2
UCRL- 6252
It would be meaningless with respect to the test to plot data for a nuclide
whose R values remain essentially unchanged since these would obviously fall
on a nearly horizontal line.
Only those species whose R values show a con-
siderable change are significant, and the R values for these species have been
plotted as y coordinates against the corresponding R values for cal},
The data plotted in this way are presented in Figs. l and2z.
The
straight lines shown are those fitted to the data ina manner described below.
It is clear that for all these species, including the shielded nuclide csiF®
the data are quite consistent with the straight-line behavior predicted by the
two-mode fission hypothesis.
In the energy range covered, there appears to
be no significant tendency toward curvature, even in the case of cst3® in ye
fission where the data are most scattered.
These plots include.all data for
these nuclides obtained in this set of experiments.
(No pertinent data from
Tables I and Il were thrown out because of large deviation from the line.)
The excitation energies produced by the neutron fluxes used are sufficiently high for us to expect that the mass yields represent significant con-
tributions from more than one nuclear species undergoing fission.
However,
the mass distributions of the two basic modes of the neighboring parent nuclides appear to be similar enough so as not to perturb the linear behavior...
The R values for thermal neutron fission of U
the corresponding lines in Fig. 1.
235
should also fall on
Since an R value is simply the relative
fission yield of a species normalizedto the relative fission yield of the same
species in thermal neutron fission of U
qo
cS
2
eS
235
, the R values for all species in
thermal neutron fission of yu“? by definition must be equal to 1.
Therefore,
the lines in the above plots representing behavior of R values in u*?
should all pass through the point (1,1).
for all the lines in u* 35 fission.
fission
Such does not appear to be the case
Since this question is of considerable sig-
nificance some additional analysis of the straight lines is warranted.