GEFY | Based fission-fragment Yield library in ENDF-format

Here you can download GEF-based fission-fragment yields in ENDF format

**GEFY 8.1 | July 2020**

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Uncertainties reflect the uncertainties of the model. They are determined from calculations with perturbed model parameters. For this purpose, a series of calculations was performed with different sets of model parameters. Each parameter in these sets was varied randomly with a standard variation corresponding to the uncertainty of the respective parameter deduced from the fit to experimental fission data.

Isomeric independent yields and cumulative yields were calculated using the decay data of JEFF 3.3. Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments, for which no experimental decay information is available, were assumed to decay by beta-minus decay only.

The calculations have been performed with the **GEF code, version version 2020/1.1**

Correction of interpolation scheme applied in January 2021.

#### TABLES OF INDEPENDENT AND CUMULATIVE FISSION-FRAGMENT YIELDS FOR DOWNLOAD :

Spontaneous fission for isotopes from Z = 89 to Z = 106. (Calculation with 10^{6} events per system)

Neutron-induced fission of target nuclei of Z 86 to Z = 98 (En=thermal to En=30 MeV in 59 steps). (Calculation with 10^6 events per system). *)

Neutron-induced fission of target nuclei in isomeric states. (Half-life > 1 s). En=thermal to En=30 MeV in 59 steps. (Calculation with 10^{6} events per system).

_{Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30}

See below the table with isomeric states.

* The tables that were given here before were calculated with only part of the isomers of JEFF-3.3 taken into account by a technial problem. The new tables are still incomplete.

See below the table with isomeric states.

**GEFY 7.2 | September 2019**

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Uncertainties reflect the uncertainties of the model. They are determined from calculations with perturbed model parameters. For this purpose, a series of calculations was performed with different sets of model parameters. Each parameter in these sets was varied randomly with a standard variation corresponding to the uncertainty of the respective parameter deduced from the fit to experimental fission data.

Cumulative yields were calculated using the decay data of JEFF 3.1.1. Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments, for which no experimental decay information is available, were assumed to decay by beta-minus decay only.

#### TABLES OF INDEPENDENT AND CUMULATIVE FISSION-FRAGMENT YIELDS FOR DOWNLOAD :

Spontaneous fission for isotopes from Z = 89 to Z = 106. (Calculation with 10^{6} events per system)

Neutron-induced fission of target nuclei of Z 86 to Z = 98 (En=thermal to En=30 MeV in 59 steps). (Calculation with 10^6 events per system).

Neutron-induced fission of target nuclei in isomeric states. (Half-life > 1 s). En=thermal to En=30 MeV in 59 steps. (Calculation with 10^{6} events per system)

Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30

See below the table with isomeric states.

**GEFY 7.1 | Februry 2019**

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Uncertainties reflect the uncertainties of the model. They are determined from calculations with perturbed model parameters. For this purpose, a series of calculations was performed with different sets of model parameters. Each parameter in these sets was varied randomly with a standard variation corresponding to the uncertainty of the respective parameter deduced from the fit to experimental fission data.

Cumulative yields were calculated using the decay data of JEFF 3.1.1. Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments, for which no experimental decay information is available, were assumed to decay by beta-minus decay only.

The calculations have been performed with the **GEF code, version version 2019/1.1**.

#### TABLES OF INDEPENDENT AND CUMULATIVE FISSION-FRAGMENT YIELDS FOR DOWNLOAD :

Energy steps in MeV : 0.1E-10, 0.0253E-6, 1.E-7, 5.E-7, 1.E-6, 5.E-6, 1.E-5, 5.E-5, 1.E-4, 5.E-4, 1.E-3, 5.E-3, 1.E-2, 2.E-2, 3.E-2, 4.E-2, 5.E-2, 6.E-2, 7.E-2, 8.E-2, 9.E-2, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20

Neutron-induced fission of target nuclei in isomeric states. (Half-life > 1 s). En=thermal to En=30 MeV in 59 steps. (Calculation with 10^{6} events per system)_{Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5}

Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30

See below the table with isomeric states.

**GEFY 6.2 | June 2018**

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Cumulative yields were calculated using the decay data of JEFF 3.1.1 with some extensions from ENSDF (Nuclear Wallet Cards database version of 6/1/2012). Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments for which no experimental decay information is available were assumed to decay by beta-minus decay only.

The calculations have been performed with the GEF code, version version 2018/1.1. Comparisons of calculated fission-fragment yields with evaluations and other data are shown in this **gallery **.

