LHC Sets Record for Particle Collisions, Marks “New Territory” in Physics

Event display of a 7 TeV proton collision recorded by ATLAS. Credit: CERN

Physicists at the CERN research center collided sub-atomic particles in the Large Hadron Collider on Tuesday at the highest speeds ever achieved. “It’s a great day to be a particle physicist,” said CERN Director General Rolf Heuer. “A lot of people have waited a long time for this moment, but their patience and dedication is starting to pay dividends.” Already, the instruments in the LHC have recorded thousands of events, and at this writing, the LHC has had more than an hour of stable and colliding beams.

This is an attempt to create mini-versions of the Big Bang that led to the birth of the universe 13.7 billion years ago, providing new insights into the nature and evolution of matter in the early Universe.

Beams collided at 7 TeV in the LHC at 13:06 CEST. This marks the first long run at an energy three and a half times higher than previously achieved at a particle accelerator.

“With these record-shattering collision energies, the LHC experiments are propelled into a vast region to explore, and the hunt begins for dark matter, new forces, new dimensions and the Higgs boson,” said ATLAS CERN collaboration spokesperson, Fabiola Gianotti. “The fact that the experiments have published papers already on the basis of last year’s data bodes very well for this first physics run.”

Scientists say the first results from this high collision rate may be published within a few months, more likely by the end of 2010.

“We’ve all been impressed with the way the LHC has performed so far,” said Guido Tonelli, spokesperson of the CMS experiment, “and it’s particularly gratifying to see how well our particle detectors are working while our physics teams worldwide are already analysing data. We’ll address soon some of the major puzzles of modern physics like the origin of mass, the grand unification of forces and the presence of abundant dark matter in the universe. I expect very exciting times in front of us.”

CERN will run the LHC for 18-24 months with the objective of delivering enough data to the experiments to make significant advances across a wide range of physics channels. As soon as they have “re-discovered” the known Standard Model particles, a necessary precursor to looking for new physics, the LHC experiments will start the systematic search for the Higgs boson. With the amount of data expected, called one inverse femtobarn by physicists, the combined analysis of ATLAS and CMS will be able to explore a wide mass range, and there’s even a chance of discovery if the Higgs has a mass near 160 GeV. If it’s much lighter or very heavy, it will be harder to find in this first LHC run.

Another display of the same 7 TeV proton collision event. Credit: CERN

For supersymmetry, ATLAS and CMS will each have enough data to double today’s sensitivity to certain new discoveries. Experiments today are sensitive to some supersymmetric particles with masses up to 400 GeV. An inverse femtobarn at the LHC pushes the discovery range up to 800 GeV.

“The LHC has a real chance over the next two years of discovering supersymmetric particles,” explained Heuer, “and possibly giving insights into the composition of about a quarter of the Universe.”

Even at the more exotic end of the LHC’s potential discovery spectrum, this LHC run will extend the current reach by a factor of two. LHC experiments will be sensitive to new massive particles indicating the presence of extra dimensions up to masses of 2 TeV, where today’s reach is around 1 TeV.

Following this run, the LHC will shutdown for routine maintenance, and to complete the repairs and consolidation work needed to reach the LHC’s design energy of 14 TeV following the incident of 19 September 2008. Traditionally, CERN has operated its accelerators on an annual cycle, running for seven to eight months with a four to five month shutdown each year. Being a cryogenic machine operating at very low temperature, the LHC takes about a month to bring up to room temperature and another month to cool down. A four-month shutdown as part of an annual cycle no longer makes sense for such a machine, so CERN has decided to move to a longer cycle with longer periods of operation accompanied by longer shutdown periods when needed.

“Two years of continuous running is a tall order both for the LHC operators and the experiments, but it will be well worth the effort,” said Heuer. “By starting with a long run and concentrating preparations for 14 TeV collisions into a single shutdown, we’re increasing the overall running time over the next three years, making up for lost time and giving the experiments the chance to make their mark.”

Source: CERN

20 Replies to “LHC Sets Record for Particle Collisions, Marks “New Territory” in Physics”

  1. I found a boson once but I threw it out. I didn’t know it belonged to anyone, much less Higgs. Sorry.

  2. What if the big bang was caused by a race of people trying to re-create the big bang…………..

  3. I’m very glad it’s running/performing as expected, especially now with the enhanced QPS in place. Very exciting time for physics, glad I’m young too 🙂

  4. Great news, and thanks for an interesting article…but “This is an attempt to create mini-versions of the Big Bang’ – misleading, and fodder for doomsday twaddle. I think Universe Today should be clear about what that statement really means, and explain the difference between 7 TeV and 10,000,000,000,000,000 TeV

  5. Watched it live, a great moment, even if I can’t remember my future afterwards, but the real event will be when the results are out, however it turns out. My money is on no Higgs but something much more interesting.

  6. Thanks for the article, it’s great news for anyone interested in physics, cosmology and astronomy. With the LHC and new telescopes coming online, this is truly a golden age. If there was more political will, there could be more going on further than just LEO too….!

  7. During the big bang in the begining absolutely nothing was there.But in LHC we have walls of LHC, atoms, gravity….. and many more.How do you say the LHC is equivalent to Big bang? Here we are starting from something instead of nothing.

