• John
  • Felde
  • University of Maryland
  • USA

Latest Posts

  • USA

  • James
  • Doherty
  • Open University
  • United Kingdom

Latest Posts

  • Andrea
  • Signori
  • Nikhef
  • Netherlands

Latest Posts

  • CERN
  • Geneva
  • Switzerland

Latest Posts

  • Aidan
  • Randle-Conde
  • Université Libre de Bruxelles
  • Belgium

Latest Posts

  • Vancouver, BC
  • Canada

Latest Posts

  • Laura
  • Gladstone
  • MIT
  • USA

Latest Posts

  • Steven
  • Goldfarb
  • University of Michigan

Latest Posts

  • Fermilab
  • Batavia, IL
  • USA

Latest Posts

  • Seth
  • Zenz
  • Imperial College London
  • UK

Latest Posts

  • Nhan
  • Tran
  • Fermilab
  • USA

Latest Posts

  • Alex
  • Millar
  • University of Melbourne
  • Australia

Latest Posts

  • Ken
  • Bloom
  • USA

Latest Posts

Warning: file_put_contents(/srv/bindings/215f6720ac674a2d94a96e55caf4a892/code/wp-content/uploads/cache.dat): failed to open stream: No such file or directory in /home/customer/www/quantumdiaries.org/releases/3/web/wp-content/plugins/quantum_diaries_user_pics_header/quantum_diaries_user_pics_header.php on line 170

Archive for May, 2008

Control Room Design

Tuesday, May 20th, 2008

I spent the day in the ATLAS control room yesterday. I was on shift at the Liquid Argon Calorimeter desk in the back right corner. The shift wasn’t very exciting. We were taking calibration data all day which is kind of like sitting in a car in the driveway with the motor running instead of driving around. It should have taken an hour or two, but it took about six hours instead due to various glitches. We are still very much in the commissioning phase here, and things aren’t working as well as they eventually will. It is understandable since the detector has just been built and it is tremendously complicated.

Anyway, I took a moment to snap a few photos of what the control room looks like nowadays from where I was sitting.

ATLAS Control room, May 19, 2008

View from my seat in ATLAS control room on May 19, 2008

It is a lot different from the control room where I spent a lot of time on my old experiment, the DZero control room.

Besides the size difference which you would expect since ATLAS is a bigger detector with more people working on it, there is a very different feel to it. The DZero control room was laid out in a circle, while everyone is facing in the same direction in the ATLAS control room. You might not think that the DZero control room was conducive to social interaction since everyone was facing outwards and away from one another. In practice, the middle of the room was where everyone talked and it was very easy to walk over to any other console in the room and chat with the person working there. Since everyone had to pass through the center of the room often, you were forced into seeing everyone and had the chance to see what was going on everywhere in the room. Also, the Shift Captain who was in charge of the room and data taking during a shift was in the center and could turn around and talk to anyone.

From talking to other particle physicists from other experiments, I think most prefer the circular style to the ATLAS style. In ATLAS, I have no idea what is going on in the far side of the room. And while I saw plenty of people walking around yesterday to each other’s consoles, I also saw a lot going on in the far corners of the room that I could only wonder about. The designers must have thought that this layout was better for some reason, but I don’t know what it is.

While I am sure the ATLAS control room will eventually take on a cozier feel for me after I’ve had the chance to pass a few overnight shifts there with my colleagues, it’s too bad our control room isn’t like the CERN control center.


Progress we take for granted

Monday, May 19th, 2008

Just for fun: One of the fun things about working at MIT is that you have a nice perch to observe the progress of technology. I was wandering around the MIT museum with the kids and came upon this:256 kB!

This object is about 50 years old and approximately 1 cubic meter in size if I remember correctly. Anyone want to guess what it is?


Make no little plans?

