1. LICENCE AND COPYRIGHT
' The development of the GEF code has been supported by the European Union,
' EURATOM 6, Framework Program "European Facilities for Nuclear Data
' Measurements" (EFNUDAT), contract number FP6-036434, the Framework
' Program "European Research Infrastructure for Nuclear Data Applications"
' (ERINDA), and by the Nuclear Energy Agency of the OECD.
'
' The GEF code is free software: you can redistribute it and/or modify
' it under the terms of the GNU General Public License as published by
' the Free Software Foundation, either version 3 of the License, or
' (at your option) any later version.
'
' This program is distributed in the hope that it will be useful,
' but WITHOUT ANY WARRANTY; without even the implied warranty of
' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
' GNU General Public License for more details.
'
' You should have received a copy of the GNU General Public License
' along with this program. If not, see .
' Copyright 2009, 2010, 2011, 2012, 2013:
' Dr. Karl-Heinz Schmidt, Rheinstraße 4, 64390 Erzhausen, Germany
' and
' Dr. Beatriz Jurado, Centre d'Etudes Nucleaires de Bordeaux-Gradignan,
' Chemin du Solarium, Le Haut Vigneau, BP 120, 33175 Gradignan, Cedex,
' France
'
2. NAME OF THE PROGRAM: GEF 2013/1.7
3. DESCRIPTION OF PROGRAM OR FUNCTION
GEF is a computer code for the simulation of the nuclear fission process.
The GEF code calculates pre-neutron and post-neutron fission-fragment nuclide
yields, angular-momentum distributions, isomeric yields, prompt-neutron yields
and prompt-neutron spectra, prompt-gamma spectra, and several other quantities
for a wide range of fissioning nuclei from polonium to seaborgium in
spontaneous fission and neutron-induced fission. Multi-chance fission (fission
after emission of neutrons) is included. For neutron-induced fission, the
pre-compound emission of neutrons is considered. Output is provided as tables
and as parameters of fission observables on an event-by-event basis.
Specific features of the GEF code:
- The mass division and the charge polarisation 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].
- 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.
- Neutron evaporation from the fragments is calculated with a Monte-Carlo
statistical code using level densities from empirical systematics [8] and
binding energies with theoretical shell effects with gamma competition included.
- Model uncertainties and covariances are determined by a series of calculations
with perturbed parameters.
- Multi-chance fission is supported.
- Pre-compound emission of neutrons is considered for neutron-induced fission.
The official GEF websites are http://www.khs-erzhausen.de and
http://www.cenbg.in2p3.fr/GEF.
4. METHOD OF SOLUTION
The Monte-Carlo method is used.
Uncertainties are deduced from perturbed calculations.
5. TYPICAL RUNNING TIME
A typical calculation with 100 000 events takes about 5 seconds on one processor
of an Intel i7 CPU (2.80GHz). Calculations with perturbed parameters and
calculations at higher excitation energies, where multi-chance fission occurs,
require somwhat more time.
6. RELATED AND AUXILIARY PROGRAMS
The main routines are written in FreeBASIC (http://www.freebasic.net/). FeeBASIC
produces compiled binary code using the C run-time library. Graphics output is
based on the X11 library. A graphical user interface is provided for Windows [a],
written in JustBasic (http://www.justbasic.com/), which has a specific run-time
library. The Windows version of GEF runs also under WINE on LINUX.
7. REFERENCES
[1] Experimental evidence for the separability of compound-nucleus and fragment properties in fission,
K -H Schmidt, A Kelic, M V Ricciardi, Europh. Lett. 83 (2008) 32001
[2] Nuclear-fission studies with relativistic secondary beams: analysis of fission channels,
C. Boeckstiegel et al., Nucl. Phys. A 802 (2008) 12
[3] Shell effects in the symmetric-modal fission of pre-actinide nuclei,
S. I. Mulgin, K.-H. Schmidt, A. Grewe, S. V. Zhdanov, Nucl. Phys. A 640 (1998) 375
[4] Entropy-driven excitation-energy sorting in superfluid fission dynamics,
K.-H. Schmidt, B. Jurado, Phys. Rev. Lett. 104 (2010) 212501
[5] New insight into superfluid nuclear dynamics from the even-odd effect in fission,
K.-H. Schmidt, B. Jurado, arXiv:1007.0741v1 [nucl-th]
[6] Thermodynamics of nuclei in thermal contact,
K.-H. Schmidt, B. Jurado, Phys. Rev. C 82 (2011) 014607
[7] Final excitation energy of fission fragments,
K.-H. Schmidt, B. Jurado, Phys. Rev. C 83 (2011) 061601(R)
[8] Inconsistencies in the description of pairing effects in nuclear level densities,
K.-H. Schmidt, B. Jurado, Phys. Rev. C 86 (2012) 044322
8. HARDWARE REQUIREMENTS
GEF can be compiled and installed under Windows [a] and Linux, using exactly
the same sources files. Specific executables are provided for the two systems.
GEF was tested on Windows [a] and Linux.
Memory < 50 MByte; Disc < 100 MByte, eventually more for event-wise output.
9. PROGRAMMING LANGUAGE(S) USED
Computer language
on Linux: FreeBASIC; on Windows [a]: FreeBASIC and JustBasic
10. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED
a) Windows [a] XP or newer
b) Any Linux distribution. Eventually, some additional packages need to be
installed, e.g. X11 developer tools.
11. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
Multi-chance fission is supported, except when a distribution of excitation
energies at fission is provided on input.
The results on neutron emission prior to fission and prompt-neutron emission
from the fragments are given separately.
The sequence of the events in the list-mode output is sorted by energy at
fission in the case of multi-chance fission in order to save computing time.
