5 Neutron Spectrum
153
Fig. 5.20 Experimental
results of the γ-ray spectrum
of 209 Bi(n, xn) 210−x Bi (x =
4–8) (Ref. [22])
200 400 600 800 1000 1200 1400 1600 1800
0
2000
4000
6000
8000
10000
12000
14000
16000
-ray energy [keV]
Counts
374.8 keV (
204
Bi; n = 6)
703.4 keV (
205
Bi; n = 5)
1847.3 keV ( 203
Bi; n = 7)
1679.6 keV (
203
Bi; n = 7)
822.7 keV (
203
Bi; n = 7)
422.1 keV ( 202
Bi; n = 8)
657.5 keV (
202
Bi; n = 8)
803.1 keV ( 203
Bi; n = 4)
Table 5.15 Comparison between calculations and experiments of reaction rate ratio 115 In(n,
n ) 115m In/ 27 Al(p, n + 3p) 24 Na (Ref. [22])
Ratio (number of neutrons per proton)
Experiment
C/E*
PHITS3.0
MCNP6.1
115 In(n, n ) 115m In/
27 Al(p, n + 3p) 24 Na
0.185 ± 0.004
1.14 ± 0.03
1.34 ± 0.03
C/E*: Calculation/Experiment
Table 5.16 Comparison between calculations and experiments of reaction rate ratio 209 Bi(n,
xn) 210−x Bi (x = 4 to 8)/ 27 Al(p, n + 3p) 24 Na (Ref. [22])
Reactions
Measured reaction rates (s −1 cm −3 )
C/E*
PHITS3.0
MCNP6.1
27 Al(p, n + 3p) 24 Na
(1.64 ± 0.01) × 10 6
–
–
209 Bi(n, 4n) 206 Bi
(8.22 ± 0.09) × 10 4
1.01 ± 0.03
0.83 ± 0.03
209 Bi(n, 5n) 205 Bi
(4.86 ± 0.25) × 10 4
1.06 ± 0.06
1.00 ± 0.06
209 Bi(n, 6n) 204 Bi
(2.23 ± 0.02) × 10 4
0.83 ± 0.02
0.92 ± 0.04
209 Bi(n, 7n) 203 Bi
(1.42 ± 0.04) × 10 4
0.69 ± 0.03
0.81 ± 0.04
209 Bi(n, 8n) 202 Bi
(0.35 ± 0.01) × 10 4
0.99 ± 0.06
1.08 ± 0.07
C/E*: Calculation/Experiment
For experimental analyses of over 20 MeV neutrons and 100 MeV protons, a
choice of the INCL model of PHITS3.0 or MCNP6.1 with LAHET150 still remained
for examining the validity of
209 Bi(n, 7n)
203 Bi reaction rate analyses. Meanwhile,
the PHITS3.0 and the MCNP6.1 codes were significantly similar with respect to
the reconstruction of reaction rates over 20 MeV neutrons and 100 MeV protons,
through a comparative study on a suitable combination (Table 5.13) of the Monte
Carlo codes and nuclear data libraries.