Monday Morning Quiz

Boy that cash versus non-cash discussion is getting heavy work. Time for a change of subject.

Your starter for ten : in what area of astrophysics can the signal be detected using sound waves, and every source has led to a Nobel Prize ?

34 Responses to Monday Morning Quiz

  1. Michael Merrifield says:

    Hmmm… how about the CMB? You can hear it’s hiss on a shortwave radio, and there is only the one source, which has already yielded up a Nobel Prize.

    So, here’s one for you: how many astronomers have won Nobel Prizes?

  2. Tony says:

    Oh dear – really must learn to read the whole page – spent half hour on Google looking for the answer and still only found half of it (found site with idea that the sound of the Big Bang attenuated the CMB but it didn’t mention the background hiss, which I ought to have remembered anyway) before rereading this page and seeing Michael’s answer from two hours ago!

  3. MikeW says:

    calling the CMB a “source” is deliberately misleading, Neither Bamber or Jeremy would be so devious.

  4. MikeW says:

    Michael: if the question is how may Nobel prizes have been won for astrophysics I think the answer is 15 or 16. But I can see we’re going to be debating this for days: do we include Hess? How about Alfven?

    Rather more difficult to work out how many laureates were astronomers by profession (day job only?) without reading a lot of bios

  5. Michael Merrifield says:

    Well, since it’s a science question, Jeremy would certainly just be blindly reading what is on the card, and raising his eyebrows in that mock-superior way when those without the luxury of the answer in front of them get it wrong. But, to be fair, the CMB is more of a source than most astrophysical objects: it was, after all, emitted by the ultimate point source, the Big Bang.

  6. Tony says:

    Wasn’t Andy saying the CMB is the signal, where the source was the Big Bang.

  7. Martin E. says:

    surely Andy is thinking of neutrinos, where the Sun is detected, too faintly and so the prize. BUT, what about SN1987A? Surely that’s a source too? DANG IT – 2 sources, 1 pirze. 😦

  8. SamuelRiv says:

    I was thinking gravitational waves, since the first detector conceived to detect them was a giant suspended cylinder that theoretically vibrated harmonically with the contraction of space (and it did vibrate, but probably due to outside noise). However, I don’t recall that ever winning a Nobel.

  9. andyxl says:

    Martin E is more or less there on part-B; two sources, one prize (2002), but two prizewinners – Ray Davis, and Masatoshi Koshiba. Although the citation doesn’t say so, clearly Davis got it for detecting the Sun with Homestake, and Koshiba for detecting SN1987A with Kamiokande. Ray Davis had an amazing career. Built this major experiment but still found time to write “Waterloo Sunset” etc.

    So … sound waves ?

  10. Watcher says:

    Antares and Ice-Cube

  11. Bob says:

    Also amazing is the career of our own e-Astronomer, who, while ostensibly on sabbatical at SLAC is (as adverts on the sides of many Edinburgh taxis can attest) actually spending August playing a much younger man in a show on the Fringe. The List says of his performance “Lawrence may be cleaner cut than the former tramp-devil he once ‘played’, but that hasn’t dampened the amusing malevolence seeping from his mouth”, while the Scotsman quotes our hero as saying “Certainly, like anyone I want to do something worthwhile with my existence. But it’s tricky with this job, because it’s an embarrassing, self-indulgent, pathetic job in a way.” A bit hard on himself, possibly.

  12. Martin E. says:

    ah, sound waves. hmm… Ice Cube is a pretty loud rapper, but somehow I don’t think anyone stuck in the ‘Waterloo Sunset’ era was thinking of him…. high energy particles at accelerators make loud pinging sounds in (liquid?) detectors, i recall, & there was just a report (Science? Nature?) of detecting something – probably cosmic rays – by sound in the Antartic ice. Am I getting warm, Andy?

  13. Martin E. says:

    Watcher: Close, but not quite. Antares and IceCube are scintillator detectors seeing the optical Cerenkov flash from a neutrino passing through the water/ice.
    let me risk html again:
    Antares ,
    IceCube

  14. andyxl says:

    Watcher : Antares and Ice Cube both detect Cherenkov light, one in ice and the other in water. No sound waves there.

    Martin : your homework is to calculate the energy generated by dropping a book on the floor, in electron volts of course.

  15. Martin E. says:

    Oww! That hurt. [a failed experimentalist at heart. Maybe I should have tried a thinner book?] From the volume of my scream, I reckon a really really energetic neutrino would either sail right on through the floor, OR, highly unlikely but it must happen, make quite a racket. Yeah?
    NB: I corrected Watcher – with WORKING LINKS- before you did. So do I get a 5 point bonus for speed, Bamber?

  16. Watcher says:

    Andy
    Yes Antares and Ice-Cube use photomultiplier strings to detect Cherenkov radiation…..but

    These detectors use acoustic signals to align the photomultiplier strings so they already use sound waves in the detector.

    And what is more Antares at least plan to investigate the detection of UHE neutrinos via acoustic signals in the deap sea (AMADEUS). See Jounal of Physics Conference Series, 60 (2007) , Proceedings of the TeV Particle Astrophysics II Workshop.

  17. andyxl says:

    OK, 5 point bonus. Now, 1 kg dropped 1 metre gives 9.81 Joules does it not ? So thats about 10**20 eV. So a 10**21 eV UHE-nu would make a pretty loud bang. The experiments I have been thinking of are SAUND and ACORNE, which both use underwater microphones. The latter is particularly appealing because its off the coast of Scotland. Apparently the big problem is shrimps.

