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CERN | Geneva | Switzerland

View Blog | Read Bio

What will we do with all these data?

Today CMS and ATLAS, the two large experiments operating at the Large Hadron Collider (LHC), have reached five inverse femtobarn of data, the goal established for 2011.

Having more data is crucial. All phenomena we study follow statistical laws and are therefore subject to statistical fluctuations. Earlier this summer, we observed small excesses that could have been seen as the first signs of the Higgs boson. Over time, these small excesses can become bigger, smaller or disappear. The only thing we can do about it is analyze more data to get a definitive answer. In time, either the signal will emerge unambiguously if it was real or it will vanish if it was only due to a statistical fluctuation.

Fortunately with statistics, when you double the data sample size, the error bar or margin for statistical fluctuations goes down as the square root of the increase. This is why we are always trying to collect more data, to reduce the size of possible statistical fluctuations. We now have five inverse femtobarns of data per experiment, that is five times more data than what was available in July.

One may think that once the analysis is defined, it is just a matter of passing all the newly accumulated data through those selection criteria to extract the type of events we want to study. That would be too easy…

Producing new results requires an incredible number of checks and cross-checks.

Our analysis technique is fairly simple: we use a theoretical model to predict new phenomena and particles, and with complex simulation methods, we reproduce what our detector response would be to such events. We do the same for all known processes, that is, we can predict the various types of collisions that will come out of the LHC. The simulated events look just like the events we collect in our detectors, except they are fabricated based on all our knowledge of what can be produced when protons collide in the LHC.

The next step is to determine a series of selection criteria designed with the sole purpose of spotting the needle from a barn full of haystacks. For this, we study in detail the characteristics of the events we are interested in, comparing these characteristics with those of other types of known processes. At this stage, the name of the game is to isolate the signal from all other types of events, those we refer to as background.

Most of the time, the background constitutes the bulk of all collected events. This is normal since the events we know best are the ones that are produced copiously and we have already had a chance to study them in depth in previous experiments.

The final step consists in comparing the sum of all simulations of known processes that would survive our selection criteria to the data we collect. We compare the sifted data to these specific events to see if we select more events than what was expected from all backgrounds, and check if these events bear any resemblance to the theoretical model under test.

And here is where all our time and effort goes: cross-checking that all is well done at each step. We constantly look at our simulated data events and compare them with real events collected in our detector. Since we are also trying to improve both our reconstruction algorithms and our simulations, every time something is modified, we need to crosscheck it against real data.

The more data we collect, the more precise these comparisons get, making it increasingly more stringent. In the end, the goal is to produce absolutely trustworthy results, excluding flaws, bugs and oversights.

Should we expect big announcements soon? It is hard to tell but we can all hope. We are tracking elusive particles that have escaped detection so far. If we don’t find anything new right away, we will at the very least show in detail where we have searched and map out all territory covered so far, where these particles can no longer hide. With lots of work, extreme rigor and huge computing facilities like the Grid, it can be done. At the very least, if we do not find new particles right away, we will be able to set limits that theorists will be able to take into account to draw a better picture of the world we live in. The more data we accumulate, the closer we get to this goal.

Pauline Gagnon

To be alerted of new postings, follow me on Twitter: @GagnonPauline or sign-up on this mailing list to receive and e-mail notification.


  • Can we have our money back? Spend it on something useful like feeding people or cleaning up the planet?

  • Fred Jones

    I see Charles that to make your point you’ve opted to use a computer and the Internet. Just two of thousands of practical products of what you presumably felt at the time was not “useful” scientific research.

  • In processing huge amounts of data, such as that produced in the LHC, scientific research projects can benefit in a huge way from the power that can be brought by projects in Public Distributed Computing, projects running on software from BOINC, http://boinc.berkeley.edu , from UC Berkeley.

    The grand daddy of all such projects, [email protected], is doing 485 TeraFLOPS per second. That is larger than many of the supercomputers in the TOP500 list.

