Important comments on KERMA factors and DPA cross-section data in ACE ﬁles of JENDL-4.0, JEFF-3.2 and ENDF/B-VII.1

. We have studied reasons of differences of KERMA factors and DPA cross-section data among nuclear data libraries. Here the KERMA factors and DPA cross-section data included in the ofﬁcial ACE ﬁles of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 are examined in more detail. As a result, it is newly found out that the KERMA factors and DPA cross-section data of a lot of nuclei are different among JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 and reasons of the differences are the followings: 1) large secondary particle production yield, 2) no secondary gamma data, 3) secondary gamma data in ﬁles12–15 mt = 3, 4) mt = 103–107 data without mt = 600s–800s data in ﬁle6. The issue 1) is considered to be due to nuclear data, while the issues 2)-4) seem to be due to NJOY. The ACE ﬁles of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 with these problems should be revised after correcting wrong nuclear data and NJOY problems.


Introduction
KERMA factors and DPA cross-section data for calculating nuclear heating and damage in nuclear analyses are stored in ACE and MATXS files [1]. It is known that KERMA factors of a lot of nuclei in the official ACE files are different among nuclear data libraries mainly because of inconsistent energy-balance [2]. We also pointed out that KERMA factors and DPA cross-section data were different among JENDL-4.0 [3], ENDF/B-VII.1 [4], JEFF-3.2 [5] and FENDL-3.0 [6] even for nuclei with consistent energy-balance by the following reasons [7]. i) Nuclear data issue -Incorrect Q value in nuclear data -Large gas production cross-section data ii) NJOY/HEATR module [1] issue -1 H of ENDF/B-VII.1 (this issue is corrected in NJOY2012.50) -mt = 102 data in file6 [8].
In this paper we study the KERMA factors and DPA crosssection data in the latest official ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 in more detail.

Method
For all the nuclei (497 nuclei) included in JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2, we extracted the total crosssection data, average heating numbers and damage energy production data from the latest official ACE files.  [13]). We converted the average heating numbers to KERMA factors and the damage energy production data to DPA cross-section data as followings, where H is an average heating number, α t is a total cross-section, E a is a damage energy production and E d is an atomic displacement energy. The KERMA factors and DPA cross-section data were plotted for comparison. If necessary, the NJOY2012.50 [1] code was used for processing nuclear data tentatively generated in this study.

Results and discussion
It is newly found out that KERMA factors and DPA cross-section data of a lot of nuclei are different among JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2. As described in the next sub-sections, reasons for most of the new differences of the KERMA factors and DPA cross-section data among the nuclear data libraries are successfully categorized as the followings, -large secondary particle production yield, -no secondary gamma data, -secondary gamma data in files12-15 mt = 3, -mt = 103-107 data without mt=600 s-800 s data in file6.

Large secondary particle production yield
The KERMA factors and DPA cross-sections of 182 W, 183 W, 184 W and 186 W in JEFF-3.2 are extraordinarily   large above 20 MeV as shown in Fig. 1. We find that these tungsten data have large particle production yields (e.g., 182 Ta in 184 W) in file6 mt = 5 as shown in Fig. 2. In order to confirm that the large particle production yields cause the large KERMA factors and DPA cross-sections, we replace the problematic particle production yield data in 182 W, 183 W, 184 W and 186 W of JEFF-3.2 with those in ENDF/B-VII.1. Then the large KERMA factors and DPA cross-sections disappear as shown in Fig. 3. The particle production yield data in 182 W, 183 W, 184 W and 186 W of JEFF-3.2 should be revised.

No secondary gamma data
A lot of nuclei in JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 have no secondary gamma data. In this case kinematic KERMA factors may be stored in ACE files (e.g., JENDL-4.0 ACE file) as the second best. Kinematic KERMA factors are expected to correspond to energybalance ones in low neutron energy, but it is found that the kinematic KERMA factors are different from the   Fig. 5. It is noted that the energy-balance and kinematic KERMA factors of the original 37 Cl in JEFF-3.2 are almost the same. The same issue also occurs in the DPA cross-section data as shown in Fig. 6. It seems that this issue is due to the NJOY code, in other words, NJOY cannot process nuclear data without secondary gamma data adequately.      ∼ 1 keV. It seems that NJOY cannot process files12-15 mt = 3 data adequately.

Secondary gamma data in
Most of the nuclear data of nuclei with secondary gamma data in files12-15 mt = 3 do not keep energybalance. Then kinematic KERMA factors may be stored in ACE files (e.g., JENDL-4.0 ACE file). The kinematic KERMA factors have the same problem as the DPA crosssection data as shown in Fig. 10. This also seems to be due to NJOY.

mt = 103-107 data without mt = 600 s-800 s data in file6
The DPA cross-section data of 39−41 K in JEFF-3.2 are much smaller than those in JENDL-4.0 and ENDF/B-VII.1 below ∼ 1 keV as shown in Fig. 11. It is noted that the gas production cross-section data of 39−41 K are very large in low neutron energy as shown in Fig. 12 and    209 Bi. Note that energy-balance KERMA factor is incorrect above a few MeV because of inconsistent energy-balance. 39−41 K in JEFF-3.2 have the file6 mt103-mt107 data for the gas production reactions, while those in JENDL-4.0 and ENDF/B-VII.1 have no file6 data for the gas production reactions. Here we consider 40 K. If the file6 mt103-mt107 data for the gas production reactions of 40 K in JEFF-3.2 are deleted, the DPA cross-section data become almost the same as those in JENDL-4.0 and ENDF/B-VII.1 below 1 keV as shown in Fig. 13. It seems that NJOY does not process the file6 mt103-mt107 data adequately.
The energy-balance KERMA factors of 39−41 K in JEFF-3.2 have no problem as shown in Fig. 14, but the kinematic KERMA factors have the same problem as the DPA cross-sections. The 209 Bi data in JEFF-3.2 have large gas production cross-section data as 39−41 K in JEFF-3.2, but the secondary charged particle data are stored in file6 mt = 600s-800s, not in file6 mt=103-107. In this case the energy-balance and kinematic KERMA factors are the same as shown in Fig. 15. It is considered that NJOY processes file6 mt = 600 s-800 s data, not file6 mt103-mt107 data.

Conclusions
We examined KERMA factors and DPA cross-section data in the official ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 in more detail. It is newly found out that KERMA factors and DPA cross-section data of a lot of nuclei are different among JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2. Reasons for most of the differences of KERMA factors and DPA cross-section data among the nuclear data libraries are successfully categorized as the followings: 1) large secondary particle production yield, 2) no secondary gamma data, 3) secondary gamma data in files12-15 mt = 3, 4) mt = 103-107 data without mt = 600 s-800 s data in file6. Incorrect nuclear data and NJOY problems should be revised based on this study and the ACE files with the problems also should be revised.