99-Es-251

Reaction 0.0253-eV Maxwellian
Average
g-factor Resonance
Integral
14-MeV Fiss. Spec.
Average
total 253.2 (b) 255.4 (b) 1.009 5.982 (b) 8.387 (b)
elastic 9.920 (b) 11.20 (b) 1.129 2.771 (b) 4.711 (b)
inelastic ( E-thr = 8.434 keV ) 312.2 (mb) 2.226 (b)
(n,2n) ( E-thr = 6.813 MeV ) 226.2 (mb) 926.9 (μb)
(n,3n) ( E-thr = 12.86 MeV ) 843.3 (μb) 265.5 (nb)
fission 43.02 (b) 43.11 (b) 1.002 23.47 (b) 2.669 (b) 1.357 (b)
(n,fission) 43.02 (b) 43.11 (b) 1.002 23.07 (b) 1.672 (b) 1.338 (b)
(n,n,fiss) ( E-thr = 2.300 MeV ) 963.4 (mb) 19.10 (mb)
(n,2n,fiss) ( E-thr = 9.000 MeV ) 31.66 (mb) 5.070 (μb)
(n,3nfiss) ( E-thr = 15.50 MeV ) 51.69e-12 (b)
capture 200.1 (b) 200.1 (b) 1.000 1.301 (kb) 951.6 (μb) 90.12 (mb)
 
νp 3.915 7.079
νd 1.938e-3 1.336e-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.