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Archive for March, 2013

Shutdown? What shutdown?

Sunday, March 24th, 2013

I must apologize for being a bad blogger; it has been too long since I have found the time to write. Sometimes it is hard to understand where the time goes, but I know that I have been busy with helping to get results out for the ski conferences, preparing for various reviews (of both my department and the US CMS operations program), and of course the usual day-to-day activities like teaching.

The LHC has been shut down for about two months now, but that really hasn’t made anyone less busy. It is true that we don’t have to run the detector now, but the CMS operations crew is now busy taking it apart for various refurbishing and maintenance tasks. There is a detailed schedule for what needs to be done in the next two years, and it has to be observed pretty carefully; there is a lot of coordination required to make sure that the necessary parts of the detector are accessible as needed, and of course to make sure that everyone is working in a safe environment (always our top priority).

A lot of my effort on CMS goes into computing, and over in that sector things in many ways aren’t all that different from how they were during the run. We still have to keep the computing facilities operating all the time. Data analysis continues, and we continue to set records for the level of activity from physicists who are preparing measurements and searches for new phenomena. We are also in the midst of a major reprocessing of all the data that we recorded during 2012, making use of our best knowledge of the detector and how it responds to particle collisions. This started shortly after the LHC run finished, and will probably take another couple of months.

There is also some data that we are processing for the very first time. Knowing that we had a two-year shutdown ahead of us, we recorded extra events last year that we didn’t have the computing capacity to process in real time, but could save for later analysis during the shutdown. This ended up essentially doubling the number of events we recorded during the last few months of 2012, which gives us a lot to do. Fortunately, we caught a break on this — our friends at the San Diego Supercomputer Center offered us some time on their facility. We had to scramble a bit to figure out how to include it into the CMS computing system, but now things are happily churning away with 5000 processors in use.

The shutdown also gives us a chance to make relatively invasive changes to how we organize the computing without potentially disrupting critical operations. Our big goal during this period is to make all of the computing facilities more flexible and generic. For the past few years, particular tasks have often been bound to particular facilities, in particular those that host large tape archives. But that can lead to inefficiencies; you don’t want to let computers remain idle at one site just while another site is backed up because it has particular features that are in demand. For instance, since we are reprocessing all of the data events from 2012, we also need to reprocess all of the simulated events, so that they match the real data. This has typically been done at the Tier-1 centers, where the simulated events are archived on tape. But recently we have shifted this work to the Tier-2 centers; the input datasets are still at the Tier 1’s, but we read them over the Internet using the “Any Data, Anytime, Anywhere” technology that I’ve discussed before. That lets us use the Tier 2’s effectively when they might have been otherwise idle.

Indeed, we’re trying to figure out how to use any available computing resource out there effectively. Some of these resources may only be available to us on an opportunistic basis, and taken away from us quickly when they are needed by their owner, on the timescale of perhaps a few minutes. This is different from our usual paradigm, in which we assume that we will be able to compute for many hours at a time. Making use of short-lived resources requires figuring out how to break up our computing work into smaller chunks that can be easily cleaned up when we have to evacuate a site.

But computing resources include both processors and disks, and we’re trying to find ways to use our disk space more efficiently too. This problem is a bit harder — with a processor, when a computing job is done with it, the processor is freed up for someone else to use, but with disk space, someone needs to actively go and delete files that aren’t being used anymore. And people are paranoid about cleaning up their files, in fear of deleting something they might need at an arbitrary time in the future! We’re going to be trying to convince people that many files on disk aren’t getting accessed, and it’s in our interest to automatically clean them up to make room for data that is of greater interest, with the understanding that the deleted data can be restored if necessary.

In short, there is a lot to do in computing before the LHC starts running again in 24 months, especially if you consider that we really want to have it done in 12 months, so that we have time to fully commission new systems and let people get used to them. Just like the detector, the computing has to be ready to make discoveries on the first day of the run!


Contrairement  à la plupart des compagnies et organisations, le CERN et ses expériences fonctionnent sur une base complètement différente. Toutes les expériences opèrent sur un mode collaboratif où chacune et chacun a le loisir de définir son rôle. Il n’y a pas de structure rigide pour imposer les directives de haut en bas. Chaque groupe et chaque individu doit trouver comment contribuer, en balançant les besoins de l’expérience et ses propres intérêts et son expertise. Un tel modèle coopératif  laisse beaucoup de place aux initiatives, à la créativité et à l’innovation.

