- Description of the model
- Ingredients
- Input
- Output
- Access to the GEF code (last modification June 2018)
- Supplemental and help information

ERINDA project (http://www.erinda.org/), of the CHANDA project (http://www.chanda-nd.eu/) and, during the years 2010 - 2016, by the OECD Nuclear Energy Agency. A detailed description of the physics of the code is given in the JEFF-Report 24 of the Nuclear-Energy Agency of the OECD.

Executables of the GEF code for Windows[a] and Linux are available. They are easy to use: Just download the ZIP file, extract the files and run GEF.bat (Windows [a]) or ./GEF (Linux) in a command window on your computer! The file README.txt contains further information.

[a] Windows is either a registered trademark or a trademark of Microsoft

Corporation in the United States and/or other countries.

Empirical fission-fragment Z and mass distributions compared with GEF calculations.

- The mass division and the charge polarization are calculated assuming a statistical population of states in the fission valleys at freeze-out. The freeze-out time considers the influence of fission dynamics and is not the same for the different collective variables.
- The separability principle [1] governs the interplay of macroscopic and microscopic effects.
- Five fission channels are considered. The strengths of the shells
in the fission valleys are identical for all fissioning systems. The
mean positions of the heavy fragments in the asymmetric fission
channels are essentially constant in atomic number, as suggested by
experimental data [2]. (Read more.)

- The stiffness of the macroscopic potential with respect to mass asymmetry is deduced from the widths of measured mass distributions [3].
- The excitation-energy-sorting mechanism [4,5,6,7] determines the
prompt neutron yields and the odd-even effect in fission-fragment
yields of even-Z and odd-Z systems. (Read more.)

- Neutron evaporation is calculated with a Monte-Carlo statistical code using level densities from empirical systematics [8] and binding energies with theoretical shell effects [9] with gamma competition included.

[1]

[2]

[3]

[4]

K.-H. Schmidt, B. Jurado, Phys. Rev. Lett. 104 (2010) 212501

[5]

[6]

[7]

[8]

[9] Global view on fission observables - new insights and new puzzles, K.-H. Schmidt, B. Jurado, Phys. Proc. 31 (2012) 147

[10] General description of fission observables - GEF model, K.-H. Schmidt, B. Jurado, Ch. Amouroux, JEFF-Report 24, Data Bank, Nuclear-Energy Agency, OECD, 2014

[11] Revealing hidden regularities with a general approach to fission, K.-H. Schmidt, B. Jurado, Eur. Phys. J. A 51 (2015) 176

[12] General description of fission observables: GEF model code, K.-H. Schmidt, B. Jurado, C. Amouroux, C. Schmitt, Nucl. Data Sheets 131 (2016) 107

[13] Influence of complete energy sorting on the characteristics of the odd-even effect in fission-fragment element distributions, B. Jurado, K.-H. Schmidt, J. Phys. G: Nucl. Part. Phys. 42 (2015) 055101 [arXiv: 14411.4478]

[14] Review on the progress in nuclear fission - experimental methods and theoretical descriptions, K.-H. Schmidt, B. Jurado, accepted by Rep. Progr. Phys.

Excitation mode and excitation energy (eventually energy distribution)

Output options

Element-yield distribution *)

Isotonic-yield distribution (pre- and post-neutron)

Isobaric-yield distribution (pre-and post-neutron) *)

Mass-chain yields (pre- and post-neutron) *)

Fragment angular-momentum distributions (for every nuclide)

Relative independent isomeric yields

Prompt-gamma spectrum

Prompt-neutron spectrum

Neutron-multiplicity distribution

Fragment total kinetic energy (pre- and post-neutron)

Energies and directions of pre- and post-scission prompt neutrons

A extended version of GEF that includes delayed processes (output of delayed-neutron multiplicities, delayed-neutron emitters, cumulative fission-fragment yields in ENDF format) is available on demand.

*) Uncertainties of fission yields from perturbed-parameter

GEF code, Version 2017/1.2 (Release: October 18, 2017, last modification January 30, 2018)

GEF code, Version 2017/1.1 (Release: September 24, 2017)

GEF code, Version 2016/1.2 (Release: November 26, 2016)

GEF code, Version 2016/1.1 (Release: October 14, 2016)

GEF code, Version 2015/2.2 (Release: September 22, 2015, numerical stability improved on September 23, 2015,

technical modifications on October 3, November 26, 2015, April 11, April 29, May 29, July 2, and Sept. 7, 2016.)

(Description of non-statistical prompt gamma energies with a new VMI model,

Improved description of fission chances and fission-fragment distributions for highly excited systems.

Improved description of fragment distributions for light fissioning systems (Z = 76 to 90).

Note: GEF Version 2015/2.1 should not be used any more.

GEF code, Version 2015/1.1 (Release: January 2, 2015, numerical stability improved on September 23, 2015)

(Extended output options, covariances between results of different systems.)

GEF code, Version 2014/2.1 (March 25, 2014)

(New global parameter set, new systematics of fission barriers)

GEF code, Version 2014/1.2 (January 25, 2014)

(Modified description of multi-chance fission.)

GEF code, Version 2014/1.1 (January 4, 2014)

(New global parameter set, modifications for better description of multi-chance fission.)

GEF code, Version 2013/2.2 (December 6, 2013)

(Even odd effect in fission-fragment neutron-number distribution revised.

Mass distribution at high excitation energies revised.

Prompt-neutron emission improved.

Output of pre-fission and post-scission neutrons extended.

Influence of temperature dependent shape oscillations on prompt-neutron emission considered.

Fission-gamma competition refined.

New global parameter set.

Multi-chance fission modified.

Spurious even-odd effect in fission probabilities removed.)

- Help information for reading a covariance or correlation matrix from the GEF output file

The covarience or correlation matrix of independent yields is listed in a special format.

The sample program correst is provided that interprets the data structure and lists the 4-dimensional (Z1, A1, Z2, A2) coordinates and the corresponding matrix values. This program may help you to read the matrices from the GEF output with your own software. - Guide for the production of covariance and correlation matrices with GEF

The technical parameters for the production of variances (and the corresponding uncertainties), covariances and correlations are discussed, and their influence on the qualitiy of the data is investigated and demonstrated this report.

Authors: Beatriz Jurado (jurado (at) cenbg.in2p3.fr)

and Karl-Heinz Schmidt (schmidt-erzhausen (at) t-online.de).