Ce-138

Reviewed by T. Nakagawa, JAERI, January 2004

**1. Files**

***ENDF/B-VI***: No data are given.

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

No data are given..

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

No data are given.

***CENDL-3***: Evaluation was made by Y.L.Han et al. in 2000.

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

**2. Thermal and resonance region**

***CENDL-3***

No resonance parameters were given.

Cross sections below 100 keV were calculated with a formula of
a+bE+C/sqrt(E).

Tables 2 and 3 compare the thermal cross sections and resonance integral
with experimental data. The capture resonance integral of CENDL-3 seems
to be too small.

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

***CENDL-3*** is recommended.

**3. Fast neutron region**

**(1) Methodology**

***CENDL-3***

Theoretical calculation was performed using the NUNF code. The optical
potential parameters were obtained by fitting to the total and
non-elastic scattering cross sections and angular distributions of
elastic scattering for natural Ce. Direct inelastic was calculated with
DWUCK-4.

Emitted particle distributions are given in MF=6. Gamma-ray production
data are also given.

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

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/Ce138.htm#mt1)Ce138.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/Ce138.htm#mt102)Ce138.htm#mt102

Maxwell averaged cross sections:

Average cross section (mb) at kT=25 keV

CENDL-3 48.3

Käppeler et al. \[Ka96\] 1935

CENDL-3 is possibly too small.

**(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/Ce138.htm#mt2)Ce138.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/Ce138.htm#mt4)Ce138.htm#mt4

Discrete levels considered in the evaluations are as follows:

CENDL-3 16 levels up to 2.4715 MeV

The direct inelastic was calculated with DWUCK4 code.

The data of continuum inelastic scattering is zero between threshold
(2.49 MeV) and 5.0 MeV. Therefore, the total inelastic has a small dip
at around 5 MeV and the capture, (n,p) and (n,) cross sections a peak at
the same energy.

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

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/Ce138.htm#mt16)Ce138.htm#mt16

Experimental data \[Qa74\] are reproduced well.

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

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/Ce138.htm#mt103)Ce138.htm#mt103

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

See Fig:
[http://www.nndc.bnl.gov/sg21/fp21/htm/](http://www.nndc.bnl.gov/sg21/fp21/htm/Ce138.htm#mt107)Ce138.htm#mt107

**(9) Other reactions**

The following reaction cross sections are given:

CENDL-3 (n,3n), (n,n), (n,np), (n,d), (n,t)

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

***CENDL-3*** is recommended.

**References**

\[He78\] Heft R.E.: *78Mayag*, p.495 (1978).

\[Ka96\] Käppeler F. et al.: *Phys. Rev.*, **C53**, 1397 (1996).

\[Ke56\] Ketelle B.H. et al. : *Phys. Rev.*, **103**, 190 (1956).

\[Mo50\] Moses A.J. and Martin D.S.: *Phys. Rev.*, **79**, 467 (1950).

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

\[Mu03\] Mughabghab S.F.: "Thermal Neutron Capture Cross Sections
Resonance Integrals and g-Factors," *INDC(NDS)*-440 (2002)

\[Po52\] Pomerance H.: *Phys. Rev.*, **88**, 412 (1952).

\[Qa74\] Qaim S.M.: *Nucl. Phys.*, **A224**, 319 (1974).

\[Se62\] Sehgal M.: *Phys. Rev.*, **128**, 761 (1962).

\[Va74\[ Van der Linden et al.: *J. Radioanl. Chem.*, **23**, 113
(1974).

Table 1 Summary for Resolved and Unresolved Resonance Region: Ce-138

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Library RRP URP Remarks

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> CENDL-3 not given not given

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Table 2. Thermal Cross Sections and Resonance Integral: Ce-138

Units: barns

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Library/Experiment Total Elastic Capture Res.Integ.

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CENDL-3 5.500 4.385 1.115 1.15

Mughabghab et al. \[Mu81\] 1.10.3

Mughabghab et al. \[Mu03\] 1.020.24

Pomeronce \[Po52\] 8.770%^\*1^

Van der Linden et al. \[Va74\] 1.210.13^\*2^

Heft \[He78\] 1.020.12^\*3^ 6.73.1

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\*1 Measured in Maxwell spectrum.

\*2 to a meta-stable state.

\*3 Measured in a reactor.

Table 3. Thermal Capture Cross Sections: Ce-138

Units: barns

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Library/Experiment ground meta ratio (M/G) total

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CENDL-3 1.115

Mughabghab et al. \[Mu81\] 1.1 0.3 0.0150005 0.0136 1.10.3

Mughabghab et al. \[Mu03\] 1.020.24 1.020.24

Moses ad Martin \[Mo50\] 0.81^\*1^

Pomeronce \[Po52\] 8.770%^\*2^

Ketelle et al. \[Ke56\] 1.0^\*3^ 0.007^\*4^

Sehgal \[Se62\] 1.260.20^\*5^ 0.0180.005^\*2^

Heft \[He78\] 1.020.12^\*6^

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\*1 Ratio of ^138^Ce(n,)/^140^Ce(n,) was measured in a reactor. The
result of 1.4 was translated to the ^138^Ce(n,) cross section by
assuming ^140^Ce(n,) of 0.58 barn \[Mu03\].

\*2 Measured in Maxell spectrum.

\*3 Measured in a reactor. ^140^Ce(n,) of 0.6 barn was assumed.

\*4 Measured in a reactor. ^136^Ce(n,)^137g^Ce of 2 barns was assumed.

\*5 Measured in Maxell spectrum. ^140^Ce(n,) of 0.6 barn was assumed.

\*6 Measured in a reactor.