Section 12.0 Useful Tables

Nuclear Weapons Frequently Asked Questions

Version 2.01: 20 February 1999


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12.0 Useful Tables

 
CONVERSION FACTORS
Unit              Equivalent To
1 kt              10^12 calories
                  4.19x10^12 joules
                  4.19x10^19 ergs
                  2.62x10^31 eV
                  2.62x10^25 MeV
                  fission of 0.241 moles of material (1.45x10^23 nuclei)
                  fission of approx. 57 g of material 
                  1.16x10^6 kilowatt-hrs
                  3.97x10^9 BTU
1 eV              1.602177 x 10^-12 erg
                  11606 degree K
1 Bar             10^5 pascals (nt/m^2)
                  10^6 dyne/cm^2
                  0.98687 atmospheres
                  14.5038 PSI
1 calorie         4.1868 J

Convenient Energy Content Approximations
Fission of U-233:  17.8 kt/kg
Fission of U-235:  17.6 kt/kg
Fission of Pu-239: 17.3 kt/kg
Fusion of pure deuterium: 82.2 kt/kg
Fusion of tritium and deuterium (50/50): 80.4 kt/kg
Fusion of lithium-6 deuteride: 64.0 kt/kg
Fusion of lithium-7 deuteride
Total conversion of matter to energy: 21.47 Mt/kg
Fission of 1.11 g U-235: 1 megawatt-day (thermal)

IMPORTANT UNITS OF MEASUREMENT
Quantity Measured           Unit      Symbol  Formula
Microscopic Cross Section   Barn       b      10^-24 cm^2
Radioactivity               Becquerel  Bq     1 decay/sec
                            Curie      Ci     3.7x10^10 decay/sec
Absorbed Radiation Dose     Gray       Gy     1 J/Kg
                            Rad        None   100 erg/g (.01 J/Kg)
Biological Equivalent Dose  Sievert    Sv     Grays*Q
                            Rem        None   Rads*RBE
Absorbed Gamma/X-Ray Dose   Roentgen   R      94 erg/g  
Immediate Explosive Energy  Kiloton    kt     10^12 calories
Radiation Biological Effect None       RBE
Radiation Quality Factor    None       Q
Pressure                    Bar        None   10^5 pascals (nt/m^2)

PHYSICAL CONSTANTS
[All constants are exact to the precision given]
Quantity                    Symbol    Value            Unit
Speed of Light in Vacuum      c     2.99792458 x 10^10 cm/sec
Planck Constant               h     6.62608 x 10^-27   erg-sec
Avogadro Constant            N_A    6.02214 x 10^23    atom/mole
Molar Gas Constant            R     8.3145 x 10^7      erg/(mole K)
Boltzmann Constant            k     1.3806 x 10^-16    erg/K
Stefan-Boltzmann Constant   sigma   5.670 x 10^-5      erg/cm^2 K^4 sec
Perfect Gas Standard Volume  V_0    2.2414 x 10^5      cm^3 
Atomic Mass Constant         m_0    1.66054 x 10^-24   g
                             m_0    9.31494 x 10^8     eV

Fissionable/Fissile Isotope Properties

Under reconstruction
Isotope Half-Life
(years)
Primary Decay Mode Spontaneous Fission Rate - SF
(F/sec/kg)
Fission Cross Section - sigma
(barns, fission spectrum avg)
SF Neutron Multiplicity - nuSF
(n/fission)
Fission Spectrum Neutron Multiplicity - nuFS
(n/fission)
Critical Mass - Mc
(kg)
Decay Heat - Q
(W/kg)
Specific Activity
(curies/kg)
Th-232 1.405 x 1010 Alpha 4.083 MeV <5 x 10-5 0.0785 - 2.16 None 2.654 x 10-6 1.097 x 10-4
Pa-231 32,760 Alpha 5.149 MeV <5 0.834 - 2.457 >188 1.442 47.23
U-232 68.9 Alpha 5.414 MeV 2 x 10 -3 2.013 2 3.296 >5 717.6 22,360
U-233 159,200 Alpha 4.909 MeV - 1.946 - 2.649 16 0.2804 9.636
U-234 245,500 Alpha 4.859 MeV 3.9 1.223 1.8 2.578 >41 0.1792 6.222
U-235 7.038 x 108 Alpha 4.679 MeV 5.6 x 10-3 1.235 2.0 2.6055 48 5.994 x 10-5 2.161 x 10-3
U-236 2.342 x 107 Alpha 4.572 MeV 2.30 0.594 1.8 2.526 >167 1.753 x 10-3 6.467 x 10-2
U-238 4.468 x 109 Alpha 4.270 MeV 5.51 0.308 1.96 2.6010 None 8.508 x 10-6 3.361 x 10-4
Isotope Half-Life Primary Decay Mode Spontaneous Fission Rate(F/sec/kg) Fission Cross Section SF Neutron Multiplicity Fission Spectrum Neutron Multiplicity Critical Mass Decay Heat (W/kg) Specific Activity (curies/kg)
Isotope Half-Life Primary Decay Mode Spontaneous Fission Rate(F/sec/kg) Fission Cross Section SF Neutron Multiplicity Fission Spectrum Neutron Multiplicity Critical Mass Decay Heat (W/kg) Specific Activity (curies/kg)