Innover, c’est bien notre domaine, bien qu’on ne sache jamais à l’avance ce qui pourra éventuellement se montrer utile. Les retombées ne sont souvent qu’un à côté de la recherche scientifique. Prenons par exemple la toile (le Web) : celle-ci a été développée au CERN suite au besoin qu’avait les chercheur-e-s d’échanger de l’information tout en travaillant sur des continents différents. Le processus scientifique nous pousse constamment à repousser les limites du possible.

S’il est impossible de prédire ce qui pourra trouver une application, en revanche il est facile de parier sur la recherche scientifique. La science est source d’innovation. Et le monde des affaires prend note.

Bien que la plupart des physicien-ne-s travaillant sur ces larges collaborations l’ignorent, nos modèles collaboratifs attirent maintenant beaucoup d’attention de la part de chercheur-e-s en gestion. Si bien que le Strategic Management Society, une organisation à but non lucratif pour universitaires et chercheur-e-s en gestion, a tenu un meeting au CERN pour leur permettre d’observer tout ça de plus près. Ils et elles voulaient voir comment nous opérons sous cette étrange, et en apparence utopique, forme de gestion.

Etant donné la complexité des tâches que nous avons à accomplir, la collaboration est probablement la seule forme de gestion possible. Pas un seul individu ou groupe d’individus n’aurait pu concevoir, encore moins bâtir les détecteurs opérant au Grand collisionneur de hadrons (LHC). Cela a requis la créativité non muselée de milliers de personnes pour y parvenir.

Habituellement dans les études statistiques, les compagnies recueillent des données et cherchent les tendances principales, négligeant souvent les points se situant à l’écart, loin de la moyenne. Cette attitude peut conduire à ignorer les comportements inhabituels. On manque du coup des possibilités intéressantes venant de ceux et celles qui s’éloignent de la meute. Et c’est ce qui a capté l’attention des membres de la Strategic Management Society qui sont justement à la recherche d’idées nouvelles hors des sentiers battus.

La rencontre a attiré quelques 300 chercheur-e-s au CERN le 21 mars pour un événement tenu à guichets fermés.  Tous ont pu visiter le détecteur ATLAS cent mètres sous terre.

J’ai demandé à quelques participant-e-s ce qui les avait attiré au CERN. « L’innovation » me lance sans hésiter le premier, m’expliquant que le monde des affaires excelle à répéter et reproduire des schémas connus mais peine souvent à innover. Plusieurs le secondent pendant qu’un autre mentionne l’attrait du transfert des connaissances. Tous et toutes avouaient avoir aussi été attiré-e par la possibilité de visiter le CERN après tout le battage médiatique des derniers temps.

En tant qu’une des nombreux guides pour la journée, ce fut un plaisir d’accueillir des visiteurs aussi intéressés avant que le groupe ne reparte pour deux autres journées de conférence dans un contexte un peu plus habituel à l‘International Institute for Management Development, (IMD) de Lausanne.

Pauline Gagnon

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Science, engine of innovation

Friday, March 22nd, 2013

Unlike most businesses and organisations, CERN and its experiments operate on a completely different basis. All the experiments are conducted in a collaborative manner where every one has a lot of liberty in defining her or his role. There is no rigid top-down decision-making process. Each group and each individual has to find a way to contribute, balancing the needs of the experiment with the skills and interests at hand. Such a collaborative model leaves plenty of room for initiatives, creativity and innovation.

Innovation is what we are good at even though we never know in advance what might become useful at some point. Spin-offs are just incidentals to the scientific process. Take the World Wide Web: it was developed at CERN out of the need to provide a communication means for scientists working on different continents. The scientific process forces us to constantly push the limits ever further.

It is impossible to predict what will find some application, but it is easy to bet on scientific research. Science is the engine of innovation. And the business world is taking notice.

Unbeknown to most physicists working on these large collaborations, such collaborative models are now drawing a lot of attention from management and business scholars. So much so that the Strategic Management Society, a non-profit organisation for management scholars and academics, held a special meeting at CERN to take a closer look. They wanted to see how we operate under this strange, seemingly utopian, form of management.

