96-Cm-243 JAEA+ EVAL-JAN10 O.Iwamoto,T.Nakagawa,T.Ohsawa,+
DIST-MAY10 20100318
----JENDL-4.0 MATERIAL 9634
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
History
06-01 Fission cross section was evaluated with GMA.
06-04 Resonance parameters were modified.
07-03 Fission spectra were evaluated.
07-05 Theoretical calculation with CCONE code was made.
08-03 Interpolation of (5,18) was changed.
Data were compiled as JENDL/AC-2008/1/.
09-08 (MF1,MT458) was evaluated.
10-01 Data of prompt gamma rays due to fission were given.
10-03 Covariance data were given.
MF= 1 General information
MT=452 Number of Neutrons per fission
Sum of MT's=455 and 456.
MT=455 Delayed neutron data
(same as JENDL-3.3)
Numbers of delayed neutrons were evaluated by Maslov et al.
/2/ which was based on Tuttle's systematics/3/.
MT=456 Number of prompt neutrons per fission
(same as JENDL-3.3)
Evaluated by Maslov et al./2/
* BASED ON THE EXPERIMENTAL DATA AT THERMAL ENERGY BY
JAFFEY AND LERNER /4/, ZHURAVLEV ET AL. /5/
AND ON THE MADLAND-NIX MODEL CALCULATION /6/, ABOVE
EMISSIVE FISSION THRESHOLD A SUPERPOSITION OF
NEUTRON EMISSION IN (N,XNF) REACTIONS /7/ AND PROMPT
FISSION NEUTRONS.
MT=458 Components of energy release due to fission
Total energy and prompt energy were calculated from mass
balance using JENDL-4 fission yields data and mass excess
evaluation. Mass excess values were from Audi's 2009
evaluation/8/. Delayed energy values were calculated from
the energy release for infinite irradiation using JENDL FP
Decay Data File 2000 and JENDL-4 yields data. For delayed
neutron energy, as the JENDL FP Decay Data File 2000/9/ does
not include average neutron energy values, the average values
were calculated using the formula shown in the report by
T.R. England/10/. The fractions of prompt energy were
calculated using the fractions of Sher's evaluation/11/ when
they were provided. When the fractions were not given by Sher,
averaged fractions were used.
MF= 2 Resonance parameters
MT=151
Resolved resonance parameters (MLBW: 1.0E-5 - 100 eV)
The parameters given in JENDL-3.3 were evaluated by Maslov et
al./2/ considering the data of Anufriev et al./12/ and
Silbert/13/. A negative resonance was based on the data of
Mughabghab/14/.
In the present work,
* capture widths were changed to 40 meV,
* new resonaces were assumed at 41.8, 43 and 61.3 eV,
* parameters were adjusted to the fission cross section
measured by Silbert/13/, and
* parameters of a negative resonance were modified so as to
reproduce the thermal cross sections.
The energies of Silbert's data were shifted down by 0.3%.
The thermal cross sections to be reproduced:
Fission = 587 +- 12 b
Bemis et al./15/, Zhuravlev anf Kroshkin/16/,
Serot et al./17/, etc.
Capture = 131.3 +- 9.6 bb
Bemis et al./15/
Unresolved resonance parameters (100 eV - 40 keV)
Parameters (URP) were determined with ASREP code/18/ so as to
reproduce the cross sections in this energy region. URP are
used only for self-shielding calculations.
Thermal cross sections and resonance integrals (at 300K)
-------------------------------------------------------
0.0253 eV reson. integ.(*)
(barns) (barns)
-------------------------------------------------------
total 727.59
elastic 8.853
fission 587.36 1550
capture 131.38 206
-------------------------------------------------------
(*) In the energy range from 0.5 eV to 10 MeV.
MF= 3 Neutron cross sections
Cross sections above the resolved resonance region except for
the total (MT=1), elastic scattering (MT=2) and fission cross
sections (MT=18, 19, 20, 21, 38) were calculated with CCONE
code/19/.
MT= 1 Total cross section
From 100 eV to 20 keV, calculated as sum of partial cross
sections.
Above 20 keV, calculated with CC OMP of Soukhovitskii et
al./20/
MT= 2 Elastic scattering cross section
From 100 eV to 20 keV, calculated with CCONE code.
Above 20 keV, calculated as total - non-elastic scattering
cross sections.
MT=18 Fission cross section
The following experimental data were analyzed in the energy
range above 100 eV with the GMA code /21/:
Authors Energy range Data points Reference
Silbert 100eV - 3.2MeV 1432 /13/
Fursov+ 135keV - 15MeV 68 /22/(*1)
(*1) Relative to Pu-239 fission. Data were converted
to cross sections using JENDL-3.3 data.
