95-Am-242 JAEA+ EVAL-FEB10 O.Iwamoto,T.Nakagawa, et al. DIST-MAY10 20100318 ----JENDL-4.0 MATERIAL 9546 -----INCIDENT NEUTRON DATA ------ENDF-6 FORMAT History 06-04 Resonance parameters were revised. 07-05 New calculation was made with CCONE code. 07-08 New calculation was made with CCONE code. 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. 10-02 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/. Am-243 = 0.006659 *1) Am-242 = 0.0049 measured by Saleh et al./3/ Am-241 = 0.003154 *1) *1) an average of systematics by Tuttle/4/, Benedetti et al./5/ and Waldo et al./6/ Decay constants calculated by Brady and England./7/ were adopted. MT=456 Number of prompt neutrons per fission (same as JENDL-3.3) Maslov's evaluation /8/ was adopted. * IDENTICAL TO THAT FOR AM-242M, WHICH WAS OBTAINED WITH MADLAND-NIX MODEL CALCULATIONS /9/ FITTED TO THE MEASURED DATA OF HOWE ET AL./10/ ABOVE EMISSIVE FISSION THRESHOLD SUPERPOSITION OF NEUTRON EMISSION IN (N,XNF) REACTIONS /11/ AND PROMPT FISSION NEUTRONS IS EMPLOYED. MF= 2 Resonance parameters MT=151 Resolved resonance parameters (below 100eV) Hypothetical resonance parameters were determined by Maslov et al./8/ For the present file, the parameters of -1.9344 and 0.35eV resonances were modified to reproduce the thermal fission /12,13/ and capture /14/ cross sections. Unresolved resonance parameters (100eV - 30keV) Parameters were determined with ASREP code/15/ so as to reproduce the cross sections in the energy range from 100 eV to 30 keV. They are used only for self-shielding calculations. Thermal cross sections and resonance integrals (at 300K) ------------------------------------------------------- 0.0253 eV reson. integ.(*) (barns) (barns) ------------------------------------------------------- total 2758.3 elastic 7.39 fission 2420.7 1050 capture 330.3 205 ------------------------------------------------------- (*) 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/. The same parameters as those for Am-242m were used in the CCONE calculation. MT= 2 Elastic scattering cross section Calculated as total - non-elastic scattering cross sections. MT=18 Fission cross section Below 70 keV, calculated with CCONE code. Above 70 keV, fission cross section of Am-242m was adopted, which was based on experimental data. 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 Assumed to be the same as Am-242m. MT=18 Fission neutron spectra Below 6 MeV, calculated with modified Madland-Nix formula considering multi-mode fission processes (standard-1, standard-2, superlong). Above 7 MeV, calculated with CCONE code. MT=455 Delayed neutron spectra Summation calculation by Brady and England /7/ 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 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./16/ for Pu-239 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 20% was assumed. MT=456 The same Covariance as Am-242m was adopted. MF=33 Covariances of neutron cross sections Covariances were given to all the cross sections by using KALMAN code/17/ and the covariances of model parameters used in the cross-section calculations. For the fission cross section, covariances of Am-242m obtained with the GMA analysis were adopted. Standard deviations were multiplied by a factor of 3. In the resolved resonance region, the following standard deviations were assuned parameters: Total 10 - 60 % Elastic scattering 20 % Fission 10 - 60 % Capture 20 - 70 % 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/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/18/ * Global parametrization of Koning-Duijvestijn/19/ was used. * Gamma emission channel/20/ was added to simulate direct and semi-direct capture reaction. 