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Space Science

IceCube Neutrino Telescope 65

Posted by michael from the more-neutrino-news dept.
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.
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IceCube Neutrino Telescope More

IceCube Neutrino Telescope

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  • particles physics was so damn cool...

    Sorry, it's 05:50 EST, and I'm still up coding... hey, Antartica's got lots of penguins, eh?

    I'll stop while I'm ahead :).

  • Seismic stability? (Score:4, Insightful)

    by seletz ( 192331 ) <stefan.eletzhofe ... e ['tzt' in gap]> on Saturday November 10, 2001 @06:53AM (#2548058) Homepage
    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? (Score:4, Informative)

      by trilucid ( 515316 ) <pparadis@havensystems.net> on Saturday November 10, 2001 @07:02AM (#2548067) Homepage Journal

      Hmm... very good question indeed. This page [usgs.gov] 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? (Score:4, Insightful)

        by seletz ( 192331 ) <stefan.eletzhofe ... e ['tzt' in gap]> on Saturday November 10, 2001 @07:15AM (#2548074) Homepage
        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 [wissenschaft-online.de].

        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?

        • Hmm... this is gonna give me brain strain... :)

          Borrowing from the PDF doc found at: this location on the public docs site [wisc.edu], here's what I could grep out:

          (from page 2, par 2): "... We show that this limit is accessible by operating a kilometer-scale neutrino observatory over several years."

          (from page 2, par 3): "... Although the flux from a single source may still be small, this conclusion is credible because a neutrino telescope will be operated for a decade."

          Basically, I think the intrinsic accuracy in the system lies largely in the fact that it will be operated for a long duration. This temporal note affects multiple portions of the problem, acting as an averaging and error-correction mechanism (at least as far as I can tell).

          So, given enough data (ala' Seti@Home), it should be possible to pay attention to the general outstanding trends produced from analysis, even given somewhat of a shift or "settling/sliding" in ice conditions.

          Please forgive me awful German; I tried to grok the site you pointed me at, but it just made my brain hurt :(. I need to bone up on more than just my native tongue (comes in handy for playing chess online too).

        • Re:Seismic stability? (Score:4, Informative)

          by trilucid ( 515316 ) <pparadis@havensystems.net> on Saturday November 10, 2001 @07:54AM (#2548117) Homepage Journal

          seletz, upon further research into your point, I happened across this document [ucsc.edu] 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? (Score:3, Interesting)

            by darkonc ( 47285 )
            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.

            That 1Metre/day is the movement of the whole ice chunk over lubricated ground. That sort of movement is not likely to affect the detector that much... More important is the warping of the ice block against itself which is more likely to be in the range of inches or feet /year (as an analogy: I may be walking at 5MPH, but my backbone is relatively stable relative to itself [unless I get hit by a car going 60MPH, in which case, all bets are off])

            As noted at one Nasa glacial site, [nasa.gov]

            Ice streams-large river-like currents of ice flowing through the ice sheets at speeds one to two orders of magnitude faster than the general ice flow-greatly increase the potential swiftness of ice-sheet collapse by rapidly transporting ice from the interior of the ice sheet to the margin.
            Glacial movements on the Antarctic shelf can vary in the range of orders of magnitude. In other words, the movement at the place chosen for the dector are probably unlikely to be moving at the 1M/day rate.. Given that the detector is apparently at the south pole, my expectation is that that section of ice sheet is going to be relatively stable.

          • 500km long, by 20-100km wide

            If entire 1km cube is moving uniformly, relative motion (within the cube) will be 0. Presumably, no effect on instantaneous measurements. May have a problem with comparing observations conducted over a matter of days.

            If works on "usual" neutrino detection method (observation of cherenkov radiation burst) then slippage might not be a problem, even then. Radiation will propagate at c, enormously faster than ice is moving. Would need "inertial" reference frame to compare location of bursts over time, but hey -- isn't that what we built GPS for?

      • Re:Seismic stability? (Score:4, Informative)

        by henrym ( 414280 ) <henry@henrymal m g r e n . c om> on Saturday November 10, 2001 @04:46PM (#2549091) Homepage
        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.

    • This note relates to the /. thread found here [slashdot.org] concerning the spacing between the detectors in the ice-bound array.

      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...

    • there is a simple test of stability, look for the telltale signs of movement which are "crevasses".

      If you don't find any then you can be pretty sure the mass of ice is not moving.
  • 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 [umr.edu] is emitted in these circumstances.