Given the complexity of the tasks we are facing, collaboration is the only way to proceed. No single individual or even team could have designed any of the Large Hadron Collider (LHC) detectors, let alone build them. It took the unbridled creativity of thousands of people to succeed.

Usually in statistical studies, businesses collect data, look for the strongest trends and ignore the “outliers”, that is, the data points sitting far from the average. But neglecting unusual behaviour may lead to missing out on interesting ideas, away from the pack. This is precisely what is catching the attention of the members of the Strategic Management Society who are looking for new ideas from non-textbook organisations.

The meeting brought 300 business and management scholars to CERN on March 21 for a sold-out conference. All of them were treated to a visit of the ATLAS detector, 100 m underground.

I asked a group of participants what drew them to CERN. “Innovation!” said one, explaining that the business world is good at repeating and reproducing known processes but often fails to innovate. Many echoed him while another said he was interested in Technology Transfer. All agreed that the opportunity to visit CERN after all the recent media coverage was an added bonus. As one of the many guides for the day, it was a pleasure to take such keen observers around, before they headed off for day two of the conference, in the more familiar surroundings of Lausanne’s International Institute for Management Development, IMD.

Pauline Gagnon

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–by T.I. Meyer, Head of Strategic Planning & Communication

I was at a seminar recently, and they posed the following question: Suppose you are 2 metres away from a solid wooden fence with a small hole cut out in it. As you watch the hole, you see the head of a dog go by, and then you see the tail of a dog go by. You see this happen, say, three times in a row. What do you conclude?

The conclusions are less interesting, I think, than, the space of all possible conclusions. Intuitively, as human beings, we would think there is a RELATIONSHIP between the head and the tail of a dog. What are the possible types of relationships?

  • Causation. We might think that the head of a dog CAUSES the tail of a dog. This is perhaps the most powerful and most natural pattern of our human brain. We are always looking for cause and effect. But, depending on how much quantum mechanics you shoot into your veins, is causation really real or is it just a human construct? Consider how sure you are, as an individual, about all the causes and effects in your life and your surroundings. Are you sure about cause and effect?
  • Coincidence. It could be that the two events (sighting of dog head and sighting of dog tail) simply were because of random chance. If we watched longer, we might see something else. How often do we mistake coincidence with cause and effect?
  • Correlation. It could be that the head of a dog is correlated with the tail of a dog, in the sense that they “arise together” on a common but not causal basis. Correlation is a powerful concept in statistics, where it suggests that two events happen often together but not because one necessarily causes the other.
  • Parts of a Whole. This is the “true” answer for the dog sighting; a dog head and a dog tail are parts of a whole that we see through the fence. Thus, there is no real cause and no correlation and no coincidence; we are simply observing two instances of some common underlying connection – that a living dog’s body has both a head and a tail.

In physics, we rely on this set of approaches. We worry about whether we have established causality, correlation, coincidence, or parts of a whole. When we measure a frequently occurring set of “particle debris” after a collision of two particles, we wonder if the collision “caused” the debris or if the debris actually reflects “part of a whole.” We apply rigorous statistical cross-checks and tests to assure ourselves that we have “watched long enough” to be confident (in a quantitative fashion) about our interpretation.

It is in this same realm that we often run into the confusion of pseudo-science that tries to pin everything on cause and effect or something else entirely. Pseudo-science almost always boils down to someone claiming cause and effect, where what they might be really be observing is simply an unexamined or unexplained relationship between two events or two occurrences. Part of the job of science is to provide a systematic methodology to tease out what these relationships are. In fact, science is aimed at mastering these observed relationships so that we can make “predictions.”

But why do humans love cause and effect so much? It certainly seems “easy to understand.”

I propose a somewhat silly response, perhaps based on Dawkins or Gould or Pinker. Cause & effect is the most precautionary approach for human beings wandering in the wild trying to survive predators, hunger, and other hazards. For instance, if you see the paw prints of a roaming tiger, the best survival strategy is to assume that a tiger caused those prints and you should get going in the other direction. A scientist might want to stop and consider whether the prints were fresh, whether they fit the characteristics of the tiger you saw yesterday, and so forth. But a human brain focused on survival is optimized for making quick calculations using the cause & effect principle to save its own skin.

So, take a look around you and your world. In how many ways and in how many places do you see that we rely on cause & effect as an explanation because it is convenient?