3) Hauser-Feshbach statistical model * Moldauer width fluctuation correction/21/ 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/22/. 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/23/,/24/ was used. The prameters are shown in Table 7. ------------------------------------------------------------------ Tables ------------------------------------------------------------------ Table 1. Coupled channel calculation -------------------------------------------------- * rigid rotor model was applied * coupled levels = 0,3,7 (see Table 2) * optical potential parameters /25/ Volume: V_0 = 48 MeV lambda_HF = 0.004 1/MeV C_viso = 15.9 MeV A_v = 12.04 MeV B_v = 81.36 MeV E_a = 385 MeV r_v = 1.255 fm a_v = 0.58 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 = 1.15 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 = 0.243 beta_4 = 0.08 beta_6 = 0.0015 * Calculated strength function S0= 1.45e-4 S1= 2.28e-4 R'= 9.66 fm (En=1 keV) -------------------------------------------------- Table 2. Level Scheme of Am-242 ------------------- No. Ex(MeV) J PI ------------------- 0 0.00000 1 - * 1 0.04409 0 - 2 0.04860 5 - 3 0.05270 3 - * 4 0.07582 2 - 5 0.09900 2 + 6 0.11400 6 - 7 0.14800 5 - * 8 0.14969 4 - 9 0.17100 4 - 10 0.19000 7 - 11 0.19770 3 - 12 0.23053 1 + 13 0.24436 3 - 14 0.26300 6 - 15 0.26990 3 + 16 0.27433 1 - 17 0.28350 7 + 18 0.28901 4 - 19 0.29284 2 - 20 0.29641 2 - 21 0.30700 5 + 22 0.32784 3 - 23 0.33071 3 - 24 0.34158 0 + 25 0.34200 5 - 26 0.35569 2 + 27 0.36470 2 + 28 0.37040 4 + 29 0.37247 4 - ------------------- *) Coupled levels in CC calculation Table 3. Level density parameters -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Am-243 17.8584 0.7698 2.0985 0.4029 -0.9548 3.1071 Am-242 18.6337 0.0000 1.6845 0.2795 -0.6541 0.9592 Am-241 18.1961 0.7730 1.7328 0.3819 -0.7226 2.8365 Am-240 18.5012 0.0000 1.3474 0.2883 -0.6831 1.0000 Am-239 18.4349 0.7762 1.5592 0.3648 -0.5528 2.6354 -------------------------------------------------------- Table 4. Fission barrier parameters ---------------------------------------- Nuclide V_A hw_A V_B hw_B MeV MeV MeV MeV ---------------------------------------- Am-243 6.200 0.800 5.150 0.520 Am-242 6.410 0.600 5.800 0.550 Am-241 6.100 0.800 5.500 0.520 Am-240 6.100 0.650 6.000 0.450 Am-239 6.000 0.800 5.400 0.520 ---------------------------------------- Table 5. Level density above inner saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Am-243 21.5049 0.8981 2.6000 0.2555 -0.6419 2.0981 Am-242 20.8697 0.0000 2.6000 0.3254 -2.4113 2.0000 Am-241 21.3526 0.9018 2.6000 0.3213 -1.4929 2.9018 Am-240 21.2764 0.0000 2.6000 0.3219 -2.3947 2.0000 Am-239 21.2001 0.9056 2.6000 0.3225 -1.4891 2.9056 -------------------------------------------------------- Table 6. Level density above outer saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Am-243 21.5049 0.8981 0.6000 0.3532 -0.8019 2.8981 Am-242 21.4288 0.0000 0.5600 0.3688 -1.8681 2.2000 Am-241 21.3526 0.9018 0.5200 0.3556 -0.7969 2.9018 Am-240 21.2764 0.0000 0.4800 0.3567 -1.6981 2.0000 Am-239 21.2001 0.9056 0.4400 0.3579 -0.7919 2.9056 -------------------------------------------------------- Table 7. Gamma-ray strength function for Am-243 -------------------------------------------------------- * E1: ER = 11.52 (MeV) EG = 2.77 (MeV) SIG = 244.72 (mb) ER = 14.31 (MeV) EG = 4.19 (MeV) SIG = 489.44 (mb) * M1: ER = 6.57 (MeV) EG = 4.00 (MeV) SIG = 1.28 (mb) * E2: ER = 10.10 (MeV) EG = 3.19 (MeV) SIG = 6.92 (mb) -------------------------------------------------------- References 1) O.Iwamoto et al.: J. Nucl. Sci. Technol., 46, 510 (2009). 2) O.Iwamoto: J. Nucl. Sci. 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