92-U -238
92-U -238 KYU+ EVAL-Mar00 T.Kawano et al.
DIST-MAR02 REV4-FEB02 20020214
----JENDL-3.3 MATERIAL 9237
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
87-01 Simultaneous evaluation for fission and capture cross
sections was completed in the energy range above 50 keV.
87-04 Other quantities were evaluated by
Y. Kanda and Y. Uenohara (Kyushu Univ.): MF's = 3, 4 and 5
above resonance region.
T. Nakagawa (JAERI) : Resolved resonance parameters and
background cross sections.
K. Hida (NAIG) : Data for gamma-ray production.
88-03 Data of total, elastic, inelastic (MT=59,60) and capture
cross sections were partly modified.
89-03 Data of total, elastic, inelastic and capture cross sections
were modified. Unresolved resonance parameters were also
modified. FP yields were added.
94-01 JENDL-3.2.
Inelastic scattering and (n,3n) cross sections re-evaluated
by Y.Kanda and T.Kawano (Kyushu Univ.)/1/
Resolved resonance parameters modified by T.Nakagawa(JAERI)
Unresolved resonance parameters modified by Y.Kikuchi(JAERI)
Fission spectra calculated by T.Ohsawa(Kinki Univ.)
Compiled by T.Nakagawa (NDC/JAERI)
00-03 JENDL-3.3.
Mainly modified by T.Kawano.
Delayed neutron data by JNDC Delayed Neutron WG.
Fission spectra calculated by T.Ohsawa(Kinki Univ.)
01-04 Compiled by T.Nakagawa (NDC/JAERI)
***** Modified parts from JENDL-3.2 ********************
(1,455)
(3,2),(3,4),(3,16),(3,17),(3,18),(3,37),(3,54,55,56,91)
(3,102)
(3,77) -- (3,83): deleted.
(4,2), (4,37), (4,91)
(5,16), (5,17), (5,18), (5,37), (5,91), (5,455)
***********************************************************
02-01 Covariances were added by K.Shibata.
MF=1 General Information
MT=451 Descriptive data and directory records
MT=452 Number of neutrons per fission
Sum of MT's= 455 and 456
MT=455 Delayed neutron data
Experimental data of Krick and Evans /2/ were renormalized
to those of Meadows /3/, and the least-squares fitting was
carried out with the SOK code /4/.
Decay constants at the thermal energy were adopted from
Keepin et al. /5/
MT=456 Number of prompt neutrons per fission
Taken from evaluation by Frehaut /6/.
MF=2 Resonance Parameters
MT=151 Resolved and unresolved resonance parameters
1) Resolved resonance parameters for RM formula
(resolved resonance region = 1.0E-5 eV to 10 keV)
Parameters were adopted from JEF-2 evaluation /7/ and the
energy range was divided into 10 intervals by assuming
hypothetical resonances outside each interval. Parameters
of the hypotetical resonances were determined by means of
SAMMY/8/.
2) Unresolved resonance parameters
(unresolved resonance region = 10 keV to 150 keV)
Parameters were obtained with the parameter fitting code
ASREP/9/ so as to reproduce the cross sections evaluated in
this energy region.
2200-m/s cross sections and calculated resonance integrals.
2200 m/s(b) res. integ.(b)
total 12.077
elastic 9.360
fission 11.8E-6 1.72
capture 2.717 277.
MF=3 Neutron Cross Sections
Below 10 keV, no background cross sections were given.
Above 10 keV, cross sections were evaluated as follows, and
they were represented with the unresolved resonance
parameters except the fission cross section.
MT=1 Total
The same as JENDL-3.2 which were based on the following
experimental data as well as the coupled-channel model cal-
culation in Ref./10/
Below 500 keV: Uttley et al./11/, Whalen et al./12/.
Poenitz et al./13/, Tsubone et al./14/
0.5 - 4.5 MeV: Poenitz et al./13/, Tsubone et al./14/,
Kopsch et al./15/.
4.5 - 15 MeV : Foster and Glasgow /16/
15 - 20 MeV : Bratenahl et al./17/, Peterson et
al./18/.
MT=2 Elastic Scattering
Calculated as (Total)-(Partial cross sections)
MT=4, 51-77, 91 Total and partial inelastic scattering
Cross sections were calculated by taking account of direct
and compound processes.
