h a l f b a k e r y
The Out-of-Focus Group.
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
or get an account
Firstly I want to insert a disclaimer: I'm happy for any kind
of particle detector to be used for this, but I don't think a
spark chamber is useful, so it's cloud or bubble chambers.
Set up a cloud or bubble chamber in a transparent bottle.
At one end, set up a particle accelerator to shoot
subatomic particles into the chamber which can be steered
using magnetic coils. This is a pretty similar situation to a
CRT, which is more or less a particle accelerator with an
evacuated glass bottle at one end, so it's not a stretch to
imagine a device like this commercially available for an
There are two alternatives here. One is to use short-lived
charged particles such as muons to produce lines oriented
three-dimensionally in the chamber like contrails, ending
when the muon annihilates. The problem with this
approach is that they will produce a streak going all the
way from the start of the chamber to the point where they
annihilate, which is hard to control. The other is to use a
neutral particle whose half-life is long enough to get it all
the way across the chamber but controlling its velocity so
that it decays into charged particles at the appropriate
position. The entire chamber is scanned like a three-
dimensional version of a raster scan display. I haven't
worked out how these particles would be steered.
That's one version of my idea. The second is less flexible
and I have [beanangel] to thank for planting the seed.
Swallowtail catastrophe graphs have more than three
dimensions. Apparently three dimensional sections of a
swallowtail catastrophe can be observed at the bottom of a
curved, three-dimensional surface illuminated by a strong
light source such as a tea cup in the sun, in the form of the
caustic projected onto the bottom of the cup. The position
of the section can be varied by moving the relative
positions of the light source and the reflecting surface. My
suggestion is this: provide a source of ionising radiation
which can be reflected by a curved surface of electrodes of
the opposite charge to the particles which can be modified
in shape, and aim the radiation into a cloud or bubble
chamber. The result should be, with appropriate
curvature, a caustic representing a three-dimensional
section of a swallowtail catastrophe in three dimensions,
and different sections can be imaged by varying the
direction of the beam of charged particles.
I don't know if this next bit is mathematically coherent. If
a swallowtail catastrophe can be imaged in this way,
perhaps the other catastrophe graphs with more than three
dimensions can too, so hypothetically with variations in the
shape of the deflecting surface it might be feasible to
produce butterfly catastrophes and the three conic section
There's still more!
There are variations of each catastrophe graph where the
points of the discontinuity can be shifted away from the
centre. If parts of the caustic remain visible in these
circumstances, this gives us relatively flat surfaces of
clouds and bubbles which could be used to construct more
conventional three dimensional shapes.
What I don't know is considerable, but one item on that list
is whether there is even an analogous effect to optical
caustics among charged particles. It seems to me that they
would tend to repel each other and in fact I don't
understand how caustics are possible in the first place as
they strike me as violating the laws of optics.
A little help with this possible pile of nonsense would be
Lasers and bubbles, but only static (so far). [neutrinos_shadow, Feb 23 2017]
||//use a neutral particle whose half-life is long enough to get it all the way across the chamber but controlling its velocity so that it decays into charged particles at the appropriate position. //
||I think you run into a problem there. Particles don't have little timers to tell them when to decay; they just have a finite probability of decaying in any given interval of time. So, your image is going to be hugely blurred out, with each line's beginning and end smeared out as some sort of Poissony smear, in a smeary way.
||A better approach might be to use two lasers that can be brought to bear on a particular point in the tank and that can, in combination, trigger the formation of a bubble, which would collapse once the lasers had moved on. This is, of course, the same method that's used to etch 3D images (as arrays of tiny bubbles) inside blocks of glass, except that the image would not persist.
||Aye, I did in fact think of that but, um, didn't find a
solution! And it occurs to me now as odd that their half-
lives all have the same kind of kurtosis and skewedness
plotted as a bell curve.
||In fact, it could presumably be smoothed out a bit by using
stable particles although they would then leave streaks all
the way through the medium.
||I gave you a crumb because I had never heard of caustics. Very cool.
||I had in my mind that I had seen an artistic 3d representation produced in a clear block by an IMRT radiation machine, but now I can't find it.
||Actually, if you could arrange two intersecting particle beams of the right sort and stupidly intense, you might create collision products at a point. Of course, the trick would be not to be anywhere near the machine when it was operating.
||So you could have a 3-D display all right but you could only watch it on
a flat screen via a camera sited in the highly radioactive environment it
||/ you might create collision products at a point/
The idea was a cube of something which darkens with ionizing radiation - like xray film. Then use the same tech now used to do conformal radiotherapy to paint a 3d image.
||I was thinking a cube full of phosphors could be make to display a moving 3d image. But I suspect that with radiotherapy the 3d shape is laid down iteratively not all at once and so the tech to make the 3d phosphor image would have to be different.
||Anything done iteratively can be made to appear to be done in parallel, if the iterations are fast enough.
||Currently wondering about the possibility of a phosphor display
sweeping up and down rapidly in a vacuum but that would mean
changing the focus of the beam at the same rate.