96-Cm-244 JAEA+ EVAL-JAN10 O.Iwamoto,T.Nakagawa,T.Ohsawa+
DIST-MAY10 20100318
----JENDL-4.0 MATERIAL 9637
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
History
06-03 Fission cross section was evaluated with GMA.
06-04 Resonance parameters were modified.
07-03 Fission spectra were evaluated.
07-05 New calculation was made with CCONE code.
07-07 Nu-p was revised.
07-10 Nu-p was revised.
07-12 Parameters of negative and 1st resonances were modified.
08-03 Interpolation of (5,18) was changed.
Data were compiled as JENDL/AC-2008/1/.
09-03 (1,452) and (1,455) were revised.
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
Determined from nu-d of the following three nuclides and
partial fission cross sections calculated with CCONE code/2/.
Cm-245 = 0.004451
Cm-244 = 0.003064
Cm-243 = 0.002114
They are averages of systematics by Tuttle/3/,
Benedetti et al./4/ and Waldo et al./5/
MT=456 Number of prompt neutrons per fission
The experimental data of 2.75+-0.08 measured by Zhuravlev et
al./6/ seems to be too small. A value of 3.00 at 0 eV
was assumed. An energy dependent term was based on the
systematics derived by Ohsawa/7/.
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 - 1000eV)
Resonance parameters given in JENDL-3.3 were based on the
data of Belanova et al./12/, Moore and Keyworth/13/ and
Maguire et al./14/
In the present work, negative and first resonances were
modified so as to reproduce thermal cross sections and
resonance integral. Background was given to the fission
cross section.
The thermal cross sections to be reproduced:
Total = 27.6 +- 1.4 b /15/
Elastic = 11.6 +- 0.7 b /15/
Fission = 1.02 +- 0.19 b
Benjamin et al. /16/, Zhuravlev et al./17/
Capture = 15.2 +- 1.2 b
Gavrilov and Goncharov/18/
Resonance integral of capture = 626 +- 53 b
Gavrilov and Goncharov/18/
Unresolved resonance parameters (1 - 100 keV)
Parameters (URP) were determined with ASREP code/19/ so as
to reproduce the cross sections in this energy range. URP are
used only for self-shielding calculations.
Thermal cross sections and resonance integrals (at 300K)
-------------------------------------------------------
0.0253 eV reson. integ.(*)
(barns) (barns)
-------------------------------------------------------
total 28.65
elastic 12.39
fission 1.022 13.3
capture 15.24 626
-------------------------------------------------------
(*) 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 elastic scattering (MT=2) and fission cross sections (MT=18,
19, 20, 21, 38) were calculated with CCONE code/2/.
MT= 1 Total cross section
The cross section was calculated with CC OMP of Soukhovitskii
et al./20/
MT= 2 Elastic scattering cross section
Calculated as total - non-elastic scattering cross sections.
MT=18 Fission cross section
The following experimental data were analyzed in the energy
range above 1 keV with GMA code /21/:
Authors Energy range Data points Reference
Moore+ 950eV - 2.83MeV 548 /13/
Fomushkin+ 0.30 - 4.0MeV 17 /22/
Vorotnikov+ 0.39 - 1.28MeV 8 /23/
Maguire Jr.+ 0.94 - 79.5keV 49 /14/
Fomushkin+ 14.1 MeV 1 /24/
Fursov+ 0.169 - 6.842MeV 45 /25/(*1)
(*1) Relative to Pu-239 fission. These data were converted
to cross sections using JENDL-3.3 data.
Between 7 and 20 MeV, data were determined by eye-guiding.
The results of GMA were used to determine the parameters in
the CCONE calculation.
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 /26/ with modified
Madland-Nix formula considering multi-mode fission processes
(standard-1, standard-2, superlong).
Above 7 MeV, calculated with CCONE code/2/.
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./27/ 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
Error of 15% was assumed below 5 MeV and above 5 MeV,
respectively.
MT=456
Covariance was obtained by fitting a linear function to the
at 0.0 and 5.0 MeV with uncertainties of 8% and 7.5%,
respectively.
MF=32 Covariances of resonance parameters
Format of LCOMP=0 was adopted.
Standard deviations were adopted from Belanova et al./12/,
Moore and Keyworth/13/ and Maguire et al./14/
For parameters having no information on uncertainties, the
following errors were assumed:
0.1% to resonance energies
10% to other parameters
MF=33 Covariances of neutron cross sections
Covariances were given to all the cross sections by using
KALMAN code/28/ and the covariances of model parameters
used in the theoretical calculations.
For the following cross sections, covariances were determined
by different methods.
MT=1, 2 Total and elastic scattering cross sections
In the resonance region (below 1 keV), uncertainty of 20%
was added.
MT=18 Fission cross section
In the resonance region, the following errors were added:
1.0e-5 to 5eV 15%
5eV to 500eV 10%
500eV to 1keV 10%
Above the resonance region, cross section was evaluated with
GMA code/21/. Error of 5 % was added to the standard
deviations obatianed.
MT=102 Capture cross section
In the resonance region from 5 eV to 1 keV, addtional error
of 10 % was given.
Above 1 keV, covariance matrix was obtained with CCONE and
KALMAN codes/28/.
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/2/ 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/29/
* Global parametrization of Koning-Duijvestijn/30/
was used.
* Gamma emission channel/31/ was added to simulate direct
and semi-direct capture reaction.
3) Hauser-Feshbach statistical model
* Moldauer width fluctuation correction/32/ 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/33/. 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/34/,/35/
was used. The prameters are shown in Table 7.
------------------------------------------------------------------
Tables
------------------------------------------------------------------
Table 1. Coupled channel calculation
--------------------------------------------------
* rigid rotor model was applied
* coupled levels = 0,1,2,3,4 (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 = 0.213
beta_4 = 0.056
beta_6 = 0.0015
* Calculated strength function
S0= 1.01e-4 S1= 3.17e-4 R'= 9.16 fm (En=1 keV)
--------------------------------------------------
Table 2. Level Scheme of Cm-244
-------------------
No. Ex(MeV) J PI
-------------------
0 0.00000 0 + *
1 0.04297 2 + *
2 0.14235 4 + *
3 0.29621 6 + *
4 0.50179 8 + *
5 0.97000 3 -
6 0.98491 0 +
7 1.02076 2 +
8 1.03800 2 +
9 1.04019 6 +
10 1.08418 2 +
11 1.10591 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-245 18.8322 0.7667 1.4601 0.3623 -0.5771 2.6382
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
--------------------------------------------------------
Table 4. Fission barrier parameters
----------------------------------------
Nuclide V_A hw_A V_B hw_B
MeV MeV MeV MeV
----------------------------------------
Cm-245 6.050 0.500 5.700 0.420
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
----------------------------------------
Table 5. Level density above inner saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Cm-245 20.7155 0.8944 2.6000 0.3342 -1.6357 2.9944
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
--------------------------------------------------------
Table 6. Level density above outer saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Cm-245 20.7155 0.8944 0.7400 0.3596 -0.8163 2.8944
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
--------------------------------------------------------
Table 7. Gamma-ray strength function for Cm-245
--------------------------------------------------------
* E1: ER = 11.43 (MeV) EG = 2.73 (MeV) SIG = 326.80 (mb)
ER = 14.33 (MeV) EG = 4.20 (MeV) SIG = 424.50 (mb)
* M1: ER = 6.55 (MeV) EG = 4.00 (MeV) SIG = 1.45 (mb)
* E2: ER = 10.07 (MeV) EG = 3.17 (MeV) SIG = 7.06 (mb)
--------------------------------------------------------
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