La-140

Reviewed by T. Nakagawa, JAERI, January 2004

**1. Files**

***ENDF/B-VI***: The data were evaluated by Schenter and Schmitroth in
1974.

***JENDL-3.3 and JENDL-3.2***:

No data are given..

***JEFF-3.0 and JEF-2.2***:

ENDF/B-V was adopted for JEF-2. Charged particle emission cross sections
(MT's = from 104 to 111) were adopted from REAC-ECN-4. JEFF-3.0 is the
same as JEF-2.2

***CENDL-3***: No data are given.

***BROND-2***: No data are given.

**2. Thermal and resonance region**

***ENDF/B-VI***

No resolved resonance parameters were given.

In the energy range below 61.274 eV, the capture cross section was
assumed to be in the 1/v form with thermal cross section of 2.7 barns
\[Mu73\] and the elastic scattering cross section to be a constant.

No unresolved resonance parameters are given.

***JEFF-3.0 and JEF-2.2***

The same as ENDF/B-VI.

**[Recommendation/conclusion for the thermal and resonance
region]{.underline}**

***ENDF/B-VI*** is recommended.

**3. Fast neutron region**

**(1) Methodology**

***ENDF/B-VI***

Theoretical calculation was performed using the optical potential of
Moldauer and statistical model. No threshold reaction cross sections
were taken into account.

All angular distributions were assumed to be isotropic. Evaporation
spectra were given to the continuum inelastic scattering.

***JEFF-3.0 and JEF-2.2***

The data of ENDF/B-VI were adopted for the total, inelastic and capture
cross sections. The charged particle emission cross sections (MT=104 to
111) were adopted from REAC-ECN-4.

**(2) Total cross section (MT=1)**

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/La140.htm#mt1)La140.htm#mt1

**(3) Capture cross section (MT=102)**

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/La140.htm#mt102)La140.htm#mt102

**(4) Elastic scattering cross section (MT=2)**

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/La140.htm#mt2)La140.htm#mt2

**(5) Inelastic scattering cross section (MT=4, 51 -- 91)**

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/La140.htm#mt4)La140.htm#mt4

Discrete levels considered in the evaluations are as follows:

ENDF/B-VI, JEFF-3.0 6 levels up to 0.581 MeV

The direct inelastic was not considered.

**(6) (n,2n) reaction cross section (MT=16)**

No data exist in the current evaluated data files.

**(7) (n,p) reaction cross section (MT=103)**

No data exist in the current evaluated data files.

**(8) (n,α) reaction cross section (MT=107)**

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/La140.htm#mt107)La140.htm#mt107

**(9) Other reactions**

The following reaction cross sections are given:

JEFF-3.0 (n,d), (n,t), (n,^3^He), (n,2p)

**[Recommendation/conclusion for the fast energy region]{.underline}**

***JEFF-3.0 (=JEF-2.2)*** is recommended.

**References**

\[Ka49\] Katcoff S. et al.: *J. Chem. Phys.*, **17**, 421 (1949).

\[Mu73\] Mughabghab S.F. and Garber D.I.: "Neutron Cross Sections, Vol.
I," *BNL*-325 3-rd Edition (1973).

\[Mu81\] Mughabghab S.F. et al.: *Neutron Cross Sections, Vol. 1, part
A*, Academic press (1981).

\[Ob67\] O'brien H.A. et al.: *J. Inorg. Nucl. Chem.*, **29**, 584
(1967).

Table 1 Summary for Resolved and Unresolved Resonance Region: La-140

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Library RRP URP Remarks

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> ENDF/B-VI not given not given 1/v region up to 61.274 eV
>
> JEFF-3.0 not given not given the same as ENDF/B-VI

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Table 2. Thermal Cross Sections and Resonance Integral: La-140

Units: barns

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Library/Experiment Total Elastic Capture Res.Integ.

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ENDF/B-VI 7.630 4.930 2.700 65.1

JEFF-3.0 7.630 4.930 2.700 65.1

Mughabghab et al. \[Mu73\] 2.7±0.3

Mughabghab et al. \[Mu81\] 2.7±0.3 69±4

Katcoff et al. \[Ka49\] 3.1±1.0\*

O'brien et al. \[Ob67\] 2.7±0.3 69±4 (0.54 eV)

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\*) Maxwell average.