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 deviation 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 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 of 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.)

- 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.)

Table of isomeric states see below.

Random files:

For a limited number of systems, a series of random files is provided on the MagentaCLOUD.

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 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 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.

List of the energy steps:

Step | 1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 | 12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |

Energy / MeV | thermal | 0.1 |
0.2 |
0.3 |
0.4 |
0.5 |
0.6 |
0.7 |
0.8 |
0.9 |
1.0 | 1.5 |
2.0 |
2.5 |
3.0 |
3.5 |
4.0 |
4.5 |
5.0 |

The calculations of the random files were 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.)

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 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.

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 download:

- Neutron-induced fission (En=thermal to En=20 MeV in 49 steps with 31 samples) for isotopes of Z = 90 to Z = 96.

226Th to 234Th,

229Pa to 236Pa,

231U to 240U,

234Np to 242Np,

237Pu to 245Pu,

239Am to 247Am,

241Cm to 249Cm.

- 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.

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 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 2015/2.2.

(New features: Improved description of fission from high excitation energies.)

Tables for download:

- Spontaneous fission for isotopes of 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 = 86 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 235,238U, 238-242Pu, 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.)

Table of isomeric states see below.

Isomeric states from ENSDF (Nuclear Wallet Cards database version of 6/1/2012) are listed in the table below. Values that are not known were replaced by zero.

Nuclide | E(isomer) | Jπ | 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+ | ≈ 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 |

Comments and suggestions are welcome. Please address these to schmidt-erzhausen (at) t-online.de .