Moreover, what other categories of relationship do you see? And what experiments would you conduct to help separate out these types of relationships?


particle physics…in space?

Monday, March 18th, 2013

I’m thinking that for the first post on this blog, maybe I should tell you a story.  Fortunately I just picked up a new little snippet about how AMS and NASA first joined forces.

The other night I was sitting here on shift in the AMS control room (called the POCC—Project Operations Control Center…I think).  I was wearing a big warm sweater and trying not to fall asleep, much like I am now (note the dark circles—yep, it’s 5AM!):

Much to my surprise at 2 AM someone walks in the door.  Normally (provided nothing horrible is happening) this place is a ghost town at 2 AM…it’s me and one other person quietly clicking away on our laptops.  So anyway, this guy walks in and I realize he’s one of the NASA guys from Houston whom we have a video conference with every Wednesday at 5PM our time.  Turns out he’s just arrived from the US and is totally jet-lagged.  He couldn’t sleep, so he came to the control room to see what’s going on.  I introduced myself, and he wanted to know how I’d come to be here (since I’m quite new).  Through the chit-chat it comes out that he’s been part of this project from very near the beginning—1994, I think it was.  And he happened to be in the meeting where Sam Ting first brought the idea of AMS to NASA.  Now, I had always assumed that this project was some sort of mutually beneficial agreement from the beginning, but it turns out it wasn’t quite that easy. He said it went like this.

Here they all were at NASA, and in comes Sam Ting (now the AMS spokesperson), and he says: I have this great idea.  I want to build an incredibly precise, amazingly delicate, super awesome particle detector.  (Emphasis on precise and delicate–he was trying to sell it, remember, and in particle physics those attributes are considered a bonus.)  And you guys are going to launch it into space and put it on the station for me.

OK, now I don’t know if you realize this, but if you’ve ever watched videos from the launches or if you ever saw a movie with a space shuttle taking off (Apollo-13 comes to mind ) you’ll know that launching is not a cake walk.  It’s complicated, stuff sometimes goes wrong and, moreover, there is a ton (actually ~2000 tons) of shaking, vibrating, jostling…it might be like your average airplane landing in a hurricane, with hail, times 1000.  Here is how two astronauts described it:

In the space shuttle, astronauts are strapped in on their backs a few hours before launch. As the main engines light, the whole vehicle rumbles and strains to lift off the launch pad. Seven seconds after the main engines light, the solid rocket motors ignite and this feels like a huge kick from behind. The vehicle shakes a lot and the ride is rough for the first two minutes as you are pressed back into your seats with twice your weight. When the solid rocket motors burn out there is a big flash of light as they separate from the big fuel tank the shuttle is strapped to. Then the ride [smooths] out. As you get higher into the thinning atmosphere and burn off most of the fuel, the vehicle accelerates faster and you are pressed back into your seat with three times your weight for the last two and a half minutes of the ride. This two and a half g’s feels like a giant gorilla is sitting on your chest making it more difficult to breathe. Eight and a half total minutes after liftoff, the main engines stop and immediately you go from the being squashed by the gorilla to being weightless.

In the Soyuz (Russian Space Capsule): Shortly before the time of launch you start hearing different noises below you and you know things are getting ready to happen. Then, it is as if a giant beast is waking up. You hear and feel the thumping and bumping of valves opening and closing as engine systems are pressurized. When the first engines light there is a terrific low frequency rumbling and things start to shake. Then the main engine lights and the rumbling and shaking get even louder. Slowly, slowly you begin to move up and away from the launch pad. But, very quickly you build up speed and the g-load, or the force of gravity or acceleration on a body, increases. You shake and rattle along and then there is a bang when the rescue system is jettisoned, another bang when the four strap on boosters separate, and another bang when the nose faring comes off. Now the windows are uncovered and you can see light coming in. At the second stage separation there is another bang and the g-load drops immediately. You go from about four and a half g’s down to about one and a half or two g’s. Then the third stage engine lights; you have a big push forward and the g-load builds again.  Eight and a half minutes after launch there is a loud bang and jerk and the last section of the rocket is jettisoned from the Soyuz spacecraft. And just like that, you are there–in space. It feels like you are hanging upside down in your shoulder harness. This is simply because there is nothing pushing you back into your seat anymore. Everything floats, including you.

