Latest experiment at Large Hadron Collider reports first results

Oct 22, 2015


By Massachusetts Institute of Technology

After a two-year hiatus, the Large Hadron Collider, the largest and most powerful particle accelerator in the world, began its second run of experiments in June, smashing together subatomic particles at 13 teraelectronvolts (TeV)—the highest energy ever achieved in a laboratory. Physicists hope that such high-energy collisions may produce completely new particles, and potentially simulate the conditions that were seen in the early universe.

In a paper to appear in the journal Physics Letters B, the Compact Muon Solenoid (CMS) collaboration at the European Organization for Nuclear Research (CERN) reports on the run’s very first particle collisions, and describes what an average collision between two protons looks like at 13 TeV. One of the study leaders is MIT assistant professor of physics Yen-Jie Lee, who leads MIT’s Relativistic Heavy Ion Group, together with physics professors Gunther Roland and Bolek Wyslouch.

In the experimental run, researchers sent two proton beams hurtling in opposite directions around the collider at close to the speed of light. Each beam contained 476 bunches of 100 billion protons, with collisions between protons occurring every 50 nanoseconds. The team analyzed 20 million “snapshots” of the interacting proton beams, and identified 150,000 events containing proton-proton collisions.

For each collision that the researchers identified, they determined the number and angle of particles scattered from the colliding protons. The average proton collision produced about 22 charged particles known as hadrons, which were mainly scattered along the transverse plane, immediately around the main collision point.

Compared with the collider’s first run, at an energy intensity of 7 TeV, the recent experiment at 13 TeV produced 30 percent more particles per collision.

Lee says the results support the theory that higher-energy collisions may increase the chance of finding new particles. The results also provide a precise picture of a typical proton collision—a picture that may help scientists sift through average events looking for atypical particles.

“At this high intensity, we will observe hundreds of millions of collisions each second,” Lee says. “But the problem is, almost all of these collisions are typical background events. You really need to understand the background well, so you can separate it from the signals for new physics effects. Now we’ve prepared ourselves for the potential discovery of new particles.”

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15 comments on “Latest experiment at Large Hadron Collider reports first results

  • Keep banging stuff together, harder and harder, and see what flies off…. Seems a bit puerile, really. Is physics at a dead end, if they can’t imagine better experiments than this? I know, biggest science experiment ever, and the reason the WWW was invented, but still. Not entirely tongue-in-cheek, I’m amazed at the effort that’s gone into the bang-it-harder school of physics, and it’s a lot better than most things that thousands of people collaborate on. Except the moon missions, they were the ultimate cool adventure, and they even managed to take an actual scientist along on the last one. And Hubble, such lovely wallpaper, and I suspect a deeper understanding of the universe than the banging-bits-brigade can ever hope for.

    Deliberately provocative, I hope, seeking informed responses from some of the sharpest minds I’ve read online. I know you’re out there.

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  • Deliberately provocative, I hope, seeking informed responses from some of the sharpest minds I’ve read online. I know you’re out there.

    Sorry to disappoint OHooligan. My mind is about as sharp as a bowling ball. I went to Nerd heaven in 2008 just before the LHC came on line. Did the tour of the facility. Our guide was a Chinese Professor who’s specialty was anti matter. Creating anti hydrogen and trying to get chemical reactions happening. I’ve got a picture of me, standing next to the shoe box that strips the electron from the proton in the hydrogen to produce the protons. Great tour. Highly recommend it. I’m told you have to book months ahead to get in now.

    a deeper understanding of the universe

    I can see a need for both. All the satellites up their mapping various electromagnetic wave lengths. Hubble. One of the greatest triumphs since homo sapiens walked upright. I see the LHC stuff as complementary. The stuff they look at at Cern, may explain the stuff they see through Hubble. Dark matter stuff. (Do you like my highly scientific terminology) If the LHC can look back to the big bang primordial soup, that may give indications as to what we see in the universe and why it is the way it is.

    I suspect the Standard Model will prevail since the Higgs boson has been fitted as the last piece of the jigsaw. Very neat. 16 particles in a 4 x 4 grid. Appeals to my OCD gene.

    Besides, it’s such a cool piece of kit to play with.

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  • How do you detect the paths of the spin-off particles? I learned about cloud chambers back in the 1950s, but I never did see how they could work without the particles hitting something.

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  • 8
    Pinball1970 says:

    Yes provocative!

    I work with of some physics applications (simple ones) and try and keep up with the LHC but that’s it, so I cannot really give a decent technical argument against your post.

    Suffice to say there is a lot more to it than that (a lot lot more) and there is fine tuning for the Higgs, other particles and the standard model.

    Dark matter particles possibly? Other dimensions? and super symmetry partners investigated which to my knowledge has not yet had any confirmatory data.

    “Smashing physics” by Jon Butterworth is the book for you, lots of books have written about the Higgs and the LHC but this is one of the most accessible.

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  • Don’t worry: it’s really not a problem. Nothing happens to the reported post unless we moderate it, and we’d never do that without checking it first to make sure there was good reason to do so.

    The mods

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  • You see a need for it. Lol. We re certainly relieved you do! Considering unlocking the secrets of the universe is the key to man s ultimate survival on our planet and off of it. For all we know it could even be a race against time….

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  • 12
    kilvehk says:

    it’s actually very important work. the higgs boson was only discovered because of the LHC. by discovering new particles we can not only fill in gaps in our knowledge we can potentially open up whole new lines of inquiry and innovation..

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  • 13
    Richard says:

    It does sound a bit puerile when you put it like that, but if you know of a better way of dissecting the building blocks of matter I’m sure CERN would love to hear it. We’ve been to Moon and into space plenty, Mars is just rock and a little bit of water, let’s not bother any more. Hubble has taken lots of lovely pictures already, why bother making bigger better telescopes?

    The LHC is just one of many huge undertakings to better understand our universe. It hasn’t been done for a bit of fun because someone thought, “Hey let’s build a 17 mile particle smasher and see what happens.” If building a bigger smashing stuff together machine is what it takes to uncover yet more understanding, then I say lets do it.

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  • OHooligan
    Oct 22, 2015 at 7:21 pm

    Keep banging stuff together, harder and harder, and see what flies off….

    Deliberately provocative, I hope, seeking informed responses from some of the sharpest minds I’ve read online. I know you’re out there.

    There are many states of matter and energy in the universe which are not naturally represented in the present physical conditions on Earth. (temperature, pressure, gravity, radiation levels etc.)
    If we wish to understand or derive applications from these, we need to experiment to determine how they work.

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