Isotope Properties and Neutron Cross Sections

This is subsection lists most isotopes of interest for direct, indirect, or theoretical nuclear weapon applications. Basic isotopes characteristics, and summary tables of significant neutron reaction cross sections are included.

The neutronic data is derived from the authoritative ENDF-VI evaluated nuclear data base compiled and maintained by the National Nuclear Data Center (NNDC) at the Brookhaven National Laboratory (BNL). The data listings below were prepared with the assistance of the Japan Atomic Energy Research Insititue (JAERI).

Notes:

Hydrogen

1-H-1

Lightest possible atom, and consequently the most efficient neutron moderator. Widely used in nuclear weapon structural materials (i.e. plastics). Due to moderating ability and light weight, used to harden weapons against outside neutron fluxes (especially in combination with Li-6).

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total             20.81       20.78                  692.0 -3     3.927  
 elastic           20.47       20.47                  692.0 -3     3.926  
 capture          332.0 -3    294.2 -3    149.1 -3    29.83 -6    39.27 -6
 ---------------------------------------------------------------------------

 

1-H-2 (Deuterium)

Best nuclear reactor moderator due to high moderating efficiency and extremely low abosrption cross section. A principal fusion fuel in thermonuclear weapons, can also be used for fusion boosting, and in neutron generators. Melting point 20.4 K, boiling point 23.67 K.

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total             3.390       3.390                  801.5 -3     2.537  
 elastic           3.389       3.390                  624.3 -3     2.532  
 (n,2n)                       (E-thr =  3.339 MeV)    177.2 -3    5.276 -3
 capture          550.0 -6    487.4 -6    286.3 -6    9.521 -6    7.076 -6
 ---------------------------------------------------------------------------

1-H-3 (Tritium)

A principal thermonuclear fuel, best used in conjunction with deuterium (the D+T reaction is the easiest by far to ignite, as well as one of the most energetic). It is produced in place by tritium breeding reactions in thermonuclear weapons. It can also manufactured and loaded into weapons (with deuterium) for use in fusion boosting of fission weapons, as the neutron source in neutron bombs and neutron generators for commercial or weapons use. Tritium is a pure beta emitter. Due to weak radiation emissions, it is used in safe luminescent displays. This nuclide is useful for thickness gauge of thin plastics.

Helium

2-He-3

This isotope is produced by the decay of tritium and so accumulates in fusion boosting reservoirs as an undesirable contaminant due to its high neutron absorption. It can be recycled to produce tritium by neutron bombardment. It is a valuable fusion fuel produced (and consumed) in the course of deuterium-deuterium fusion. Very rare in nature.

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total            5.331 +3    4.743 +3                 1.168       2.941  
 elastic           3.135       3.135                  954.4 -3     2.121  
 nonelastic       5.328 +3    4.722 +3    2.381 +3    213.8 -3    819.6 -3
 capture          54.01 -6    47.88 -6    246.9 -6    35.18 -6    39.24 -6
 (n,p)            5.328 +3    4.722 +3    2.381 +3    139.7 -3    816.9 -3
 (n,d)                        (E-thr =  4.362 MeV)    74.07 -3    2.647 -3
 ---------------------------------------------------------------------------

2-He-4

Most common natural isotope of helium. Widely used in industry as an inert gas. Produced as an end product of fusion reactions. This isotope has a zero cross section for all neutron reactions except scattering for neutron energies below 20 MeV.

