On Oct 25, 2009, at 7:42 AM, Jed Rothwell wrote:
Horace Heffner wrote:
5. By making the grid elements small, say under 0.1 cm, there will
be a clear marking of a scale on the micrographs and this will
hopefully assist in counting and locating tracks, although the hole
diameter should of course be larger that the thickness of the
primary metallic layer (base),
Is this supposed to be 0.1 mm?
No. This is the suggested grid element size - the spacing between
hole centers. The holes at that spacing would have to be less than
0.5 mm in diameter. One of the problems with this grid idea is the
problem of bubble removal. I think the holes will quickly have
bubbles covering the tops of them, but surface tension will continue
to wet the inside surface and provide the ion flow path. It should
take some experimenting to find the best hole size, including
possibly adding sonic cell shakers to limit bubble size.
With cumulative detectors like this, such as x-ray film and CR39, I
recommend some sort of mask; that is, something that blocks the
particles you are trying to detect, and casts a shadow.
Yes, and of course masks of various thicknesses and kinds are useful
for particle discrimination. The use of a grid of lots of tiny cells
in a single experiment makes feasible aligning many different kinds,
thicknesses, and patterns of discriminators with specific holes in
the grid. This in effect, can provide many experiments for the price
of one, which, with a little trouble, all run with the same voltage,
current, chemical, and field time line profiles.
Not seeing particles is a good as seeing them, in a sense. Italian
researchers used dental x-ray film to detect x-rays in aqueous
electrochemical cells. The anode cast a shadow on the film, and
they used this shadow to make various analyses. It was remarkable
how much information they got out the x-rays.
- Jed
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
