Saturday, December 26, 2009


While the LHC is hibernating until February next year, outreach efforts are not on hold. Here in Germany, there is a nice exhibition on tour, called "Die Weltmaschine". This means literally the "world machine" – somewhat better than the "big bang machine", but finding a catchy but not misleadingly bombastic name for the LHC seems to be a challenge.

Anyway, the exhibition, organized by DESY, the German particle physics laboratory based in Hamburg, was on display this December in Heidelberg, in the large foyer of the Kirchhoff Institute for Physics of the University. Experimentalist from Heidelberg are contributing to the ATLAS, ALICE, and LHCb experiments.

The exhibition provides a nice introduction in the known facts and open issues of particle physics, and in the techniques to accelerate particles and detect and analyse the collision products. I was there on Saturday afternoon last week, and was surprised that quite a lot of people were around, despite the cold and the snow that had gripped Heidelberg that weekend.

The most fascinating exhibit to me was a spark chamber, where the ionisation of gas by charged particles triggers sparks between high-voltage wires.

Although this is detector technology that is not used anymore at the LHC, it is compelling how it makes visible the constant shower of ionising particles in the cosmic radiation, which we usually are completely unaware of. It was quite easy to catch a couple of events with my digital camera, just by photographing the chamber at random moments:

The next stopover of the exibition will be Frankfurt – if you are around by chance in the second half of January, it is worth a visit.


  1. Hi Stefan,

    This was a very interesting post of yours which again has me briefly envious of not being a German citizen at times:-) This is one of those events where I would be easy to spot for if spoken to it might require elevating your voice quite a bit, not because of being hard of hearing, which unfortunately is slowing becoming true with time, yet rather because in such circumstance I also have been discovered(to the annoyance of some) to be hard of listening :-) That’s because when I find something to be interesting I tend to zone out everything else in the world to the exclusion of only it.

    I would like to see such a chamber since it holds a close relationship with the Wilson's cloud chamber which for the first time gave one a glimpse of the path of atomic particles that before were only a thing in theory (not forgetting of course Rutherford) with no clearly obvious evidence that it be something able to be demostrated in a realistic sense. It also served as being the thing that Einstein would make reference to on occasion when waves where sighted as being the only true element of reality. Perhaps it would be an idea to see if PI would sponsor such an exhibit travelling here to Canada that would serve both to extend its public outreach mission and reinforce the bonds between those representing North American and European physics programs.



  2. Hi Stefan & Bee,

    Perhaps off topic yet I just realized that this annoying triat I have in regards to zoning out on occasion might still prove useful in certain circumstances. :-)

    Best of the season,


  3. Uncle Al would call it "Der Nu├čknacker." Whether the LHC finds something, or more likely nothing at all, it will bust some nuts.

  4. /* was quite easy to catch a couple of events with my digital camera..*/
    Nice. You just proved experimentaly, photon is a pin-point particle with positive surface curvature of space-time...

  5. Hi Phil,

    actually, there is also a small cloud chamber as part of the exhibition, which nicely shows the constant activity of cosmic radiation - also fascinating! Unfortunately, I couldn't take a photo, it was too dark, and the flashlight wouldn't have worked...

    Cheers, Stefan

  6. Hi Stefan,

    A cloud chamber as well as a spark chamber; now I’m really green with envy as up close and personal I’ve seen neither. I wonder as you mentioned because of technological advances having them becoming somewhat obsolete I might be able to pick up a used one cheap. I guess though when it comes to effect you can’t beat the old plasma lamps:-)

    Also as you serving as a reminder I am looking forward to the LHC starting to make some runs at energy levels coming closer to its design capacities. Problem is it will be some time before the data analysis will confirm anything that it produces. The common misconception is a Higgs boson or sub atomic black hole is just going to pop up have it plain it did. One good thing about the devices you’ve seen is that the phenomena presents itself in real time and is obvious. Ironic isn’t it how the public perception and the reality differ as more than likely if the LHC were to produce a black hole it would be most likely announced six months or more after the event. I wonder how people will react when they are informed they missed to even notice a black hole being created:-)



  7. Hello Phil,
    Yes indded, cloud chambers, especially of the
    continuous (or "diffusion") type
    are really impressing.
    If You have access to dry ice,
    You can tinker one rather easily.

    I have seen a commercial version for
    school use, wich was operated at
    minus 30 °C, that is easyly achieved with a Peltier cooler
    or two of them cascaded.
    (or maybe operatable on Your porch?)
    I did not understand this:
    ..this annoying triat I have in regards to zoning out on occasion might still prove useful in certain circumstances. :-)
    What is a "triat" and what is that
    link to the circus band good for?

  8. Hi Georg,

    I believe Phil meant "trait" and I suspect the link is a reference to one of my recent twitter updates: "Posaunenchor der Freiwilligen Feuerwehr. GRAU-EN-VOLL. Wo ist der Ausgang," that left Phil somehwat confused as to its meaning. Best,


  9. Hi Georg,

    Yes Bee was correct I meant trait not triat, that’s the problem when your right hand gets ahead of your left, or perhaps it’s the left brain getting ahead of right :-) Also thanks for the cloud chamber instructions although it rarely gets to minus 30 on my front porch. If I build one it might make a excellent gift for our extended family’s Christmas tradition of a Auction gift draw, which is held after we exchange our usual ones. The way it works is every one brings a gift with no name tag attached to the wrapped present. It supposes to be inexpensive, yet the utility of it is left up to the giver. We then all draw lots to see what order we get to pick a gift and are also left the option of picking one or taking one that was already selected; which in such case gives the one who it was taken another pick. In the mix there will be a few useless gifts such as grape peeler and such or gag gifts like rubber chickens, with also being nice ones which people wouldn’t mind having. It would be interesting to see the reaction of someone opening a package to find a cloud chamber; I could even write on it compliments of Georg :-) Oh well I’ll have to wait until next year.



  10. Hi Bee,

    I was just wondering if that band was the one so renowned for their cafe serenades :-)



  11. Hello Bee, Phil,
    thank You. Trait is a interesting word,
    of latin/french origin.
    German "Zug" is very similar, I think
    it was copied/translated by the
    The "Posaunenchor der freiwilligen
    Feuerwehr" is rather unusual,
    normally "Posaunen" are a Prostestant Church business.

  12. Hi Georg,

    When I query google to decipher ‘Zug’ it gives me ‘train’ although when I translate trait to German is appears as the fifth of six possible options as I show below. Howvever it still leaves me to wonder how a train would be held to be synonymous with an aspect of character. Although given the one I have it fits in at times in having a one track mind:-)

    1. Eigenschaft
    2. Merkmal
    3. Charakterzug
    4. Wesenszug
    5. Zug
    6. Gesichtszug



  13. Hi Bee, hi Stefan,

    a happy new year for you both. All the best and a healthy future.

    Best Kay


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