First thing is that they did not need to test "everything" to get it started. When you have 450 GeV protons in the ring, you dont need 7-8 Tesla magnetic field... So they got it started because they could and decided that they can test the high magnetic field setting later.
Second: The incident happened as they *were* testing it in a break from the low energy collisions schedule.
Third: It was more like 6 tons of helium...
Yes. It is used here as a unit of energy that *one* particle carries. Take a look at:
http://en.wikipedia.org/wiki/Electron_volt
The proton weighs 1GeV. 7TeV (Terra electron volts) which the LHC should run at, means that a poor proton will be so energetic that it will have 7000 times the energy that is it's mass. The higher energy a particle, the higher the magnetic field needs to be to curve it around the 27km ring. If the magnets can not handle the design current than that limits the magnetic field, which in turn limits the energy of the particles that you can accelerate.
Incidentally, a 7TeV proton has about the same kinetic energy as a mosquito. But imagine that all the energy is being carried by *one* proton. Now, there are 100 billion protons in a beam bunch and 2000 of these bunches running around the LHC, according to the design and in the end, the total kinetic energy comes close to that of an aircraft carrier going at some reasonable speed, I am told...
ps. I am not the AC who posted earlier.
True. But it is the *scale* that matters. ~27km long cryogenic line... has that been done before?
For example, many off the shelf cryogenics components were not available before the LHC came along... So much was custom made. And now many components became off the shelf with the R&D money that CERN injected into the industry and so MRI machines and other cryogenics systems are becoming cheaper for those who want to use/study them.
Take a look at the
It is the layer of the ATLAS detector that is closest to the interaction point where collisions happen. The first layer (cylinderical) only 5 cm away.
As for the radioactivity being "potentially dangerous" -- well, I would not want to ingest any of it or sleep next to it, if that's what you mean... But actually no, we will be able to take the detector out and replace it if needed. Remember that exposure is what counts and that depends on distance, as well as how long you have been exposed to it. So in this case, the answer is that given what we have to do with it, it is not dangerous.
The short answer is yes. But the longer answer is well, it depends... on things like luminosity and how good the LHC is on steering the beam. (ie. if it happens to dump the beam in our end-cap calorimeter, well... hmm... ) The beam halo for the LHC is significantly bigger -- and the design luminosity is 10^4 higher than the one at Fermilab. But I think there will be none until we get to design luminosity... but chances are that we wont there for another 2 years. Once we are there, I would try to keep out of the end-cap areas...
One number I like quoting is that our inner silicon tracker will get 10^10 chest X-ray equivalent amount of radiation per year at design luminosity. So, yes, after 10 years of operation, I would not want to look at it for extended periods of time.
Yes, visitors are allowed to take pictures. Tripod will be a bit tricky as it will be crowded -- but I dont see why not. Everything at CERN is public so yes, you can take whatever photos you like and show them online.
Err... No, no.. The whole cavern wont be radioactive! Actually, we dont have any "normal radioactive materials" but yes, there is radiation when the beam is on. The beam will be on sometime in July. But we will activate the biometic sensors and other precautionary measures at the LHC doors starting in May to debug them in a timely fashion before July so that's why we cant have any visitors after the 1st of May. When the beam is on, yes, there is some substantial radiation... But almost all particles stop in the calorimeters -- remember??! (Your tour guide should have said this...) What is "evil" is the material that gets activated -- but that will take a few years. The remaining "evil" is the neutrons that bounce around in the cavern. But the neutron lifetime is 10 minutes so actually, when we have the first beam on and then we turn it off, we can go into the cavern after ~10minutes...
Also, I think CMS is simpler to understand just because it's got a simpler setup than ATLAS.
You *just* made my day... I am forwarding this now to all my CMS buddies.. I dont think they will like to think that they have a simpler setup than ATLAS...:)
Well, OK. I can claim to be one... But I will out of own for the Open Day... unfortunately.
The thing is that at CERN almost everyone is clueful but about "one thing" mostly. It is hard to find someone who has the "large picture"... The ones who do are generally people who have not been working on the LHC for the past 15 years but those who have been working on it since 2-3 years and before that was working at Fermilab or somewhere else like that. Then they can tell you what's new or revolutionary and put things in better perspective.
