91-Pa-231

Reaction 0.0253-eV Maxwellian
Average
g-factor Resonance
Integral
14-MeV Fiss. Spec.
Average
total 212.3 (b) 216.7 (b) 1.021 5.823 (b) 7.624 (b)
elastic 10.59 (b) 11.80 (b) 1.114 2.788 (b) 4.412 (b)
inelastic ( E-thr = 9.246 keV ) 353.2 (mb) 2.170 (b)
(n,2n) ( E-thr = 6.850 MeV ) 1.283 (b) 3.434 (mb)
(n,3n) ( E-thr = 12.67 MeV ) 20.56 (mb) 6.255 (μb)
fission 23.65 (mb) 23.15 (mb) 0.979 3.240 (b) 1.377 (b) 849.8 (mb)
(n,fission) 23.65 (mb) 23.15 (mb) 0.979 2.728 (b) 558.2 (mb) 827.5 (mb)
(n,n,fiss) ( E-thr = 2.000 MeV ) 794.4 (mb) 22.26 (mb)
(n,2n,fiss) ( E-thr = 10.00 MeV ) 24.54 (mb) 9.776 (μb)
(n,3nfiss) ( E-thr = 15.00 MeV ) 628.8e-12 (b)
capture 201.7 (b) 204.9 (b) 1.016 541.8 (b) 1.190 (mb) 186.8 (mb)
 
νp 2.086 3.973
νd 1.083e-2 8.785e-3

These cross sections are calculated from JENDL-4.0 at 300K.
The background color of each cell noted a cross section means the order of the cross-section value.
The unit of cross section, (b), means barns, and SI prefixes are used as following.
(kb) → 103(b),   (mb) → 10−3(b),  (μb) → 10−6(b),  (nb) → 10−9(b).

Maxwellian Average :
σmacs(T) =
2
 
 
π
EU
 
EL
σ(E,T) ⋅ E ⋅ exp (
E
  
kBT
) dE
 
EU
 
EL
E ⋅ exp (
E
  
kBT
) dE
,
where T denotes the temperature, and kB the Boltzmann constant. The upper and lower limits of integration, EL and EU are set to 10−5 eV and 10 eV, respectively.
Resonance Integral :
σri(T) =
EU
 
EL
σ(E,T) ⋅
1
 
E
dE ,
with  EL = 0.5 eV  and  EU = 10 MeV.
U-235 Thermal Fission-Neutron Spectrum Average (Fiss. Spec. Average) :
σfacs(T) =
EU
 
EL
σ(E,T) ⋅
 
4
 
πa3b
⋅ exp (
ab E
     
4 a
) ⋅ sinh
 
bE
dE
 
EU
 
EL
 
4
 
πa3b
⋅ exp (
ab E
     
4 a
) ⋅ sinh
 
bE
dE
,
with  EL = 10−5 eV  and  EU = 20 MeV. The parameters a and b are 0.988 MeV and 2.249 MeV−1, respectively.
Westcott g-factor :
g(T) =
σmacs(T)
 
σ(0.0253 eV,T)
 .


νp, νd : numbers of prompt and delayed neutrons per fission.