An optional enhancement factor may be specified. A value >1 increases the
statistics of the Monte-Carlo calculation and hence reduces the statistical
uncertainties of the results. Default value is 1.E5 events. With this value,
the statistical uncertainties are already smaller than the model uncertainties
in most cases. Higher statistics may be useful to compare different systems, to
study systematic trends and to determine reliable covariances.
GEF provides all results event by event in a list-mode file on demand.
12. NAME AND ESTABLISHMENT OF AUTHORS
K.-H. Schmidt, Rheinstr. 4, 64390 Erzhausen, Germany
B. Jurado, CENBG, CNRS/IN2 P3, Chemin du Solarium B.P. 120, F-33175 Gradignan, France
13. MATERIAL AVAILABLE
FreeBASIC [c] source files. JustBasic [d] executable and run-time-library.
Executables for Windows [a] and Linux.
ReadMe file with technical instructions.
14. CATEGORIES
Nuclear fission
Keywords: Monte-Carlo method, event generator, macroscopic-microscopic model,
separability principle, energy sorting, statistical model,
pre-equilibrium emission, multi-chance fission, neutron evaporation,
prompt-gamma emission, uncertainties and covariance matrix of fission-fragment yields.
15. PRACTICAL HINTS
Please keep the sub-folder structure of GEF.zip. (If the subfolders "/out"
and "/tmp" do not exist, they are created automatically.)
On Windows [a]:
The file GEF.zip provides an executable of the main programm (GEF.exe)
and - in the subfolder GUI - a graphical user interface.
GEF is started by running "GEF.bat" (!) in a command window.
All user input must be entered by the GUI window!
If you want to apply any changes, use an IDE (e.g. FBIDE [b]) for editing
any of the source files (*.BAS). Compile the main routine GEF.BAS under
FreeBASIC [c]. The other files are automatically included in the compilation
process. The GUI is written in JustBasic [d].
On Linux:
The file GEF.zip provides an executable (GEF) that runs directly in a
terminal by entering "./GEF". (Do not forget to set the file properties to
"execute as a programm".)
The GUI that is provided in the Windows version may also be used under Linux
by running the Windows version of GEF under Wine [e] without any loss of
performance.
If you want to make any changes to GEF, prepare an executable, using
an IDE (e.g. GEANY [f]) with the FreeBASIC [c] compiler. GEF.BAS is the main
routine. The other files are automatically included in the compilation process.
Remark: The graphics output requires the installation of the X11 library.
If the graphics does not work, you may suppress it by commenting the line
( #Include Once "Plotting.bas" ) in GEF.BAS.
Required input of GEF:
Z and A of fissioning nucleus or target
Excitation mode and excitation energy
Output options
Quantities available on output of GEF:
Contributions of fission chances
Relative yields of fission channels
Element-yield distribution*)
Isotonic-yield distribution (pre- and post-neutron)
Isobaric-yield distribution*)
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
(Many more quantities are internally calculated and may be listed.)
*) Including uncertainties and covariances.
Advanced options:
- UNCERTAINTIES
Uncertainty analysis from calculations with perturbed parameters is available.
These calculations are also used to determine covariances between different
observables as required by the model.
- ENERGY DISTRIBUTION
Instead of a single energy, also a distribution of excitation energies
above the ground-state at fission may be provided in a file.
The file name is fixed: Espectrum.in.
- Example:
3.9 0.1
4.0 0.2
4.1 0.4
4.2 0.7
...
Each line gives an energy (in MeV) and a weight.
Energy steps of about 100 keV are recommended. The spectrum may be
un-normalized.
The corresponding option is chosen by the GUI under Windows or by the
option "ES" under Linux. Note that GEF calculates only first-chance fission
for this option.
- INPUT LIST
GEF supports reading an input list from file. This option is chosen if
the file "file.in" is found.
Instructions:
1. Create a file with the following information:
First line: Statistical enhancement factor (default = 1 corresponds
to 10^5 events per system). A larger factor increases
the number of calculated events accordingly.
Second line: Energy value or list of energy values
For neutron-induced fission: List of energy values in ascending order.
For spontaneous fission: Energy value. (Only one value is allowed.)
Following lines: Specification of the fissioning system.
(Z_CN, A_CN, kind of fission)
- Example for spontaneous fission:
10
0
98, 250, "GS"
98, 252, "GS"
...
- Example for neutron-induced fission:
2
0.0253E-6, 0.4, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
92, 234, "EN"
92, 236, "EN"
...
In the case of neutron-induced fission, a sequence of calculations is
performed with the energies given in the second line of the input file.
- Example for fission from a shape isomer:
(The isomers must be listed in the file NucProp.bas.)
100
0
94, 241, "IS1"
94, 242, "IS1"
...
2. Create the file "file.in", which only contains the name of the
input file in the first line. (At the moment, only one input file
is allowed at a time.)
- PARALLEL COMPUTING
GEF also supports starting several processes in parallel, which calculate
the systems given in the input file in parallel in a coordinated way.
This enables making efficient use of modern multiprocessor machines.
Before starting a new sequence of calculations, the files "done.ctl" and
"thread.ctl" must be deleted. Multi-processor calculations should be done
without graphics output.
[a] Windows is either a registered trademark or a trademark of Microsoft
Corporation in the United States and/or other countries.
[b] FBIDE is available from http://fbide.freebasic.net/ with no cost.
[c] FreeBASIC is available from http://www.freebasic.net/ with no cost.
[d] JustBasic is available from http://www.justbasic.com/ with no cost.
[e] Wine is a windows compatibility layer for Linux (http://www.winehq.org/)
[f] Geany is available from http://www.geany.org/ with no cost.
In case of problems, please contact schmidt-erzhausen at t-online.de .