90-Th-230 JAEA+ EVAL-FEB10 O.Iwamoto, T.Nakagawa, et al. DIST-DEC21 20100318 ----JENDL-5 MATERIAL 9034 -----INCIDENT NEUTRON DATA ------ENDF-6 FORMAT History 05-11 Fission cross section was evaluated with GMA code. 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-tptal, nu-p and nu-d were revised. 10-03 Covariance data were added. 21-11 revised by O.Iwamoto (MF3/MT19-21,38) deleted (MF8/MT4,16-18,37,102) 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/ MT=456 Number of prompt neutrons per fission Fitting to the experimental data of Boldeman/5/. MF= 2 Resonance parameters MT=151 Resolved resonance parameters (MLBW: 10e-5 - 500 eV) Parameters of JENDL-3.3 were based on the parameters obtained by Kalebin et al./6/ These parameters were revised to reproduce the capture cross section at 0.0253 eV. Capture = 23.4 +- 1.1 b Pomerance/7/, Cabell/8/ Fission widths were ignored. The fission cross section is given as background cross sections. Unresolved resonance parameters (0.5 - 70 keV) Parameters (URP) were determined with ASREP code/9/ 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 32.813 elastic 10.392 fission 0.0095 0.786 capture 23.411 1040 ------------------------------------------------------- (*) In the energy range from 0.5 eV to 10 MeV. Kalebin et al./6/ reported the total cross section of 70+- 3.8b at 0.0253 eV. This data was ignored because it was too large. MF= 3 Neutron cross sections Cross sections above the resolved resonance region except for elastic scattering and fission cross sections (MT's =2, 18-21, 38) were calculated with CCONE code/10/. MT= 1 Total cross section The cross section was calculated with CC OMP of Soukhovitskii et al./11/ MT=2 Elastic scattering cross section Calculated as total - non-elstic scattering cross sections MT=18 Fission cross section Below 260 eV, 1/v shape was assumed. The cross section at 1 eV was assumed to be 1.51 mb which was determined from CCONE calculation/10/ reducing by a factor of 0.04 because experimental data for Th-232 are smaller by a factor of about 0.04 than CCONE calculation. From 260 eV to 100 keV, assumed to be 9 micro-b. From 100 to 400 keV, calculated with CCONE code. In the energy range from 400 keV to 9 MeV, the following experimental data were analyzed with the GMA code/12/: Authors Energy range Data points Reference Karzarinora+ 14.6 MeV 1 /13/ Muir+ 0.3 - 2.96 MeV 181 /14/ James+ 0.625 - 1.4 MeV 50 /15/ Meadows 0.737 - 9.4 MeV 15 /16/(*1) Blons+ 0.5 - 4 MeV 1764 /17/ Boldeman+ 0.697 - 0.744 MeV 68 /18/ Meadows 14.7 MeV 1 /19/(*1) Petit+ 1 -9.9 MeV 90 /20/ (*1) Relative measurment to U-235 fission. They were converted to Th-230 fission by using JENDL-3.3 data. Above 10 MeV, results of CCONE calculation were adopted. The parameters of CCONE were adjusted using the results of GMA bellow 9 MeV and the experimental data of Meadows/19/ above 9 MeV. 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/10/. 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/10/. MF= 6 Energy-angle distributions Calculated with CCONE code/10/. 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./21/ 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 data at 0.0 and 5.0 MeV with an uncertainty of 5%. MF=32 Covariances of resonance parameters MT=151 Resolved resonance parameterss Format of LCOMP=0 was adopted. Uncertainties of parameters were taken from Mughabghab /22/. For the parameters without any information on uncertainty, the following uncertainties were assumed: Resonance energy 0.1 % Neutron width 10 % Capture width 20 % Fission width 20 % They were further modified by considering experimental data of the capture cross section at the thermal neutron energy. MF=33 Covariances of neutron cross sections Covariances were given to all the cross sections by using KALMAN code/23/ and the covariances of model parameters used in the cross-section calculations. For the fission cross section, covariances obtained with the GMA analysis were adopted. Standard deviations (SD) were multiplied by a factor of 1.5. SD's of 75% and 18% were assumed in the energy region below 400 keV and above 10 MeV, respectively. In the resolved resonance region, the following standard deviations were added to the contributions from resonance parameters: Total 2 b Elastic scattering 20 % Fission 50 % 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/10/ 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/24/ * Global parametrization of Koning-Duijvestijn/25/ was used. * Gamma emission channel/26/ was added to simulate direct and semi-direct capture reaction. 3) Hauser-Feshbach statistical model * Moldauer width fluctuation correction/27/ 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/28/. 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/29/,/30/ was used. The prameters are shown in Table 7. ------------------------------------------------------------------ Tables ------------------------------------------------------------------ Table 1. Coupled channel calculation -------------------------------------------------- * rigid rotor model was applied * coupled levels = 0,1,2,3,6 (see Table 2) * optical potential parameters /11/ 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= 0.98e-4 S1= 2.42e-4 R'= 9.82 fm (En=1 keV) -------------------------------------------------- Table 2. Level Scheme of Th-230 ------------------- No. Ex(MeV) J PI ------------------- 0 0.00000 0 + * 1 0.05320 2 + * 2 0.17410 4 + * 3 0.35660 6 + * 4 0.50816 1 - 5 0.57177 3 - 6 0.59410 8 + * 7 0.63490 0 + 8 0.67760 2 + 9 0.68670 5 - ------------------- *) 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-231 18.7090 0.7895 3.3191 0.3770 -0.9082 3.0943 Th-230 18.6395 1.5825 3.2401 0.4059 -0.4442 4.2813 Th-229 18.1256 0.7930 3.2566 0.4250 -1.3952 3.6819 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 -------------------------------------------------------- Table 4. Fission barrier parameters ---------------------------------------- Nuclide V_A hw_A V_B hw_B MeV MeV MeV MeV ---------------------------------------- Th-231 5.800 0.800 6.050 0.550 Th-230 6.000 1.040 5.800 0.500 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 ---------------------------------------- Table 5. Level density above inner saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Th-231 19.6937 0.9211 2.6000 0.3507 -1.7165 3.1211 Th-230 19.9772 1.8463 2.6000 0.3178 -0.3511 3.6463 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 -------------------------------------------------------- Table 6. Level density above outer saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Th-231 19.3357 0.9211 -0.1800 0.4080 -1.0331 3.2211 Th-230 20.1556 1.8463 -0.2200 0.3610 0.3158 3.6463 Th-229 19.1918 0.9251 -0.2600 0.3882 -0.7797 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 -------------------------------------------------------- Table 7. Gamma-ray strength function for Th-231 -------------------------------------------------------- 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 = 6.68 (MeV) EG = 4.00 (MeV) SIG = 2.80 (mb) * E2: ER = 10.27 (MeV) EG = 3.34 (MeV) SIG = 6.25 (mb) -------------------------------------------------------- References 1) O.Iwamoto et al.: J. Nucl. Sci. 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