At 03:55 PM 10/7/2012, mix...@bigpond.com wrote:
While what you say is true, a track created by a single proton is not
necessarily indicative of neutrons, as the track could be caused by
any reaction
producing a proton, or any charged particle for that matter. However
the triple
track created by the C12 breakup is strongly indicative of fast neutrons.
Yes, the triple track is distinctive. However, if you have lots of
small tracks, as protons will produce, in a place where no charged
particle radiation would penetrate, you can be quite sure you are
looking at neutron-caused proton knock-on.
In the experiment we ran, we had the following arrangement:
c = cathode wire, originally 250 micron diameter, plus plating,
against the cell wall.
h = acrylic cell wall, 1/16". (about 1600 microns)
p = polyester LR-115 base material, 100 microns
d = detector layer, cellulose nitrate, 6 microns
d
p
p
d
d
p
cover piece of acrylic plastic holding down the films
that's four layers of LR-115, as two pairs, emulsion-to-emulsion
We would expect to find, aside from neutron-produced tracks, only
background radiation from previous storage, plus radiation during the
experiment. Charged particle radiation from the cathode would not
penetrate the cell wall, nor the base layer. Ambient radiation would
mostly fail to reach the detector material. (Particles carrying radon
or other radioisotope could be trapped between the film laters, but a
single alpha from them would only penetrate one detector layer. The
hope was to look for coincident tracks on adjacent layers as clearly
indicating tracks generated during the experiment, and only from two
sources: the cathode, or cosmic radiation from outside the experiment.)
The detectors, etched, from our run, are remarkably free of clear
tracks, all the way through the detector layer, while control chips
exposed to Am-241 show brilliant, clear tracks.
(I expected to see much more background radiation; these detectors
were stored in my refrigerator for more than a year before they were used.)
I am thinking of doing a wet experiment, i.e., with the LR-115
immersed in the electrolyte, with various orientations. I don't know
if LR-115 can handle the wet environment, but, hey, it still takes
hot lye to develop it, might be worth trying.