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total            759.3 -3    759.3 -3                 1.052       3.685  
 elastic          759.3 -3    759.3 -3                 1.052       3.685  
 ---------------------------------------------------------------------------

Lithium

3-Li-6

Natural lithium isotope used as a thermonuclear weapon fusion fuel, in the form of lithium deuteride, due to its production of tritium through the (n,t) reaction. The very high cross section of this reaction for thermalized neutrons, combined with the light weight of the Li-6 atom, make it useful in the form of lithium hydride for hardening of nuclear weapons against external neutron fluxes.

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total             941.1       837.2                   1.431       1.900  
 elastic          734.5 -3    735.2 -3                906.4 -3     1.422  
 nonelastic        940.4       836.5       427.5      525.0 -3    478.0 -3
 inelastic                    (E-thr =  1.751 MeV)    412.0 -3    142.8 -3
 (n,2n)                       (E-thr =  6.614 MeV)    78.05 -3    190.5 -6
 capture          38.50 -3    34.11 -3    17.47 -3    82.11 -6    28.06 -6
 (n,p)                        (E-thr =  3.185 MeV)    6.766 -3    4.264 -3
 (n,t)             940.3       833.4       424.9      28.04 -3    330.7 -3
 ---------------------------------------------------------------------------

3-Li-7

Predominant isotope of natural lithium. Due to the large cross section for the (n,t) reaction at high neutron energies this isotope can breed substantial quantities of tritium in a fusion-driven chain reaction and thus serve as a fusion fuel. Although less efficient that Li-6 for this purpose, and not used in modern thermonuclear weapons it served this function in some early high yield weapons.

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total             1.015       1.012                   1.470       1.845  
 elastic          970.0 -3    971.7 -3                 1.025       1.660  
 nonelastic       45.40 -3    40.38 -3     1.078      444.9 -3    184.8 -3
 inelastic                    (E-thr =  0.546 MeV)    365.0 -3    184.7 -3
 (n,2n)                       (E-thr =  8.300 MeV)    70.09 -3    38.53 -6
 capture          45.40 -3    40.24 -3    20.43 -3    1.930 -6    6.903 -6
 (n,d)                        (E-thr =  8.868 MeV)    9.763 -3    10.98 -6
 total (n,t)                  (E-thr =  2.822 MeV)    302.9 -3    20.04 -3
 ---------------------------------------------------------------------------

Beryllium

4-Be-9

Beryllium is both an excellent neutron reflector and moderator, and is in addition very light. It has one of the highest neutron scattering cross sections per unit volume, and has very low neutron absorption. Beryllium is commonly used as a neutron reflector to make compact light-weight fission weapons. Beryllium also undergoes (n,2n) neutron multiplication reactions, which are not important for fission-spectrum neutons, but may have a significant role in fusion boosted systems. Beryllium can slo generate neutrons through Be-9(gamma,n)Be-8 and Be-9(a,n)C-12 reactions. When combined with an isotope that is a strong alpha-emitter but a weak gamma-emitter (usually Po-210), Be has been used in modulated neutron initiators for fission weapons. Pu-239/Be sources have been used as convenient laboratory neutron sources; Ra-226/Be and Am-241/Be neutron sources are useful for moisture gauges.

 ---------------------------------------------------------------------------
  REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                  (barns)     (barns)     (barns)      (barns)    (barns)    
 ---------------------------------------------------------------------------
 total             6.159       6.158                   1.494       2.834  
 elastic           6.151       6.151                  959.3 -3     2.673  
 nonelastic       7.600 -3    6.754 -3     1.164      534.5 -3    161.1 -3
 inelastic                    (E-thr =  8.784 MeV)    22.90 -3    38.95 -6
 (n,2n)                       (E-thr =  1.868 MeV)    269.1 -3    53.83 -3
 (n,2na)                      (E-thr =  1.749 MeV)    17.49 -3    4.938 -3
 (n,2n)to 1st                 (E-thr =  2.701 MeV)    168.6 -3    66.50 -3
 (n,2n)to 2nd                 (E-thr =  7.561 MeV)    28.68 -3    133.4 -6
 capture          7.600 -3    6.735 -3    3.419 -3    323.1 -9    1.156 -6
 (n,p)                        (E-thr = 14.260 MeV)                20.25 -9
 (n,d)                        (E-thr = 16.300 MeV)                32.68 -9
 (n,t)                        (E-thr = 11.610 MeV)    18.36 -3    2.751 -6
 (n,a)                        (E-thr =  0.670 MeV)    9.419 -3    35.65 -3
 ---------------------------------------------------------------------------

