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) -------------------------------------------------------- References 1) O.Iwamoto et al.: J. Nucl. Sci. 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