Honestly, it looks like the OpenDay will be a mad house. We are expecting at least 40,000 people. The queues are going to be awfully long! I feel like we should have a couple more of these OpenDays to accommodate this huge interest but hey, I am not in the management!! I am just a post-doc!
That said, I have given lots of tours at CERN already. I have taken at least 400 people underground just this past year. (Only 12 people are allowed to go at a time with one guide... ) I think the well-known things like ATLAS and CMS will be completely and utterly packed. So I would like to point out a rare gem... It's the LHC-b cavern where you can actually see the insides of the experiment which installed before LHC-b was installed and is now decommissioned and sitting nearby. The problem with ATLAS and CMS is that they are "done" -- meaning, the experiments are assembled wholly and therefore, it is hard to see it's guts. But you can see the guts of this decommissioned detector, which is kind of neat. I work for ATLAS and I love ATLAS to pieces but I think to try to see it on Open Day, one would need to be at CERN and queueing at 8am... or earlier.
If you have never seen a tape reader with robots running around before, the tour to the Computing Center is really cool -- but then again, since there will be no radiation there, you can visit that even after the 1st of May. (1st of May is the date set by the LHC management board to be the last day of public tours to the LHC and experiments. The rest of CERN will still be "visitable" after that.)
If you can not see ATLAS or CMS on the OpenDay or cant be here on the OpenDay but want to see them, there is a cheat... Most of everyone's requests goes through CERN Visitors Service. And they have a pool of guides but the experiments also have a pool of guides. The visitors service is no longer offering tours as they are completely booked until the 1st of May with their guides. But the experiments might still allow for visitors. The way to increase your chances of getting a private tour to one of the experiments is as follows: Find 11 other people who are interested in seeing the experiment with you and then e-mail the ATLAS or CMS secretariat asking for a tour for 12 people on a April xxth at xx:xx. Then they will forward this request to their pool of guides and someone (like me) might actually give you a tour. We like 12 people tours as this is the maximum we can take down and it is a much better "waste" of our time if the tour group is at maximum number... The e-mails for the secretariats are as follows: atlas.secretariat@cern.ch and cms.secretariat@cern.ch
Good luck!
I thought he would but Mr. Ertugrul doesn't sound like such an idiot actually. See this interview.
http://www.mefeedia.com/entry/recent-posts-blip-tv-beta/7018654/
I am starting to think that there is something to it. I'd rather have the ISP know something about some random number then real with all those cookies.
Answer: "That's only 300MB/s 24/7 for more than half a year for writing the raw data to storage. Then there are the other three experiments with the same amount of data, actually one of them does 1.2GB/s of raw data. The data ends up on disk first with an aggregate write speed of ~1.5GB/s (let's not exaggerate). The data is read immediately from disk again to be written to tape (our final storage media), so ~1.5GB/s reads... Then, all this data is being exported to external computing centers pretty much immediately too (multiple copies etc. etc., so aggregate is much higher than 1.5GB/s), so we get ~3GB/s of reads just from this data export (it can, potentially, be a lot more. we have already a total of 120Gbit/s of network connectivity to those sites). So, we are already at ~6GB/s of I/O and nobody even had a look into the data itself!! If we talk data analysis, we talk about repeated reprocessing runs over the entire collection of raw data in order to "create" the data format that physicists can more easily use for their analysis, we talk about several thousand people accessing all the accumulated data in a perfectly random way... mind you, we keep all the raw data active, so 10 years there will be at least 100PB, probably more like 150PB, maybe even 200PB of active storage. The current estimate for the I/O caused by the data analysis is in the order of 50GB/s (big B). "
I'll talk about one of the experiments, ATLAS. Yes we "generate" petabytes of data per day. It's rather easy to calculate actually. One collision in the detector can be compressed down to about 2MB raw data-- after lots of zero-suppression and smart-storage of bits from a detector that has ~100 million channels worth of readout information.
There are ~30 million collisions a second -- as the LHC machine runs are 40Mhz but has a "gap" in its beam structure.
Multiplying: 2 * 10^6 * 30 * 10^6 = 6* 10^13 Bytes per second. So ATLAS "produces" 1 petabyte of information in about 13 seconds!!:)
But ATLAS is limited to being able to store about ~300 MB per second. This is the limit coming from how fast you can store things. Remember, there are 4 LHC experiments after all, and ATLAS gets its fair share of store capability.