So now Professor Ting wants to take this extremely precise and delicate (and also quite expensive) equipment…and launch it?

And that’s just getting there.  Once you’re there, you have to deal with changing conditions all the time.  The most shocking example is the temperature: if there were no temperature control, the difference between the sunny side to the dark side of the station would be up to 500 degrees Fahrenheit!  (Remember, space itself is cold, but the sun without any atmosphere for shielding—super hot!  (You can read about how they keep the astronauts from becoming fried eggs.)  Particle detectors do not like temperature changes.  Any temperature changes.  At all.  500 degrees?!?!?

Not surprisingly, the NASA folks thought this idea was nuts (to put it politely).

But somehow, throughout history, the best physics ideas have always sounded crazy, so keep this in mind next time some poor physicist comes begging for money or attention, sporting a big ego and bartering an idea that sounds “impractical”, “unfeasible” or just downright “impossible”.  Be careful, because if you tell that person what you think of their idea, you may very well find yourself eating your words.

Fortunately, NASA clearly has some experience dealing with bizarre-o ideas.  They played it well…here they were, thinking this project was absolutely crazy, never going to work.  But, you can’t very well tell someone who’s got a Nobel Prize in Physics that you think their idea is…well, not quite what you might call…possible.  So they told him he’d have to build his detector within all kinds of really stringent (but 100% necessary) specifications, and if he managed to do this, then maybe…if the money worked out…they would consider launching it.  He said OK and, somehow, after 19 years of sleepless nights and days spent arguing and sweating for an idea that everyone thought was impractical, unfeasible and just downright impossible, the dream has been accomplished: we’re up and running…in space.

Hello world, this is AMS, reporting for duty.

(I just bet Sam Ting goes to sleep with a little smirk on his face every night:  Ha, told you so.)

So there you have it.  If you want a good story, go sit in a control room.  Control rooms may look awesome with all the flashing lights and monitors, but they tend to be rather dull places (that is, until something horrible happens and panic ensues).  This means that people have time to kill and out come the old stories.  (Seriously, who needs a campfire anymore when you’ve got a control room?)  I think it’s important to capture these stories—the stories of how the great experiments came to be, the trials and tribulations of the generations before…they remind us that science is more than just a numbers game—we are, all of us, human, and subject to all of the follies and foibles that that implies.

Let me leave you with my favorite NASA video, which I think is a good reminder of our humanity—especially if you notice how thin the atmosphere really is!




Et voilà, fini les euphémismes sur le nouveau boson découvert l’an dernier. Les collaborations CMS et ATLAS, les deux grandes expériences opérant au Grand collisionneur de hadrons (LHC) du CERN, ont maintenant accumulé suffisamment  d’évidence pour qu’on parle désormais d’un boson de Higgs. Remarquez qu’on dira bien « un » boson et non pas « le » boson de Higgs puisqu’il faudra encore plus de données pour déterminer de quel type de boson de Higgs il s’agit. Mais toutes les vérifications faites jusqu’à maintenant indiquent fortement qu’on a bien affaire à un type de boson de Higgs.

Le Modèle Standard ne prévoit qu’un seul boson de Higgs et jusqu’à maintenant, notre boson est tout à fait compatible avec ce boson. Mais il pourrait aussi s’agir d’un des cinq types de bosons de Higgs postulés par la supersymétrie. Cette théorie encore hypothétique engloberait le modèle standard tout en allant plus loin afin de pouvoir expliquer non seulement toute la matière qu’on connaît, mais aussi fournir des réponses sur la mystérieuse matière noire.

ATLAS et CMS ont vérifié non seulement la masse mais aussi les couplages du nouveau boson. Pour tous les cas auxquels les expériences sont sensibles, les mesures sont compatibles avec le modèle standard. Mais la vérité pourrait se cacher dans les détails. Prenons par exemple la force du signal, une quantité qui mesure combien d’évènements venant du boson de Higgs on trouve dans les différents canaux de désintégration comparés aux prédictions du modèle standard. Un boson de Higgs du modèle standard aurait une force de signal égale à un dans tous les canaux. Mais s’il existe des particules encore non découvertes, elles offriraient d’autres alternatives de désintégration au boson, augmentant la force de signal. Ou encore s’il existe plusieurs types de bosons de Higgs, on verrait alors une force du signal réduite dans certains canaux de désintégration.

