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

**66-Dy-164 Review**

Qjng-Biao Shen, CNDC, January 30, 2002

Files

ENDF/B-VI: Year of origin 1974, taken from ENDF/B-V, last revision 1998

JEF-2: Year of origin 1982, data taken mostly from ENDF/B-IV, last
revision 1988

CENDL-3: Year of origin 1999, last revision 2001

**Thermal and resonance region**

ENDF/B-VI, The new evaluation was made in 1998. The upper limit of the
resolved resonance range is 16 keV. The number of the resolved
resonances is 117. The first positive level is at 146.97 eV, the
negative level at --1.88 eV. The unresolved resonance range is 16 to 50
keV.

JEF-2: Thermal cross sections and resonance parameters were taken from
ENDF/B-IV. The upper limit of the resolved resonance range is 272 eV.
The number of the resolved resonances is 2. The positive level is at
145.5 eV and the negative level at --1.89 eV. The unresolved resonance
range is 272 eV to 10 keV.

CENDL-3: Thermal cross sections and resonance parameters were taken from
ENDF/B-VI.

**Recommendation/Conclusion: ENDF/B-VI (or CENDL-3) recommended.**

**Fast neutron region**

● Methodology

ENDF/B-VI, JEF-2: Spherical OM for MT=1; capture from NCAP code;
inelastic cross sections (MF=3, MT=4, 51-91) from COMNUC-3 code, no
preeq corrections; elastic cross section obtained as (MT1-MT102-MT4);
isotropic angular distribution assumed for MF=4, MT=2 in CM system.

CENDL-3: Spherical OM and unified preeq-statistical model code SUNF;
DWBA code DWUCK4 to calculate direct inelastic scattering.

● MT=1

ENDF/B-VI, JEF-2, CENDL-3 agree with the experimental value of Djumin
(1977) at 14.2 MeV. (Fig.1). ENDF/B-VI, CENDL-3 agree with the
experimental values of Dy-Nat. (Fig.2).

● MT=102

ENDF/B-VI, CENDL-3 agree with the experimental values below 0.5 MeV and
at 14.8 MeV (Fig.3). Figs.4-6 show the experimental data of (n, g) cross
sections of neighboring nuclide Gd156, Gd158, Gd160, respectively.
Dy164, Gd156, Gd158, Gd160 all have even proton and even mass number.
From Figs.4-6 one can see that the experimental values of (n, g) cross
sections between 0.5-3.0 MeV become higher since the structure of the
even mass number nuclide. They supports the CENDL-3 results. From Fig.3
one can see that the (n, g) cross section of C3 at 6-10 MeV energy
region has a deep valley from where the contribution of the direct and
semi-direct capture becomes rising as the energy increases.

● MT=4

Fig.7 shows the comparison of the evaluation (n, inl) cross sections of
Dy164 with the (n, inl) experimental data of the Dy-Nat. The result of
CENDL-3 is basically agreement with the experimental data of the Dy-Nat
and it is a little higher than the experimental data as Dy164 is the
existed heaviest isotope of the element Dy in the nature.

● MT=16

Figs.8-10 show the comparisons of the evaluation (n,2n) cross sections
of Dy164 with the (n,2n) experimental data of the neighboring nuclide
Gd158, Gd160, and Tm169, respectively, in which the thresholds maybe are
different. The shapes of the distributions of the experimental data
support the CENDL-3.

● MT=103

Fig.11 shows the comparison of the evaluation (n, p) cross sections with
the experimental data. CENDL-3 is in good agreement with the
experimental data. That in ENDF/B-VI was constructed.

● MT=107

Fig.12 shows the comparison of the evaluation (n, alpha) cross sections
with the experimental data. The result in CENDL-3 was calculated and
that in ENDF/B-VI was constructed. The experimental data of Wille (1960)
and Khurana (1965) were recommended.

**Recommendation/Conclusion: CENDL-3 recommended in fast energy region
50 keV - 20 MeV, CENDL-3 probably is in better agreement with the
measured data and accounting for direct inelastic scattering.**

**Table 1. Summary for Resolved and Unresolved Resonance Region:
Dy-164**

+---------+-----+------------+--------+--------+---------------------+
| Library | Y   | Authors    | RRR    | URR    | Remark              |
|         | ear |            |        |        |                     |
+---------+-----+------------+--------+--------+---------------------+
| END     | 1   | Wright     | 16 keV | 50 keV | Resonance           |
| F/B-VI, | 998 | (ORNL)     |        |        | parameters based on |
|         |     |            | MLBW   |        | BNL-325 (1984). No  |
|         |     | Leonard    |        |        | File 3 background.  |
|         |     | (BNW)      |        |        |                     |
|         |     |            |        |        |                     |
|         |     | Stewart    |        |        |                     |
|         |     | (BNW)      |        |        |                     |
+---------+-----+------------+--------+--------+---------------------+
| JEF-2   | 1   | Scientific | 272 eV | 10 keV | Data taken from     |
|         | 988 | Co         |        |        | ENDF/B-IV.          |
|         |     | ordination | MLBW   |        |                     |
|         |     |            |        |        | Last revision 1988. |
|         |     | Group      |        |        | Pointwise data up   |
|         |     |            |        |        | to 2.229 eV.        |
+---------+-----+------------+--------+--------+---------------------+
| CENDL-3 | 2   | Y          | 16 keV | 50 keV | Resonance           |
|         | 001 | .X.Zhuang, |        |        | parameters taken    |
|         |     |            | MLBW   |        | from ENDF/B-VI.     |
|         |     | Z.G.Ge,    |        |        |                     |
|         |     |            |        |        |                     |
|         |     | Z          |        |        |                     |
|         |     | .J.Zhuang, |        |        |                     |
|         |     |            |        |        |                     |
|         |     | Q.B.Shen   |        |        |                     |
|         |     |            |        |        |                     |
|         |     | (CNDC)     |        |        |                     |
+---------+-----+------------+--------+--------+---------------------+

**Table 2. Thermal Cross Sections for Dy-164**

+-----------------+-----------------+-----------------+-----------------+
| Library/        | Total           | Capture         | Elastic         |
|                 |                 |                 |                 |
| Experiment      |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| ENDF/B-VI       | 2977.5 b        | 2650.6 b        |                 |
+-----------------+-----------------+-----------------+-----------------+
| JEF-2           | 2911 b          | 2521 b          |                 |
+-----------------+-----------------+-----------------+-----------------+
| CENDL-3         | 2977.5 b        | 2650.6 b        |                 |
+-----------------+-----------------+-----------------+-----------------+
| Vertebnyj       | 3000(+45,-70) b | 2740(+45,-70) b |                 |
| (1970)          |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| Ohno (1968)     | 2780(60) b      |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| Alstad (1972)   |                 | 2800(110) b     |                 |
+-----------------+-----------------+-----------------+-----------------+
| Ryves (1974)    |                 | 2700(200) b     |                 |
+-----------------+-----------------+-----------------+-----------------+
| BNL-325 (1973)  |                 | 2700(75) b      | 347(30) b       |
+-----------------+-----------------+-----------------+-----------------+
| BNL-325 (1984)  |                 | 2650(100) b     | 319(10) b       |
+-----------------+-----------------+-----------------+-----------------+

![](media/image1.png){width="5.833333333333333in" height="4.375in"}

**Fig.1**

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**Fig.2**

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**Fig.3**

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**Fig.4**

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**Fig.5**

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**Fig.6**

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**Fig.7**

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**Fig.8**

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**Fig.9**

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**Fig.10**

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**Fig.11**

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**Fig.12**