    In fact, there are two such projects running right now for the LHC. You can access these projects at http://lhcathome.cern.ch/ . One project runs simulations for magnet tuning for the beamline. The other project runs simulatons of collision “events”.

    These projects run on users’ personal computers and cost CERN absolutely nothing. Take a look at the two projects, if you like what you see, install the BOINC software and attach to one or both projects. Then, tell your colleagues at CERN and also in your home base universities and institutions.

  • guilherme

    Charles wt hypócrate you are hummm
    why u dont cut off ur high speed internet and feed the homeless and the poor in your region?

  • Fred & guilherme: That something “useful” came out of some megaproject does not, by itself, counter the criticism that said megaproject might have been a waste of money. You take what you can get, and if velcro and teflon what you have to show for a space programme, gosh darn, you take it! I happen to support (most) scientific megaprojects – but not because they may yield some everyday benefit: they’re pretty inefficient at doing that, these days. If you spend an obscene amount of money on almost anything, it’ll inevitably result in something good coming from it, but I think it’s a valid criticism to point out that these benefits could have been had much cheaper by following alternate investments.

    Rather, I support scientific megaprojects because they divert money from military megaprojects! And because they’re just damn cool.

  • Tyler

    i think we should give up trying to observe new physics … it would give us answers but i know better than to think anything practical could come from it. the ability to observe and the ability to manipulate are two completely different things.

    microprocessors are an example of building on the knowledge and manipulating elements on very small scales and results in real-life benefits … and we can build on practical things like this like shrinking these processes.

    i guess the differences would be seeing into space or exploring new continents … which has resulted more benefits? … scrap projects like this and invest in real-life technology which is advancing … when we can’t advance our technology, we should try ridiculous things like this experiment … only 100 times in scale.

  • hmm..

    How much per year is spent fighting in the middle east?

    How much did the executives of financial institutions get paid in salaries and bonus and other perks?

  • anna v

    Please keep in view that any research “mega project” costs the tax payer as much as just one airplane http://en.wikipedia.org/wiki/Nimitz_class_aircraft_carrier. There are ten such running around the globe on the “precautionary principle” and they will be scrapped for more expensive ones in a few years. Let alone that a simple hurricane or some act of god could easily make oneof them useless.

    LHC, as a world project, which it is, is cheap for the tax payer at the price . And it is not only the side products coming out, already the GRID technology is pushing frontiers in data storage and manipulation.

    It is the promise of making a break in our study of the microcosm and attendant theories. Keep in mind that it takes two or three generation for the true benefits of a new paradigm in science to bear fruit for the everyday man. For example about the time it took for quantum mechanics to enable the nuclear technology and transistor technology. When Maxwell formulated his equations did anybody have an idea how electromagnetic technology would cradle the modern civilization?

  • Alec Deimos

    Hi Charles,

    After studying carefully your petition, and observing the contrast between the benefits of following the science enterprise and…well you … and your personal bias, our answer is an unambiguous No.

    Best regards….and read a book.

  • anna v

    You are advocating a static model of society. Humans have been through those: the thousand year Chinese dynasties, the thousand year Byzantine and western Roman civilizations. Society becomes static when there are no new inputs coming in to fire the imagination of creative scientists and engineers, for various reasons. Most of them similar to yours, dogmatic and “better wheels are useful what’s all this with electricity from clouds and cats”?

    We have been lucky that the age of enlightenment in the western world did not hit a wall of dogmatic channeling of science. Exploration of all frontiers was considered a desirable goal for students of all disciplines. You are advocating that we stop this progress on frontiers and go into introspection, keep refining the wheel, because of costs. As I said in my previous answer to C.E.Frith at the top, the cost of LHC seen in the framework of “unnecessary military expenses” is minimal, to the tax payer, the price of an aircraft carrier.