    • Re:Must be like a vacuum. (Score:2, Informative)

      by Soft ( 266615 )
      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 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.

      • Re:Must be like a vacuum. (Score:2, Informative)

        by Soft ( 266615 )
        Oops, wait, hate to follow-up on my own post... I should have read the article more closely!

        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.

  • It isn't "extraordinarily transparent" to me... (Score:3, Interesting)

    by tonyc.com ( 520592 ) on Saturday November 10, 2001 @06:58AM (#2548066) Homepage
    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?
    • ...I found this line in the original proposal [wisc.edu]: "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 [uci.edu] that faint Cherenkov radiation can travel more than 24 meters through deep Antarctic ice before being completely attenuated. So that question is answered.

      • "maximum attenuation length of ice exceeds 24 meters"


        Does _not_ mean, that the light can travel a maximum of 24 meters. The intensity is just reduced to 1/e. For IceCube the attenuation length is expected to be at about the string spacing (100-125 meter). That means, that you can see the light emitted at one side of the detector on the other side (1km) (assuming you start with a reasonable amount of light, e.g. from a muon from neutino interaction)

    • Pressure (Score:3, Informative)

      by KM1 ( 409622 )
      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
  • ``Last chance to see...'' with the polar caps melting fast, I guess it's now or never...
  • A cubic kilometer of ice is a lot -- you can fit the entire world's population in that amount of space!

    Can't remember where I originally heard this from...

    • While you might beable to, chances are you'd need to compress them to the point where it would just be a hell of alot of meat. Basicly what I mean is that anyone who told you 6 billion people could fit in a cubic kilometer was either 1)full of it or 2) talking about much, much smaller people then I know
      • Actually it looks like it's right; say a person is 1.8m tall, 50cm wide and 20cm thick (about 6' by 20" by 8" for those unmetrified savages <g>). That would fit in 0.18 cubic meter, so we could have five people in a cubic meter with margin to spare. A cubic kilometer holding a billion cubic meter (1000 * 1000 * 1000), draw the conclusion...
      • 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.
    • "Average" adult: ~180cm high, 50cm wide, 25cm deep = 225,000cm^3. Reduce by a fudge factor of around 20% due to empty space = 180,000cm^3.
      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 [census.gov] 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 [mori.co.jp], which isn't done yet (expected completion: 2004), and the Petronas Twin Towers [kiat.net] 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.

  • well kickass, i'm gonna be rich....my refrigerator makes ice cubes all the time...
  • If that whole neutrino thing doesn't work out ...
    • The NSF can draw some more revenue out of Congress to cover the settlement with rapper Ice Cube.
    • Astrophysicists can keep their drinks cold for the next 10^5 years.
    • Stanley Cup 2012.

  • Ice is cool but... (Score:4, Interesting)

    by rakerman ( 409507 ) on Saturday November 10, 2001 @08:39AM (#2548169) Homepage Journal
    So is SNO [queensu.ca]

    • Re:Ice is cool but... (Score:3, Interesting)

      by FTL ( 112112 )
      > So is SNO [queensu.ca]

      Moderators, that was most certainly *not* offtopic.

      I would be very much interested in a comparison between the Ice Cube and SNO. My guess is that the Ice Cube is a lot cheaper, but that the SNO is a lot more accurate.

      • I wouldn't waste your breath. The moderator that did that, must have just taken a toke off his crackpipe.

        Still, I can't wait for metamoderation.

      • Re:Ice is cool but... (Score:4, Informative)

        by ErfC ( 127418 ) on Saturday November 10, 2001 @03:02PM (#2548873) Homepage
        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 [queensu.ca], 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.)

  • Misread this at first. Thought you meant "Neutrino ice cube detector" which would have been a really convoluted way to detect ice cubes. Then again, is there a better way to detect them?

  • Just to stay in the subject, and for those who might be interested, check out this detector [in2p3.fr].

    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 [in2p3.fr].

  • But... (Score:2, Funny)

    by snilloc ( 470200 )
    ... will it come with a parental advisory sticker?

    Ice Cube is one bad*ss mutha... - shut yo mouth.

  • I am sure a neutrino telescope is important for detecting many things - including observing super nova.

    What about more resources and money for something that could hit MUCH closer to home?!

    agbert...

