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Monica Dunford | USLHC | USA

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Magnet Tests

Tuesday, June 17th, 2008

Who doesn’t love magnets. I remember as a kid having these two bar magnets and spending hours trying to move them around the kitchen table without actually making them touch (yes, this classifies as fun when you grew up in a small farming town that was 30 miles from the closest movie theater). The ATLAS magnets inspire the same feeling except now these magnets are superconducting and the size of a building (and we generally prefer it when they stay in one place).

ATLAS has two separate magnet systems used for bending the tracks of charge particles in the detector. The magnet surrounding the inner detector is a solenoid (the magnetic field points along the beam pipe). And the magnet for the muon system is a toroid (the magnetic field is circular around the beam pipe). The toroid magnet itself is in three sections: the barrel and two end-caps. And for a sense of size, here is one of the ‘little’ end-cap toroids being transported to the pit many months ago.

End cap toroid

Now that we are in the last steps of closing the detector, the final commissioning of the magnets has begun. The plan of the magnet commissioning is to test each of the four magnets separately (the two endcap toroids, the barrel toroid and the solenoid in that order) and then do the full combined test. And since you can’t have people working on other parts of ATLAS when there are large magnetic fields, all the testing is done at night. Over the past few weeks, the tests on one of the end-cap toroids have concluded (successfully!). Unfortunately in the second end-cap toroid, a helium leak was discovered (helium being used to cool the magnets). As a result, tests with this magnet had to be stopped in order to repair the leak. This does not delay us any but it does involve some reshuffling of the magnet commissioning schedule. Tonight will be the first test of the barrel toroid. Fingers crossed that it goes well!

Oh and Spain in an absolutely, spectacular goal in the last minute of injury time beat Sweden to secure their position in the quarter finals!! One step closer to Euro Cup glory!


Ah Priorities

Friday, June 13th, 2008

My ability to focus this week is essentially non-existent. For starters we just ended a three-week long detector integration run. And second it is the start of the Euro Cup. So basically there is no hope for me.

In one corner, we have Work. In the other corner, Soccer.
Work. Soccer. Work. Soccer.
Soccer. Work. Soccer. Work.
Soccer. Soccer. Work. Soccer.
Soccer. Soccer. Soccer. Soccer.
Work? What work?
Soccer. Soccer. Soccer. Soccer.

In one corner, we just finished the 7th Milestone week (which was actually three weeks). Just like the 5th and 6th milestone weeks, the aim is to combine all the sub-detectors and try to run as if there was beam. We try to push the system as much as we can, try to have fixed all the bugs from the previous integration weeks and try to debug the new problems that have occurred. It is an important milestone.

In the other corner, Spain destroyed Russia in their opening match! Very important.

For you non-soccer fans, in only two weeks the rest of us will all be back to normal again. And I might be able to once again focus.


Cern Relay

Saturday, June 7th, 2008

Once a year, the CERN running club organizes a six person relay race within the main site of CERN. The distances in the relay are 1000m, 2x800m, 2x500m and 300m. And the race is open to the public. Now if your first impression is that this is a fun, leisurely race, mainly consisting of physics geeks trotting around the main site, let me correct you. This race is incredibly competitive. With teams training much in advance to win it. It is also very popular, with 76 teams (456 people) participating. But although most people take the run very seriously, we still insist on having geeky names like ‘Tile Missing Energy’ or ‘The Powercuts’ or ‘We’re cold’ (this IS a race at a particle physics lab after all).

For the past two years, I have run with a team of ATLAS women aptly named ‘The Running Athenas’ (‘Athena’ referring to the name of ATLAS’ detector simulation software). And for the second year in a row, we have taken second place! But this is also the second year in a row that we have lost to the CMS women’s team.

Hmmm… This does not bode well….

Here is our team on the 2nd place podium. Unfortunately this is not a particularly good picture but it is the only picture I have. But looking at this, I think it is pretty obvious why CMS is better. They have matching shirts. And it is a universal truth that any team with matching shirts runs faster.

So next year, Running Athenas, we are going to train! No excuses.

Or at a minimum we will get matching shirts.

ATLAS women's team


In Final Position

Saturday, May 31st, 2008

It is a moment both longed for and dreaded: The closing of the calorimeters. To us on TileCal the calorimeters closing says two things. On one hand it says, ‘What a relief! Finally no more repair work’. And on the other it says, ‘What! We are closed? Now there is no more repair work.’ The thing about hardware people is that we get very, very uncomfortable when we can’t actually touch the hardware. So the closing is a very painful but necessary transition. While we are all very glad that the calorimeters have finally closed, we are all still a bit nervous about it. But this will fade.

The Tile calorimeter is divided into three parts, two of which are movable. There is one ‘barrel’ section of about six meters in length and two ‘extended barrels’ (on each side of the barrel) of about three meters long. In the ‘open’ position, the two extended barrels can be moved about three meters apart from the barrel section. The movement of the extended barrels back into their usual position (next to the barrel) is an engineering feat on its own. Not only is it big and heavy, it also has thousand of cables connected to it. As it took years to connect all the cables going to the extended barrel, it is not possible to disconnect them before moving. Instead the cables were made longer (for some slack) and then put in ‘flexible trays’, so that when the extended barrels move the flexible trays can move with it. Hence no recabling!