For JENDL-3.3, the contriburion from direct process was
re-calculated for MT=54, 55 and 56.
1) Direct process
Coupled-channel model code ECIS88/19/ was used for calcula-
tion of direct inelastic cross sections to the excited levels
which belog to the vibrational bands and the ground state
rotational band. For the levels of MT = 65, 68, 73, 76 and
77, the direct cross sections were not included. The optical
potential parameters were taken from Ref./10/.
V0=46.2 - 0.3E, Ws = 3.6 + 0.4E, Vso = 6.2 (MEV)
r = 1.26, rs=1.26, rso=1.12 (fm)
a = 0.63, as=0.52, aso=0.47 (fm)
beta-2 =0.198, beta-4 =0.057
The band coupling strength (beta) was determined from the
experimental cross section data/20, 21, 22, 23, 24/ and
DDX data/25/.
2) Compound process:
Compound inelastic scattering cross sections to the 1st and
2nd levels were calculated with ECIS88/19/. Those to the
other levels were calculated using Hauser-Feshbach-Moldauer
(HFM) theory/26/. The optical potential parameters/27/
used in HFM calculation are as folllows:
V0 = 50.378-0.354E-27.073(N-Z)/A, (MeV)
WS = 9.265-0.232E+0.03318E**2-12.666(N-Z)/A, (MeV)
Vso= 6.2, (MeV)
r = 1.264, a = 0.612, (fm)
rs = 1.256, as = 0.553+0.0144E, (fm)
rso= 1.1, aso= 0.75 (fm)
The calculated cross sections with HFM theory were renorma-
lized in order to obtain consistency with the calculations
for the first and second levels. Finally a factor of 0.91
was multiplied to the calculated compound cross sections to
get better agreement with experimental data of the total
inelastic scattering cross section/25, 28, 29/.
Level Scheme /30/
--------------------
NO. ENERGY(MEV) SPIN-PARITY
G.S. 0.0 0 +
1 0.044910 2 +
2 0.14841 4 +
3 0.30721 6 +
4 0.6801 1 -
5 0.7319 3 -
6 0.8267 5 -
7 0.9257 0 +
8 0.9308 1 -
9 0.9502 2 -
10 0.9673 2 +
11 0.993 0 +
12 0.9975 3 -
13 1.0373 2 +
14 1.0566 4 +
15 1.0595 3 +
16 1.0603 2 +
17 1.1057 3 +
18 1.1126 1 -
19 1.127 4 +
20 1.1287 2 -
21 1.168 4 +
22 1.1704 3 -
23 1.2242 2 +
24 1.2326 4 -
25 1.2692 6 +
26 1.2785 1 -
27 1.2858 5 -
Continuum levels were assumed above 1.29 MeV.
MT=16 (n,2n)
Smooth cross section was determined on the basis of Frehaut
et al./31/ below 15 MeV, and Veeser et al./25/ and Karius et
al./32/ above 15 MeV. The cross sections in JENDL-3.2 were
slightly modified near 14 MeV.
MT=17 (n,3n)
Calculated cross sections with the GNASH code were normalized
to the experimental data of Veeser et al./33/
MT=18 Fission
Below 100 keV : Taken from JENDL-3.2.
Above 100 keV : Simultaneous evaluation /4/ was made for
JENDL-3.3.
MT=37 (n,4n)
Calculated with the GNASH code, and a normalization factor
applied for the (n,3n) reaction was multiplied.
MT=102 Capture
Below 300 keV, evaluation was mainly based on the data
measured by Kazakov et al./34/. Above 300 keV, data were
taken from JENDL-2 which were determined mainly from the
measurements by Poenitz /35/, Panitkin and Sherman /36/,
Moxon /37/, Fricke et al. /38/ and Menlove and Poenitz
/39/.
Above 1 MeV, statistical model calculation was made, and
direct and semi-direct capture cross section was calculated
with DSD code /40/.
MF=4 Angular Distributions of Secondary Neutrons
MT=2 Calculated with ECIS/41/, CASTHY/42/ and
ELIESE-3/43/.
MT=51,52 Calculated with ECIS88/19/.