Boron

5-B-10

  • Atomic Mass: 10.012937027 +- 0.000000397 (amu)
  • Excess Mass: 12050.761 +- 0.370 keV
  • Binding Energy: 64750.700 +- 0.370 keV
  • Beta Decay Energy: B- -3647.807 +- 0.091 keV
  • Stable Isotope
  • Atomic Percent Abundance: 19.9%
  • Spin: 3+

    This natural isotope is the best absorber of fast neutrons, and an excellent absorber of slow neutrons. As a component of natural boron, it is commonly used as a neutron absorber (control rod or burnable poison) in nuclear reactors. The separated isotpe has been used to harden nuclear weapons against external neutron fluxes, and to reduce the neutron preheating of fusion stages by fission triggers in thermonuclear weapons. Use of B-10 has been proposed to create "clean" (low fallout and low neutron emission) thermonuclear weapons.

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total            3.840 +3    3.415 +3                 1.467       2.638  
     elastic           2.144       2.144                  942.5 -3     2.062  
     nonelastic       3.838 +3    3.413 +3    1.726 +3    524.2 -3    575.3 -3
     inelastic                    (E-thr =  0.791 MeV)    268.5 -3    70.84 -3
     (n,2n)                       (E-thr =  8.980 MeV)    26.83 -3    33.22 -6
     capture          500.0 -3    443.1 -3    224.9 -3    21.26 -6    76.03 -6
     (n,p)            3.000 -3    2.659 -3    94.96 -3    37.51 -3    15.25 -3
     (n,d)                        (E-thr =  4.801 MeV)    47.63 -3    1.249 -3
     (n,a)            3.837 +3    3.400 +3    1.719 +3    48.95 -3    435.5 -3
     (n,t2a)          12.00 -3    10.63 -3    305.2 -3    94.66 -3    52.28 -3
     ---------------------------------------------------------------------------
    

    5-B-11

  • Atomic Mass: 11.009305466 +- 0.000000451 (amu)
  • Excess Mass: 8667.984 +- 0.420 keV
  • Binding Energy: 76204.800 +- 0.421 keV
  • Beta Decay Energy: B- -1982.547 +- 0.854 keV
  • Stable Isotope
  • Atomic Percent Abundance: 80.1%
  • Spin: 3/2-

    B-11 is the majority component of natural boron, and thus appears in boron mixtures used for nuclear applications where B-10 has not been separated.

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             5.050       5.050                   1.415       2.425  
     elastic           5.045       5.045                  934.9 -3     2.396  
     inelastic                    (E-thr =  2.320 MeV)    298.3 -3    28.81 -3
     (n,2n)                       (E-thr = 12.510 MeV)    1.414 -3    496.7 -9
     (n,na)                       (E-thr =  9.460 MeV)    101.0 -3    27.54 -6
     (n,np)                       (E-thr = 12.260 MeV)    1.104 -3    211.0 -9
     (n,n2a)                      (E-thr = 12.150 MeV)    17.96 -3    3.696 -6
     (n,nd)                       (E-thr = 17.270 MeV)                1.335 -9
     (n,nt)                       (E-thr = 12.250 MeV)    747.4 -6    169.8 -9
     capture          5.075 -3    4.513 -3    2.542 -3     0.000      5.473 -6
     (n,p)                        (E-thr = 11.710 MeV)    4.021 -3    579.7 -9
     (n,d)                        (E-thr =  9.830 MeV)    9.200 -3    4.074 -6
     (n,t)                        (E-thr = 10.430 MeV)    14.96 -3    3.443 -6
     (n,a)                        (E-thr =  7.240 MeV)    31.38 -3    63.13 -6
     ---------------------------------------------------------------------------
    

