GEF 2015/2.2

General description of fission observables. Released September 24, 2015.
Last modifications: Overflow problem for very large event numbers solved (November 26, 2015).
                               Overflow problem in corrected (April 11, 2016), thanks to K. Kern.
                               Subscriptrange problem in output corrected (April 29, 2016), thanks to V. Tobosaru.
                               Prompt-neutron spectrum with variable binsize added in folder "/out" (May 29, 2016).
                               Prompt-gamma spectrum with conditions on fragment mass and with variable binsize added in folder "/dmp/EgammaA" (June 1, 2016).
                               Accumulation of prompt-neutron spectrum with variable bin size corrected (July 2, 2016)
                               GEFSUB: Technical correction that speeds up the code (September 7, 2016), thanks to R. Reifarth.
 - By the extensions implemented in GEF 2015/2.1, the quality of the code at low excitation energy deteriorated. This has been essentially recovered by a new adjustement of the parameters in GEF 2015/2.2.
GEF 2015/2.1 should not be used any more.

Most important developments for GEF 2015/2.1 that are still present in GEF 2015/2.2:
We are happy about any feed-back (mail to schmidt-erzhausen<at> 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).

Quick start on Windows:

Quick start on Linux:

Windows version

Input mask of the graphical user interface:

Input maks of GEF GUI

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


Input files for extended input options
Distribution of entrance energies (example)
List of input parameters (example)
See Readme file for more detailed information.
Data tables in XML format (example)
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


FORTRAN version