96-Cm-245 JAEA+ EVAL-JAN10 O.Iwamoto,T.Nakagawa,T.Ohsawa,+ DIST-MAY10 20100318 ----JENDL-4.0 MATERIAL 9640 -----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 New calculation was made with CCONE code. 07-12 Resonance parameters 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-246 = 0.006482 Cm-245 = 0.004451 Cm-244 = 0.003064 They are averages of systematics by Tuttle/3/, Benedetti et al./4/ and Waldo et al./5/ Decay constants calculated by Brady and England./6/ were adopted. MT=456 Number of prompt neutrons per fission (same as JENDL-3.3) Evaluated by Maslov et al./7/ * BASED ON THE EXPERIMENTAL DATA OF KHOKHLOV ET AL./8/ AND MADLAND-NIX MODEL CALCULATIONS/9/, ABOVE EMISSIVE FISSION THRESHOLD A SUPERPOSITION OF NEUTRON EMISSION IN (N,XNF) REACTIONS /10/ 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/11/. 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 2000/12/ does not include average neutron energy values, the average values were calculated using the formula shown in the report by T.R. England/13/. The fractions of prompt energy were calculated using the fractions of Sher's evaluation/14/ 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) JENDL-3.3 adopted the data evaluated by Maslov et al./7/ They considered the data of Browne et al./15/ and Moore and Keyworth/16/. For the present file, the parameters of levels below 20 eV were modified so as to reproduce better the thermal cross sections and measured fission cross sections/15,17/, and capture resonance integral/18/. The thermal cross sections to be reproduced: Fission = 2054 +- 28 b Benjamin et al./19/, Browne et al./15/, etc. Capture = 347 +- 15 b Halperin et al./20/, Gavrilov et al./18/ Capture resonance integral = 108 +- 81 b Gavrilov and Goncharov/18/ Unresolved resonance parameters (100 eV - 40 keV) Parameters were determined with ASREP code/21/ so as to reproduce the cross sections. They are used only for self- shielding calculations. Thermal cross sections and resonance integrals (at 300K) ------------------------------------------------------- 0.0253 eV reson. integ.(*) (barns) (barns) ------------------------------------------------------- total 2411.4 elastic 10.25 fission 2054.1 832 capture 347.0 108 ------------------------------------------------------- (*) 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./22/ 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 with the GMA code/23/: Authors Energy range Data points Reference Moore+ 80eV - 2.83MeV 3162 /16/ White+ 13.6keV - 9.8MeV 65 /24/ Fomushkin+ 0.26 - 6.21MeV 30 /25/ Fomushkin+ 14.1MeV 1 /26/ Gokhberg+ 0.176 - 5MeV 21 /27/ Fursov+ 0.13 - 15MeV 49 /28/(*1) Gerasimov+ 0.16 - 16keV 7 /29/ Ivanin+ 14keV - 9.0MeV 10 /30/ (*1) Ratio to Pu-239 fission. JENDL-3.3 data was used to convert them to cross sections. Above 7 MeV, an eye-guided cross-section curve was dwawn adopting the data of Fursov et al./28/ at 14.9 MeV. 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/31/ with modified Madland-Nix formula considering multi-mode fission processes (standard-1, standard-2, superlong). Above 7 MeV, calculated with CCONE code/2/. MT=455 Delayed neutron spectra (same as JENDL-3.3) Summation calculation by Brady and England/6/ was adopted. 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./32/ 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 experimental data /8,33,34,35,36/ Discrepancies between Maslov evaluation/7/ and the fitting results were taken into uncertainties. MF=32 Covariances of resonance parameters Format of LCOMP=0 was adopted. Standard deviations were adopted from Mughabghab's recommendation /37/. For parameters having no information on uncertainties, the following errors were assumed: 0.1% to resonance energies 10% to neutron and fission widths 20% to capture widths MF=33 Covariances of neutron cross sections Covariances were given to all the cross sections by using KALMAN code/38/ 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 100 eV), uncertainty of 10 % was added. MT=18 Fission cross section In the resonance region, standard deviation of 5 % was added. Above the resonance region, cross section was evaluated with GMA code/23/. Standard deviations obtained were multiplied by a factor of 2.0. Above 10 MeV, they were assumed to be 15%. MT=102 Capture cross section In the resonance region, addtional error of 10 % was given. Above 100 eV, covariance matrix was obtained with CCONE and KALMAN codes/38/. 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/39/ * Global parametrization of Koning-Duijvestijn/40/ was used. * Gamma emission channel/41/ was added to simulate direct and semi-direct capture reaction. 3) Hauser-Feshbach statistical model * Moldauer width fluctuation correction/42/ 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/43/. 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/44/,/45/ was used. The prameters are shown in Table 7. ------------------------------------------------------------------ Tables ------------------------------------------------------------------ Table 1. Coupled channel calculation -------------------------------------------------- * rigid rotor model was applied * coupled levels = 0,1,2,3,21 (see Table 2) * optical potential parameters /22/ 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= 1.13e-4 S1= 3.04e-4 R'= 9.11 fm (En=1 keV) -------------------------------------------------- Table 2. Level Scheme of Cm-245 ------------------- No. Ex(MeV) J PI ------------------- 0 0.00000 7/2 + * 1 0.05481 9/2 + * 2 0.12160 11/2 + * 3 0.19740 13/2 + * 4 0.25280 5/2 + 5 0.29572 7/2 + 6 0.35064 9/2 + 7 0.35590 1/2 + 8 0.36140 3/2 + 9 0.38818 9/2 - 10 0.41660 11/2 + 11 0.41870 5/2 + 12 0.43100 7/2 + 13 0.44284 11/2 - 14 0.49800 13/2 + 15 0.50900 13/2 - 16 0.53200 9/2 + 17 0.54500 9/2 + 18 0.55500 11/2 + 19 0.55800 3/2 + 20 0.58800 15/2 - ------------------- *) 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-246 18.8984 1.5302 1.7310 0.3608 0.1621 3.4286 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 -------------------------------------------------------- Table 4. Fission barrier parameters ---------------------------------------- Nuclide V_A hw_A V_B hw_B MeV MeV MeV MeV ---------------------------------------- Cm-246 6.300 1.040 5.100 0.600 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 ---------------------------------------- Table 5. Level density above inner saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Cm-246 20.7882 1.6500 2.6000 0.3263 -0.7728 3.6500 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 -------------------------------------------------------- Table 6. Level density above outer saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Cm-246 20.7882 1.7852 0.7800 0.3658 -0.0107 3.8852 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 -------------------------------------------------------- Table 7. Gamma-ray strength function for Cm-246 -------------------------------------------------------- * E1: ER = 11.42 (MeV) EG = 2.72 (MeV) SIG = 328.24 (mb) ER = 14.32 (MeV) EG = 4.20 (MeV) SIG = 426.38 (mb) * M1: ER = 6.54 (MeV) EG = 4.00 (MeV) SIG = 1.46 (mb) * E2: ER = 10.05 (MeV) EG = 3.16 (MeV) SIG = 7.06 (mb) -------------------------------------------------------- References 1) O.Iwamoto et al.: J. Nucl. Sci. Technol., 46, 510 (2009). 2) O.Iwamoto: J. Nucl. Sci. 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