170
H. Utsunomiya et al.
Fig. 2 (Color online)
Comparison of the revised
total experimental cross
section with the TALYS
predictions for two values of
the Levinger parameter
L = 6.5 (solid line) and
L = 20 (dashed line)
Present
Harvey et al. (1964)
209 Bi( ,tot)
( ,tot) [mb]
E [MeV]
L=6.5
L=20
10 1
10
15
20
25
30
35
40
10 2
10 3
Here, we show the total photoneutron cross section in Fig. 2, leaving details
on partial photoneutron cross sections in Ref. [13]. The asymptotic value of the
total cross section is reproduced by the default pre-equilibrium calculation with
an ordinary value (L = 6.5) of the Levinger parameter for the quasi-deuteron
contribution. Previously we discussed the large cross section at the high energies
in terms of an increase of the L value and the surface effect. With the corrected
cross sections, however, there is no need to require a large value L = 20 nor to
invoke the surface effect anymore.
5.2 159 Tb
Figure 3 shows partial photoneutron cross sections (γ, xn) with x = 1 and 2 for
159 Tb. The 159 Tb is one of 19 nuclei for which the Livermore and Saclay data of
partial photoneutron cross sections show serious discrepancies [14]. One can see
that the present (γ, n) cross section is rather consistent with the Saclay data, while
the (γ, 2n) cross section agrees with the Livermore data.