics) are made up of smaller constituents. So too with your analogy quantum particles are entirely plausible. Just because things act like fluids does not mean it can’t be many smaller particles acting together as a whole.

    Just a thought and welcome your input