    Cobalt

    27-Co-59

  • Atomic Mass: 58.9332002 +- 0.0000015 amu
  • Excess Mass: -62223.609 +- 1.420 keV
  • Binding Energy: 517308.113 +- 1.422 keV
  • Beta Decay Energy: B- -1072.484 +- 0.561 keV
  • Stable Isotope
  • Atomic Percent Abundance: 100%
  • Spin: 7/2-

    Although the concept of the enhanced fallout "cobalt bomb", in which radioactive Co-60 is produced by fusion neutrons, is well known this isotope is not known to have been seriously considered for weapons applications. The 5.26 year half-life of Co-60 is too long to be of real military interest, which favors more intense shorter term effects.

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             43.19       38.98                   2.653       3.678  
     elastic           6.018       6.018                   1.265       3.015  
     inelastic                    (E-thr =  1.118 MeV)    542.3 -3    655.5 -3
     (n,2n)                       (E-thr = 10.630 MeV)    690.0 -3    180.0 -6
     (n,na)                       (E-thr =  7.069 MeV)    1.765 -3    558.8 -9
     (n,np)                       (E-thr =  7.496 MeV)    61.93 -3    56.52 -6
     capture           37.18       32.96       75.51      1.121 -3    5.704 -3
     (n,p)                        (E-thr =  0.796 MeV)    53.00 -3    1.484 -3
     (n,d)                        (E-thr =  5.233 MeV)    5.673 -3    2.480 -6
     (n,a)             0.000       0.000      20.24 -3    32.20 -3    165.1 -6
     ---------------------------------------------------------------------------
    

    Tantalum

    73-Ta-181

  • Atomic Mass: 180.9479963 +- 0.0000031 amu
  • Excess Mass: -48441.085 +- 2.892 keV
  • Binding Energy: 1452238.715 +- 2.903 keV
  • Beta Decay Energy: B- -187.890 +- 4.549 keV
  • Stable Isotope
  • Atomic Percent Abundance: 99.988%
  • Spin: 7/2+

    Comprising nearly all of natural tantalum, this isotope was studied for possible use in enhanced fallout radiation weapons by the U.S. in the 1950s. Compared with Co-60 the shorter half-life of Ta-182 (115 days vs 2.56 years) and the higher cross section for epithermal neutrons made Ta-181 a more desirable candidate for this use.

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             26.32       24.02                   5.370       7.005  
     elastic           5.650       5.640                   2.991       4.614  
     inelastic                    (E-thr =  0.006 MeV)    241.9 -3     2.295  
     (n,2n)                       (E-thr =  7.686 MeV)     2.133      5.149 -3
     (n,3n)                       (E-thr = 14.300 MeV)                6.300 -6
     (n,np)                       (E-thr =  5.968 MeV)    163.1 -6    55.01 -9
     capture           20.67       18.38       660.0      205.5 -9    85.66 -3
     (n,p)                        (E-thr =  0.242 MeV)    3.723 -3    2.305 -6
     (n,a)            45.94 -6    47.65 -6     1.579      116.4 -6    3.588 -3
     ---------------------------------------------------------------------------
    

    Thorium

    90-Th-232

  • Atomic Mass: 232.0380504 +- 0.0000022 amu
  • Excess Mass: 35443.677 +- 2.036 keV
  • Binding Energy: 1766691.409 +- 2.061 keV
  • Beta Decay Energy: B- -494.958 +- 7.826 keV
  • Atomic Percent Abundance: 100%
  • Half Life: 1.405E10 Y
    Specific Activity: 1.097E-7 curie/g
    Radioisotopic Power: 2.654E-9 W/g
    Primary Mode of Decay: Alpha to Ra-228
    Secondary Mode of Decay: SF Spontaneous fission
  • Spin: 0+
  • Critical mass: None

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             21.11       20.23                   5.740       7.634  
     elastic           13.71       13.70                   2.683       4.579  
     inelastic                    (E-thr =  0.049 MeV)    726.0 -3     2.875  
     (n,2n)                       (E-thr =  6.465 MeV)     1.181      14.46 -3
     (n,3n)                       (E-thr = 11.610 MeV)    800.0 -3    113.6 -6
     fission           0.000       0.000      636.3 -3    350.0 -3    78.48 -3
     capture           7.400       6.532       84.35       0.000      85.70 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    Protactinium

