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.

Comments

Seismic stability?

[seletz]

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...

Re:Seismic stability?

[trilucid]

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?

Re:Seismic stability?

[seletz]

Well, ok. Basically this means that the whole area is quite stable (because of not being located near any tectonic folds/bounds).

Ok, now what about the ever changing nature of ice itself? I mean, this ice built up due to snow falling on the surface and then beeing compressed slowly to ice. In this month's german edition of Scientific American there's an article 'bout that somewhere here.

Ice keeps on "flowing" like some liquid, but only slower (way slower). What about the tension built up because of that? Ice is brittle, don't constantly keep cracks and canyons build up?

Re:Seismic stability?

[trilucid]

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...

Re:Seismic stability?

[henrym]

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.

Ice is cool but...

[rakerman]

So is SNO

Re:Ice is cool but...

[ErfC]

I think Ice Cube can measure neutrinos with much higher energy than SNO can. I'm having a hard time finding SNO's energy range on their site, so someone in the know should please correct me, but it seems IceCube can measure well into the 100 TeV range -- that's about a thousand to a million times higher than SNO measures (I think SNO only gets up into the GeV's, but again I"m not sure; this is coming from my poor memory of some of the neutrino talks I've been to).

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.)