Parmi les nouveaux résultats présentés à la conférence de Moriond QCD la semaine dernière, CMS a montré une mise à jour de ses résultats sur les désintégrations du Higgs en deux photons basés sur l’ensemble des données recueillies, tandis qu’ATLAS a fait de même pour les désintégrations en une paire de bosons W. CMS a en fait montré le résultat principal ainsi qu’une contre-vérification venant d’une méthode d’analyse différente. Ils obtiennent 0.78±0.27 pour l’analyse principale et 1.11±0.31 pour la vérification. ATLAS mesure une de force de signal de 1.0±0.3 pour le canal WW et 1.30±0.21 pour tous les canaux combinés. Tous ces résultats sont compatibles avec une valeur de un tel que prédit par le modèle standard à l’intérieur des marges d’erreurs expérimentales.

Les derniers résultats présentés à la conférence de Moriond constituent un pas important dans l’étude du boson de Higgs mais servent aussi de rappel : il reste encore bien du travail à accomplir. Il semble bien qu’on ait un boson de Higgs, reste à savoir maintenant à quel type on a affaire.

Pauline Gagnon

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No more Higgs-like, Higgs-ish or even Higgsy boson. The CMS and ATLAS collaborations, the two large experiments operating at the Large Hadron Collider (LHC) at CERN, have now gathered sufficient evidence to say that the new boson discovered last summer is almost certainly “a” Higgs boson. Note that we are going to call it “a” Higgs boson and not “the” Higgs boson since we still need more data to determine what type of Higgs boson we have found. But all the analysis conducted so far strongly indicates that we are indeed dealing with a type of Higgs boson.

The Standard Model predicts there should be only one Higgs boson and so far, our Higgs boson is compatible with being the Standard Model Higgs boson. But it could still be one of the five types of Higgs bosons postulated by supersymmetry, a theory that would build on the Standard Model and complete it in a way that it would not only be able to explain the world made of matter that we know, but also provide a possible explanation for something still completely unknown called dark matter.

Both ATLAS and CMS checked not only the mass but also the couplings of the new boson. In all cases where the experiments have sensitivity, the couplings are consistent with the Standard Model. But the truth may lie in the tiniest detail. Take for example the signal strength, a quantity that measures how many signal events are found in different decay channels compared with the numbers expected from the Standard Model. The Standard Model boson would then come out with signal strength of one in all decay channels. But if other, yet undiscovered particles exist, then they would provide more options in the ways the Higgs boson could decay, and we should start seeing more signal events or if additional Higgs bosons exist we might see less signal strength in some channels.

Among new results shown this week at the Moriond QCD conference, CMS reported updated results for a Higgs decaying into two photons and ATLAS had an update on the Higgs decaying to a pair of W bosons.  CMS presented their main result and a result from a cross-check analysis using a different analysis approach. The two results, of 0.78±0.27 for the main analysis and 1.11±0.31 for the cross-check, are consistent within uncertainties.  ATLAS measured a signal strength of 1.0±0.3 in the WW channel and, 1.30±0.21 for all channels combined.  These results are so far in reasonable agreement with a value of one predicted by the Standard Model. Values different from one can come from statistical fluctuations as well as from new physics as mentioned earlier. Only more data and more study will allow us to tell.

The latest results presented at Moriond mark an important step forward in the Higgs analysis, but also serve as a reminder that we still have a long way to go. It looks very much as though we have “a” Higgs boson, the question now is what kind?

Pauline Gagnon

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International school Excellence in Detectors and Instrumentation Technologies 2013 (EDIT 2013) will be held March 12-22 at KEK, the High Energy Accelerator Research Organization, in Tsukuba, Japan. The EDIT is a school for graduate students and young post-doctral researches to learn indepth knowledge of major aspects of detectors and instrumentation technologies. The school started at CERN in Geneve, Switzerland in 2001, followed by the EDIT 2012 at Fermi National Accelerator Laboratory in Batavia, USA. The EDIT 2013 is the third of the series.


A Ustream live channel of the plenary lectures will be broadcasted during March 12-22 (except March 17) via the following URL. All the lectures are in English.


