-8-
For a parabola described by the equation x = ky?, a line passing from a point
(x), y,) on the parabola through a point (-x,, 0) on the x axis is tangent to the
parabola at the point (x), Y¥,)) (Fig. 5).
Inthe region of interest, the para-
bolic arcs can be approximated reasonably well by straight lines.
lector foil was cut (Fig. 6) into a series of pieces of equal area.
The colThe method
of cutting accepts particles of energies between 1 and 3 MeV per unit charge.
These pieces were dissolved separately and analyzed radiochemically for a
variety of fission products.
The total remaining area of the foil in the quadrant
where activity is expected was also analyzed to give a measure of the total
beam intensity.
A measure of background level was obtained by analysis of
that part of the foil lying in the other quadrants.
From Eq. (3) above, 7 =k: 2 + x; from the method of cutting, x is
taken as constant.
On analyzing for a product of a particular mass, we only
expect to find activity for integral values of q.
It is convenient, therefore, to
plot a graph of counts per minute as ordinate against y" as abscissa, with y
measured to the center of the trapezoidal section.
We expect to find equally
Spaced maxima, the difference in abscissa between maxima corresponding to
a change of q of one electronic charge.
The spacing between the ordinate axis
and the first maximum should be the same as the spacing between adjacent
peaks if the first maximum does indeed represent a singly-charged species.
Figure 7 represents results obtained by counting the total gamma radia- tion emitted by sections of the collector foil cut as for analysis.
The predicted
positions of the various species are indicated on the figure, H and L standing
respectively for heavy group" and "light group,'' and the number representing ionic charge.
There is a general background level which is probably due
to fission-product activity thermally evaporated from the source; however,
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