    91-Pa-231

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             210.7       189.2                   5.746       7.515  
     elastic           9.961       9.815                   2.556       4.165  
     inelastic                    (E-thr =  0.009 MeV)    252.0 -3     2.231  
     (n,2n)                       (E-thr =  6.844 MeV)    724.0 -3    5.849 -3
     (n,3n)                       (E-thr = 12.660 MeV)    134.0 -3    21.01 -6
     fission          19.66 -3    16.99 -3     4.605       2.080      833.8 -3
     capture           200.7       179.3       595.5       0.000      273.7 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    Uranium

    92-U-232

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             162.3       141.5                   5.774       7.639  
     elastic           10.80       10.74                   3.230       5.083  
     inelastic                    (E-thr =  0.048 MeV)    19.42 -3    509.2 -3
     (n,2n)                       (E-thr =  7.286 MeV)    150.0 -3    484.1 -6
     (n,3n)                       (E-thr = 13.210 MeV)    5.000 -3    562.0 -9
     fission           76.66       66.42       363.8       2.370       2.013  
     capture           74.88       64.38       172.9       0.000      28.47 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    92-U-233

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             588.4       522.2                   5.920       7.665  
     elastic           11.97       11.94                   2.889       4.447  
     inelastic                    (E-thr =  0.041 MeV)    174.6 -3     1.198  
     (n,2n)                       (E-thr =  5.779 MeV)    406.9 -3    4.078 -3
     (n,3n)                       (E-thr = 13.060 MeV)    2.049 -3    1.380 -6
     fission           531.2       468.9       774.2       2.450       1.946  
     capture           45.25       41.34       138.4      13.71 -9    70.30 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    92-U-234

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             119.2       106.8                   5.721       7.696  
     elastic           19.42       19.25                   2.733       4.692  
     inelastic                    (E-thr =  0.044 MeV)    320.2 -3     1.557  
     (n,2n)                       (E-thr =  6.873 MeV)    473.0 -3    4.811 -3
     (n,3n)                       (E-thr = 12.650 MeV)    127.0 -3    14.54 -6
     fission          6.218 -3    5.536 -3     6.718       2.067       1.223  
     capture           99.75       87.53       631.3      25.77 -6    217.7 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    92-U-235

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             698.2       608.4                   5.865       7.705  
     elastic           15.04       14.95                   2.871       4.566  
     inelastic                    (E-thr =  0.000 MeV)    350.3 -3     1.804  
     (n,2n)                       (E-thr =  5.321 MeV)    542.9 -3    11.56 -3
     (n,3n)                       (E-thr = 12.190 MeV)    41.79 -3    7.074 -6
     fission           584.4       506.8       278.1       2.056       1.235  
     (n,4n)                       (E-thr = 17.970 MeV)                8.408 -9
     capture           98.81       86.67       133.0      160.7 -9    89.07 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    92-U-236

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             13.69       13.09                   5.748       7.735  
     elastic           8.336       8.330                   2.757       4.769  
     inelastic                    (E-thr =  0.045 MeV)    326.0 -3     2.256  
     (n,2n)                       (E-thr =  6.578 MeV)    487.3 -3    7.645 -3
     (n,3n)                       (E-thr = 11.900 MeV)    522.9 -3    66.34 -6
     fission          61.29 -3    54.44 -3     7.764       1.659      594.0 -3
     capture           5.295       4.703       345.6      366.6 -9    107.6 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    92-Uranium-238

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             12.09       11.77                   5.805       7.786  
     elastic           9.360       9.356                   2.704       4.804  
     inelastic                    (E-thr =  0.045 MeV)    698.3 -3     2.595  
     (n,2n)                       (E-thr =  6.179 MeV)    910.0 -3    12.07 -3
     (n,3n)                       (E-thr = 11.330 MeV)    350.0 -3    61.90 -6
     fission          11.77 -6    10.45 -6     2.020       1.136      308.4 -3
     capture           2.717       2.414       278.1      1.943 -3    66.40 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    Neptunium