The results of GMA were used to determine the parameters in
the CCONE calculation.
In the energy region from 8 to 20 MeV, the data of JENDL-3.3
were adopted.
MT=19, 20, 21, 38 Multi-chance fission cross sections
Calculated with CCONE code, and renormalized to the total
fission cross section (MT=18).
MF= 4 Angular distributions of secondary neutrons
MT=2 Elastic scattering
Calculated with CCONE code.
MT=18 Fission
Isotropic distributions in the laboratory system were assumed.
MF= 5 Energy distributions of secondary neutrons
MT=18 Fission neutron spectra
Below 6 MeV, calculated by Ohsawa /23/ with modified Madland-
Nix formula considering multi-mode fission processes
(standard-1, standard-2, superlong).
Above 7 MeV, calculated with CCONE code/19/.
MF= 6 Energy-angle distributions
Calculated with CCONE code.
Distributions from fission (MT=18) are not included.
MF=12 Photon production multiplicities
MT=18 Fission
Calculated from the total energy released by the prompt
gamma-rays due to fission given in MF=1/MT=458 and the
average energy of gamma-rays.
MF=14 Photon angular distributions
MT=18 Fission
Isotoropic distributions were assumed.
MF=15 Continuous photon energy spectra
MT=18 Fission
Experimental data measured by Verbinski et al./24/ for
Pu-239 thermal fission were adopted.
MF=31 Covariances of average number of neutrons per fission
MT=452 Number of neutrons per fission
Combination of covariances for MT=455 and MT=456.
MT=455
Standard deviation was roughly estimated as 15% below 6 MeV,
20% from 6 to 8 MeV and 20% from 8 to 20 MeV.
MT=456
Covariance was obtained by fitting to the data of 3.43+-0.07
at 0 MeV and 4.083+-0.20 at 5 MeV.
MF=32 Covariances of resonance parameters
Format of LCOMP=0 was adopted.
Standard diviations of resonance parameters up to 15 eV were
taken from recomendattion of Mughabghab/14/.
For other resonances, the following standard diviations were
assumed:
resonance energy 0.1 %
neutron width 10%
capture width 20%
fission width 10%
MF=33 Covariances of neutron cross sections
Covariances were given to all the cross sections by using
KALMAN code/25/ and the covariances of model parameters
used in the theoretical calculations.
For the following cross sections, covariances were determined
by different methods.
MT=1 Total cross section
Uncertainties of 20% were added to the contributions from
resonance parameters in the energy range from 10 to 100 eV.
MT=2 Elastic scattering
Uncertainties of 10% were added to the contributions from
resonance parameters in the energy below 100 eV.
MT=18 Fission cross section
Evaluated with GMA code/21/. Standard deviation obtained
was multiplied by a factor of 2.0. Above 8 MeV, standard
deviation was assumed to be 10%.
MT=102 Capture cross section
Uncertainties of 30% were added to the contributions from
resonance parameters in the energy range from 10 to 100 eV.
MF=34 Covariances for Angular Distributions
MT=2 Elastic scattering
Covariances were given only to P1 components.
MF=35 Covariances for Energy Distributions
MT=18 Fission spectra
Below 6 MeV, covarinaces of Pu239 fission spectra given in
JENDL-3.3 were adopted after multiplying a factor of 9.
Above 6 MeV, estimated with CCONE and KALMAN codes.
*****************************************************************
Calculation with CCONE code
*****************************************************************
Models and parameters used in the CCONE/19/ calculation
1) Coupled channel optical model
Levels in the rotational band were included. Optical model
potential and coupled levels are shown in Table 1.
2) Two-component exciton model/26/
* Global parametrization of Koning-Duijvestijn/27/
was used.
* Gamma emission channel/28/ was added to simulate direct
and semi-direct capture reaction.
3) Hauser-Feshbach statistical model
* Moldauer width fluctuation correction/29/ was included.
* Neutron, gamma and fission decay channel were included.
* Transmission coefficients of neutrons were taken from
coupled channel calculation in Table 1.
* The level scheme of the target is shown in Table 2.
* Level density formula of constant temperature and Fermi-gas
model were used with shell energy correction and collective
enhancement factor. Parameters are shown in Table 3.
* Fission channel:
Double humped fission barriers were assumed.
Fission barrier penetrabilities were calculated with
Hill-Wheler formula/30/. Fission barrier parameters were
shown in Table 4. Transition state model was used and
continuum levels are assumed above the saddles. The level
density parameters for inner and outer saddles are shown in
Tables 5 and 6, respectively.