Ustream Lecture Program (Schedules in Japan Standard Time)
March 12(Tue)9:10-10:40
Introduction to particle detectors
TAJIMA, Hiroyasu (Nagoya University)

March 13(Wed)8:30-10:00
Detectors for luminosity frontier collider experiments
KRIZAN, Peter (Josef Stefan Institute)

March 14(Thu)8:30-10:00
Detectors of LHC experiments ATLAS and CMS
KONDO, Takahiko (KEK)

March 15(Fri)8:30-10:00
Probing origin of matter with high intensity hadron beams
NARUKI, Megumi (KEK)

March 16(Sat)8:30-10:00
Underground experiments
INOUE, Kunio (Tohoku University)

March 18(Mon)8:30-10:00
Detectors in long baseline neutrino experiments
ICHIKAWA, Atsuko (Kyoto University)

March 19(Tue)8:30-10:00
Physics of Muons and Neutrons
KUNO, Yoshitaka (Osaka University)

March 20(Wed)8:30-10:00
MOSTAFA, MIGUEL(Colorado State University)

March 21(Thu)8:30-10:00
The Cosmic Microwave Background: Detection and Interpretation of
the First Light
WOLLACK, Edward J. (NASA Goddard Space Flight Center)

March 22(Fri)8:30-10:00
Detectors for luminosity frontier collider experiments
LE Dû, Patrick (IPN Lyon)

Linear Collider Detectors
YAMAMOTO, Hitoshi (Tohoku University)


This post was written by Brookhaven Lab scientists Shigeki Misawa and Ofer Rind.

Run 13 at the Relativistic Heavy Ion Collider (RHIC) began one month ago today, and the first particles collided in the STAR and PHENIX detectors nearly two weeks ago. As of late this past Saturday evening, preparations are complete and polarized protons are colliding with the machine and detectors operating in “physics mode,” which means gigabytes of data are pouring into the RHIC & ATLAS Computing Facility (RACF) every few seconds.

Today, we store data and provide the computing power for about 2,500 RHIC scientists here at Brookhaven Lab and institutions around the world. Approximately 30 people work at the RACF, which is located about one mile south of RHIC and connected to both the Physics and Information Technology Division buildings on site. There are four main parts to the RACF: computers that crunch the data, online storage containing data ready for further analysis, tape storage containing archived data from collisions past, and the network glue that holds it all together. Computing resources at the RACF are split about equally between the RHIC collaborations and the ATLAS experiment running at the Large Hadron Collider in Europe.

Shigeki Misawa (left) and Ofer Rind at the RHIC & ATLAS Computing Facility (RACF) at Brookhaven Lab

Where Does the Data Come From?

For RHIC, the data comes from heavy ions or polarized protons that smash into each other inside PHENIX and STAR. These detectors catch the subatomic particles that emerge from the collisions to capture information—particle species, trajectories, momenta, etc.—in the form of electrical signals. Most signals aren’t relevant to what physicists are looking for, so only the signals that trip predetermined triggers are recorded. For example, with the main focus for Run 13 being the proton’s “missing” spin, physicists are particularly interested in finding decay electrons from particles called W bosons, because these can be used as probes to quantify spin contributions from a proton’s antiquarks and different “flavors” of quarks.

Computers in the “counting houses” at STAR and PHENIX package the raw data collected from selected electrical signals and send it all to the RACF via dedicated fiber-optic cables. The RACF then archives the data and makes it available to experimenters running analysis jobs on any of our 20,000 computing cores.

Recent Upgrades at the RACF

Polarized protons are far smaller than heavy ions, so they produce considerably less data when they collide, but even still, when we talk about data at the RACF, we’re talking about a lot of data. During Run 12 last year, we began using a new tape library to increase storage capacity by 25 percent for a total of 40 petabytes—the equivalent of 655,360 of the largest iPhones available today. We also more than doubled our ability to archive data for STAR last year (in order to meet the needs of a data acquisition upgrade) so we can now sustain 700 megabytes of incoming data every second for both PHENIX and STAR. Part of this is due to new fiber-optic cables connecting the counting houses to the RACF, which provide both increased data rates and redundancy.

With all this in place, along with those 20,000 processing cores (most computers today have two or four cores), certain operations that used to require six months of computer time now can be completed often in less than one week.