Which means that about of 30 million collisions per second, ATLAS can only store 150 collisions per second.... which it turns out is just fine!! The *interesting* physics only happens **very** rarely -- due to the nature of *weak* interactions. At the LHC, we are no-longer interested in the atom falling apart, and spitting its guts (quarks and gluons out). We are interested in rare processes such as dark-matter candidates or Higgs, or top-top production (which will dominate the 150Hz btw) and interesting and rare things. In most of the 30 million collisions, the protons spit their guts out and much much *rare* things occur. The catch of the trigger of ATLAS (and any other LHC experiment for that matter) is to find those *interesting* 150 events out of 30 million every second -- and do this in real time, and without a glitch. ATLAS uses about ~2000 computers to do this real-time data reduction and processing... CMS uses more, I believe.
In the end, we get 300 MB/second worth of raw data and that's stored on tape at Tier 0 at CERN permanently -- and until the end of time as far as anyone is concerned. That data will never *ever* be removed. Actually the 5 Tier 1 sites will also have a full-copy of the data among themselves.
Which brings me to my point that CERN storage is technically not a SAN (Storage Area Network)... (My IT buddies are insisting on this one. ) I am told that CERN storage counts as a NAS (Network Attached Storage). But I am going to alert them to this thread and will let them elaborate on that one!
Yeah, but it's in Cambridge where software engineers are used to be tucked into tiny cubicles!
But then again, it being Cambridge, the land of the FSF, MS is walking into pretty hostile territory. How many MIT hacks will be pulled on that office is beyond my guess...
I agree with you. Storm Trojan hasn't yet shown its true power and when it does, lets see how long it lasts...
SETI@HOME is a grear project, but does not have the huge computing power of the EGEE but is quite similar... So the fact that they included *one* Grid project is a good start!:) -- Honestly, I had that adrenaline rush when I thought "but would they count the Grid as a wonder?!" and was quite relieved to see it on the list -- Not that the list matters, I suppose... (It also probably means, I should get back to work and submit some jobs.)
I think the greatest snub is to the GNU project. Yes, the kernel is great. Yes, the kernel is wonderful. Yes, where would we be without the kernel?! But hell, who would adopt "just a kernel" for an operating system?? All those who make the switch from Microsoft to GNU/Linux do it because several GNU project have now reached the maturity level for them to be attractive to your garden-variety PC user.
I had the same reaction. Bummer...
But honestly, it is good that astronomers are catching up to something which for particle physicists, is business as usual.
If morality was an issue here, surely, I would hope that you would feel "some" urge to give back to the community... I am not seeing that here.
In general, I do not have an issue with "rich" people. I know/knew 5 billionaires personally and I have to say that 2 of them are/were extremely nice people. But then again, Poisson statistics...
I see a tiny little blue dot left in the emptiness of space-time, drifting, with half of its population not far away from starvation, with AIDS and other diseases spreading... I look at the world and see myself as part of this larger family. I care for them. So you could just say that your definition and my definition of a family is different. Maybe that's all!
And if you think your family is really that special... Just wait until you are in your death bed and see how your children will be fighting... The money may not even last 5 generations! I wish you no evil and I hope that won't happen. But then again, that's precisely what happened to a close friend of mine who just happened to be a billionaire... May he rest in peace.
If I had as much money as you claim to have, I certainly would try to give some of it back to the community that fostered you. I am sure you can do that without seriously hampering your own ability to protect and provide for your family. Afterall, if some nasty highly-contagious disease that we have no cure for, strikes the world, we are all in the same boat. Those pesky things don't care about how much money you have.
Slashdot Mirror
First thing is that they did not need to test "everything" to get it started. When you have 450 GeV protons in the ring, you dont need 7-8 Tesla magnetic field... So they got it started because they could and decided that they can test the high magnetic field setting later.
Second: The incident happened as they *were* testing it in a break from the low energy collisions schedule.
Third: It was more like 6 tons of helium...
But OK, you've got most of the story right.
You need to watch this: http://www.thedailyshow.com/watch/thu-april-30-2009/large-hadron-collider
No kidding. Eventually, we'll see a neutrino interaction even, I guess...
