Fission Product Yield Data for the Transmutation of Minor Actinide ...
Fission Product Yield Data for the Transmutation of Minor Actinide ...
Fission Product Yield Data for the Transmutation of Minor Actinide ...
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3.3.4. Results and discussion<br />
The results <strong>of</strong> <strong>the</strong> normal spline fit are given in<br />
Annex 3.3.2, while <strong>the</strong> results <strong>of</strong> <strong>the</strong> spline fit with<br />
symmetric reflection are given in Annex 3.3.3. Both<br />
are compared with <strong>the</strong> evaluated experimental data<br />
(Figs 3.3.2–3.3.5).<br />
Total yields under <strong>the</strong> light and heavy mass<br />
peaks, as well as v – , were calculated in order to check<br />
<strong>the</strong> correctness <strong>of</strong> <strong>the</strong> spline fit curve. The<br />
borderline between <strong>the</strong> light and heavy mass peaks<br />
was taken at mass 124, which was calculated from<br />
<strong>the</strong> mass number <strong>of</strong> 252 Cf and v – = 3.7661<br />
(Table 3.3.2). As shown by <strong>the</strong> normal spline fit, <strong>the</strong><br />
integral yield under <strong>the</strong> heavy mass peak is in good<br />
agreement with 100%, while <strong>the</strong> total yield under<br />
<strong>the</strong> light mass peak is in similar agreement within an<br />
uncertainty <strong>of</strong> 1.3%, and v – is in agreement with <strong>the</strong><br />
internationally recommended value <strong>of</strong> 3.7661 within<br />
an uncertainty <strong>of</strong> 2.93%. Similarly, <strong>for</strong> <strong>the</strong><br />
symmetric fit <strong>the</strong> integral yield under <strong>the</strong> light and<br />
heavy mass peak is in agreement with 100% within<br />
an uncertainty <strong>of</strong> 1.0%, and v – is in agreement with<br />
<strong>the</strong> internationally recommended value <strong>of</strong> 3.7661<br />
within an uncertainty <strong>of</strong> 1.86%.<br />
A comparison between <strong>the</strong> results <strong>of</strong> fits with<br />
and without symmetric reflection is shown in<br />
Fig. 3.3.6. These data are in very good agreement,<br />
but <strong>the</strong>re are some differences in <strong>the</strong> peak regions.<br />
The light mass peak without symmetric reflection is<br />
narrower than <strong>the</strong> equivalent peak with symmetric<br />
reflection, and <strong>the</strong> situation is <strong>the</strong> reverse <strong>for</strong> <strong>the</strong><br />
heavy mass peak. Also, <strong>the</strong> right hand side <strong>of</strong> <strong>the</strong><br />
light peak is narrower <strong>for</strong> <strong>the</strong> normal fit than <strong>for</strong> <strong>the</strong><br />
symmetric fit, but <strong>the</strong> left hand side <strong>of</strong> <strong>the</strong> heavy<br />
mass peak is <strong>the</strong> opposite (see Figs 3.3.1 and 3.3.8).<br />
c 2 is 1.551 <strong>for</strong> <strong>the</strong> normal fit and 1.795 <strong>for</strong> symmetric<br />
fit, indicating that <strong>the</strong> mass distribution is not<br />
completely symmetric around <strong>the</strong> reflection point.<br />
The fits to <strong>the</strong> results imply that <strong>the</strong>re is a<br />
systematic trend towards <strong>the</strong> light fragment peak<br />
being higher and narrower and <strong>the</strong> area under <strong>the</strong><br />
peak being slightly smaller. Individual experimental<br />
data by different authors also exhibit <strong>the</strong> same<br />
92<br />
FIG. 3.3.6. Comparison <strong>of</strong> regular and symmetric spline fit:<br />
mass distribution.<br />
FIG. 3.3.7. Comparison <strong>of</strong> regular and symmetric spline fit:<br />
light mass peak.<br />
trend. Table 3.3.3 shows some <strong>of</strong> <strong>the</strong> results from<br />
different authors, who measured a wide range <strong>of</strong><br />
fission products so that integrals <strong>of</strong> <strong>the</strong> yields under<br />
<strong>the</strong> peaks can be calculated more reliably. These<br />
integral data are given in <strong>the</strong> papers by Li Ze et al.<br />
and Chen et al., and were calculated <strong>for</strong> Schmitt et<br />
al. and Fraser et al. by using <strong>the</strong>ir original data<br />
without any adjustments. The yields under <strong>the</strong> light<br />
mass peak are smaller than those under <strong>the</strong> heavy<br />
mass peak in all four cases. Comparing <strong>the</strong> light and<br />
heavy mass peak yields <strong>of</strong> Li Ze et al. and Schmitt et<br />
al. (Figs 3.3.9 and 3.3.10), <strong>the</strong> light peak can be seen<br />
to be narrower than <strong>the</strong> heavy peak — this<br />
TABLE 3.3.2. REDUCED c 2 , TOTAL YIELD AND v – FROM FITTED DATA<br />
Fit mode Reduced c 2<br />
Total yield<br />
Light peak Heavy peak Total<br />
Normal 1.551 98.76 99.77 198.52 3.8764<br />
Symmetric 1.795 98.98 98.96 197.95 3.6962<br />
v –