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IceCube Neutrino Telescope
AMANDA writes: "Ice Cube is a neutrino telescope located at the south pole. It has just received the congressional support for $15 million dollars from the NSF. It will be the largest scientific instrument in the world. It promises a view into the most energetic phenomena in the universe." The idea is to use a cubic kilometer of Antarctic ice as a detector. Impressive.
I wonder how the keep the ice from wandering/changing.
As in glaciers, I suppose that antarctic ice is constantly changing (or at last i think so). And 1Km^3 of ice is quite a big mass.
Just my $.02 tough...
They say there are going to be about 5000 detectors spaced throughout the cube; that's a spacing of about 55-60 meters between them. Is the "extraordinarily transparent Antarctic ice" so clear that the detectors can pick up Cherenkov light through that much of it, or is that distance sufficient to visually isolate each detector completely from its neighbors? I guess my question is, how much of the cube is really being used in the detector, and how much is just optical insulation?
``Last chance to see...'' with the polar caps melting fast, I guess it's now or never...
Got time? Spend some of it coding or testing
oh, nevermind.
Sometimes boldness is in fashion. Sometimes only the brave will be bold.
...I found this line in the original proposal: "These constraints lead to a strawman design consisting of 81 strings 125 m apart, arranged on a square 9×9 grid. Each string holds 60 optical modules separated by 16 m."
There are good graphics showing how they'll be arranged, and explanation of how this design will facilitate ~1 resolution in muon trail reconstructions. Impressive!
I also found elsewhere that faint Cherenkov radiation can travel more than 24 meters through deep Antarctic ice before being completely attenuated. So that question is answered.
The thing that helps out here is the wieght of the ice above the detector. The pressure from the ice above the ice in the detector changes the normally opaque ice into a very clear form of ice. The small gaspockets that make ice opaque is forced into the ice crystal structure making it even clearer. Thanks to this you can have a sight of well above 20 meters. There is already one neutrione detector using the antarctic ice, the European/American collaboration AMANDA. http://amanda.berkeley.edu/amanda/amanda.html
Do the math before you scoff. The average human weight is 542.7 N (122 pounds), isn't it? That implies an average mass of 55.3 kg. Assuming an average density around 1 g/cm (since some folks float in water and some sink), that'd give an average human volume of around 55.3 liters, or 0.0553 m.
Now, divide a cubic kilometer of ice by the current population of the world, and you get about 0.161 m per person. So only about one third of that cubic kilometer would be occupied by human mass.
Of course, I'm sure no one would assume that they'd fit comfortably, and I'm also pretty sure that the original poster was not suggesting this as a standard for public housing, so let's all make like neutrino astronomers and chill out.
I don't think so: neutrinos, as their name implies, are electrically neutral. Bearing no charge, they don't interact with electromagnetic fields, i.e. photons, so there can't be any Cerenkov radiadion emitted. It is not the same as with charged beta particles (electrons or positrons) blasting out of a nuclear reactor into water.
The neutrino detectors are using a completely different subatomic process, but my subatomic physics isn't advanced enough to tell what it is. What I know is that they need a lot of matter (e.g. kilometer-thick ice) because neutrinos scarcely interact at all and can go through anything unnoticed. So the thicker the wall, the more chance there is that some of them will hit once in a while.
Neutrinos do not produce Cerenkov radiation, but the by-products of their colliding with something in the ice, electrons or muons, do, and that's how they are detected.
1m^3 = 1,000,000cm^3, so 1Mcm^3/180Kcm^3 can fit about 5.5 people (only 4.4 without the fudging).
We bring in the trash compactor method of squeezing people down, knock off another 10% and we get 5 people per cubic meter. One km^3 is 1,000,000,000m^3, so you get about 5 billion people mashed into a cubic kilometer. That "factoid" may have been correct when it was first stated, but the planet's WAY past the 5 billion population mark. Check out the World POPClock Projection from the U.S. Bureau of the Census.
The thing is, while it's not too difficult to corectly imagine square kilometers (humans are good with area), we pretty much suck once volume's involved. According to some architects I know (and some others in a documentary on skyscrapers), we do have the technology to build something a kilometer high, but we ain't even close to it yet, for a lot of reasons.
The tallest we've gone so far: Shanghai World Financial Center, which isn't done yet (expected completion: 2004), and the Petronas Twin Towers in Kuala Lumpur (Malaysia), which, at 1483 ft (452m), is only 10m higher than the Sears Tower in Chicago. And still not even half a kilometer high.
And there's not many buildings that have a square kilometer footprint, which would cover more than 12 streets and 6 avenues in Manhattan. That's a lot of space. Or ice.
The real reason we're so interested in this is probably because penguins live in Antarctica, which happens to be where most of the TuxRacer location shots were filmed.
woof.
There's no need to mod this as off-topic -- it's a tangent, but not unrelated. I also didn't take the +1. Save your mod points to knock off the flames, trolls, ASCII art and racist/nationalist crap which is sure to fill this story.
This note relates to the
I suppose that as long as the detectors maintain something above the minimum radiation traversal distance (I believe quoted in that thread as ~24 meters, don't know about the validity of that number), but within some outer bound distance limit, all should be well with the detection project.
Now, from grokking what I could from the PDF documents available at the primary project site, I believe the detectors are arranged in a "straw man" type formation specifically for the purpose of getting the most area out of the 1km^3 volume of ice. This would probably allow for some variance in the specific arrangement of the detectors (again, if this were monitored as I assume it will be).
God, I need to get back to work. This staying up for three days business can't last forever. Coffee is my friend...
So is SNO
Just to stay in the subject, and for those who might be interested, check out this detector.
It's sort of like the water version of the ice-cube detector.
Much nicer site for a vacation, too. 8^)
The home page is here.
Ice Cube is one bad*ss mutha... - shut yo mouth.
Ice T's decision to turn himself into phased sub-boson colission chamber?
Snoop Doggy Dog's work as a superstring detector?
The Beastie Boys' turning themselves into a distributed gamma ray burster radio observatory?
The Notorious BIG's role as a high energy muon accelerator that ultimately resulted in his untimely death?
And needless to say, what Slashdot reader could be ignorant of the tremendous theoretical work that MC Hawking has done?
It's high time these rapper/physicist's contributions to society were recognized!
Lawrence Person (lawrencepersonh@gmailh.com (remove all "h"s to mail)
http://www.lawrenceperson.com/
For my master's thesis (late 80s) I worked on a cosmic ray shower detector. Basically it was a bunch of particle detectors spread over a mountain side. The atmosphere can be considered to be part of the detector, as it turns the primary cosmic ray into a shower of millions of lower energy particles, which we detect. If they can claim the ice as part of their detector, we can claim a few cubic km of atmosphere as part of ours (and ours was not one of the biggest such arrays - it covered a few hectares at ground level.)
(It was the "JANZOS" array, and it was disassembled a few years ago.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.