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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.
My understanding of this phenonemon is that the neutrinos are travelling faster than the speed of light in water or ice but not faster than c, the speed of light in vacuum. Cerenkov radiation is emitted in these circumstances.
I really hate Dan Patrick.
Hmm... very good question indeed. This page shows the major tectonic plates involved.
It seems to me that they've got a fairly wide berth in area (given the relatively small size of the selected region for usage) for the purposes of the project. Apparently, the vast majority of Antarctica is comprised on a single major plate.
To the best of my knowledge (albeit limited), the greater portion of this region is relatively seismically stable as a result. Of course, they'd want to stay away from "boundary regions".
That's about all I've got. Anyone got more firm data on this?
...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
seletz, upon further research into your point, I happened across this document on the UCSC site. It discusses the "slippage" behavior of the West Antarctic ice sheet in particular. I'm not certain what region specifically the proposed neutrino study site lies in (hopefully the Eastern sheet???), but this definitely lends weight to your inquiry into the changing nature of the ice.
Here's an excerpt concerning this region:
"The ice streams can be seen in satellite images as large features within the ice sheet about 500 kilometers (300 miles) long and 20 to 100 kilometers (10 to 60 miles) wide. They move at a rate of 1 to 2 meters per day, sliding over a bed of sediment saturated with liquid water. But if the bed becomes cold enough for the water in it to start freezing, the loss of lubrication causes the ice stream to slow and eventually stop moving, Tulaczyk said."
Now, that is definitely some significant movement in the ice sheet. One can only presume that the researchers on this project have very carefully chosen the coordinates for the "telescope" placement to avoid this kind of nasty possibility. However, even the general settling and compacting of ice layers will inevitably produce some movement, even in an area limited to 1^3K.
As per my earlier reply, I guess that close monitoring of and allowances for such shifts have been incorporated into the project design specifications. At least, for $15M USD I'd certainly hope so!
It remains to be seen, however, if our species can manage to mess up the climate in the chosen region enough over 10 years to irreparably skew the results...
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.
At this energy, IceCube is then sensitive to all three types of neutrinos (e, mu, and tau); SNO can only see the first two, because the tau lepton (that the neutrino has to turn into to be detected) is so huge it's way outside SNO's energy range.
I know that SNO has about 9600 phototubes, and IceCube has about 5000, so SNO might be a bit more accurate for this reason.
Besides that, IceCube is huge. SNO is a sphere 12 metres across, or just under 2000 cubic metres. IceCube is a cubic kilometer, or 1000000 cubic metres. So it'll see a whole lot more neutrinos! (This may be related to why IceCube has a higher energy range.)
-Erf C.
Cthulu always calls collect...
Let me give you a first person perspective on the ice movement at the pole. I'm currently the Network Engineer for the US South Pole station for the next 12 months. The ice sheet that the entire station is on is slowing moving towards grid NW at about 10 meters per year which works out to about 1 inch per day. In fact every year on Jan 1st, we hold a ceremony where the correct location of the pole is calculated, and we place a new marker. Looking out from the current pole you can see a line of markers from previous years which track the movment of the station nicely. The thing is that the entire sheet is moving at the same pace, so we're remarkably stable from a seismic point of view.
The IceCube array is one of the more exciting projects we're looking at, but the logistics to support it are enormous. It won't happen for a few years yet, untill the new station has finished construction. Check out www.polar.org for more details.