90-Th-228 JAEA+ EVAL-FEB10 O.Iwamoto, T.Nakagawa, et al.
DIST-MAY10 20100319
----JENDL-4.0 MATERIAL 9028
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
History
07-06 Theoretical calculation was performed with CCONE code.
07-07 Data were compiled as JENDL/AC-2008/1/.
10-02 Data of prompt gamma rays due to fission were given.
Nu-total, nu-p and nu-d were revised.
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
Average values of systematics of Tuttle/2/, Benedetti et
al./3/ and Waldo et al./4/ were adopted.
MT=456 Number of prompt neutrons per fission
Based on the semi-empirical formula of Ohsawa/5/.
MF= 2 Resonance parameters
MT=151
Resolved resonance parameters (MLBW: 10e-5 - 13 eV)
Parameters of JENDL-3.3 which were based on the data obtained
by Simpson et al./6/ were adopted. A negative resonance
recommended by Mughabghab/7/ was added so as to reproduce
the thermal cross sections.
Fission widths were ignored. The fission cross section is
given as background cross sections.
Unresolved resonance parameters (13 eV - 70 keV)
Parameters (URP) were determined with ASREP code /8/ 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 154.35
elastic 31.30
fission 0.15 1.38
capture 122.90 1120
-------------------------------------------------------
(*) In the energy range from 0.5 eV to 10 MeV.
MF= 3 Neutron cross sections
Cross sections except for the elastic scattering (MT=2) and
fission cross sections (MT=18,19) below 100 keV were calculated
with CCONE code/9/.
MT= 1 Total cross section
The cross section was calculated with CC OMP of Soukhovitskii
et al./10/.
MT= 2 Elastic scattering cross section
Calculated as total - non-elastic scattering cross sections.
MT=18,19 Fission cross section, (n,f) cross section
Below 4.5 keV, 1/v shape was assumed. The cross section at
0.0253 eV was assumed to be 0.15 b which was determined from
"< 0.3 b" recommended by Mughabghab/7/.
From 4.5 to 100 keV, assumed to be 0.34 mb.
From 100keV to 20 MeV, calculated with CCONE code/9/.
The fission cross section measured by James et al./11/ were
used to adjust parameters of CCONE code.
MF= 4 Angular distributions of secondary neutrons
MT=2 Elastic scattering
Calculated with CCONE code/9/.
MT=18 Fission
Isotropic distributions in the laboratory system were assumed.
MF= 5 Energy distributions of secondary neutrons
MT=18 Prompt neutrons
Calculated with CCONE code/9/.
MF= 6 Energy-angle distributions
Calculated with CCONE code/9/.
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 which was estimated from its
systematics, 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./12/ for
U-235 thermal fission were adopted.
MF=31 Covariances of average number of neutrons per fission
MT=452 Number of neutrons per fission
Sum of covariances for MT=455 and MT=456.
MT=455
Error of 15% was assumed.
MT=456
Covariance was obtained by fitting a linear function to the
at 0.0 and 5.0 MeV with an uncertainty of 5%.
MF=32 Covariances of resonance parameters
MT=151
Format of LCOMP=0 was adopted.
Uncertainties of parameters were taken from Mughabghab /7/
and Simpson et al./6/ For the parameters without any
information on uncertainty, unceratainties of 0.1% and 10%
were assumed to resonance energies and resonance widths,
respectively.
MF=33 Covariances of neutron cross sections
Covariances were given to all the cross sections by using
KALMAN code/13/ and the covariances of model parameters
used in the cross-section calculations.
In the resolved resonance region (up to 13 eV), the following
standard deviations were added to the contributions from
resonance parameters:
Total 12.6 %
Elastic scattering 50 %
Fission 90 %
Capture 10 %
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
Estimated with CCONE and KALMAN codes.
*****************************************************************
Calculation with CCONE code
*****************************************************************
Models and parameters used in the CCONE/9/ 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/14/
* Global parametrization of Koning-Duijvestijn/15/
was used.
* Gamma emission channel/16/ was added to simulate direct
and semi-direct capture reaction.