Well, here is an AC that clearly writes from the inside... Thanks!
Yes. It is used here as a unit of energy that *one* particle carries. Take a look at: http://en.wikipedia.org/wiki/Electron_volt The proton weighs 1GeV. 7TeV (Terra electron volts) which the LHC should run at, means that a poor proton will be so energetic that it will have 7000 times the energy that is it's mass. The higher energy a particle, the higher the magnetic field needs to be to curve it around the 27km ring. If the magnets can not handle the design current than that limits the magnetic field, which in turn limits the energy of the particles that you can accelerate. Incidentally, a 7TeV proton has about the same kinetic energy as a mosquito. But imagine that all the energy is being carried by *one* proton. Now, there are 100 billion protons in a beam bunch and 2000 of these bunches running around the LHC, according to the design and in the end, the total kinetic energy comes close to that of an aircraft carrier going at some reasonable speed, I am told... ps. I am not the AC who posted earlier.
True. But it is the *scale* that matters. ~27km long cryogenic line... has that been done before? For example, many off the shelf cryogenics components were not available before the LHC came along... So much was custom made. And now many components became off the shelf with the R&D money that CERN injected into the industry and so MRI machines and other cryogenics systems are becoming cheaper for those who want to use/study them.
About right... There are 1232 dipole magnets in total.
Take a look at the
It is the layer of the ATLAS detector that is closest to the interaction point where collisions happen. The first layer (cylinderical) only 5 cm away.
As for the radioactivity being "potentially dangerous" -- well, I would not want to ingest any of it or sleep next to it, if that's what you mean... But actually no, we will be able to take the detector out and replace it if needed. Remember that exposure is what counts and that depends on distance, as well as how long you have been exposed to it. So in this case, the answer is that given what we have to do with it, it is not dangerous.
The short answer is yes. But the longer answer is well, it depends... on things like luminosity and how good the LHC is on steering the beam. (ie. if it happens to dump the beam in our end-cap calorimeter, well... hmm... ) The beam halo for the LHC is significantly bigger -- and the design luminosity is 10^4 higher than the one at Fermilab. But I think there will be none until we get to design luminosity... but chances are that we wont there for another 2 years. Once we are there, I would try to keep out of the end-cap areas...
One number I like quoting is that our inner silicon tracker will get 10^10 chest X-ray equivalent amount of radiation per year at design luminosity. So, yes, after 10 years of operation, I would not want to look at it for extended periods of time.
Yes, visitors are allowed to take pictures. Tripod will be a bit tricky as it will be crowded -- but I dont see why not. Everything at CERN is public so yes, you can take whatever photos you like and show them online.
Hey... when CMS has a control room, I'd like to visit that!!! :P ;) Until then, yes, ATLAS control room rocks!
Err... No, no.. The whole cavern wont be radioactive! Actually, we dont have any "normal radioactive materials" but yes, there is radiation when the beam is on. The beam will be on sometime in July. But we will activate the biometic sensors and other precautionary measures at the LHC doors starting in May to debug them in a timely fashion before July so that's why we cant have any visitors after the 1st of May. When the beam is on, yes, there is some substantial radiation... But almost all particles stop in the calorimeters -- remember??! (Your tour guide should have said this...) What is "evil" is the material that gets activated -- but that will take a few years. The remaining "evil" is the neutrons that bounce around in the cavern. But the neutron lifetime is 10 minutes so actually, when we have the first beam on and then we turn it off, we can go into the cavern after ~10minutes...
Also, I think CMS is simpler to understand just because it's got a simpler setup than ATLAS. You *just* made my day... I am forwarding this now to all my CMS buddies.. I dont think they will like to think that they have a simpler setup than ATLAS... :)
Well, OK. I can claim to be one... But I will out of own for the Open Day... unfortunately.
The thing is that at CERN almost everyone is clueful but about "one thing" mostly. It is hard to find someone who has the "large picture"... The ones who do are generally people who have not been working on the LHC for the past 15 years but those who have been working on it since 2-3 years and before that was working at Fermilab or somewhere else like that. Then they can tell you what's new or revolutionary and put things in better perspective.
Honestly, it looks like the OpenDay will be a mad house. We are expecting at least 40,000 people. The queues are going to be awfully long! I feel like we should have a couple more of these OpenDays to accommodate this huge interest but hey, I am not in the management!! I am just a post-doc!