  8. @ Fredwho: That is a good question, and one which can only be answered partially. Above the electroweak unification scale, around several TeV, particle fields should obey something called a renormalization group (RG) flow. This occurs at an energy scale above where the Higgs field confers mass to particles. This RG flow tells us that physics at the 10 TeV range is essentially the same as physics at the 10^{16} TeV range (the Planck energy), but where various amplitude values are “smoothly” adjusted from near unity at this Planck scale to smaller values logarithmically. This means that there should be detectable physics associated with much higher energy.

    The Higgs field, or phenomenology that is Higgs-like, should be observable. The Higgs field is really a phenomenology generic to a whole range of physics, from superconductivity to the onset of ferromagnetism. This is so absolutely pervasive in physics that it would be very surprising if it did not apply to the unification of the electromagnetic and weak interactions.

    The other find which should be made is supersymmetry. The Coleman-Mandula theorem indicates that the Lorentz group of general relativity can not be naively combined with a gauge theory by a tensor product. This was a “no-go” theorem to attempts at unification of gauge fields with gravity. What was subsequently found is that there is a loop hole that involves the spinorial representation of the Lorentz group. The Haag-Lopuszanski-Sohnius theorem illustrates that graded charges or supersymmetric generators do permit such a unification. Hence was born the topic of supergravity.

    @Arun : The nothing involved here is the vacuum state. At high energy the Higgs field is restored, or the Goldstone boson is liberated and the degrees of freedom in the electroweak sector restored. And the vacuum becomes what is referred to as the false vacuum. This false vacuum is really a low energy version of the general false vacuum — which is what is called “nothing.”


  9. Ooooh baby – we’re comin’ for ya Higgsy! We’re comin’ for ya!

    The Higgs is almost certain to be found (it would be the biggest shake-up in physics since the advent of quantum mechanics itself if it wasn’t), but what will be far more interesting is the hints that will hopefully be dropped about the possible extensions to the standard model. We know the standard model is not fully correct, so this is going to be a very exciting coming decade for particle physics.

    Sorry Tevatron – your time in the limelight is on the wane… You were great to us though!

  10. It was great to watch this live on the CERN webcast!

    This is an attempt to create mini-versions of the Big Bang that led to the birth of the universe 13.7 billion years ago,

    My reaction is that of Fredwho, on the logarithmic scale this is far from such conditions. This will go back to the electro-weak regime, so there’s the Planck, GUT and inflation regimes in between still unexplored.

    @ Arun: That LBC said. When inflation stopped (or big bang started, if that is your preferred theory), you had physical laws. We know this not least because our type of universes seems to be zero energy.

    So not only did you have physical laws, we know from classical energy-time complementarity that they remained basically the same. (Modulo symmetry breaking and all that nice stuff that was going on at the time.)

    A better model comes from Vic Stenger. Since physics were more symmetric as we follow worldlines back in time or reversely symmetries spontaneously break, the ultimate ‘nothing’ is maximum symmetry. If there ever was an initial ‘nothing’, it was then (satisfyingly, perhaps) both ‘more and less’ of everything.

    [And that is, I believe, what you would expect from such things initial quantum fluctuations from other universes, or ab initio fluctuations, if such beasts exist. Everything else, as well as those inflation theories that may lack this ‘nothing’ state, then follows from anthropic principles or some less parsimonious theory like classical “just so” unique physics.

    So the preexistence of laws is not really a problem at the current state of knowledge, there are predictions to choose from. We’ll see that happens in the LHC though. :-o]

  11. @Torbjorn Larsson OM: The logarithm is our friend in this case. I don’t know to what extend I want to get into renormalization theory here, but the integration of a G(k,k’) ~ 1/|k -k’| gives the logarithm in the momentum value. With the cut off at Lambda there is then a logarithmic dependency on the k or ~ log(Lambda/k), so the behavior is not so bad. Of course this theory for gauge field theory and supersymmetry is more complex and involves the renormalization group equation, but this captures the main idea.

    Mind you if we get AdS/CFT and black hole amplitudes from the LHC they will still be “whispers” of sort.

    The Stenger idea of zero energy for the universe has its problems. Indeed in general relativity unless there is a Killing vector which is directed along the time vector &/&t (& = partial) there is no isometry corresponding to energy conservation. The Petrov-Penrose-Pirani (PPP) type for cosmologies is a type O, which do not have this isometry. The PPP classification scheme is based on finding eigen-Killing vectors of the Weyl curvature. In fact the metric coefficients for the FLRW and de Sitter vacuum cosmologies are time dependent, which is a signature of no such Killing vector. This might sound surprising to some, I even had an arm wrestling with Carroll over this (where he seems to have come around), but globally energy conservation is not something which is really established in cosmology.


  12. Lawrence B. Crowell:

    I was under the impression that not only was universal energy conservation not well established, but that it was completely impossible in a universe where expansion is accelerating.

  13. That is generally the case. There are a few “loopholes” around this though. For the pressure equal to negative the energy density (modulo factors of c etc) this prevents the build up of energy density in local regions of the universe. Further in the FLRW cosmology for k = 0 the spatial aspect of the universe is infinite. So the lack of energy conservation is concealed by “infinity,” so to speak.

    Ultimately energy conservation is a local principle where one can establish a coodinate frame for a unique S-matrix or fields in general.


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