Directory: fission/
File:      levden-hfbcs.readme (January 15, 2002)
**************************************************


       levden-hfbcs-inner/zxxx.dat & levden-hfbcs-outer/zxxx.dat

	 Compilations of microscopic nuclear level densities
	     at the inner and outer fission saddle points
	     (provided by S. Goriely on January 15, 2002)
         *****************************************************
                      
	  MICROSCOPIC NUCLEAR LEVEL DENSITIES AT THE FISSION
			    SADDLE POINTS

			      S. Goriely
	       Universite Libre de Bruxelles (Belgium)
			       M. Samyn
	       Universite Libre de Bruxelles (Belgium)
 
			   January 15, 2002
 

Content
-------
Nuclear Level Densities (NLD) at fission saddle points for some 2300
nuclei with 78 <= Z <= 120 included in the ETFSI compilation [1].  The
fission barriers and saddle point deformations are determined within
the Extended Thomas-Fermi plus Strutinsky Integral (ETFSI) method.
For each nucleus a maximum of two barriers are given, one "inner" and
one "outer".  They correspond to the highest saddle point among the
"slightly" and the "strongly" deformed ones.  Those two groups of
saddle points correspond to well separated values of the elongation
parameter c.  In most cases, for the inner barrier c < 1.6 and the
outer c > 1.6.  The nuclear shapes are limited to axially symmetrical
deformations.  These are described by the so-called Brack
parametrization (c,h,alpha) where c is the elongation parameter
(c<1,=1 and >1 for oblate, spherical and prolate shapes, resp.), h is
related to the "necking" of the nuclear surface and alpha measures the
left-right asymmetry (alpha = 0 for symmetric shapes).  The calculated
inner and outer barriers as well as the deformation parameters at the
corresponding saddle point can be found in the "fis-barrier-etfsi.dat"
file.

At each saddle point, the NLD is estimated within the statistical
partition function approach.  The NLD calculation is based on the
realistic microscopic single-particle level scheme determined within
the HF-BCS mass model obtained with the MSk7 Skyrme force [2]. For
each saddle point, the single-particle level scheme is calculated
consistently by the HF-BCS model constrained on the corresponding
quadrupole, octupole and hexadecapole moments.  The same pairing
strength (within the constant-G approximation) as the one used for the
NLD calculation at the ground-state equilibrium deformation is used
[2] (the ground-state NLD can be found in the level-densities-hfbcs"
sub-directory of the densities Segment). No damping of the collective
effects at increasing excitation energies is considered.  The NLD for
nuclei with left-right asymmetric fission barriers is increased by a
factor of 2.

As for the ground-state description, the NLD model includes

 -  BCS pairing (in the constant-G approximation) with a renormalized
    strength and  blocking effect for odd-mass and doubly odd nuclei.  
 -  Gaussian-type spin dependence with microscopic shell and pairing
    effect on the spin cut-off parameter  
 -  Deformation effects are included in
     1.the single-particle spectrum  
     2.the collective contribution of the rotational band on top of 
       each intrinsic state  
 -  Improved description at very-low energies.

The NLD are provided, separately at the inner and outer saddle points,
in a table format for the 2300 nuclei with 78<=Z<=120 included in the
ETFSI compilation of fission barriers.  Each table includes
spin-dependent NLD for energies up to U = 150 MeV and spin up to J =
29(59/2). Also included in the tables are the nuclear temperature, the
cumulative number of levels and the total level and state densities.


Format
------
Each isotopic chain is included in one unique file named by the
elemental symbol Z.  A title line includes for each isotope, in
addition to the charge and mass number, the saddle point deformation
in the (c,h,alpha) parametrization and the fission barrier height in
MeV In each file, the NLDs are given for each isotope in a table
format with an excitation energy grid ranging from U=0.25MeV up to
U=150MeV.  At each excitation energy U (in MeV), are provided (per
row)

   T     : the nuclear temperature in MeV
   NCUMUL: the cumulative number of predicted levels
   RHOOBS: the total level density in MeV-1 [=Sum RHO(U,J)]
   RHOTOT: the total state density in MeV-1 [=Sum (2J+1) RHO(U,J)]
   RHO(J): the spin-dependent level density for J=0 (1/2) up to 29
             (59/2). 

The corresponding FORTRAN format is (f7.2,f7.3,1x,33e9.2)


References
----------
[1] A. Mamdouh, J. M. Pearson, M. Rayet and F.Tondeur (2001), Nucl. Phys. 
    A679, 337.
[2] S. Goriely, F. Tondeur, J. M. Pearson (2001), Atomic Data Nuclear 
    Data Tables 77, 311.
[3] P. Demetriou, S. Goriely (2001), Nucl. Phys. A695, 95.