Comments on: Billion Dollar Baby (The CMS Silicon Tracker) http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/ Random samplings from a universe of ideas. Sun, 08 Nov 2009 21:31:31 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: Rando M http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-90345 Rando M Tue, 11 Aug 2009 01:34:42 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-90345 Not quite. That's the energy per particle, and the beam has several of these particles. 600 megajoules worth. Not quite. That’s the energy per particle, and the beam has several of these particles. 600 megajoules worth.

]]> By: five 0h http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30567 five 0h Thu, 09 Aug 2007 19:16:55 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30567 please corrrect me if im wrong but 1 tev is about 1.6 x 10 ^ -7 joules, making 7 of them (LHC design beam energy) 1.12 x 10 ^ -12 joules. now assuming that a mouse weighs 200 grams and can sprint at a rate of 1 m a second (running from kitty) its kinetic energy would equal ~ 10 ^ -1 joules. what we have here is kinetic energy of the proton beam being ~11 orders of magnitude less than a sprinting mouse. my point : the tracker will be fine. the silicon however, that will need to be replaced eventually since the radiation will damage the lattice over time. if the beam were to spill into the silicon, this process would be shortened dramatically :P please corrrect me if im wrong but 1 tev is about 1.6 x 10 ^ -7 joules, making 7 of them (LHC design beam energy) 1.12 x 10 ^ -12 joules. now assuming that a mouse weighs 200 grams and can sprint at a rate of 1 m a second (running from kitty) its kinetic energy would equal ~ 10 ^ -1 joules.

what we have here is kinetic energy of the proton beam being ~11 orders of magnitude less than a sprinting mouse.

my point : the tracker will be fine.

the silicon however, that will need to be replaced eventually since the radiation will damage the lattice over time.

if the beam were to spill into the silicon, this process would be shortened dramatically :P

]]> By: Mike Saelim http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30562 Mike Saelim Mon, 30 Jul 2007 18:34:47 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30562 Hey! I'm in the University of Michigan REU at CERN this summer, and one of the people in our program is working at the TIF. Look around for a girl named Teesa from MIT! Hey! I’m in the University of Michigan REU at CERN this summer, and one of the people in our program is working at the TIF. Look around for a girl named Teesa from MIT!

]]> By: Ellipsis http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30565 Ellipsis Mon, 30 Jul 2007 05:57:26 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30565 Alexey -- green and orange are the most widely-available colors of the shielding of commercial fiber optic cable. They are chosen to be very easily visible, because fiber optic is less happy about being stepped on, for example, than regular copper cable. I'm not sure which lines the CMS tracker has chosen to be green and which to be orange. (I'm actually on Atlas -- of course that doesn't make me any less anonymous than the name "Ellipsis" -- same is of course true for CMS.) Possibly they are using orange for trigger info and green for the event info that has passed the level-2 trigger. Or it could be green for TIB and orange for TOB? A CMS tracker person would have to answer. Anyway, it is often interesting to note (you know this, but the average member of the public doesn't) that in most modern tracking detectors, the _vast_ majority of the data coming out of the detector is actually for the trigger decisions and is subsequently thrown away, as compared with the much smaller amount of data that actually is saved (for the events that pass the trigger). (About 10 Terabytes / s, vs. 1 GB / s for both Atlas and CMS, at the nominal beam luminosity.) Alexey — green and orange are the most widely-available colors of the shielding of commercial fiber optic cable. They are chosen to be very easily visible, because fiber optic is less happy about being stepped on, for example, than regular copper cable.

I’m not sure which lines the CMS tracker has chosen to be green and which to be orange. (I’m actually on Atlas — of course that doesn’t make me any less anonymous than the name “Ellipsis” — same is of course true for CMS.) Possibly they are using orange for trigger info and green for the event info that has passed the level-2 trigger. Or it could be green for TIB and orange for TOB? A CMS tracker person would have to answer.

Anyway, it is often interesting to note (you know this, but the average member of the public doesn’t) that in most modern tracking detectors, the _vast_ majority of the data coming out of the detector is actually for the trigger decisions and is subsequently thrown away, as compared with the much smaller amount of data that actually is saved (for the events that pass the trigger). (About 10 Terabytes / s, vs. 1 GB / s for both Atlas and CMS, at the nominal beam luminosity.)

]]> By: Alexey Petrov http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30564 Alexey Petrov Sun, 29 Jul 2007 02:33:33 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30564 Is there a reason for some wires being green and some - orange? Or someone is just a fan of the University of Miami? :-) Is there a reason for some wires being green and some – orange? Or someone is just a fan of the University of Miami? :-)

]]> By: Ellipsis http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30563 Ellipsis Sat, 28 Jul 2007 23:45:35 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30563 Joanne (since John apparently is too busy to answer his questions...): If there are problems like that, they tend to be (at least one hopes) structural rather than active elements (the head of a bolt, say, or a cable connector) that could be refitted without disturbing the silicon itself. It would have to be a <i>pretty</i> big error if the pixels themselves actually overlapped with the strips (if the latter were the case, I think the Japanese refer to what would result as "seppuku"). :/ Most of the time these sorts of things do fit without any problems, though. But note that just a couple years ago, the beryllium inner cylinder of the Babar tracker was scraped by an errant bolt head on the insertion of the silicon detector (very luckily the damage was patchable)! Joanne (since John apparently is too busy to answer his questions…):
If there are problems like that, they tend to be (at least one hopes) structural rather than active elements (the head of a bolt, say, or a cable connector) that could be refitted without disturbing the silicon itself. It would have to be a pretty big error if the pixels themselves actually overlapped with the strips (if the latter were the case, I think the Japanese refer to what would result as “seppuku”). :/

Most of the time these sorts of things do fit without any problems, though.

But note that just a couple years ago, the beryllium inner cylinder of the Babar tracker was scraped by an errant bolt head on the insertion of the silicon detector (very luckily the damage was patchable)!

]]> By: Coin http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30561 Coin Sat, 28 Jul 2007 21:18:02 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30561 Aaron, when he says "robotics", he means "bronze sphere rolling down an inclined plane". Very simple robotics, basically. Aaron, when he says “robotics”, he means “bronze sphere rolling down an inclined plane”.

Very simple robotics, basically.

]]> By: Aaron F. http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30559 Aaron F. Sat, 28 Jul 2007 15:18:47 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30559 Hey, wait! Galileo couldn't have done robotics in high school! That comment must be from an imposter!!! I'm sure the last comment this blog recieved from Galileo was real, though. Because... yeah. *Shifty eyes.* Hey, wait! Galileo couldn’t have done robotics in high school! That comment must be from an imposter!!! I’m sure the last comment this blog recieved from Galileo was real, though. Because… yeah. *Shifty eyes.*

]]> By: Galileo http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30560 Galileo Sat, 28 Jul 2007 15:16:01 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30560 <blockquote>What if it doesn’t fit inside the tracker? It’s not like you can just shave off a few pixels...</blockquote>Well, when I was in high school robotics, all we needed to meet the size requirement was a file and some hammers... ;)

What if it doesn’t fit inside the tracker? It’s not like you can just shave off a few pixels…

Well, when I was in high school robotics, all we needed to meet the size requirement was a file and some hammers… ;)

]]> By: eugene http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/comment-page-1/#comment-30566 eugene Fri, 27 Jul 2007 21:04:43 +0000 http://blogs.discovermagazine.com/cosmicvariance/2007/07/26/billion-dollar-baby-the-cms-silicon-tracker/#comment-30566 great cable management :) great cable management :)

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