#### TABLES OF INDEPENDENT AND CUMULATIVE FISSION-FRAGMENT YIELDS FOR DOWNLOAD :

** **Spontaneous fissionfor isotopes from Z = 89 to Z = 106. (Calculation with 10^{6}events per system, produced with version GEF-2018/1.1)

Neutron-induced fission (En=thermal to En=30 MeV in 59 steps for isotopes of Z = 86 to Z = 98). (Calculation with 10^{6} events per system, produced with version GEF-2018/1.1)._{}_{}

Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30

**Neutron-induced fission of target nuclei in isomeric states **(half-life > 1 s). En=thermal to En=30 MeV in 59 steps. (Calculation with 10^{6} events per system, produced with version GEF-2018/1.1)

_{}_{}

_{Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30}

See below the table with isomeric states.

**GEFY 6.1 | November 2016**

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Cumulative yields were calculated using the decay data of JEFF 3.1.1 with some extensions from ENSDF (Nuclear Wallet Cards database version of 6/1/2012). Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments for which no experimental decay information is available were assumed to decay by beta-minus decay only.

The calculations have been performed with the GEF code, version 2016/1.1 or version 2016/1.2 (see notice below).

**Notice :** We observed that GEF-2016/V1.1 overestimates the fragment excitation energies for incoming neutron energies above 10 MeV. New GEFY tables with the corrected version GEF-2016/V1.2 are successively provided. The random files are already calculated with GEF-2016/V1.2.

#### TABLES FOR DOWNLOAD

**Spontaneous fission** for isotopes from Z = 89 to Z = 106. (Calculation with 10^{8} events per system, produced with version GEF-2016/1.1)

**Neutron-induced fission **(En=thermal to En=30 MeV in 59 steps for isotopes of Z = 86 to Z = 98). (Calculation with 10^{6} events per system, produced with version GEF-2016/1.2).

_{}_{}

_{Energy steps in MeV : 0.0253E-6, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30}

**Neutron-induced fission for ^{235,238}U, ^{238-242}Pu, ^{241}Am** (En=10

^{-11}to 20 MeV in 77 steps) . (Calculation with 10

^{8}events per system, produced with version GEF-2016/1.2.)

Energy steps in MeV : 0.1E-10, 0.0253E-6, 1.E-7, 5.E-7, 1.E-6, 5.E-6, 1.E-5, 5.E-5, 1.E-4, 5.E-4, 1.E-3, 5.E-3, 1.E-2, 2.E-2, 3.E-2, 4.E-2, 5.E-2, 6.E-2, 7.E-2, 8.E-2, 9.E-2, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20

**Neutron-induced fission of target nuclei in isomeric states **(half-life > 1 s). En=thermal to En=30 MeV in 59 steps. (Calculation with 10^{6} events per system, produced with version GEF-2016/1.1)

See below the table with isomeric states.

RANDOM FILES :

For a limited number of systems, a series of random files are provided **here**.

These random files provide fission-fragment yields in ENDF format with an indirect numerical presentation of variances and covariances according to the GEF model. For each system and each energy, a series of 500 calculations were performed with perturbed parameters. The parameters of each of these calculations were chosen independently within the uncertainty range of the GEF model.

The tables are intended for model calculations based on fission yields in ENDF format. By performing these calculations with the different random files for the same system and the same incoming-neutron energy, the uncertainties and the covariances of the yields according to the GEF model are included in the calculation. This procedure has several advantages. For example, no special format for the covariances is required and the production of random fission-yield data on the basis of the covariances is not needed. Moreover, the restriction by the functional form of the multivariate distribution is not an issue.

Step | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
---|---|---|---|---|---|---|---|---|---|---|---|

Energy/MeV |
Thermal | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 |

Step | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | |||

Energy/MeV |
1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 |

The calculations have been performed with the GEF code, version 2016/1.2.

Explanation of the file names : *GEFY_92_235_n_Ei_Rj.rnd contains the calculated yields for neutron-induced fission from a 235U target, incident-neutron energy step number « i » and perturbed-parameter set « j ». (Note that all perturbed parameter sets are different. They are all chosen independently at random. Also those with the same number but for different targets are not the same.)*

**GEFY 5.3 | March 2016**

Random files of independent and cumulative fission-fragment yields for neutron-induced fission.

This is a special collection of tables that provides fission-fragment yields in ENDF format with an indirect numerical presentation of variances and covariances according to the GEF model. For each system and each energy, a series of calculations was performed with perturbed parameters. The parameters of each of these calculations were chosen independently within the uncertainty range of the GEF model. The tables are intended for model calculations based on fission yields in ENDF format. By performing these calculations with the different random files for the same system and the same incoming-neutron energy, the uncertainties and the covariances of the yields according to the GEF model are included in the calculation. This procedure has several advantages. For example, no special format for the covarainces is needed, and the production of random fission-yield data on the basis of the covariances is not needed. Moreover, the restriction by the functional form of the multivariate distribution is not an issue.

