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Posts Tagged ‘comics’

When the LHC gives you lemons…

Friday, December 12th, 2008

This week was one of the quarterly big CMS collaboration meetings.  I didn’t go, as it’s the last week of classes here, but I’ve been following it as much as I can from here.  What we’re seeing is some impressive work with real CMS data.  “But wait,” you are saying, “the accelerator broke three months ago, what real data are you talking about?”  Ah, but I said CMS data, not LHC data.  Cosmic rays are still raining down on CMS, and the collaboration spent several weeks this fall recording data from muons that came through the detector.  This took a lot of operational effort, and it really seems to be paying off in our understanding of how the detector works, and how our software interprets the data that come out of it.

There are a lot of questions you can answer with these data.  In any given cosmic-ray event, you expect to see one and only one muon come through.  Do you see only one, or do you reconstruct additional fake charged particles?  You can measure the muon momentum in either the muon system or the silicon-based tracker.  Do the two measurements agree?  There should be very little activity elsewhere in the detector.  Is that so?  If not, we’d better understand it; many searches for new physics will revolve around looking for energy imbalances in the detector, and if the energy is already imbalanced when there is nothing happening, we’re in trouble.

And then you can also do some studies related to the cosmic rays themselves.  Do you observe the right ratio of positive and negative muons?  Do they have the right angular distribution (predominantly from directly above, but falling off with the square of the cosine of the angle from vertical)?  Can you see the shadow of the moon when it is overhead?  These are harder to do (that last one in particular is tricky, but appears to be worth trying), but they could show that we really are getting a grasp on how this detector, in the making for years, actually works.  We’d rather have collision data, of course, but my colleagues are really making the most of the data we have.

Lemonade, anyone?

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“This is terrible,” I muttered over breakfast. “I haven’t posted anything on the blog in two weeks. All of my posts are supposed to have something to do with particle physics, but I must say that the particle physics I have done in the past two weeks has been either been politics that I wouldn’t want to dump on my readers, or totally boring. Or both. My post about trying to keep track of datasets was boring enough.”

My wife peered over the edge of the section with the comics. “Your statement is predicated on the idea that you actually have readers,” she said. “Have you been reading Dilbert this week? He built a particle accelerator. You could write about that.”

True enough — take a look over here. (Scott Adams owes me for directing millions of readers to his site.) Dilbert has built a particle accelerator in his basement, and has used it to create an antimatter Dilbert. The comic strip isn’t totally off base; Dilbert realizes that if his antimatter partner comes into contact with matter, he will disappear in a puff of energy. How anti-Dilbert solves the problem isn’t so scientific, but, hey, it’s the comics. (Suffice it to say that anti-Dilbert doesn’t survive the week at the office, and not just because of the pointy-haired boss.)

Richard Feynman, one of the iconic physicists of the second half of the 20th century, had an interesting anecdote about the idea of meeting an intelligent alien made out of antimatter; you can read a version of it here. We expect to be creating quite a lot of antimatter at the LHC…but an anti-Dilbert would be unexpected. But boy, if we could make an anti-pointy haired boss to annihilate with certain university administrators….

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