At 09:32 AM 10/7/2012, Jones Beene wrote:
Robin
The cross-section for alpha emission from carbon is way too small for the
explanation you suggest.
Apparently not. Triple tracks are not common, though. If you are not
familiar with it, you should read the SPAWAR publications, including
the Pamela Mosier-Boss report on "triple tracks" and her followup
report. There are some beautiful images of triple-tracks, she creates
them by combining images from two different focus depths, using a
different color for each focus.
She concludes, ultimately, that the neutrons are at about 14 MeV.
It should be understood that she is talking about a very low neutron
flux; these tracks have been accumulated for weeks.
Wiki sez: in the radiation detection application, CR-39 material is exposed
to proton recoils caused by incident neutrons. The proton recoils cause ion
tracks, which are enlarged by an etching process in a caustic solution of
sodium hydroxide. The enlarged ion tracks are counted under a microscope
(commonly 200x), and the number of ion tracks is proportional to the amount
of incident neutron radiation.
Yeah, that's what they say.
I'm seeing finer track images, in LR-115, using about 400X.