* Gamma-ray strength function of Kopecky et al/31/,/32/
was used. The prameters are shown in Table 7.
------------------------------------------------------------------
Tables
------------------------------------------------------------------
Table 1. Coupled channel calculation
--------------------------------------------------
* rigid rotor model was applied
* coupled levels = 0,1,3 (see Table 2)
* optical potential parameters /20/
Volume:
V_0 = 49.97 MeV
lambda_HF = 0.01004 1/MeV
C_viso = 15.9 MeV
A_v = 12.04 MeV
B_v = 81.36 MeV
E_a = 385 MeV
r_v = 1.2568 fm
a_v = 0.633 fm
Surface:
W_0 = 17.2 MeV
B_s = 11.19 MeV
C_s = 0.01361 1/MeV
C_wiso = 23.5 MeV
r_s = 1.1803 fm
a_s = 0.601 fm
Spin-orbit:
V_so = 5.75 MeV
lambda_so = 0.005 1/MeV
W_so = -3.1 MeV
B_so = 160 MeV
r_so = 1.1214 fm
a_so = 0.59 fm
Coulomb:
C_coul = 1.3
r_c = 1.2452 fm
a_c = 0.545 fm
Deformation:
beta_2 = 0.25
beta_4 = 0.066
beta_6 = 0.0015
* Calculated strength function
S0= 1.30e-4 S1= 2.21e-4 R'= 9.16 fm (En=1 keV)
--------------------------------------------------
Table 2. Level Scheme of Cm-243
-------------------
No. Ex(MeV) J PI
-------------------
0 0.00000 5/2 + *
1 0.04200 7/2 + *
2 0.08740 1/2 +
3 0.09400 9/2 + *
4 0.09400 3/2 +
5 0.13000 7/2 +
6 0.15300 5/2 +
7 0.16400 5/2 -
8 0.18700 9/2 +
9 0.21900 11/2 -
10 0.22800 7/2 -
-------------------
*) Coupled levels in CC calculation
Table 3. Level density parameters
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Cm-244 19.1414 1.5364 1.5347 0.3530 0.2436 3.3454
Cm-243 18.3259 0.7698 1.3577 0.3635 -0.5169 2.5698
Cm-242 18.6337 1.5428 1.3581 0.3517 0.3362 3.2428
Cm-241 18.5675 0.7730 1.0938 0.3935 -0.8080 2.9546
Cm-240 18.5012 1.5492 1.2421 0.3627 0.2677 3.3492
--------------------------------------------------------
Table 4. Fission barrier parameters
----------------------------------------
Nuclide V_A hw_A V_B hw_B
MeV MeV MeV MeV
----------------------------------------
Cm-244 6.100 0.900 5.100 0.600
Cm-243 6.150 0.600 5.800 0.400
Cm-242 6.200 1.040 4.900 0.600
Cm-241 6.300 0.800 5.000 0.520
Cm-240 6.000 1.040 5.000 0.600
----------------------------------------
Table 5. Level density above inner saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Cm-244 20.6427 1.7925 2.6000 0.3275 -0.6303 3.7925
Cm-243 20.5699 0.8981 2.6000 0.3281 -1.5248 2.8981
Cm-242 20.4971 1.7999 2.6000 0.3288 -0.6230 3.7999
Cm-241 20.4242 0.9018 2.6000 0.3294 -1.5211 2.9018
Cm-240 20.3513 1.8074 2.6000 0.3300 -0.6156 3.8074
--------------------------------------------------------
Table 6. Level density above outer saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Cm-244 20.6427 1.7925 0.7000 0.3455 0.2502 3.5925
Cm-243 20.5699 0.8981 0.6600 0.3619 -0.8115 2.8981
Cm-242 20.4971 1.7999 0.6200 0.3631 0.0909 3.7999
Cm-241 20.4242 0.9018 0.5800 0.3643 -0.8066 2.9018
Cm-240 20.3513 1.8074 0.5400 0.3656 0.0996 3.8074
--------------------------------------------------------
Table 7. Gamma-ray strength function for Cm-244
--------------------------------------------------------
* E1: ER = 11.44 (MeV) EG = 2.73 (MeV) SIG = 325.35 (mb)
ER = 14.35 (MeV) EG = 4.21 (MeV) SIG = 422.62 (mb)
* M1: ER = 6.56 (MeV) EG = 4.00 (MeV) SIG = 1.44 (mb)
* E2: ER = 10.08 (MeV) EG = 3.18 (MeV) SIG = 7.07 (mb)
--------------------------------------------------------
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