Friday, May 16th, 2008

This week, US CMS held a “run-plan” workshop at Fermilab. The goal of the workshop was to really get a grip on what needs to be done when the LHC starts running and CMS starts taking data. Did we meet this goal? Do we actually have a plan now? Well, at the very least we have a better picture of what’s going on, and for someone like myself, who sits in Nebraska and spends most of his time thinking about computing, it is helpful to get the broader view. Here’s a sampler of some of the things going on:

  • As you can read from some of the other posts on this site, there is a tremendous amount of work going on with the detector. We recently completed several days of data-taking with as much of the detector as we can, but with no beam (of course!) and no magnetic field. Even that is a huge effort; getting all these pieces of the detector working at once is quite complicated. And this is not just an operational exercise — the data that were recorded are potentially quite useful. Yes, we recorded a whole lot of nothing, but if you analyze that, you ought to observe…nothing. If instead you see something, then there is some detector effect going on that can contaminate beam-collision data, such that you would see something when you ought to see nothing. And when you are looking for new physics, and you don’t quite know what it’s going to look like, then nothing that looks like something is going to be a lot of trouble. One thing we hope to do is superimpose these “empty” events on top of simulations of “real” events, and see how badly our simulations degrade as a result.
  • I spent most of my time in a working group focusing on computing issues. The most interesting presentation we had was from a student who has been busy using the computing system for several months. He of course has found ways to get his work done most efficiently…which were not necessarily the ways we imagined people using the system! It was great to what he and others find to be the most difficult things to do; we came up with some ideas for improvements that can be made. On balance, though, the system is working pretty well, even if we still have further to go.
  • No one said that they had too many people working on a project. Everything still needs more effort. It’s encouraging in that any help that is offered will be welcomed.

I gave a couple of presentations at the workshop, one on what tasks have calls on the resources of Tier-2 centers, and one on some of the issues we need to think about in analyses involving leptons plus jets in the final state. These went well enough. More importantly, by coming to the workshop I had a chance to see some of my friends and colleagues face to face. Video conferencing is OK, but you can learn a lot by chatting in the cafeteria. There are some physics things that I really do want to get going on, especially now that the summer is here, and I spoke to a few far-flung collaborators who want to launch similar efforts. We all agreed to phone and email and so forth. One colleague emphasized to me that we must really seize the day now. I knew this already, but it was reinforced — the next few years will be a unique time in my entire scientific career, which still has a few decades to go, so I should make the most of it.

The title of this posting comes from Daniel Burnham, who was the principal planner for the layout of the city of Chicago, one of our great American cities; he believed that every resident should be within walking distance of a park, and decreed that the lakefront should always be free and accessible to the public. “Make no little plans,” he said, “They have no magic to stir men’s blood and probably will not themselves be realized.” It worked out well for Chicago; let’s make it the same for the LHC.


What data?

Thursday, May 15th, 2008

This week has been very eventful for me. For one thing CMS had a very successful global run where we collected so many cosmic ray events that we decided to give ourselves a weekend off, but at the same time we were also doing a Computing Challenge (which Ken can surely write about) to test that we can ship the LHC data around as quickly as it arrives (and do some basic operations on it). For now we were using fake (so simulated) data for the latter, as even though the cosmic run was successful, the data volume was no way near what we expect once we get collisions.

So how did those activities affect me? Well, I am responsible for the databases and software that ensures we can read out the CMS pixel detector. This meant I had to check that the pixel data was coming out of the cosmic run (it was) and that the simulated pixel data was correct so the the people responsible for analyzing the data can check that their software works. Which effectively meant being the first person to look at all data. Of course simulated data is something we have been dealing with for the last few years, so at least from the pixel side there was not much excitement there. However, I was really looking forward to looking at the first *real* hits coming from a pixel detector in the real system.

To give you some ideas of things that you have to deal with in these matters let me explain the configuration in the cosmic run. As the CMS pixel detector can only be installed once the CMS beam pipe (the part of the accelerator that goes through the CMS detector) is installed, we instead connected only a small part of the pixel detector to the readout electronics. This small part we call the Pixel In a Box (PIB, in CMS you need to have an acronym for your activity. It almost seems you do not get taken seriously otherwise). In a few weeks we will have a real detector installed, it is ready and we’re keeping it at a random cleanroom at CERN for now (and the other half of it in Zuerich) but the beam pipe needs to be ready first. The PIB was connected to the entire system just like the real pixel detector would be, and taking data just like the rest of the detector. Of course a small pixel detector (it’s about 10 square inches of active material in total) does not find many cosmic rays so this really was just a exercise in cooperating with the rest of the detector. Still, exciting and definitely a new phase.

The pixel in a box run was a success, data was taken and it very quickly arrived at the lowest level grid analysis facilities (the CERN tier zero) where the responsible expert (read: me) took a look at it. And then the trouble started. There was nothing in the data! Of course the first step is to prove I wasn’t doing something wrong myself, but a few days and many discussions with the other experts later it turned out that…. the PIB was supposed to create no data. Actually the PIB was set up in such a way that all pixels were turned off. In some sense it is a good thing that I could prove this but some way or another it just does not feel the same as when you get actual data out.