3) Hauser-Feshbach statistical model
* Moldauer width fluctuation correction/17/ 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/18/. 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/19/,/20/
was used. The prameters are shown in Table 7.
------------------------------------------------------------------
Tables
------------------------------------------------------------------
Table 1. Coupled channel calculation
--------------------------------------------------
* rigid rotor model was applied
* coupled levels = 0,1,2,4,7 (see Table 2)
* optical potential parameters /10/
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 = 0.066
beta_6 = 0.0015
* Calculated strength function
S0= 1.07e-4 S1= 2.55e-4 R'= 9.88 fm (En=1 keV)
--------------------------------------------------
Table 2. Level Scheme of Th-228
-------------------
No. Ex(MeV) J PI
-------------------
0 0.00000 0 + *
1 0.05776 2 + *
2 0.18682 4 + *
3 0.32800 1 -
4 0.37818 6 + *
5 0.39608 3 -
6 0.51919 5 -
7 0.62250 8 + *
8 0.69560 7 -
9 0.83182 0 +
10 0.87447 2 +
11 0.91180 10 +
12 0.92080 9 -
13 0.93858 0 +
14 0.94420 1 +
15 0.96837 3 -
16 0.96897 2 +
17 0.97950 2 +
18 1.01641 2 +
19 1.02253 3 +
20 1.05993 4 -
21 1.09102 4 +
22 1.12295 2 -
23 1.15347 2 +
24 1.16000 10 -
25 1.16837 3 -
26 1.17451 5 +
27 1.17539 2 +
28 1.18980 11 -
29 1.20054 3 +
-------------------
*) Coupled levels in CC calculation
Table 3. Level density parameters
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Th-229 17.7702 0.7930 3.2566 0.4327 -1.4313 3.7239
Th-228 17.7035 1.5894 3.0590 0.3964 -0.1539 3.9563
Th-227 17.6369 0.7965 3.1200 0.4219 -1.2457 3.5201
Th-226 17.5702 1.5965 2.8637 0.4068 -0.2170 4.0544
Th-225 17.5034 0.8000 2.7304 0.3997 -0.9049 3.1303
--------------------------------------------------------
Table 4. Fission barrier parameters
----------------------------------------
Nuclide V_A hw_A V_B hw_B
MeV MeV MeV MeV
----------------------------------------
Th-229 5.500 0.800 6.000 0.520
Th-228 3.900 1.040 6.400 0.600
Th-227 4.100 0.800 6.400 0.520
Th-226 3.900 1.040 8.200 0.600
Th-225 4.200 0.800 8.000 0.520
----------------------------------------
Table 5. Level density above inner saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Th-229 19.9026 0.9251 2.6000 0.3339 -1.4862 2.9251
Th-228 19.8280 1.8543 2.6000 0.3346 -0.5570 3.8543
Th-227 19.7533 0.9292 2.6000 0.3352 -1.4822 2.9292
Th-226 19.6786 1.8625 2.6000 0.3359 -0.5488 3.8625
Th-225 19.6038 0.9333 2.6000 0.3366 -1.4780 2.9333
--------------------------------------------------------
Table 6. Level density above outer saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Th-229 19.9026 0.9251 -0.2600 0.3799 -0.7708 2.9251
Th-228 19.8280 1.8543 -0.3000 0.3812 0.1590 3.8543
Th-227 19.7533 0.9292 -0.3400 0.3826 -0.7655 2.9292
Th-226 19.6786 1.8625 -0.3800 0.3840 0.1685 3.8625
Th-225 19.6038 0.9333 -0.4200 0.3854 -0.7601 2.9333
--------------------------------------------------------
Table 7. Gamma-ray strength function for Th-229
--------------------------------------------------------
K0 = 1.502 E0 = 4.500 (MeV)
* E1: ER = 11.03 (MeV) EG = 2.71 (MeV) SIG = 302.00 (mb)
ER = 13.87 (MeV) EG = 4.77 (MeV) SIG = 449.00 (mb)
* M1: ER = 6.70 (MeV) EG = 4.00 (MeV) SIG = 2.81 (mb)
* E2: ER = 10.30 (MeV) EG = 3.36 (MeV) SIG = 6.26 (mb)
--------------------------------------------------------
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