The calculations have been performed with the GEF code, version 2015/2.3.

Due to the relatively large size of the files, GEFY 5.3 covers only a rather limited number of nuclei and does not include spontaneous fission for the moment. If there is some interest, the tables could be extended.

#### TABLES FOR DOWLOAD:

Neutron-induced fission (En=thermal to En=20 MeV in 49 steps) for isotopes of Z = 90 to Z = 96.

_{}_{} Neutron-induced fission (4 selected systems 235U, 238U, 239Pu, 241Pu, 0.5 MeV or thermal with 500 samples).ENDF files

Explanation of the file names : GEFY_90_226_n_Ei_Rj.rnd contains the calculated yields for neutron-induced fission from a 226Th target, incident-neutron energy step number « i » and perturbed-parameter set « j ». (Note that all perturbed parameter sets are different. They are all chosen independently at random. Also those with the same number but for different targets are not the same.) GEFY_90_226_n.dat contains the calculated yields for neutron-induced fission from a 226Th target with all indicent-neutron energies and nominal parameters, including the uncertainties determined from the series of calculation with perturbed parameters.

**GEFY 5.2 | September 2015**

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Cumulative yields were calculated using the decay data of JEFF 3.1.1 with some extensions from ENSDF (Nuclear Wallet Cards database version of 6/1/2012). Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments for which no experimental decay information is available were assumed to decay by beta-minus emision only.

The calculations have been performed with the GEF code, version 2015/2.2. (New features : Improved description of fission from high excitation energies.)

Independent and cumulative fission-fragment yields.

Multi-chance fission is considered.

Cumulative yields were calculated using the decay data of JEFF 3.1.1 with some extensions from ENSDF (Nuclear Wallet Cards database version of 6/1/2012). Nuclides with half-lives longer than 1.E6 years were treated as stable. Very neutron-rich fragments for which no experimental decay information is available were assumed to decay by beta-minus emision only.

The calculations have been performed with the GEF code, version 2015/2.2. (New features : Improved description of fission from high excitation energies.)

#### TABLES FOR DOWLOAD:

Neutron-induced fission (En=thermal to En=20 MeV in 49 steps) for isotopes of Z = 90 to Z = 96.

Spontaneous fission for isotopes from Z = 89 to Z = 106. (Calculation with 10^6 events per system, produced with version GEF-2015/2.2)

Neutron-induced fission (En=thermal to En=30 MeV in 59 steps for isotopes of Z = 89 to Z = 98). (Calculation with 10^6 events per system, produced with version GEF-2015/2.2)

Neutron-induced fission (En=10^-11 to 20 MeV in 77 steps for selected systems 235,238U, 238-242Pu, and 241Am). (Calculation with 10^8 events per system, produced with version GEF-2015/2.2.)

Neutron-induced fission of target nuclei in isomeric states (half-life > 1 s). En=thermal to En=30 MeV in 59 steps. (Calculation with 10^6 events per system, produced with version GEF-2015/2.2)

See below the table with isomeric states.

Nuclide | E(isomer) | Spin/parity | Half-life (ENSDF) | File name |
---|---|---|---|---|

222Ac | > 0 keV | ? | 63 s | GEFY_89_222m1_n.dat |

229Th | 100 eV | (3/2+) | 2 min ? | GEFY_90_229m1_n.dat |

234Pa | 73.9 keV | (0-) | 1.159 min | GEFY_91_234m1_n.dat |

235U | 0.1 keV | 1/2+ | about 26 min | GEFY_92_235m1_n.dat |

236Np | > 0 keV | 1 | 22.5 h | GEFY_93_236m1_n.dat |

240Np | > 0 keV | (1+) | 7.22 min | GEFY_93_240m1_n.dat |

242Np | > 0 keV | (6+) | 5.5 min | GEFY_93_242m1_n.dat |

242Am | 48.6 keV | 5- | 141 y | GEFY_95_242m1_n.dat |

244Am | 86.1 keV | 1+ | 26 min | GEFY_95_244m1_n.dat |

246Am | > 0 keV | 2(-) | 25.0 min | GEFY_95_246m1_n.dat |

248Bk | > 0 keV | 1(-) | 23.7 h | GEFY_97_248m1_n.dat |

250Es | > 0 keV | 1(-) | 2.22 h | GEFY_99_250m1_n.dat |

254Es | 83.7 keV | 2+ | 39.3 h | GEFY_99_254m1_n.dat |

256Es | > 0 keV | (8+) | 7.6 h | GEFY_99_256m1_n.dat |

250Fm | > 0 keV | ? | 1.93 s | GEFY_100_250m1_n.dat |