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GEF 2023/3.2 

General description of fission observables,
released on December 16, 2023.
Last update on January 14, 2024 (memory allocation and parallel computing revised, slight parameter adjustment).

Short characterisation of GEF 2023/3.2:

Compared to GEF 2023/3.1 the following modification have been made:
1.   The description of the suppression of extreme elongations at small E*, introduced in GEF 2023/3.1 is modified (see https://hal.in2p3.fr/in2p3-04489502)
The new description is valid for all nuclei; there is no special treatment for single systems with locally adjusted parameters necessary any more.
2.  All model parameters have been optimized.
3.  The treatment of parallel computing is revised.
4.  The calculation of angular momentum introduced in neutron-, proton-, and alpha-induced fission is revised.
5. The organization of allocated memory has been revised.
GEF allocates now around 30 MByte, instead of more than 200 MByte before. This makes it easier to run several GEF calculations in parallel, for example in batch mode.

Mass yields of U235T in comparison with JEFF 3.3

The mass distribution of 235U(nth,f) from GEF-2019/1.1 (red points) in comparison with the JEFF 3.3 evalution (black symbols with error bars). The calculated contributions from different fission channels are traced in green. 10 million events have been calculated.
We are happy about any feed-back (mail to schmidt-erzhausen<at>t_online.de). This helps to correct errors, to improve the quality of the model and to better respond to the needs and preferences of the users.

Use of the GEF code is subject to the GNU GENERAL PUBLIC LICENSE agreement that you find here: <License>.

Stand-alone version (Monte-Carlo method)

The stand-alone version of the GEF code is written in FreeBASIC (a). The FreeBASIC compiler produces binary code from the same source on Windows (b) and on Linux. The executable uses the C library.  For  the Windows version, a GUI is provided, written in JustBasic (c). The Windows version runs also on Linux with Wine (d).  The Windows version runs also on OS X (e) with Wine (d). 

a) FreeBASIC is available from http://www.freebasic.net/ with no cost.
b) Windows is either a registered trademark or a trademark of Microsoft Corporation in the United States and/or other countries.
c) JustBasic is available from http://www.justbasic.com/ with no cost.
d) Wine is a windows compatibility layer for Linux and Mac OS X (http://www.winehq.org/).
e) OS X is a trademark of Apple Inc., registered in the U.S. and other countries.

Quick start on Windows:

Quick start on Linux:
Windows version Input mask of the graphical user interface:

GUI for GEF on Windows

For Windows and Linux

Complete package


Readme file (Technical information, list of relevant publications)
JEFF-Report 24, part I (Comprehensive documentation of the GEF model.)
JEFF-Report 24, part II (Technical information on the GEF code.)

Source (for Windows and Linux)

Source files

An extended version of GEF-2023/3.2 that includes delayed processes (output of delayed-neutron multiplicities, delayed-neutron emitters, cumulative fission-fragment yields in ENDF format) is available here.
It provides also an option for producing random files of fission-fragment yields in ENDF format.

List-mode file (example)   (short sample of most complete event list)
Raw data for the multi-variate distribution of fission-fragment yields from calculations with perturbed parameters (example)
See Readme file for more detailed information.

You may consider using the Windows version of GEF on Linux with Wine in order to profit from the more comfortable input handling offered by the graphical user interface. This option may also solve problems of missing libraries under Linux.

Subroutine (Folding method) 

The subroutine aims for being used in combination with other nuclear-reaction codes. For a given fissioning nucleus with excitation energy E* and angular momentum I it calculates complete distributions of a number of fission observables before emission of prompt neutrons and prompt gamma radiation with the GEF model.


Technical description of the subroutine

FreeBASIC version

In preparation

FORTRAN version

In preparation

Additional data

List of fission barriers