JAEA-Conf 2011-002 - 日本原子力研究開発機構

JAEA-Conf 2011-002
Table 1 Comparison between ENDF/B-VII and UDV/TAGS [5] of mean - and -ray energies
Figure 1 Comparison of the FP decay-heat calculations of the -ray component of Pu-239
before and after the introducing UDV/TAGS data (taken from A.Algora et al.[1])
3. Evaluation
3.1 Pandemonium Problem Revisited
The cause of the pandemonium-problem lies in the difficulty in detecting all of the large
number of -rays emitted following a -decay, and a lot of -rays, even though they were
detected, cannot find their correct positions in the complex decay scheme. They are called
the unplaced gammas. Therefore, nuclides having a lot of unplaced gammas are surely
influenced by the pandemonium-problem. In the case of short-lived nuclides, the highest
known levels of their daughter nuclides tend to be much lower than their Q-values in the
decay schemes now available, which are constructed on the basis of the current
high-resolution -ray data. In the case of JENDL, for most of the short-lived FP nuclides
where the highest known levels in their daughter nuclides is much lower than 0.7Q, the
gross theory of beta decay was introduced and this treatment lead to a good agreement
between the calculations and the measurements [2]. When the -feeding to a single
particular level is very large, these nuclides tend to be free from the pandemonium-problem