    93-Np-237

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             192.1       171.2                   5.539       7.799  
     elastic           27.46       27.14                   2.606       4.965  
     inelastic                    (E-thr =  0.033 MeV)    105.6E-3     1.321  
     (n,2n)                       (E-thr =  6.657 MeV)    492.5E-3    3.120E-3
     (n,3n)                       (E-thr = 12.370 MeV)    87.93E-3    14.05E-6
     fission          22.49E-3    19.58E-3     7.058       2.247       1.335  
     capture           164.6       144.0       661.2      228.6E-9    173.4E-3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    Plutonium

    94-Pu-238

  • Decay Energy: 5.593 MeV
    Secondary Mode of Decay: Spontaneous fission
  • Spin: 0+
  • Critical mass: 9 kg (Lovins, A.B. Nature. 283, p. 818, 1980), 5.26 kg (one-group calculation)
     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             586.7       501.1                   6.876       8.829  
     elastic           28.54       27.85                   3.584       6.014  
     inelastic                    (E-thr =  0.044 MeV)    1.155 -3    716.6 -3
     (n,2n)                       (E-thr =  7.028 MeV)    514.7 -3    3.669 -3
     (n,3n)                       (E-thr = 12.930 MeV)    54.45 -3    13.71 -6
     fission           17.89       15.18       32.69       2.721       1.994  
     capture           540.3       458.0       153.6      5.861 -9    99.30 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    94-Pu-239

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total            1.026 +3     980.2                   5.990       7.712  
     elastic           7.968       7.787                   2.984       4.394  
     inelastic                    (E-thr =  0.008 MeV)    366.3 -3     1.460  
     (n,2n)                       (E-thr =  5.680 MeV)    290.1 -3    4.045 -3
     (n,3n)                       (E-thr = 12.710 MeV)    11.50 -3    2.762 -6
     fission           747.4       698.3       302.5       2.338       1.800  
     (n,4n)                       (E-thr = 18.590 MeV)               176.2 -12
     capture           270.3       274.2       181.5      7.930 -9    52.94 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    94-Pu-240

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             291.1       265.2                   5.890       7.723  
     elastic           1.642       1.527                   2.716       4.319  
     inelastic                    (E-thr =  0.043 MeV)    432.6 -3     1.950  
     (n,2n)                       (E-thr =  6.561 MeV)    373.1 -3    3.547 -3
     (n,3n)                       (E-thr = 12.230 MeV)    113.5 -3    14.86 -6
     fission          58.77 -3    53.41 -3     8.938       2.254       1.357  
     (n,4n)                       (E-thr = 19.260 MeV)                6.280 -9
     capture           289.4       263.6      8.103 +3    800.0 -6    93.28 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    94-Pu-241

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total            1.385 +3    1.275 +3                 5.799       7.840  
     elastic           11.35       11.14                   3.290       5.168  
     inelastic                    (E-thr =  0.042 MeV)    2.002 -3    884.0 -3
     (n,2n)                       (E-thr =  5.262 MeV)    114.3 -3    21.37 -3
     (n,3n)                       (E-thr = 11.820 MeV)    95.00 -3    18.00 -6
     fission          1.012 +3     938.0       572.6       2.298       1.648  
     (n,4n)                       (E-thr = 17.500 MeV)                22.74 -9
     capture           361.5       326.1       179.9      105.0 -9    118.2 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    94-Pu-242

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             27.11       25.12                   5.954       7.934  
     elastic           8.318       8.294                   2.922       4.810  
     inelastic                    (E-thr =  0.043 MeV)    279.0 -3     1.900  
     (n,2n)                       (E-thr =  6.336 MeV)    433.3 -3    6.667 -3
     (n,3n)                       (E-thr = 11.600 MeV)    289.2 -3    43.45 -6
     fission          2.557 -3    2.279 -3     5.577       2.027       1.127  
     (n,4n)                       (E-thr = 18.160 MeV)                133.1 -9
     capture           18.79       16.82      1.130 +3    800.0 -6    87.87 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    Americium

