ETFSI fission barriers

This data file contains the predictions of the fission barriers and saddle point deformations obtained within the Extended Thomas-Fermi plus Strutinsky Integral (ETFSI) method. A brief description of the ETFSI method as well a useful references may be found here

The present ETFSI compilation of fission barriers includes 2301 nuclei with 78 <= Z <= 120. Their masses range from slightly neutron deficient to very neutron rich nuclei (close or up to the calculated neutron drip line), up to A = 318. This compilation contains the nuclei considered in [1], for which experimental barriers are known, and a slightly extended version of the set published in [2]. 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, cin and cout (see below). In most cases cin < 1.6 and cout > 1.6 (in some cases 1.5 < cout <1.6).

In addition to the calculated inner and outer barriers, the deformation parameters at the corresponding saddle points are also included. The nuclear shapes are limited to axially symmetrical deformations. These are described by the so-called Brack parametrization (c,h,a) where c is the elongation parameter (c<1,=1 and >1 for oblate, spherical and prolate shapes, resp.) and h is related to the "necking" of the nuclear surface. The shapes corresponding to different regions of the (c,h) plane are described in detail in [1]. The parameter a measures the left-right asymmetry (a = 0 for symmetric shapes). The asymmetry parameters ain and aout listed in the file refer not to a but to the quantity ` a~ defined ( [1] ) by a~ = a.c3. In term of this quantity, the mass ratio of the two fission fragments is roughly given by (1+3a~/8)/(1-3a~/8). All the calculated barriers have deformation parameters within the following domain: 1.00<c<2.36, -0.26<h<+0.22, 0<=a~<0.75.

Each record of the data file contains (last update Jan. 12, 2001):

  • Z, A, S : charge and mass numbers, element symbol '''
  • cin , hin , a~in : c, h, a~ of the inner barrier
  • Bin : inner barrier (in MeV)'
  • cout , hout , a~out : c, h, a~ of the outer barrier
  • Bout : outer barrier (in MeV)

The corresponding fortran format is (2i4,1x,a2,1x,8f9.2)

References:

[1] A. Mamdouh, J.M. Pearson, M. Rayet and F.Tondeur (1998) Nucl. Phys. A644, 389-414

[2] A. Mamdouh, J.M. Pearson, M. Rayet and F.Tondeur (2001) Nucl. Phys. A679, 337-358

The fission barriers are derived with the Skyrme and pairing forces (SkSC4) on which the ETFSI-1 mass formula is based (Y. Aboussir, J.M. Pearson, A.K. Dutta and F.Tondeur (1995) At. Data and Nucl. Data Tables 61, 127). Its parameters are fitted to the masses of 1761 (A>35) nuclei with a root mean square error of 745 keV. With no further adjustment of these parameters, the experimental primary (i.e. highest) barriers are reproduced within 1.5 MeV (except for elements with Z < 87 which have barriers above 10 MeV) [1].

The parameters of SkSC4 (see [1] for their meaning) are given by :

t0-1789.42 MeV fm3
t1283.467 MeV fm5
t2-283.467 MeV fm5
t312782.3 MeV fm4
x00.79
x1-0.5
x2-0.5
x31.13871
W0124.877 MeV fm5
g0.333333
V-220.0 MeV fm3