GEFY   GEF-based fission-fragment yield library in ENDF format

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See also partner web site at the CENBG.


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 deviation 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 2020/1.1.


Tables of independent and cumulative fission-fragment yields for download:
- Spontaneous fission for isotopes of 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). 


Table of isomeric states see below.
   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 (En up to 20 MeV in 77 steps) of 235U, 238U, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, and 241Am with 10^6 events per system. (Not yet available.)
   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

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 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. 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 2019/1.2.


Tables of independent and cumulative fission-fragment yields for download:
- Spontaneous fission for isotopes of 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).
Table of isomeric states see below.
   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 (En up to 20 MeV in 77 steps) of 235U, 238U, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, and 241Am with 10^6 events per system. (Not yet available.)
   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


GEFY 7.1 (February 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 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. 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 2019/1.1.


Tables of independent and cumulative fission-fragment yields for download:
- Spontaneous fission for isotopes of Z = 89 to Z = 106  (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)
Table of isomeric states see below.
   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 (En up to 20 MeV in 77 steps) of 235U, 238U, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, and 241Am with 10^6 events per system.
   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

GEFY 6.2 (June 2018):

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 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 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 fission for isotopes of 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.)
Table of isomeric states see below.
   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


GEFY 6.1 (November 2016):

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 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 of independent and cumulative fission-fragment yields 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.)
   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 (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-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.)
Table of isomeric states see below.
   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


Random files of independent and cumulative fission-fragment yields:

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.)




The files of GEFY 5.2 (September 2015) and GEFY 5.3 (March 2016) are not available any more.





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) 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





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