90-Th-228 JAEA+ EVAL-FEB10 O.Iwamoto, T.Nakagawa, et al. DIST-DEC21 20100319 ----JENDL-5 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. 21-11 revised by O.Iwamoto (MF3/MT19-21,38) deleted (MF8/MT16-18,102) JENDL/AD-2017 adopted (MF8/MT4) added 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) -------------------------------------------------------- References 1) O.Iwamoto et al.: J. Nucl. Sci. 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