“9.
UCRL- 6252
Since Pi j and qi are functions only of C., d., Cy and d, and are therefore
independent of energy, Eq.(4) represents a straight-line relationship between
the fission yields’ of the mass chains i and j relative to the standard mass
chain.
‘We find it-more convenient to deal with a quantity that is proportional
to the relative fission yield and is usually known as an 'R value.i* The R
value for mass chain i may be defined as follows:
(y,/y,) given experiment
1
(y./y,) thermal neutrons on U“?9
Use of R values obviates the necessity of absolute counting, thereby making
it possible to measure an R value more precisely than the fission yield itself.
It should be noted that the denominator of the above expression is a fixed
quantity, depending only on mass chain i and the choice of a reference standard.
Therefore, the R value for mass chain i may be written
R, = kiy/y) ;
We can now rewrite Eq. (4) as
R. = a, jf, + By
where oe and B are constants.
(5)
Thus we may use experimental R values to
test whether or not there exist linear relationships between relative fission
yields. °
Tests of the two-mode fission hypothesis may be made by comparing
_the behavior of experimental mass-yield data with that predicted by the
straight-line relationships just developed.
There are a few things worthy of
special note when seeking data with which to test the two-mode fission hypothesis.
An adequate test of the predicted behavior requires that the mass yield |
data cover a sufficient range of values for both coordinates of the straight
line.
The greater the range in the excitation energies, the wider the range
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