WPEC SG 21: Assessment of Neutron Cross-Section Evaluations for the Bulk
of Fission Products

**Ag-109**

Reviewed by Shen Qingbiao, CIAE, February, 2003

**1. Files**

***ENDF/B-VI***: Evaluation was made in 1983 for ENDF/B-V. It was
converted to ENDF/B-VI in 1990. The new/modified ENDF/B-VI evaluation
was made in 1999 in which the resonance parameters and the smooth cross
sections for MF=3, MT=1,2,102 up t0 134 MeV were modified.

***JENDL-3.2, CENDL-3 (CENDL-2.1)***:

The evaluation was made by Liu (Chinese), Nakagawa (Japanese), Shibata
(Japanese) in 1987 for JENDL-3. After some modification it was converted
to JENDL3.2 in 1994.In CENDL2.1 and CENDL3 the same file is kept

***JEF-2.2***: Evaluation data were taken from RCN-3 evaluation in 1983.
After more modification in 1985, 1986, 1989, 1990 it was converted to
JEF2.2 in 1992.

***BROND-2***: The evaluation was made in1985. The revision was made for
unresolved resonance region in 1989.

Figs: <http://www.nndc.bnl.gov/~sirakov/fp/fp21/htm/Ag109.htm#mt1>

**2. Thermal and resonance region**

\(1\) Resolved resonance parameters

***ENDF/B-VI*** (1.0e-5 eV -- 4.9963 keV)

The resolved resonance parameters up to 2.506 keV were based on
Mughabghab \[Mu81\]. Below this energy region, spin assignment of Corvi
\[Co97\] and neutron widths of Lowie \[Lo97\] were incorporated.
Parameters in energy region 2.6 -- 5.0 keV were based on Macklin
\[Ma82\] and Mizumoto \[Mi83\].

***JENDL-3.2, CENDL-3 (CENDL-2.1)*** (1.0e-5 eV -- 7.0095 keV)

The resolved resonance parameters of JENDL3.2 are the same as those of
JENDL2. The evaluation for JENDL-2 was based on the experimental data of
Moxon et al. \[Mo61\] and so on. P-wave resonances with capture area
were added.

***JEF-2.2*** (1.0e-5 eV -- 0.984 keV)

The resolved resonance parameters were replaced by data from BROOKHAVEN
compilation \[Mu81\].

***BROND-2*** (1.0e-5 eV -- 1.0 keV)

MLBW with resonance parameters from Mughabghab et al. \[Mu81\] were
used. .

\(2\) Unresolved resonance parameters

***ENDF/B-VI*** (4.9963-- 88.815 keV)

Given as 'all energy-dependent parameters'. \<D0\> and S0 were based on
the fitting of reduced widths of resolved resonances to the
Porter-Thomas distribution. S0 was adjusted to reproduce capture cross
section measurements of Macklin \[Ma82\], Bokhovko \[Bo87\], and
Mizumoto \[Mi83\]. Energy- and J-dependence of level spacing were
calculated according to the Gilbert- Cameron's level density formula
with associated parameters from Mughabghab \[Mu98\].

***JENDL-3.2, CENDL-3 (CENDL-2.1***) (7.0095-- 100 keV)

The parameters were determined with code ASREP \[Ki\*\*\] to reproduce
the capture and total cross sections, which were based on experimental
data \[Po83\], \[Mi82\].

***JEF-2.2*** (0.984-- 80 keV)

Strength function: capture cross section with code FISPRO-RCN; other
cross sections with code SASSI-RCN.

***BROND-2*** (1.0 -- 200 keV)

The energy dependent representations for resonance widths are used. They
were calculated from statistical description of the neutron capture
cross sections with code EVPAR \[Ma83\].

\(3\) Recommendation/conclusion for resonance region

The resonance parameters of ***ENDF/B-VI*** is the newest and is
recommended. The others are also better.

**3. Fast neutron region**

\(1\) Methodology

***ENDF/B-VI***

Theoretical calculation was widely used. The optical model and
Hauser-Feshbach theory were used. The 20 levels up to 1.66 MeV were
considered for the inelastic scattering.

Legendre coefficients of elastically scattered neutrons were calculated.
Isotropic distributions were given to the other reactions..

Evaporation spectra were given to the continuum inelastic scattering.

