On Dec 7, 2009, at 1:41 PM, [email protected] wrote:
In reply to Jones Beene's message of Mon, 7 Dec 2009 14:32:56 -0800:
Hi,
[snip]
your underlying assumptions - then one of them could be this. Al-
Najjar et
al. (1986) reported that the threshold energy of the neutron
required to
fission a carbon atom (three alpha) is 9.6 MeV. The authors
apparently
agree, and cite this reference several times.
[snip]
I wonder how that is derived? The actual energy required to fission
C12 is only
7.3 MeV.
Perhaps it was measured, and the number of fissions below 9.6 MeV
was so small
as to go undetected?
You see a lot of different minimum energies referenced. The problem
is the three alphas have to have enough kinetic energy left over to
make tracks in the CR-39, which is about 1 MeV/alpha.
The CR-39 triple tracks look to be from better than 9 MeV neutron
tracks.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