I now try to comfort myself by telling myself that at least I proved I could see there was no data before someone standing next to the PIB could see there was no data. But it still is a bit disappointing.


Student Life

Wednesday, May 14th, 2008

Looking through the biography page, I find that I am the sole representative graduate student blogging here, from the new crew or the old, so perhaps I ought to be writing about what it’s like to be a student. The thing is, being a student here at CERN is not so different from being a postdoc or a researcher. (It’s the professors who are weighed down with other obligations, apparently.) I work full-time on the experiment, and my colleagues of whatever academic level ask me for help on things that I know, just like I would ask them. (Last Friday, for example, I helped a faculty member on the other side of the world figure out how to submit additions to our software.) Obviously, though, I know less than those with more experience, so I’m usually the one asking the questions.

Life was a little different when I started out as a student, of course. For my first two or so years at Berkeley, I took classes—hard ones with scary titles like Quantum Field Theory or (worse) Classical Electrodynamics. Although these were necessary prerequisites to my work, I would say most of what I’ve learned has been from going to talks and group meetings, and above all from diving in and learning by doing.

Students at Berkeley also have to take two rather formidable exams. The second, called the Qualifying Exam, I just took this past January. It essentially consisted of going into a little room with five professors, telling them about a project I might do for my Ph.D., and answering questions on any topic they felt like asking about. As you can imagine, those three hours were not among the least stressful of my entire life. If you’re interested, you can see part of my talk for the exam here:

You have my sincerest apologies if you find it less than readable; I’ll explain the project better in a future post. I should also mention that the talk, being for an examination, is not any kind of official ATLAS proposal or document, nor are its contents necessarily an accurate reflection of anyone’s views other than my own. I did pass, though.

Of course, one thing that’s different for students than for other scientists on the experiment is that, since we’re students, we get paid a stipend instead of a salary—the two being pretty much the same, except that the former is significantly smaller. And with the number of Swiss Francs you can buy with a dollar having gone down by 25% since I got to Geneva, it’s even smaller than it used to be. I’m fortunate in that my group was able to supplement that stipend to account for the extra costs of living in Geneva instead of Berkeley, and that the amount has been adjusted for the falling exchange rate as far as the (rather tight) budget allowed. Students at other universities have had more trouble making ends meet, though.


The nomadic summer

Monday, May 12th, 2008

Ah, just spent some time getting the summer organized. The plan of attack is to abandon wife and family for June at CERN, then they come over to visit (feel a little like I’m in prison! They get visitation rights!) for a week in July, plus see some old friends, I head back in August and visit them, and maybe come back to CERN for a bit before returning to MIT for fall classes (which will be interesting, since I am also “course administrator” which is a code word for lots of chores with little fun- it’s one of those things you can really only mess up…).

Plus, there’s a trip to Cyprus for our collaboration meeting. It’s the first CMS meeting away, and so will be pretty interesting. When these meetings happen at the lab, most people tend to ignore the meeting, and focus on keeping up on their regular day to day activities instead. When they put the meeting elsewhere, there’s not much you can do about the day to day, so it tends to be more focused, and therefore more productive. In addition, people tend to spend more time with their collaborators eating and finding entertainment outside of meeting hours, which is better for collaboration building. However, I noticed a very strange thing about Cyprus, which I will share with you.

Cyprus flights

For reasons which are yet a mystery to me, flying to Cyprus for a reasonable amount of money means arriving in the middle of the night. The return is the same way – the reasonable flights all leave between 2 AM and 4 AM. The only flight which doesn’t arrive way early involves a 17 hr with 11 hours at Heathrow (ick). I’m a little worried about why this is, if anyone cares to explain it to me, I guess I want to hear it.

Anyway, it will be very exciting at CERN this summer – and a bit frustrating. Think about finally getting to do what you have planning to do for twenty years or so and then having all these annoying little issues that keep putting things off. This is what it is like, when you have a small chance of something breaking in any of many many components, there is a fair amount of unforseen issues that have to be dealt with. They’re not showstoppers, but with everyone holding their breath for the first interaction, you can get a lot of oxygen deprivation, let’s say. The Tracker cooling is experiencing something like that right now – first time working with the full system, some new issues being discovered or failures of supposedly reliable components, most of which we of the Tracker group don’t even have control over (they fall into someone else’s scope) but we are still waiting to get all the services lined up to be able to turn the detector on fully, and everyone is getting a little antsy. I keep telling my students to get used to it, every detector system goes through these growing pains, and the LHC detectors will be no different…so dear readers I guess you should know too that while I fully believe we’ll get the machine and detectors running, it may take a while, so only hold your breath if you look good in blue.