***JENDL-3.2, CENDL-3 (CENDL-2.1)***:

The total, elastic and inelastic scattering, and capture cross sections
were calculated with the spherical optical model and statistical model
code CASTHY and TNG. The 14 levels up to 1.099 MeV were considered for
the inelastic scattering.

The angular distributions of elastic scattering were calculated with
CASTHY code and the angular distributions of inelastic scattering were
calculated with TNG code. Isotropic distributions were assumed to the
other reactions.

The energy distributions were calculated with TNG code.

***JEF-2.2***

All cross sections were calculated with code SASSI-RCN.

***BROND-2***

All cross sections above 200 keV were taken from ENDF/BV excepting
capture cross sections. The capture cross sections in the energy region
from 200 keV to 800 keV were calculated in the frame of statistical
model, in region of 800 keV-8 MeV were taken from empirical description
of the experimental data, above 8 MeV were evaluated in the frame of
direct-collective neutron capture model, which was based on systematics
of the experimental data.

The angular distributions of elastic scattering were calculated with
optical model. Isotropic distributions were assumed to the other
reactions.

The evaporation energy distributions were given. .

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

Only one experimental data at around 14 MeV can be found for Ag-109. The
following figure compares the

evaluated data with the measured total cross section of natural Ag. From
this figure, it is seen that ***ENDF/B-VI, JENDL-3.2, CENDL-3
(CENDL-2.1)*** reproduce well the experimental data.

![](media/image1.png){width="6.490277777777778in"
height="6.857638888888889in"}

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

***ROND-2*** is better in agreement with the experimental data and its
shape is reasonable. ***ENDF/B-VI,*** and ***JENDL-3.2 (CENDL-3)*** are
also better in agreement with the experimental data but their shapes in
8-20 MeV region are not reasonable.

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

This cross section was obtained as (total cross section) -- (sum of
partial cross sections) in the all

libraries.

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

Excited levels considered in the files.

> ENDF/B-VI 20 levels up to 1.66 MeV
>
> JENDL-3.2, CENDL-14 levels up to 1.099 MeV
>
> JEF-2.2 14 levels up to 0.911 MeV
>
> BROND-2 5 levels up to 0.702 MeV

No experimental data are available for Ag109 total inelastic scattering
cross section. The shapes of total inelastic scattering cross section of
all libraries are reasonable and acceptable.

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

The following figure shows the evaluated data and the measured ground
state (G) or isomeric state (M) (n,2n) cross sections. It is seen that
the total (n,2n) cross sections (G+M) of ***ENDF/B-VI***, ***JENDL-3.2,
CENDL-3 (CENDL-2.1), JEF-2.2*** are reasonable and acceptable. The value
of ***ROND-2*** is too larger.

![](media/image2.png){width="6.490277777777778in"
height="6.686111111111111in"}

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

***ENDF/B-VI*** is in better agreement with the (n,p) experimental data.
The next is ***JENDL-3.2, CENDL-3 (CENDL-2.1),*** then is ***JEF-2.***
The results of ***ROND-2*** is not good compared with the experimental
data.

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

The measured total (n,α) cross section at 14.8 MeV by S. K. Mukherjee et
al. (INDSAH) on the facility CCW is 12±3 mb, whereas the measured
isometric (n,α) cross section at 14.0 MeV by C. S. Khurana et al.
(INDMUA) on the same facility CCW is 38±9.5 mb. It is impossible. The
measured isometric (n,α) cross section at 14.3 MeV by T. B. Ryves et al.
is 2.1±0.2 mb. The following figure shows the evaluated data and the
measured data of the closed odd A nucleus In115. It is seen that the
measured values by Indian scientists are too large. The shapes and
values of ***ENDF/B-VI*** and ***JENDL-3.2, CENDL-3 (CENDL-2.1)*** are
reasonable and acceptable.

![](media/image3.png){width="6.490277777777778in" height="6.31875in"}

\(9\) Other reactions

The following other reaction cross sections are given in the files.