That said, I have given lots of tours at CERN already. I have taken at least 400 people underground just this past year. (Only 12 people are allowed to go at a time with one guide... ) I think the well-known things like ATLAS and CMS will be completely and utterly packed. So I would like to point out a rare gem... It's the LHC-b cavern where you can actually see the insides of the experiment which installed before LHC-b was installed and is now decommissioned and sitting nearby. The problem with ATLAS and CMS is that they are "done" -- meaning, the experiments are assembled wholly and therefore, it is hard to see it's guts. But you can see the guts of this decommissioned detector, which is kind of neat. I work for ATLAS and I love ATLAS to pieces but I think to try to see it on Open Day, one would need to be at CERN and queueing at 8am... or earlier.
If you have never seen a tape reader with robots running around before, the tour to the Computing Center is really cool -- but then again, since there will be no radiation there, you can visit that even after the 1st of May. (1st of May is the date set by the LHC management board to be the last day of public tours to the LHC and experiments. The rest of CERN will still be "visitable" after that.)
If you can not see ATLAS or CMS on the OpenDay or cant be here on the OpenDay but want to see them, there is a cheat... Most of everyone's requests goes through CERN Visitors Service. And they have a pool of guides but the experiments also have a pool of guides. The visitors service is no longer offering tours as they are completely booked until the 1st of May with their guides. But the experiments might still allow for visitors. The way to increase your chances of getting a private tour to one of the experiments is as follows: Find 11 other people who are interested in seeing the experiment with you and then e-mail the ATLAS or CMS secretariat asking for a tour for 12 people on a April xxth at xx:xx. Then they will forward this request to their pool of guides and someone (like me) might actually give you a tour. We like 12 people tours as this is the maximum we can take down and it is a much better "waste" of our time if the tour group is at maximum number... The e-mails for the secretariats are as follows: atlas.secretariat@cern.ch and cms.secretariat@cern.ch
Good luck!
But, there are quite a few very smart people working for the LHC who understand all that and more. Here is a link to the CERN LHC Safety webpage.
I didnt build the damn thing but surely, I'll be in the control room when they turn it on. I think I will play "Wake up little Susy"... SUSY .
"Yes, Pinky, we *did* try taking over the world several times... But c'est la vie, it didn't work"
"So what do we do now, Brain"?
"Obvious. Same thing we do everyday. Try to destroy the world!"
I thought he would but Mr. Ertugrul doesn't sound like such an idiot actually. See this interview. http://www.mefeedia.com/entry/recent-posts-blip-tv-beta/7018654/ I am starting to think that there is something to it. I'd rather have the ISP know something about some random number then real with all those cookies.
Can't imagine why you write this as AC, but ok...
Answer: "That's only 300MB/s 24/7 for more than half a year for writing the raw data to storage. Then there are the other three experiments with the same amount of data, actually one of them does 1.2GB/s of raw data. The data ends up on disk first with an aggregate write speed of ~1.5GB/s (let's not exaggerate). The data is read immediately from disk again to be written to tape (our final storage media), so ~1.5GB/s reads ... Then, all this data is being exported to external computing centers pretty much immediately too (multiple copies etc. etc., so aggregate is much higher than 1.5GB/s), so we get ~3GB/s of reads just from this data export (it can, potentially, be a lot more. we have already a total of 120Gbit/s of network connectivity to those sites). So, we are already at ~6GB/s of I/O and nobody even had a look into the data itself!! If we talk data analysis, we talk about repeated reprocessing runs over the entire collection of raw data in order to "create" the data format that physicists can more easily use for their analysis, we talk about several thousand people accessing all the accumulated data in a perfectly random way ... mind you, we keep all the raw data active, so 10 years there will be at least 100PB, probably more like 150PB, maybe even 200PB of active storage. The current estimate for the I/O caused by the data analysis is in the order of 50GB/s (big B). "
I'll talk about one of the experiments, ATLAS. Yes we "generate" petabytes of data per day. It's rather easy to calculate actually. One collision in the detector can be compressed down to about 2MB raw data-- after lots of zero-suppression and smart-storage of bits from a detector that has ~100 million channels worth of readout information.
