Directory: gamma/
File: gamma-strength-analytic.readme (October 2, 2002)
-------------------------------------------------------
gamma-strength-analytic.tgz
Code for calculation of E1 gamma-strength functions
(provided by V. Plujko on October 2, 2002)
(adapted to UNIX by M. Herman)
*****************************************************
Content
-------
FORTRAN subroutine gamma-strength-analytic.f for calculation of E1-gamma
strength functions for gamma-decay and photo-absorption at fixed excitation
and gamma-ray energy along with the auxiliary routines and data files for
running test calculations. The radiative strength functions can be
calculated within the framework of any of the following models:
SLO - Lorentzian with the energy-independent width [1] (Ch.6).
EGLO - Enhanced generalized Lorentzian model [1] (Ch.6),[2].
GFL - Generalized Fermi liquid model [3] with extension for gamma- ray
energies near GDR-energies. The term
'(Egamma*Gamma_g^m(Egamma,T,beta)**2'was added to the
dominator of the Eq.(5) [3] to avoid singularity near
GDR-energies in a way similar to the other models for E1 strength.
The calculations in the case of non even-even nuclei are performed
with the use of the quantity 'S2Plus=(E2+)*beta**2' as input
parameter or with the global parameterization:
S2Plus=(E2+)*beta**2 = 217.16/A**2 (see, Eqs.(2) and (13) of [10]).
MLO1 - Modified Lorentzian model corresponding to the thermodynamic
pole approximation (TPA)[4-6] derived with micro-canonical ensemble
for initial states [7]. The response function width is calculated
within semi-classical second RPA and with collisional relaxation
time based on the doorway state mechanism of the relaxation [8].
MLO2 - Modified Lorentzian model corresponding to the TPA approach
with response function width within the extended Steinwedel- Jensen
model with friction (ESJ) [9] and with collisional relaxation
time based on the doorway state mechanism of the relaxation.
MLO3 - Modified Lorentzian model corresponding to the TPA approach with
the response function width within the ESJ model and with collisional
relaxation time according to the Fermi-liquid theory.
Files
-----
gamma-strength-analytic.tgz contains:
- gamma-strength-analytic.f : FORTRAN source of the subroutine
and auxiliary files for stand-alone testing:
- main.f : main code preparing input data and
calling gamma-strength-analytic.f
- densitydata.f : extracts level density parameters
- gdrgfldata.f : assigns GDR parameters and deformations
needed for the GFL model
- temperature.f : calculates nuclear temperature
- beijingn.dat : compilation of experimental GDR parameters
- deflib.dat : deformation parameter (|beta2|) for the
first collective 2+ level
- defeff.dat : excitation energy and deformation parameter
(beta) for the first collective 2+ level [10]
- denslib.dat : level density parameters (BSFGM)
- gnuplot.ini : input/output file to be used with gnuplot
to obtain plots of gamma-strength functions
by typing:
gnuplot
load 'gnuplot.ini'
Input description
-----------------
The subroutine GAMMA_STRENGTH, contained in the gamma-strength-analytic.f
file is prepared for being called from any nuclear reaction code in order
to calculate the dipole radiative strength function. The arguments of the
subroutine are the following:
Znucleus : atomic number of a nucleus
Anucleus : mass number of a nucleus
Eexcit : - initial state excitation energy (for gamma-decay)
- excitation energy of the absorbing nucleus (for photo-absorption)
Egamma : gamma-ray energy
Temperf : nuclear temperature at:
- Eexcit-Egamma for gamma-decay
- Eexcit for photo-absorption
Keyshape : key to specify strength-function model to be used:
- 1 for MLO1
- 2 for MLO2
- 3 for MLO3
- 4 for EGLO
- 5 for GFL
- 6 for SLO
The remaining input parameters must be transfered through the commons:
COMMON /PARGDR/ EG1, GW1, CS1, EG2, GW2, CS2, NG
COMMON /GFLPARAM/ BETagfl2, S2Plusgfl
where:
EG1 : energy of the first peak
GW1 : full width of the first peak at half-maximum
CS1 : peak cross section of the first peak
EG2 : energy of the second peak
CS2 : peak cross section of the second peak
GW2 : full width of the second peak at half-maximum
CS2 : peak cross section of the second peak
NG : 1 for a single peak (spherical nucleus)
2 for double peaks (deformed nucleus)
BETagfl2 : square of "deformation" parameter 'beta' associated
with the nuclear quadrupole moment
S2Plusgfl: product of first-excited 2+ state energy (in MeV) and the
square of the deformation parameter ((E2+)*beta**2)
[see, S.Raman,C.W.Nestor,Jr, P.Tikkanen, Atom. Data Nucl.