> ENDF/B (n,3n), (n,nα), (n,np), (n,d), (n,t), (n,He-3) (n,xp), (n,xd),
> (n,xt), (n,xHe-3), (n,xα)
>
> JENDL-3.2, CENDL-3: (n,3n), (n,nα), (n,np)
>
> JEF-2.2 (n,d), (n,t), (n,He-3), (n,2p)
>
> BROND-2 no

\(10\) Recommendation/conclusions for fast neutron region

***ENDF/B-VI*** or ***JENDL-3.2, CENDL-3 (CENDL-2.1)*** is recommended.
But the shapes and values of the capture cross sections above 8 MeV are
not reasonable for ***ENDF/B-VI*** and ***JENDL-3.2, CENDL-3
(CENDL-2.1).*** The (n,p) cross sections and the capture cross sections
at low energy region of ***ENDF/B-VI*** seems a little better than
***JENDL-3.2, CENDL-3 (CENDL-2.1).***

**References**

\[Bo87\] M.V. Bokhovko et al.,report INDC(CCP)-280/L (1987) p. 15

\[Co97\] F. Corvi, private comm.; also see Nuclear Data for Sci. and
Technology, Proc. Conf., Trieste, May 1997 (Italian Physical Soc., 1997)
p. 731

\[Ha50\] S. P. Harris et al., J, PR, 79, 11 (1950).

\[Ke63\] B. Keish, J, PR, 129, 769 (1963).

\[Ki\*\*\] Y. Kikuchi, Private Communication.

\[Lo97\] L.Y. Lowie et al., Phys.Rev.C 56, 90 (1997)

\[Ma82\] R.L. Macklin, Nucl.Sci.Eng. 82, 400 (1982)

\[Ma83\] G.N. Manturov et al., Nuclear Constants, 1(50), 50 (1983).

\[Mi82\] M. Mizumoto et al., 'Proc. Inter. Conf. on Nucl. Data for
Science and Technology', Antewerp, p.226 (1982)

\[Mi83\] M. Mizumoto et al., J.Nucl.Sci.Technol. 20, 883 (1983)

\[Mo61\] M. C. Moxon et al., 'Proc. EANDC Conf. on Time-of-Flight
Method. Saclay, 1961', 439.

\[Mu01\] Mughabghab S.F.: *INDC(NDS)*-424, p.69 (2001).

\[Mu81\] S.F. Mughabghab et al., Neutron Cross Sections, Vol.1, Part A
(Academic Press, 1981)

\[Mu98\] S.F. Mughabghab and C.L. Dunford, Proc. Int. Conf. on Physics
of Nuclear Sci. and Technol., Long Island, October 1998 (American
Nuclear Soc., 1998) p. 784

\[Po52\] H. Pomerance, J, PR, 88, 412 (1952).

\[Po83\] W. P. Poenitz et al., ANL-NDM-80(1983).

\[Se47\] L. Seren et al. J, PR, 72, 888 (1947)

\[Si68\] G. H. E. Sims et al. J, JIN, 30, 349 (1968).

\[Ta60\] R. B. Tattersall et al., J, JNE/A, 12, 32 (1960).

Table 1. Summary for Resolved and Unresolved Resonance Region: Ag-109

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

Library RRP URP Remarks

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

ENDF/B-VI 4.9963 keV MLBW 88.815 keV

JENDL-3.2, CENDL-3 7.0095 keV MLBW 100 keV

JEF-2.2 0.984 keV SLBW 80 keV

BROND-2 1.0 keV MLBW 200 keV

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

Table 2. Thermal Cross Sections and Resonance Integral: Ag-109

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

Library/Experiment Total Elastic Capture Res.Integ.

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

ENDF/B-VI 92.9407 2.1058 90.8349 1473.28

JENDL-3.2, CENDL-3. 93.0182 2.48259 90.5356 1470.25

JEF-2.2 93.0086 2.29851 90.7101 1467.62

BROND-2 92.7444 2.27076 90.4737 1468.46

Mughabghab et al. \[Mu81\] 2.55±0.06 91.0±1.0 1400±48

Mughabghab \[Mu01\] 91.0±1.0

Seren \[Se47\] 99.3±19.86\*1

Pomerance \[Po52\] 84.0±6.72\*1

Keish \[Ke63\] 92.2±4.02\*1

Tattersall \[Ta60\] 92.0±2.0 1870±200

Harris \[Ha50\] 1213.0

Sims \[Si68\] 81.1±2.2

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

\*1) Maxwellian averaged

**[Attachment 2]{.underline}**

Figures: <http://www.nndc.bnl.gov/~sirakov/fp/fp21/htm/Ag109.htm#mt1>