Looking Ahead

If pending budgets allow for the full 15-week run planned, we expect to collect approximately four petabytes of data from this run alone. During the run, we meet formally with liaisons from the PHENIX and STAR collaborations each week to discuss the amount of data expected in the coming weeks and to assess their operational needs. Beyond these meetings, we are in continual communication with our users, as we monitor and improve system functionality, troubleshoot, and provide first-line user support.

We’ll also continue to work with experimenters to evaluate computing trends, plan for future upgrades, and test the latest equipment—all in an effort to minimize bottlenecks that slow the data from getting to users and to get the most bang for the buck.

— Shigeki Misawa – Group Leader, RACF Mass Storage and General Services

— Ofer Rind – Technology Architect, RACF Storage Management


Dedicated to Johanna[1]

There are two observations about women in physics and mathematics that are at odds with each other. The first is that there are relatively few women in science. In a typical seminar or conference presentation I have counted that just over ten percent of the audience is female. The second is that, despite the relatively few women, they are by no means second-rate scholars. The first person to ever win two Nobel Prizes was a woman–Marie Curie (1867–1924). But I do not have to go far-far away and long-long ago to find first rate women scientists. I just have to go down the corridor, well actually down the corridor and up a flight of stairs since my office is in the ground floor administrative ghetto while the real work gets done on the second floor.  Since women are demonstratively capable, why are there so few of them in the mathematical sciences?

A cynic could say they are too bright to waste their time on such dead end fields but as a physicist I could never admit the validity of that premise. So why are there so few women in physics and mathematics? It is certainly true that in the past these subjects were considered too hard or inappropriate for women. Despite her accomplishments and two Nobel prizes, Madam Curie was never elected to the French Academy of Sciences. Since she was Polish as well as a woman the reason may have been as much due to xenophobia as misogyny.

Another interesting example of a successful woman scientist is Caroline Herschel (1750–1848). While not as famous as her brother William (1738–1822), she still made important discoveries in astronomy including eight comets and three nebulae. The comment from Wikipedia is in many ways typical: Caroline was struck with typhus, which stunted her growth and she never grew past four foot three. Due to this deformation, her family assumed that she would never marry and that it was best for her to remain a house servant. Instead she became a significant astronomer in collaboration with William. Not attractive enough to marry and not wanting to be a servant she made lasting contributions to astronomy.  If she had been considered beautiful we would probably never have heard of her! Sad.

Sophie Germain (1776–1831) is another interesting example. She overcame family opposition to study mathematics. Not being allowed to attend the lectures of Joseph Lagrange (1736–1813) she obtained copies of his lecture notes from other students and submitted assignments under an assumed male name. Lagrange, to his credit, became her mentor when he found out that the outstanding student was a woman. She also used a pseudonym in her correspondence with Carl Gauss[2] (1777–1855). After her death, Gauss made the comment: [Germain] proved to the world that even a woman can accomplish something worthwhile in the most rigorous and abstract of the sciences and for that reason would well have deserved an honorary degree. High praise from someone like Gauss, but why: even a woman? It reminds one of the quote from Voltaire (1694–1778) regarding the mathematician Émilie du Châtelet (1706–1749): a great man whose only fault was being a woman. Fault? And so it goes. Even outstanding women are not allowed to stand on their own merits but are denigrated for being women.

But what about today, does this negative perception still continue? While I have observed that roughly ten percent of attendees at physics lectures tend to be female, the distribution is not uniform. There tend to be more women from countries like Italy and France. I once asked a German colleague if she thought Marie Curie as a role model played a role in the larger (or is that less small) number of female physicists from those counties. She said no, that it was more to do with physics not being as prestigious in those counties. Cynical but probably true; through prejudice and convention women are delegated to roles of less prestige rather than those reflecting their interests and abilities.

My mother is probably an example of that. The only outlet she had for her mathematical ability was tutoring hers and the neighbour’s children, and filling out the family income tax forms. From my vantage point, she was probably as good at mathematics as many of my colleagues. One wonders how far she could have gone given the opportunity, a B. Sc., a Ph. D? One will never know. The social conventions and financial considerations made it impossible. Her sisters became school teachers while she married a small time farmer and raised five children. It is a good thing she did because otherwise I would not exist.

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[1] A fellow graduate student who died many years ago of breast cancer.

[2] Probably the greatest mathematician that ever existed.