At 04:22 AM 9/10/2009, you wrote:
2009/9/10 Abd ul-Rahman Lomax <[email protected]>:
> At 03:45 PM 9/9/2009, you [Jed] wrote:
>> Ah. CR-39 is opaque. You mean looking around it, from another angle.
>
> No. There are different kinds of CR-39. It's true, I've never seen a CR-39
> chip as used in this field, personally,
See in top photograph here
http://www.earthtech.org/CR39/A_B/reportAB.html the cathode wire
bearing part with a "1" and an "A" scratched in it. Doesn't look very
opaque to me, at least not in the visible spectrum (Jed, can you
provide refs showing opaque CR-39 used in this field?)
It's possible some is opaque, I assume that Jed isn't blowing smoke.
He'll respond, I assume as well.
It can be made in different colors, it can be designed as an optical filter.
Suggestion, if you want to video the cathode, better look at it from
the side, I gather deposits can form on the bottom. Videoing through
the CR-39 seems a good idea to me, if nothing else it will show how
the plating, dendritic or spongy, forms vs time (hard dendritic
plating is a requirement for pit forming it seems).
Yeah, I think it's an interesting idea. The CR-39 may become cloudy
from damage, but, on the way there, we'd still get some interesting
images or videos, I think. To me, an important goal is to discover
immediate evidence that a cell is active, it doesn't have to prove
radiation, rather, it then allows much more rapid engineering.
You could drill a round window through the flat side wall of the cell,
and press the cathode bearing CR-39 against the wall via e.g. a PTFE
gasket around the hole to prevent leaks. Note such an arrangement also
allows "PACA" experiments by interposing a few microns mylar film,
plus, I suggest, a thin layer of air guaranteeing no electrolyte vs
CR-39 chemical interaction whatsoever while only negligibly slowing
down energetic particles.
mmm... actually, this is good, because the cathode can be located in
the little well formed by the wall of the cell, so the cathode can be
at optimal distance from the CR-39, it's got to allow electrolyte
penetration, but if it is too large, it cuts down too much on the
radiation. It is possible to use non-glass cells, then, and the cell
walls could be thick, which leads to some other interesting
possibilities, such as operating at higher pressure. I wonder how
high one could go?
thin layer of air, or, possibly even better, thin layer of material
that generates neutrons from hot alphas with high cross-section. If
transparent, great! If not, then part this material, part CR-39 of
the same thickness. Layers of CR-39, not exposed to the electrolyte,
should rule out all but the weirdest of chemical interactions. But it
could also be air for that layer, the airspace maintained by the
pieces of alpha absorber.