    Ahh .. while I have been typing Watcher has replied. I didn’t know about AMADEUS. So ten points to The Watcher there, and s/he streaks into the lead.

  18. Martin E. says:

    1kg dropped from 1 meter = 6.2e9 GeV. Oops, that’s 100 times above the IceCube range. Better stick with dropping an audiobook CD instead.

  19. Martin E. says:

    ARENA 2008 is the Third meeting on acoustic detection of neutrinos. Session 7 includes AMADEUS, and the one I had heard of “SPATS”, which is meant to go with IceCube. Good idea, they use anticoincidence between Cerenkov, Acoustic and Radio to reduce background. [Only possible in ice, they claim.] Frozen shrimp are probably pretty quiet too.

  20. Michael Merrifield says:

    So, what was wrong with the CMB as an answer, Bamber/Andy (Bamby? Bandy?)? Anyone with a shortwave radio can detect the signal using sound waves, and every source has won a Nobel prize (not a quarter of one, like the neutrino sources).

  21. andyxl says:

    Mike – if I had meant the CMB, the phrase “every source” would have been naughtily misleading of me. W.r.t. radio hiss, any signal can be transformed into an audio equivalent; but those UHE neutrinos actually really go BANG when they hit the water … If I was marking an essay I’d give you points for an interesting answer. But as I’m not I won’t.

    p.s. showing your age by referring to Bamber rather than Jeremy …

  22. Michael Merrifield says:

    It was more than I couldn’t find any mildly insulting way of combining the names Jeremy and Andy… Incidentally, did you know that Bamber Gascgoine’s real name is Arthur Bamber?

  23. andyxl says:

    … I always preferred Amber Grassgroin…

  24. Martin E. says:

    Sorry to keep this going, but what if someone had a TeV neutrino stop in them? Quite a punch, you’d think. But is it likely?
    IcdCube at ~1km^2 area expects about 10 TeV events/yr. People have a similar density to ice, so the cross-section of the whole world population of 6 billion is more like 5000 km^2 (say 1/2 m^2 each (the high X-section US population being offset by lots of thin folks elsewhere), so that’s 10,000 interactions/year!
    A few tens of Joules may not be too noticeable (heartburn in the wrong place?), but it if hit your brain or heart (& maybe some other bits) you’d be a goner, surely. The X-section of heart+brain ~0.02 m^2, 25 times smaller, so that’s a mere few hundred neutrino caused deaths/year. Surprisingly high, but undetectable against the background, I s’pose. A good murder mystery premise though.
    Did I get that right?

  25. andyxl says:

    Martin – its the volume that matters, not the detector area. As the interaction cross section is very tiny, they don’t overlap, so the total cross section is column density times interaction cross section. IceCube will have a cubic km, i.e. 10**9 m**3. If people have cross section 0.5m**2 as you suggest, but are say 0.2m thick, then six billion people is 3 times 10**8 m**3. So thats not 10,000 smashes per year, but it does still seem to be 3 per year …Hmm .. have we got this right yet ?

  26. […] gold in them thar neutrinos So whats with the neutrino puzzle thing […]

  27. Michael Merrifield says:

    I would have thought that some significant fraction of the reaction/recoil products of such an interaction would have sufficiently small cross sections at those energies that they would emerge leaving a rather insignificant “exit wound.”

  28. MikeW says:

    Andy: I set this as an exam question last year – work out how many neutrinos interact in your body in your lifetime. From memory the answer was a few tens using sensible cross-section values (this was just for the solar neutrino flux). You are quite right about the volume being the relevant parameter. Many of of my students spent half their answer making complicated estimates of their cross-sectional area. All you actually need is your mass and your density (~1 in cgs assuming you float) to get volume!

  29. David says:

    Did they get extra marke for taking middle aged spread into account? Does anyone know the half-life of a narrow waist? My memory doesn’t stretch back that far, I’m afraid.

  30. Michael Merrifield says:

    In the distant past, I recall Bob Kirschner showing that one person somewhere in the World probably saw a flash of Cherenkov light when a neutrino from SN87A interacted with their eyeball. Sadly, they didn’t send in an IAU telegram, though.

  31. Keith A. says:

    I’m surprised John Updike hasn’t been quoted yet. So, here is his (scientifically-incorrect) poem :

    Neutrinos, they are very small.
    They have no charge and have no mass
    And do not interact at all.

    The Earth is just a silly ball
    To them, through which they simply pass,
    Like dustmaids down a drafty hall
    Or photons through a sheet of glass.

    They snub the most exquisite gas,
    Ignore the most substantial wall,
    Cold-shoulder steel and sounding brass,
    Insult the stallion in his stall,

    And, scorning barriers of class,
    Infiltrate you and me! Like tall
    And painless guillotines, they fall
    Down through our heads into the grass.

    At night, they enter at Nepal
    And pierce the lover and his lass
    From underneath the bed — you call
    It wonderful; I call it crass.

  32. andyxl says:

    So when was that written Keith ? Before we knew neutrinos had mass ?

  33. Keith A. says:

    Yes, it was published in 1960. Still, “And hardly interact at all” would have been more accurate than “And do not interact at all” but not as a good for the poem.

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