Is it art or science ?

Monday, May 12th, 2008

Over the past few decades heavy ion and high energy accelerators have inspired not only scientists but also artists to look at the amazing machinery and images we have generated from alternate points of view.

The immediate connection to the art world is obvious in science fiction novels that were inspired by experiments at large collider facilities. The trend was probably started by John Cramer, a physics professor and RHIC colleague of mine from the University of Washington, who also writes sci-fi novels in his free time. His 1997 novel, Einstein’s Bridge, plays at a completed (hence sci-fi) Superconducting Super Collider (SSC), where an experiment generates a ‘bridge’ to another universe inhabited by lots of bad guys.

RHIC was used prominently in Gregory Benford’s 1999 novel, Cosm, where a scientist creates a false vacuum, i.e. a fast evolving miniature universe, during RHIC’s heavy ion collisions.A final example is an early novel of the omnipresent Dan Brown, Angels and Demons, which starts at CERN with the death of a famous physicist and then goes off into Brown’s land of conspiracy and religious evil-doers. As expected, any doomsday scenario will also inadvertently be picked up by Hollywood, and ‘The Void’, an atrocious B-movie from 2001, is playing very poorly on the famous Black Hole scenario, albeit with a cast that includes one the kings of B-movies, Malcolm McDowell.

Now sci-fi novels or movies might be good examples, but they are all too obvious, because the same geeks (myself included) that actually conduct the experiments will also read these books or watch these movies with great pleasure.

But what about ‘real art’ ? Let me state two quite remarkable incidences, which exemplify the value of visualization and imaging conducted at relativistic heavy ion experiments. The STAR event display was probably the most cited science image of 2005. It popped up in every article about RHIC and its physics, made it onto the cover of text books (Tipler and Llewellyn: Modern Physics) and popular science books (Seife: From Alpha to Omega), and it signalled a fact that many scientists often tend to forget, namely that ‘a picture tells a thousand (literally) stories’. But how did it affect the art world ?The first example comes from an artist, named Steve Miller, who approached BNL in 2000 in order to integrate RHIC images in his art. His work culminated in a 2001 exhibition in New York, named Neolithic Quark. You can still see the exhibition on the web, and although art is as always in the eye of the beholder, I think it is fascinating to see how our work inspires artists to look at nature’s art.

The second example, probably slightly more mundane, but nevertheless deeply rooted in pop culture, and therefore probably more timely than any of the others, comes courtesy of the New York Garage Rock Band, The Strokes. The Strokes were the buzz of 2001, when everybody anticipated their debut album, Is This It, to hit stores in the summer of that year. The record came out in international distribution in July, and it featured a provocative album cover showing a naked female body and a shiny black glove. For most music aficionados this was outrageously funny because it pretty much spoofed the famous fictitious Spinal Tap Album, Smell the Glove. But as expected some big chains in the U.K. and elsewhere in Europe threatened to boycott the sale of the album, and the record company in the U.S. feared censorship and so decided to ask the group for an alternate cover for the U.S. distribution. In a now famous interview, Julian Casablanca, the Strokes’ lead singer, said that the group was truly inspired by the new cover they chose, which is an event display from the Big European Bubble Chamber (BEBC), a device that was operational at CERN during the 70’s. And although the ‘Smell the Glove’ cover is still a collector’s item, the BEBC cover generated more discussion and hype on the internet and on blogs than most other album covers.

In that sense any press is good press, and although it is sometimes amusing to read explanations of the BEBC cover on the web, the moral of the story is that every penny spent on a good event display at the LHC, will be a good investment in the future and in the eternal preservation of our field for generations to come. As soon as science creates or inspires art we have achieved a level of immortality that transcends the fundamental scientific findings of our field.


A new record, alas

Friday, May 9th, 2008

I typically start my morning at home by scanning my overnight email while I eat breakfast. (This sets a horrible example for my daughter; I will have to stop when she becomes more cognizant of what I’m doing.) When you have 2000 collaborators, and most of them are seven time zones ahead of you, there is usually some amount of mail to get through, so I like to get a jump on it before heading to the office.