There are ~30 million collisions a second -- as the LHC machine runs are 40Mhz but has a "gap" in its beam structure.
Multiplying: 2 * 10^6 * 30 * 10^6 = 6* 10^13 Bytes per second. So ATLAS "produces" 1 petabyte of information in about 13 seconds!! :)
But ATLAS is limited to being able to store about ~300 MB per second. This is the limit coming from how fast you can store things. Remember, there are 4 LHC experiments after all, and ATLAS gets its fair share of store capability.
Which means that about of 30 million collisions per second, ATLAS can only store 150 collisions per second.... which it turns out is just fine!! The *interesting* physics only happens **very** rarely -- due to the nature of *weak* interactions. At the LHC, we are no-longer interested in the atom falling apart, and spitting its guts (quarks and gluons out). We are interested in rare processes such as dark-matter candidates or Higgs, or top-top production (which will dominate the 150Hz btw) and interesting and rare things. In most of the 30 million collisions, the protons spit their guts out and much much *rare* things occur. The catch of the trigger of ATLAS (and any other LHC experiment for that matter) is to find those *interesting* 150 events out of 30 million every second -- and do this in real time, and without a glitch. ATLAS uses about ~2000 computers to do this real-time data reduction and processing... CMS uses more, I believe.
In the end, we get 300 MB/second worth of raw data and that's stored on tape at Tier 0 at CERN permanently -- and until the end of time as far as anyone is concerned. That data will never *ever* be removed. Actually the 5 Tier 1 sites will also have a full-copy of the data among themselves.
Which brings me to my point that CERN storage is technically not a SAN (Storage Area Network)... (My IT buddies are insisting on this one. ) I am told that CERN storage counts as a NAS (Network Attached Storage). But I am going to alert them to this thread and will let them elaborate on that one!
Yeah, but it's in Cambridge where software engineers are used to be tucked into tiny cubicles!
But then again, it being Cambridge, the land of the FSF, MS is walking into pretty hostile territory. How many MIT hacks will be pulled on that office is beyond my guess...
I agree with you. Storm Trojan hasn't yet shown its true power and when it does, lets see how long it lasts... SETI@HOME is a grear project, but does not have the huge computing power of the EGEE but is quite similar... So the fact that they included *one* Grid project is a good start! :) -- Honestly, I had that adrenaline rush when I thought "but would they count the Grid as a wonder?!" and was quite relieved to see it on the list -- Not that the list matters, I suppose... (It also probably means, I should get back to work and submit some jobs.)
I think the greatest snub is to the GNU project. Yes, the kernel is great. Yes, the kernel is wonderful. Yes, where would we be without the kernel?! But hell, who would adopt "just a kernel" for an operating system?? All those who make the switch from Microsoft to GNU/Linux do it because several GNU project have now reached the maturity level for them to be attractive to your garden-variety PC user.
I had the same reaction. Bummer... But honestly, it is good that astronomers are catching up to something which for particle physicists, is business as usual.
He-he. That's pretty funny actually. I think you are some fake character at this point. Otherwise, you are really out of touch with reality.
Oh, and really, don't speak too soon! It ain't over till it's over! :)
If morality was an issue here, surely, I would hope that you would feel "some" urge to give back to the community... I am not seeing that here.
In general, I do not have an issue with "rich" people. I know/knew 5 billionaires personally and I have to say that 2 of them are/were extremely nice people. But then again, Poisson statistics...
I see a tiny little blue dot left in the emptiness of space-time, drifting, with half of its population not far away from starvation, with AIDS and other diseases spreading... I look at the world and see myself as part of this larger family. I care for them. So you could just say that your definition and my definition of a family is different. Maybe that's all!
And if you think your family is really that special... Just wait until you are in your death bed and see how your children will be fighting... The money may not even last 5 generations! I wish you no evil and I hope that won't happen. But then again, that's precisely what happened to a close friend of mine who just happened to be a billionaire... May he rest in peace.
If I had as much money as you claim to have, I certainly would try to give some of it back to the community that fostered you. I am sure you can do that without seriously hampering your own ability to protect and provide for your family. Afterall, if some nasty highly-contagious disease that we have no cure for, strikes the world, we are all in the same boat. Those pesky things don't care about how much money you have.