This picture was taken during the movement of one of the extended barrels. The perspective is from the bottom of the extended barrel looking up. The blue boxes on the outside are where Tile’s power supplies are located. But despite our unhappiness with no longer being able to touch the hardware, now that the extended barrels are in their final position, we can certainly breath easier. The movement went very smoothly, nothing crashed or crushed or squished or squeezed. And now we are one step closer to being ready for beam!

Atlas Calorimeter


Event Viewing

Thursday, May 22nd, 2008

Being able to visualize events in the detector is critical to understanding whether everything is functioning properly. But creating a program to display events in practice is incredibly difficult. I have the utmost respect for people who attempt it.

Obviously the big hurdle to event viewing is trying to display a three-dimensional detector on a two-dimensional screen. ATLAS has two solutions to this. One is Atlantis, the tried-and-true event viewer. The philosophy of Atlantis is to try and present the ATLAS detector in every two-dimensional slice possible. Such as this picture here.

Atlantis Event Viewer

From top left going clockwise, you see the full detector as if you were looking down the beam pipe, then the same cross section zoomed in on the calorimeters, then again the same cross section showing the inner detector, then a ‘bird’s eye’ view looking down on the beam pipe, and lastly a side profile of the detector (where the beam pipe is now the horizontal plane).

Atlantis as a tool is very useful but as for style… hmmm, not so much. It does have that retro look and while retro in fashion is considered acceptable, retro in computing is generally not.

Our second option is Visual Point 1 or VP1. VP1 takes the opposite approach. Going totally 3-dimensional, allowing the users to to place himself/herself at any point in the detector. In this picture, the view point is outside the calorimeter.

Atlas VP1 Viewer

The detector is just a shadow, barely seen in the picture and only the hits are shown (in yellow here). While VP1 definitely has that more modern feel, the jury is still out for me. It kind of reminds me of Tron. And it is too touchy. You accidentally hold the mouse button down too long and you are transported to some strange view point. And then you have no idea where you are, or what you are looking at.

It is a thankless job that is for sure!


The Pain of Documenting

Wednesday, May 7th, 2008

Truly. Is there anything in the world more painful than writing documentation?

So painful and yet so necessary. There is nothing more frustrating than trying to figure out a system that has little, bad, out-of-date or no documentation. The irony is everyone really, really appreciates well-written documentation and yet no one actually wants to do it. I mean is there anyone who wakes up in the morning and thinks, ‘Yes! I get to write documentation today!’?

The wiki system was supposed to revolutionize all this. ATLAS uses a system like this. The idea being that instead of a few people being responsible for updating the documentation, we ALL could update things quickly. But I think all we have achieved is to more easily pass the blame. Now that everyone is responsible, no one is responsible. Apathy towards documentation is a much deeper human trait that cannot be overcome with mere software.

It is also a universal truth that when you are pressed for time, the interruptions are constant. Yet, when you are longing to be interrupted (such as now), nothing. Ever. It is like some subconscious message is sent to all people in the area, ‘This woman wishes to be interrupted. Do not disturb’. I am currently trying to find any excuse to not have to update the ‘TileCal Shifter Instruction Manual’. I am becoming quite creative in my possible reasons. For example, the man outside mowing the lawn, he looks like he could use some help or maybe just a spectator. Or perhaps something on TileCal need soldering. Will make a few phone calls… No. Nothing to solder. Darn. An interruption please! Or I could reply to all those old emails in my inbox… Okay, I just found something worse than writing documentation. ‘TileCal Shifter Instruction Manual’ it is!


The Chancellors Visit

Friday, May 2nd, 2008

Never a dull moment at ATLAS. On tuesday, in the midst of our usual action-packed combined detector running and the final last-minute installations, the Chancellor of Germany, Angela Merkel came for a visit and tour.

Now, on a normal day, the control room is immaculate, as I have noted before. But I didn’t realize until Tuesday that there can be another level of clean which is beyond immaculate. The morning before her visit, there were more people cleaning in the control room and the downstairs counting rooms than there are physicists on ATLAS. And hours before she arrived, there were photographers everywhere. I felt almost famous with all the flashing lights.

Just by looking around the control room, you could tell something was up though. (I mean besides the battalion of cleaners and photographers or the fact that the parking lot around the surface building had been completely barricaded off for days beforehand, or that all the furniture in the meeting room adjacent to the control room had been gutted and replaced with very expensive chairs, nice glasses and imported bottles of water, or the podium with microphones constructed outside for any impromptu speeches, or the little red carpet set-up on the stairs leading to the control room). Smaller details were noticeable. Such as the level of dress was just a little higher. Not a lot. Just a little. For example instead of old, torn faded jeans, the jeans were slightly newer on average. Instead of having their cell phones at the ready, most people were equipped with an easily accessible digital camera. And of course the proportion of Germans to the total control room population was much higher than usual.