    95-Am-241

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             614.6       545.4                   5.741       7.784  
     elastic           11.14       10.73                   2.722       4.833  
     inelastic                    (E-thr =  0.041 MeV)    49.94 -3     1.340  
     (n,2n)                       (E-thr =  6.610 MeV)    262.4 -3    620.4 -6
     (n,3n)                       (E-thr = 12.650 MeV)    46.74 -3    10.02 -6
     fission           3.018       2.711       13.86       2.660       1.378  
     capture           600.4       532.0      1.305 +3    229.9 -9    229.6 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    95-Am-243

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             86.10       78.00                   5.759       7.854  
     elastic           7.480       7.428                   2.728       4.824  
     inelastic                    (E-thr =  0.042 MeV)    308.5 -3     1.754  
     (n,2n)                       (E-thr =  6.391 MeV)    360.5 -3    3.728 -3
     (n,3n)                       (E-thr = 11.950 MeV)    221.1 -3    33.16 -6
     fission          116.1 -3    103.3 -3     7.585       2.140       1.080  
     (n,4n)                       (E-thr = 18.570 MeV)                2.068 -9
     capture           78.50       70.46      1.823 +3    230.7 -9    189.4 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    Californium

    98-Cf-249

  • Atomic Mass: 249.0748468 +- 0.0000030 amu
  • Excess Mass: 69719.351 +- 2.806 keV
  • Binding Energy: 1863369.394 +- 2.826 keV
  • Beta Decay Energy: B- -1451.000 +- 30.000 keV
  • Half Life: 351 Y
    Specific Activity: 4.089 curie/g
    Radioisotopic Power: 0.1526 W/g
    Primary Mode of Decay: Alpha to Cm-245
    Secondary Mode of Decay: Spontaneous fission
  • Spin: 9/2-
  • Critical mass: no published estimate, 5.90 kg (one-group calculation)
     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total            2.177 +3    1.869 +3                 5.817       8.082  
     elastic           6.223       5.989                   2.747       4.952  
     inelastic                    (E-thr =  0.063 MeV)    65.64 -6     1.249  
     (n,2n)                       (E-thr =  5.616 MeV)    662.0 -3    14.19 -3
     (n,3n)                       (E-thr = 12.620 MeV)    118.0 -3    24.69 -6
     fission          1.666 +3    1.430 +3    2.219 +3     2.290       1.741  
     (n,4n)                       (E-thr = 18.660 MeV)                3.046 -9
     capture           504.5       433.6       694.9     328.2 -12    120.8 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    98-Cf-251

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total            7.889 +3    6.712 +3                 5.838       8.148  
     elastic           76.09       70.15                   2.754       4.814  
     inelastic                    (E-thr =  0.025 MeV)    10.20 -3    862.9 -3
     (n,2n)                       (E-thr =  5.132 MeV)    268.1 -3    12.34 -3
     (n,3n)                       (E-thr = 11.780 MeV)    325.2 -3    44.33 -6
     fission          4.935 +3    4.196 +3    2.774 +3     2.478       2.430  
     (n,4n)                       (E-thr = 17.400 MeV)                59.29 -9
     capture          2.878 +3    2.446 +3    1.604 +3    11.11 -9    27.45 -3
     ---------------------------------------------------------------------------
    

    Average neutron induced Nu_p (prompt neutrons/fission)

    98-Cf-252

     ---------------------------------------------------------------------------
      REACTION        2200-m/s    Maxw.Avg.   Res.Integ     14-MeV    Fiss.Avg.   
                      (barns)     (barns)     (barns)      (barns)    (barns)    
     ---------------------------------------------------------------------------
     total             64.77       58.49                   5.848       8.186  
     elastic           11.04       11.02                   2.758       5.144  
     inelastic                    (E-thr =  0.046 MeV)    10.29 -3    731.5 -3
     (n,2n)                       (E-thr =  6.195 MeV)    86.60 -3    4.930 -3
     (n,3n)                       (E-thr = 11.330 MeV)    223.0 -3    35.17 -6
     fission           33.03       29.20       110.7       2.770       2.251  
     (n,4n)                       (E-thr = 17.980 MeV)                11.66 -9
     capture           20.71       18.27       47.34      185.6 -9    51.29 -3
     ---------------------------------------------------------------------------
     

    Average neutron induced Nu_p (prompt neutrons/fission)