Contribution to Subgroup 21

Eu-153

Reviewed by A.Ignatyuk, March, 2004

**1. Files**

***ENDF/B-VI***: Evaluation was made in 1986 for ENDF/B-VI and resonance
parameters were revised for the Release 7 in 1999.

***JENDL-3.3***: Evaluation was made for JENDL-2 in 1984. JENDL-2 data
were revised in 1989 for JENDL-3.1, modified for JENDL-3.2 in 1994 and
transformed to JENDL-3.3 in 2001 with some corrections.

***JEF-3.0***: JENDL-3.2 was adopted in 2002.

***BROND-2***: Evaluation was made in1985. Resonance parameters and
threshold reaction cross sections were revised in 1989.

***CENDL-3***: Evaluation was performed in 1999.

**2. Thermal and resonance region**

***(1) Resolved resonance parameters***

***ENDF/B-VI*** (1.0e-5 -- 97.8 eV)***)***: The resonance parameters
were taken from the compilation of Mughabghab \[Mu84\]. MLBW formalism
was used. The average radiative width of 93 meV was assigned to
resonances for which widths had not been determined from measurements.
All the observed resonances were assigned as s-wave according to
Bayesian analysis and resonance spins were assigned randomly to those
resonances for which the spin is unknown.

***JENDL-3.3*** (1.0e-5 eV -- 97.2 eV): The resonance parameters were
evaluated for JENDL-2 by Kikuchi et al. \[Ki86\]. MLBW formalism was
used. Negative resonance parameters were adjusted to reproduce the
thermal capture and scattering cross sections.

***BROND-2*** (1.0e-5-- 100. eV): The parameters were taken in
accordance with the recommendation of Mughabghab \[Mu84\]. MLBW
formalism was used. A negative resonance was included to reproduce the
thermal cross sections.

***CENDL-3*** (1.0e-5 eV -- 97.2 eV): JENDL-3.2 was adopted.

***(2) Unresolved resonance parameters***

***ENDF/B-VI*** (97.8 eV -- 83.91 keV): Average s-wave resonance
parameters, obtained from the resolved resonance region, were applied
without adjustments in the unresolved resonance region: D0=1.14 eV,
S0=2.37, =93 meV. S2=5.40 was adopted from the compilation \[Mu84\]. The
p-wave strength function S1=0.60 was adjusted to reproduce the capture
cross sections \[Bo85, Ma87, Yu93, Xi94\].

***JENDL-3.3*** (97.2 eV -- 100 keV): The neutron strength functions
S0=2.60 and the average radiative width of 94 meV were taken from the
analysis of resolved resonances. S1=1.39 and S2=2.95 were estimated from
the optical model calculations. The resonance spacing D0=1.489 eV was
determined to reproduce the capture cross section \[Ma87\] at 30 keV.

***BROND-2*** (0.1 -- 100 keV): The statistical model was used with the
parameters fitted to experimental data on the capture cross section. The
neutron strength function S0=2.5 and the resonance spacing D0=1.37 were
taken from the analysis of resolved resonances, the strength functions
S1=0.8 and S2=6.5 were estimated from the optical model calculations,
and the average gamma-ray widths were determined to reproduce the
capture cross section.

***CENDL-3*** (97.2 eV -- 100 keV): JENDL-3.2 was adopted.

***(3). Thermal cross sections and resonance integrals*** (in barns)
calculated for the corresponding files are compared in the following
table:

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Library/Experiment Total Elastic Capture Cap.Res.Integ.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

ENDF/B-VI 321.0 9.0 312.0 1410

JENDL-3.3 323.0 10.3 312.7 1410

JEF-3.0 321.0 9.0 312.0 1410

BROND-2 322.1 9.5 312.6 1428

CENDL-3.2 323.0 10.3 312.7 1410

Mughabghab \[Mu84\] 9.7(7) 312(7) 1420(100)

Mughabghab \[Mu03\] 312(7) 1420(100)

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

***(4) Recommendation/conclusion for resonance region***

There are no essential differences in the parameters of resolved neutron
resonances. Some difference is available between adopted values of
neutron strength functions for s- and d- waves, which is partially
compensated by adjustment of the resonance spacing and radiative
strength functions. As a result, there is a good agreement between the
evaluated cross sections for unresolved resonances (Fig. 1). ENDF/B-VI
evaluation looks preferable a little due its adjustment to the full set
of recent experimental data on the capture cross sections \[Bo85, Ma87,
Yu93, Xi94\].

![](media/image1.wmf)

Fig. 1. Calculated group cross sections for the region of unresolved
resonances

**3. Fast neutron region**

***(1) Methodology***

Statistical model calculations were widely used for all evaluations.
However the optical potential parameters and the corresponding
statistical codes were rather different that reflected into the obtained
results.

***ENDF/B-VI***

The total, elastic and inelastic scattering, and capture cross sections
were calculated with the deformed optical model and the statistical
model code GNASH. The contribution of direct and preequilibrium
processes was taken into account. Parameters for the preequilibrium
model were adjusted to improve agreement with available experimental
data. Preequilibrium model calculations were also used for evaluations
of secondary neutron energy spectra. Charged-particle production data
were taken from ENDF/B-V, which were calculated with the TRESH code.
Gamma-ray production cross sections and spectra were included on the
basis of GNASH calculations.