  • Another Neutrino Telescope (in Canada) (Score:3, Informative)

    by pomakis ( 323200 ) <pomakis@pobox.com> on Saturday November 10, 2001 @02:44PM (#2548834) Homepage
    The Sudbury Neutrino Observatory [queensu.ca] near Sudbury, Ontario, Canada is another interesting neutrino telescope. It's not nearly as large as the Ice Cube, but it's still very impressive. From their web page:
    The Sudbury Neutrino Observatory (
    SNO) is taking data that has provided revolutionary insight into the properties of neutrinos and the core of the sun. The detector, shown in the artist's conception below, was built 6800 feet under ground, in INCO's Creighton mine [queensu.ca] near Sudbury, Ontario. SNO is a heavy-water Cherenkov detector that is designed to detect neutrinos produced by fusion reactions in the sun. It uses 1000 tonnes of heavy water [queensu.ca], on loan from Atomic Energy of Canada Limited (AECL), contained in a 12 meter diameter acrylic vessel. Neutrinos [queensu.ca] react with the heavy water (D2O) to produce flashes of light called Cherenkov radiation. This light is then detected by an array of 9600 photomultiplier tubes mounted on a geodesic support structure [queensu.ca] surrounding the heavy water vessel. The detector is immersed in light (normal) water within a 30 meter barrel-shaped cavity [queensu.ca] (the size of a 10 story building!) excavated from Norite rock. Located in the deepest part of the mine, the overburden of rock shields the detector from cosmic rays. The detector laboratory is extremely clean to reduce background signals from radioactive elements present in the mine dust which would otherwise hide the very weak signal from neutrinos.
  • It's good to see that Ice Cube's decision to turn himself into a neutrino detector is finally bringing recognition to the vital role rappers have played in cutting edge astrophysics over the last few years. But where are the equally important mentions of:

    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!

  • Planets, moons, and comets also have cubic kilometers of ice from which to build neutrino telescopes. I was the first to conceive of this, and publish technical details in such
    places as:

    "HUMAN AND ROBOTIC PRECURSOR MISSIONS
    TO THE POLAR ICECAPS OF MERCURY"

    http://magicdragon.com/ComputerFutures/SpacePubl ic ations/Mercury_Ice.html

    and

    Jonathan V. Post, "Lunar Farside,
    Mars Polar Cap, and Mercury Polar Cap
    Neutrino Experiments", Proceedings of
    Space 92 (3rd International Conference
    on Engineering, Construction and
    Operations in Space), pp. 2252-2263, ed.
    Willy H. Sadeh, Stein Sture, Russell J.
    Miller, 31 May - 4 June 1992, Denver,
    CO, American Society of Civil
    Engineers, New York [1st published
    proposal for robotic & human missions
    to icy poles of Mercury]

    The south pole of Mars (water plus dry ice) is one other place where we can do this ... giving us
    a good baseline for "binocular vision" between Earth-based and planet-based neutrino telescopes.

    We can also use undergound tanks of oxygen and hydrogen beneath a Moon Base, where the fuel and human consumable storage does double duty as a science instrument.

    Think big! The solar system is ours to hack!
  • 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.)
  • Reading over the few comments here.. Yes, they do know a lot about drift rates for the amanda holes. The whole pole plateau around pole move pretty uniformly, but it does move. Amanda has a few GPS units on top of MAPO ( the observatory where most of their electronics are housed ) that read out where they are located as well as very good timing information. ( but good point.. they may have trouble with the sept 11 GPS network changes ) Anyway, 15 million will come nowhere close to funding the monster which is IceCube. The real price tag is up there, at my own back of the envelope calculation, at least 250-300 million ( includes support costs ). The fuel to melt one amanda / ice cube hole is 3 LC-130 flights. There are 80 holes planned. This translates to almost one year just for fuel. The equipment for one string is probably going to at least be 2-3 flights by itself ( 2KM of cables and a few dozen photo multipliers, high voltage supplies and readout electronics). They would require a new building ( stealing a bearthing building ) the elevated dorm ( or beaker box for short ). Anyway, I don't know how they can expect $300 million without producing much. A breeze through astro-ph shows the papers in the last 12 months ( 3 of them ) are related to data in 1997. I could be wrong, but it's somewhat suggestive.. Actually I think it's not quite true that IceCube if funded would be the largest scientific instrument ever. There is a radio telescope project called the Very Long Baseline Array. Ten sites spread across the states ( hawaii to st croix ). If you calculate the size of the single dish nessesary to get the same results it's in the neighborhood of the size of the whole continent of Antarctica. Well, you could probably make a case either way. All in the holy crusade for funding, yes? Of course I'm biased.. If you couldn't tell.. I work in radio astronomy...

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