Her visit to CERN is of specific interest not only because Germany contributes a large amount of funding to CERN but also because she is a physicist by training. So we were all very excited to show off our detector to a fellow enthusiast. And the fact that she is the most powerful political woman in the world was more like a footnote.

When she came into the control room, she was standing right in front of my desk, listening to Peter Jenni (our illustrious ATLAS spokesperson) give an overview of the detector. Unfortunately at that very moment, I was having extreme frustrations configuring Tile Cal for some tests we were doing. I tried my best to keep my frantic hand gestures and exasperated muttering at the computer screen to a minimum. But I suppose the occasional cursing physicist adds to the realism of the tour.

Of course immediately after she left the control room to tour the detector, we all had to sneak outside to check out her motorcade (because who doesn’t love a good motorcade). It was very fun to be able to see her. But then it was back to work as usual.


Beam Schedule

Wednesday, April 23rd, 2008

The beam schedule. It is a constant source of anxiety at CERN. If you are interested in the latest-minute fluctuation in the beam schedule, I am not the person to ask. As a principle I refuse to worry about it because there is absolutely nothing that I can do to change it. The beam schedule will be what the beam schedule is regardless of whether I worry or not.

Instead I prefer to lose sleep over preparing ATLAS for beam readiness. Because it would be quite embarrassing with all the hype about the beam schedule to then not have a working detector. And preparing ATLAS for beam is something that at least I can contribute directly to.

The other reason I don’t try to determine the beam schedule on a daily basis is because then I would have to interpret charts like this.


But there are some major announcements worth noting. First the current schedule plans that the machine will be cold (to superconducting temperatures) by mid-June. And that we could expect single beam in July. The first physics run in 2008 will be at an energy of 10TeV. (The machine design is 14TeV and for comparison the Tevatron accelerator in Chicago is 1.96 TeV).

There is disappointment from some that the first run will not be at the full design power. But for me, any beam will do. We have been building and testing this detector for so long. We all want to take it for a test drive. Even a ‘little’ 10 TeV one.


Racing Again

Tuesday, April 15th, 2008

To escape the continual control room chaos, I decided that a little mini-break to back to California was in order. I always go back at this time because the first weekend of April is San Diego Crew Classic, one of the biggest crew races on the west coast. And every year my old rowing teammates from college get together and race. Usually people’s response to this is, ‘You are going to fly 15 hours back to California for eight minutes of racing?’ And the answer is Yes! Absolutely. Without hesitation. I love racing but racing with old friends who I once spent four years training with is priceless.

In college, Crew Classic was a very important race for determining standing and rankings. But now, as alumni, we’re all about just finishing respectably. And finishing respectably means not being so far behind that we are beaten by the official’s motor boat which follows slowly behind the race. These days we take our mantra from a Toby Keith’s song which proclaims, ‘I ain’t as good as I once was but I’m as good once as I ever was’. In other words, we might be good for eight minutes but don’t ask us to race for nine.

But despite the low standard of ‘just finishing respectably’ that we set for ourselves, we managed to do very well. We took 5th place out 15 teams (9 of which were collegiate teams). Including beating our own UCI JV team (which the JV team understandably was not very happy about. Sorry guys). The fact that we can beat any college team is really amazing. Now if, heaven forbid, we were to actually train before the race (compared to showing up completely jet-lagged from a 15 hour flight for example), imagine how well we could do. We promise that every year though: ‘For next year’s Crew Classic, we will train!’. Never happens.



The Control Room Life

Tuesday, April 1st, 2008

If you were to analyze my daily life based on my posts, you would probably conclude that my average day consists of sitting around in the control room, sitting around in meetings, taking cosmic data, being interrupted by power cuts and cabling things. And today I am certainly 4 for 5 in that list. I spent most of the week in the control room, squeezed in a few meeting, took some cosmic data and was stopped by a full power cut thus ending all attempts at data taking. I have yet to cable anything, but the day is still young.

We are in yet another ‘combined running’ week which is a lot like one of the milestone weeks. But unlike the Milestone weeks which combined all sub-systems in ATLAS, in this week we are only combining the calorimeters: TileCal, Liquid Argon, and the level-one calorimeter trigger. Pretty much from now until beam, we will be having combined running weeks. For example Calo-week this week, or Muon-week, or Inner Detector week or Muon-Calo week, etc.

What we get with the combined running weeks is priceless: the chance to see the sub-systems all running together and to be part of the intensity in the control room as everyone works to get ATLAS ready for beam. But it is not without frustration. When you build any detector, especially something this big, patience is a necessity. Take this week for example, we want to run some tests of our timing but we are delayed several hours because of DAQ problems. Finally we start the tests and the control goes dark due to the power cut. This is life when commissioning a detector. It is a 3-to-1 ratio. What you think will take one hour, always ends up taking three. And it is incredibly frustrating but there is nothing you can do but wait.

That is the control room life. Long periods of nothing, followed by intense periods of frantic activity. Ah! The power is back. The waiting is over, its time to go again!