***JENDL-3.3***

The total, elastic and inelastic scattering, and capture cross sections
were calculated with the spherical optical model and the statistical
model code CASTHY. The contribution of preequilibrium processes was
taken into account through the PEGASUS code. The gamma-ray strength
function was adjusted to reproduce the capture cross section of 680 mb
at 250 keV measured by Macklin and Young \[Ma87\]. Direct and
semi-direct capture cross sections at high energies were estimated
according to the procedure of Benzi and Reffo \[Be69\] and normalized to
1 mb at 14 MeV. The threshold reaction cross sections were calculated
with the GNASH code. The (n,p) and (n,) reaction cross sections were
normalized to the systematics of Forrest \[Fo86\] at 14.5 MeV. GNASH
calculations were also used for evaluations of secondary neutron energy
spectra. Gamma-ray production cross sections and spectra were included
on the basis of GNASH calculations.

***BROND-2***

The total, elastic and inelastic scattering cross sections were
calculated with the spherical optical model and the statistical model
code. Capture cross section calculations were adjusted to the
experi-mental data \[Bo85, Ma87\]. The capture cross section above 5 MeV
was estimated in accordance with the systematics based on the
direct-collective radiative capture model \[Be84\]. Threshold reaction
cross sections were taken from ENDF/B-IV evaluations renormalized to
available experimental data. The temperature approximation was used for
neutron evaporation spectra. Gamma-ray production cross sections and
spectra were included on the basis of GROGI-3 calculations.

***CENDL-3***

The total, elastic and inelastic scattering cross sections were
calculated with the spherical optical model and the contributions of
direct processes were taken into account with the DWUCK-4 code. The
inelastic scattering and all threshold reaction cross sections were
calculated with the statistical model code SUNF. The same code was used
for calculations of angular and energy distributions of secondary
neutrons.

***(2) Intercomparison of evaluations***

**Total cross section** (MT=1, Fig:
http://www.nndc.bnl.gov/sg21/fp/nucl/Eu153/Eu153tot.htm):

All calculations performed with the optical model are rather similar.
They reproduce the available experimental data on the total cross
section for natural europium at energies above 10 MeV. ENDF/B-VI seems
preferable due to more consistent description of inelastic cross
sections.

**Capture cross section** (MT=102, Fig.:
http://www.nndc.bnl.gov/sg21/fp/nucl//Eu153/Eu153cap.htm):

All evaluations are very similar and well describe experimental data
below 1 MeV. Some difference of evaluated cross sections above 2 MeV is
not important for most applications considering too low values of cross
sections. JENDL-3.3 and BROND-2 look a little better at high energies
owing to more consistent models.

**Inelastic scattering** (MT=4, Fig.
http://www.nndc.bnl.gov/sg21/fp/nucl//Eu153/Eu153inl.htm):

BROND calculations based on the spherical optical models certainly give
too low inelastic scattering cross sections above 10 MeV. JENDL-3.3
seems contradictive at energies below 10 MeV and also above 15 MeV.
ENDF/B-VI and CENDL-3, which take into account direct and preequilibrium
processes, look preferable for the whole energy region.

**(n,2n) cross section** (MT=16, Fig:
http://www.nndc.bnl.gov/sg21/fp/nucl//Eu153/Eu153n2n.htm):

Evaluations of ENDF/B-VI, JENDL-3.3, and CENDL-3 are based on very
similar codes and any of them looks reasonable enough.

**(n,p) and (n,) cross sections** (Figs.
http://www.nndc.bnl.gov/sg21/fp/nucl//Eu153/Eu153np.htm ,
http://www.nndc.bnl.gov/sg21/nucl//Eu153/Eu153na.htm):

Charge-particle production cross sections have very low importance for
reactor applications. Experimental data are scant and contradictive as a
rule. All evaluations are normalized to the same data and any of them
seems acceptable.

***(3) Recommendation/conclusions for fast neutron region***

ENDF/B-VI and CENDL-3 can be considered as good evaluations for most
cross sections in the fast neutron region. ENDF/B-VI can be given a
rather small preference due to consistent consideration of full set of
required cross sections including gamma-ray yields.

**References**

\[Be84\] Belanova T.S. et al.: Radiative Neutron Capture -- Handbook.
Moscow, Energoatomizdat, 1986.

\[Be69\] V.Benzi, G.Reffo, Report CCDN-NW/10 (1969).

\[Bo85\] Bokhovko,M.V. et al., Yad.Konst.,1985(2),44 (1985)

\[Fo86\] Forrest R.A.: *AERE-R* 12419 (1986).

\[Ki86\] Y.Kikuchi et al. JAERI-M 86-30 (1986).

\[Ma87\] R.Macklin, P.Young, Nucl.Sci.Eng.,95, (1987) 189.

\[Mu84\] S. Mughabghab. Neutron Cross Sections, Vol.1, Part B, Academic
Press, 1984.

\[Mu03\] S. Mughabghab.Thermal Neutron Capture Cross Sections, Resonance
Integrals and G-factors. Report INDC(NDS)-440, IAEA, Vienna, 2003.

\[Yu93\] Yu Weixiang et al., Chinese J.Nucl.Phys.,15, (1993) 71.

\[Xi94\] Xia YiJin et al., Proc. Conf. on Nucl. Data for Sci. Technol.(
Gatlinburg, May 1994, p.251.