    If all impetus to study the structure of physics in the microcosm is stifled now, and it will be stifled when there are no experiments to test theories against, there will be another stasis for science maybe for another thousand years, because research builds up systematically from the knowledge and the data base of previous research and if a generation or two lose the ball the game is over. Is that a desirable goal?

  • Tyler

    anna v, lawyers long before you have proven that anything can be argued right or wrong.

    the simple matter is, to justify these experiments, they set out expected results and expected benefits … and although their implementation was successful, their results have fallen short of their promises.

    so, anna v … although you might want continued experiments like these, any argument which would involve a cost equal or greater to that of this current experiment, for the purposes of further research would of course be rejected … it’s common sense. you gonna pay for it? … no!

    a great deal of the costs were the data centers and processing capabilities of handling all the data however … these costs will decline, so experiments like these could have been far easier to implement with patience and time. likewise, this experiment would have been impossible 50 years ago.

    so, anna v … you have no control, it’s not a phylosophy, it’s common sense … don’t try to complicate matters. it’s not my opinion, it’s fact.

    i’m head of IT for a sector in the telecommunications industry, i’m dealing with advancements every day in how people communicate and relate and consume and use technology, so i have a great deal of interest in experiments like these from a technical stand-point. so, anna v … your personal references to me are just rediculous.

  • Ralph Lausa

    The LHC is pure (as pure as can be) SCIENCE. Such studies have always been poo-poo’d by the sightless as wastes of time and so it will always be that someone in such studies is being asked:

    What’s the use of studying things that have no “practical” value?

    Likely someone was asking Vesalius:
    why he studied the minutia of the human body?
    Or Clerk Maxwell:
    why he spent such effort on his “silly” formulas about electro-magnetic forces?
    These “pure” science and basic studies have become more complicated and expensive as deeper and deeper we delve into the unknown, but in the long run it always has been worth the cost or the time or the difficulty.

    Best to ignore the misguided who think only the present and the “really needed” should be addressed first.

  • Tyler

    i can think outside the box enough to imagine unlimited potential … but i’m not limited to imagine also a limited potential to unlimited research.

    i also don’t have a superiority complex thinking that we’re the most intelligent species possible and are able to figure out anything, if it means not giving up. and that if we figure it out, it would hold some ultimate power and we’d be able to control it.

    micro, nano, quantum … history has actually shown less practical results the further you go. you can graph it, if you want some visual proof. no need to quote 1 example from the past … besides, the experiments at cern are governed on the laws of averages right?

  • Agner Sorensen

    In understanding the make up of particles I would hope this will lead to a safe nuclear power that mankind can use millions of years into the future, millions of years after fossil fuels have been exhausted.

  • Mike

    Shouldn’t the figure on the front page read that 350 million million is 3.5 x 10^14, not 35 x 10^14?
    Just fact checking.

  • Quantum Diaries

    Mike, can you point out where you’re seeing the 350 million million figure?

  • Mike

    The CERN front page where the link to this diary is.


  • miquel

    Investing in science is necessary, key and paramount for the future of our societies. That said, I very much doubt that particle physicis in paticular deserve that much money. Other areas of investigation would probably be more beneficial in the short and long term of us.
    If all we’re going to get from this (the LHC) is a bunch of new theories that to be proved or disproved need another huge accelarator that costs 3 times more, that would be sad.

  • Quantum Diaries

    We’ll look into this. Thanks for pointing it out.

  • miquel

    Precisely, this money would be best invested in the ITER. I dont think, but might be wrong, they need the results from LHC to build it.

  • NAMoosedog


    How much per year is spent fighting in the middle east?”

    Very good point. The US spends more money each year in Iraq and Afghanistan than the cost of the entire NASA budget since 1962.

  • ParkerSnowe

    Cern is wonderful, a center of the brightest minds we have right now!
    Who cares how much it costs- the people financing it are happy, the scientists are moving forward. New frontiers are on the horizon!