MT=53-64,66,67,69-72,74,75
Calculated with ECIS88, Hauser-Feshbach-Moldauer
(HFM) theory.
MT=65,68,73,76,77
Calculated with HFM theory.
MT=16,17,18,37,91
Assumed to be isotropic in the lab. system.
MF=5 Energy Distributions of Secondary Neutrons
MT=16,17,91
Calculated with EGNASH/44/.
MT=37
Evaporation spectrum is given. The temperature was calculated
with the GNASH code.
MT=18
Distributions were calculated with the modified Madland-Nix
model/45,46/. The compound nucleus formation cross
sections for fission fragments (FF) were calculated using
Bechetti-Greenlees potential/47/. Up to 3rd-chance-fission
were considered at high incident neutron energies.
A preequilibrium emission was taken into account above 10 MeV
as described in Ref./48/. The prefission neutron spectrum
was calculated with the Feshbach-Kerman-Koonin theory /49/.
The Ignatyuk formula/50/ were used to generate the level
density parameters.
Parameters adopted:
Total average FF kinetic energy = 167.41 - 172.65 MeV
Average energy release = 186.115 - 186.364 MeV
Average mass number of light FF = 99 - 111
Average mass number of heavy FF = 128 - 140
Level density of the light FF = 10.106 - 10.963
Level density of the heavy FF = 11.441 - 7.811
Ratio of nuclear temperature
for light to heavy FF = 1.0
Note that the parameters vary with the incident energy
within the indicated range.
MT=455
Taken from Brady and England /51/. Group abundace
parameters were adjusted so as to reproduce total delayed
neutron emission rate measured by Keepin /5/, and East
/52/.
MF=12 Photon Production Multiplicities (option 1)
Given for the following sections below 934.74 keV.
MT=18 Fission
The thermal neutron-induced fission gamma spectrum of U-235
measured by Verbinski /53/ was adopted for the whole energy
region. The intensity of photon below 0.14 MeV, where no
data were given, was assumed to be the same as that between
0.14 and 0.3 MeV.
MT=51-57 Inelastic
Photon branching data were taken from Ref./54/, and
converted to photon multiplicities.
MT=102 Capture
Calculated with GNASH/44/. In the case where the obtained
multiplicities were too large, they were renormalized by
using energy balance.
MF=13 Photon Production cross sections
MT=3 Non-elastic
Photon production cross section calculated with GNASH /44/
were grouped into the non-elastic in the energy range above
934.74 keV. Transmission coefficients for incident channel
were generated with ECIS/41/, and those for exit channel
with ELIESE-3/43/. The data for fission were based on the
measured U-235 spectra /53/. Further details are given in
Ref./55/
MF=14 Angular Distributions of Photons
Isotropic distributions were assumed for all sections.
MF=15 Continuous Photon Energy Spectra
MT=3 Non-elastic
Calculated with GNASH /44/.
MT=18 Fission
U-235 spectra measured by Verbinski/53/.
MT=102 capture
Calculated with GNASH/44/.
MF=31 Covariances of Average Number of Neutrons per Fission
MT=452
Constructed from MT=455 and 456.
MT=455
Based on experimental data. A chi-value was 0.67./56/
MT=456
Based on experimental data. A chi-value was 2.96./56/
MF=32 Covariances of resonance paremeters
MT=151
Resolved resonance
The covariances were obtained by using kalman./57/
Unresolved resonance
The covariances were obtained by using kalman./58/
MF=33 Covariances of Cross Sections (ref.66)
MT=1
Based on experimental data. A chi-value was 1.51.
MT=2
Constructed from MT=1, 4, 16, 17, 18, 37, and 102.
MT=4, 51-77, 91
Based on experimental data. A chi-value was 2.0.
MT=16
Based on experimental data. A chi-value was 2.37./56/
MT=17
Based on experimental data. a chi-value was 2.00./56/
MT=18
Based on the simultaneous evaluation /4/.
MT=37
Based on experimental data./56/
MT=102
Based on experimental data. A chi-value was 4.79./56/
MF=34 Covariances of Angular Distributions (ref.58)
MT=2
The covariances of p1 coefficients were obtained by using
kalman. A chi-value was 3.82.
MF=35 Covariances of Energy Distributions
MT=18
The covariances were obtained by using kalman./59/
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