On Tuesday of this week, I believe I set a new record — there were 82 new mail messages waiting for me and my Cheerios. (They’re actually the generic store-brand cereal, not the name-brand.) Now, admittedly many of these were the skim-and-delete types. (All of you people out there who are having semi-private conversations and cc’ing everything to some mailing list — please stop. It just makes me cranky, and the O’s get increasingly soggy as I hit the delete key over and over.) But some of them needed further contemplation, which stretched well into the work day.

Why now? Part of it was the recovery from the May Day holiday weekend; as people came back to work in Europe, they had a lot to catch up on themselves. But a lot of it was the computing challenges that are now underway. These startup phases are always challenging; all sorts of technical things haven’t been tested at scale, and not all sites have completely gotten the message on what they are supposed to be doing, and sometimes there are policy issues that haven’t been thought out yet either. The good news, however, is that there has been a lot of good performance out there. We have about 30 Tier-2 computing sites (I know, I haven’t explained the tier system yet) participating — about as many as I could imagine — and by and large things are working. There are a number of sites that have definitely exceeded my expectation for how many jobs they could handle and how many of them would finish successfully. (I’m not going to name names, because I don’t want to embarrass sites that I had low expectations of!) The unfortunate exception has been my own cluster at Nebraska. It’s been a tough week for us, as we’ve been fighting multiple problems and arbitrating among various demands on the system. It took a while for the challenge jobs to start running, and when the did, 98% of them promptly failed. The important thing is that we understand why, so that we can be more successful the next time around, and it sounds like our admins are gaining on that. But at the same time, I feel like we just got caught with our pants down.

Through the wonders of the Internet, I am able to follow this (and annoy our admins with questions) while far from home. This weekend I find myself in Kalamazoo, MI, where my wife is attending the rather huge annual congress on medieval studies that Western Michigan University hosts. There are at least 3000 medievalists here, a bigger turnout than we typically get for the biggest particle physics conferences of the year. My job for the weekend is looking after my daughter, who is attending her first Kalamazoo meeting. Our hotel is one of the kinds with breakfast included. I’ve been leaving the computer in the room, to be polite. No O’s among the breakfast selections.


Is that what I think it is…?

Thursday, May 8th, 2008

After reading recently about the 15th anniversary of the World Wide Web, I took a little surf over to the location of the world’s first website, http://info.cern.ch. I was looking at screen captures from one of the early web browsers, from 1993, when I saw this:

ATLAS on Tim Berners-Lee’s 1993 Web Browser

[CERN copyright]

The color scheme threw me off for a second, but that image looked really familiar. I must have seen an experiment like that somewhere before… And indeed, if you click on the photo to zoom in, the highlighted text is “ATLAS.” Anyway, I’d recognize those toroids anywhere.

This is an amazing reminder of just how long it takes to build a modern collider detector, and of just how different life was fifteen years ago. When you wanted to buy something, you went to a store or ordered it on the phone. When you had to look up an obscure fact, you went to the library. When you had a random opinion to share, unless you were really famous, you could only deliver it to people you met in person. I was eleven. Yet physicists and engineers had been working toward building the ATLAS detector for years already, and on paper—and on a little experiment in information-exchange being developed at CERN—it was already looking almost exactly like its final form.

The amount the world has changed since then is staggering, but so is the amount of effort that has gone into making ATLAS, the LHC, and the other experiments a reality. It’s a lot better to be able to see ATLAS on a webcam than just on a web browser.


1143536 events at the second I started typing this, to be exact. We are currently operating a portion of the detector again for a week, with many goals, but the biggest is to run as many parts of the detector together as possible. The RCT is in this one, working well, helping collect data. At about this point you start counting the hours until you can go home and crawl into your bed. Shift ends at 7am. Its a bit like flying overseas, and when you only do one day, it is tough. I have had coffee, diet coke and sugar…and I’ve just run out of coffee. There is a machine here, but at some point you have to stop, or you won’t sleep, or at least I won’t. It might take a lot for that now, though. Smooth running is super, but a bit boring. The room is a little cold, which probably doesn’t help the sleepiness either. But it is mostly empty:


Though there are a few of us dedicated souls here, including Jessica, a Wisconsin graduate student:


I will not think about warm beds, or that my husband and cat are in my warm bed…until later.

P.S. I apologize for the lack of clarity – my cell phone was used to take the pictures.

P.P.S. Just read Monica’s blog, and I now know how I can fill the last few hours: I can write documentation!