  • jomo

    Charles, you’re right. We don’t need projects like CERN, because you already confirmed the existence of the dark matter. It is in your head instead of brain. Sorry. Because of peoples like you the science moving forward soo slow.. ;(

  • hi all…..first of all…i do not wanna waste my time about thinking of spent colorful printed paper(to think about…paper is mainly made out of trees!!)..

    what i find interessting should be the fact…- if there now could be already made any cross-reference to the huge amounts of collected AMS-2 (ISS) data ??
    did any data from AMS-2 interact with some knowledge, we found out on producing the collisions on ourselfs.

    in fact, i obviously consider 2 think about, what we do there in Geneva…cooling a huge area(technical operating ring of LHC-the system!!) on the earthcrust down 2 outerathmosphereCOOLNESS, making high magnetic-experiments just some little few kilometers over the hot liquid magma…–
    think about the EARTH as an chaotic system!!or I use to compare sometimes the EARTH gets pinned from LHC like a vodoo-puppet, with cause and effect on some other regions on the moving crust.

    realizing, that natural sun-caused neutrinos build up in stratosphere upper thunderstormclouds,(if much, then causing satellite-failures in outer atmoshere-orbits— if there are much thunderstrikes on the crust into trees-not the fatal destructed and burnt out from hit-, i realized, that the trees bring out fastly some new tribes 4 new leafs, which brings really woderful nature sometimes into the/my view of the eye)…—and even the cut away leafs(are shields for wintertimes!), when they do not land on a street, they make something good 4 the tree, in bringing the small animals downside some food, and afterwards it gets some humus for the tree 2 grow even bigger..

    And then there comes the message, that neutrinos are moving faster than light from LHC 2 granSasso..interessting!!..and maybe do not interfere with things happening around US (WE scientific HUMANS, like ants on this small earthCRUST) in these days…

    maybe , if I think about the elementary grid of the life and all and everything, got caused by neutrinos…

    so my equation of my thoughts is!!
    0 = – / +
    so from zero, there was a split into +++++(matter) and —–(antimatter) in tha biggest bang….

    and maybe the neutrinos caused eventual the evolution on this planet, the galaxy and even more.

    It is time to think about all research…maybe the data already collected and compared brings us the point 2 all what we wanna know…

    would be wonderful, if some more people could get into my thinkings !!!hopefully there soon we strike a hit on our research!!

  • Range

    Thank you Charles for sharing your depth of understanding, your extensive knowledge of the multiverse, your reason, your logic, your capacity to fully comprehend the underpinnings of everything, everywhere at all times, in all cases.

    You are so far beyond, you are beyond yourself. So, go grab a beer and lay some sod.

  • Tyler

    what would the world be like, if america never went to war? … very different

    what would the world be like, if america didn’t conduct quantum physics experiments? … the same … however, we’d have more resources for war as a result.

  • Oyvind Aspen

    Hi! I see that the discussion is about science and the bige use of money is a issue here. But my question is what can science and spesically the LHC do to improve our understanding of the basics particle in the universe and then our self? What can prosject like the OPERA project do to understand the theories we have on what is the absolute speed limit? Does this have a praticle use? Can this solve a problem we have struggle with in decades or centuries? Like, is there limits that even we can’t aproach? Could we use Higgis singlet (if they exist) to do as physicist Tom Weiler suggest as a use for the LHC? Some of these questions are really relevant for the science community but also as humankind as a whole.Is the a ways to change the things we do it now? Can we use the data to understand better how we understand the universe and the maybe change the pat we do things?

  • Robert

    I’m a simple fisheries biologist, anagomous species.
    I know there’s amazing stuff taking place at CERN. I can read about it, I can imagine, but for the life of me I really wish I could fully understand.
    Alas, it’s in fact way over my head.

    The folks working at CERN are the best and brightest in the world. The information and data they receive from all the tests they run now, will be helpful to mankind for the entire future of our planet.