Data Tabl. 78(2001)1 for beta and E2+ values]
Running a stand-alone code
--------------------------
Compile all FORTRAN sources, for example with:
g77 -o gstrength *.f
and type:
gstrength
to run the code. Type nucleus A and Z when requested. The results will
be stored in a number of files with extension 'dat', separately for each
gamma strength-function model, and in the summary file rsf_E.dat. Plots
can be obtained by typing:
gnuplot
load 'gnuplot.ini'
providing 'gnuplot' package is installed on the system.
When running the stand-alone version the GDR parameters are initially
searched in the beijingn.dat file. This file is numerically
equivalent with the gdr-parameters-exp.dat file of RIPL-2. If more than
one experimental data set for a given nuclide is listed the first
entry in beijingn.dat is taken. Only if experimental data are absent,
the GDR parameters are calculated by global systematics with effective
quadrupole deformation parameters based on the mass-frdm95.dat file.
The parameters of the GFL model (E2+ and 'beta') are searched in the
defeff.dat file. This file is based on Table 1 of Ref. 10. If 'beta'
is absent in the defeff.dat file a value (|beta2|) from the deflib.dat
file is used. If all these fails, global parameterization S2Plus =
(E2+)*beta**2 = 217.16/A**2 is invoked (see, Eqs.(2),(13) of [10]).
The level density parameters ('a' and 'backshift') are taken from: (i)
denslib.dat file based on the beijing_bs1.dat file of RIPL-1 using
rigid-body moment inertia, (ii) systematics of von Egidy et al. [11]
(Eq.10).
NOTE: these back-shifted Fermi-gas model parameters are not consistent
with the RIPL-2 recommendations.
Format
------
Tarred and gzipped archive. On UNIX/Linux systems use
tar xvzf gamma-strength-analytic.tgz
or
gunzip gamma-strength-analytic.tgz
tar xvf gamma-strength-analytic.tar
to explode the archive. On MS Windows WinZip should be used instead.
Platform
--------
Code is running on Linux/UNIX and MS Windows, other platforms with FORTRAN
compiler are likely to work.
Testing
-------
Code was tested by M. Herman on Red Hat 7.3 Linux with g77 compiler.
References
----------
[1] Handbook for calculations of nuclear reaction data.RIPL.IAEA-
TECDOC-1034, August 1998; http: //www-nds.iaea.or.at /ripl/.
[2] J. Kopecky, M. Uhl, R. E. Chrien, Phys.Rev. C47(1993)312.
[3] S. F. Mughabghab, C. L. Dunford, Phys.Lett.B487(2000)155.
[4] V. A. Plujko. Nucl.Phys. A649(1999)209c.
[5] V. A. Plujko, Acta Phys. Pol. B31(2000)435.
[6] V. A. Plujko, Proceedings of the 9 th Inter. Conf.Nucl. Reaction
Mechanisms, Varenna, June 5- 9, 2000. Ed. E. Gadioli. Universita'
degli Studi di Milano, Suppl. N.115, 2000, pp.113- 124.
[7] V. A. Plujko (Plyuiko), Yad.Fiz. 52(1990)1004 [Sov. J. Nucl. Phys.
52(1990)639].
[8] V. A. Plujko,O.M. Gorbachenko, M.O. Kavatsyuk.
Acta Phys. Slov., 51(2001)231.
[9] J. M. Eisenberg, W. Greiner, Nuclear Theory, v.1, Nuclear Models,
Collective and Single-Particle Phenomena, North-Holl., Amsterdam,
1987. Ch. 14, \S \S 3-5.
[10] S. Raman, C. W. Nestor,Jr, P. Tikkanen, Atom.Data Nucl.Data Tabl.
78(2001)1.
[11] T. Von Egidy, H. H. Schmidt, A. N. Behkami, Nucl.Phys.A481(1988)189.