95-Am-240 JAEA+ EVAL-FEB10 O.Iwamoto, T.Nakagawa, et al. DIST-MAY10 20100304 ----JENDL-4.0 MATERIAL 9540 -----INCIDENT NEUTRON DATA ------ENDF-6 FORMAT History 07-10 Theoretical calculation was performed with CCONE code. Data were compiled as JENDL/AC-2008/1/. 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 Estimated from systematics by Tuttle/2/, Benedetti et al./3/ and Waldo et al./4/ MT=456 Number of prompt neutrons per fission Estimated from Howerton's systematics/5/. MF= 2 Resonance parameters MT=151 No resonance parameters are given. Thermal cross sections and resonance integrals (at 300K) ------------------------------------------------------- 0.0253 eV reson. integ.(*) (barns) (barns) ------------------------------------------------------- total 1792.1 elastic 11.32 fission 1500.4 997 capture 280.1 186 ------------------------------------------------------- (*) In the energy range from 0.5 eV to 10 MeV. MF= 3 Neutron cross sections Below 0.2 eV: * Elastic scattering cross section is 11.3 b calculated from scattering radius of 9.497 fm/6/. * Fission cross section is in the 1/v shape. 1500 b at 0.0253 eV was estimated from systematics. * Capture cross section is in the 1/v shape. Cross section of 280 b at 0.0253 eV was estimated from capture to fission ratio calculated at 1 eV/6/, and the thermal fission cross section. Above 0.2 eV: Cross sections calculated with CCONE code/6/ were adopted. MT= 1 Total cross section The cross section was calculated with CC OMP of Soukhovitskii et al./7/ The OMP was adjusted by Am-241(n,tot) cross section. MT=18 Fission cross section The simulated (n,f) cross sections of Britt and Wilhelmy/8/ were used to determine the parameters in the CCONE calculation. 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 spectra Calculated with CCONE code. 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./9/ 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 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=33 Covariances of neutron cross sections Covariances were given to all the cross sections by using KALMAN code/10/ and the covariances of model parameters used in the cross-section calculations. Covariances of the fission cross section were determined from experimental data. For the following cross sections, standard deviations in the energy region below 0.2 eV were assumed as follows: Total 77 % Elastic scattering 90 % Fission 90 % Capture 90 % 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/6/ 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/11/ * Global parametrization of Koning-Duijvestijn/12/ was used. * Gamma emission channel/13/ was added to simulate direct and semi-direct capture reaction. 3) Hauser-Feshbach statistical model * Moldauer width fluctuation correction/14/ 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/15/. 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/16/,/17/ was used. The prameters are shown in Table 7. ------------------------------------------------------------------ Tables ------------------------------------------------------------------ Table 1. Coupled channel calculation -------------------------------------------------- * rigid rotor model was applied * coupled levels = 0,1,4,6,9 (see Table 2) * optical potential parameters /7/ 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 = 0.213 beta_4 = 0.08 beta_6 = 0.0015 * Calculated strength function S0= 1.00e-4 S1= 2.61e-4 R'= 9.50 fm (En=1 keV) -------------------------------------------------- Table 2. Level Scheme of Am-240 ------------------- No. Ex(MeV) J PI ------------------- 0 0.00000 3 - * 1 0.04100 4 - * 2 0.05300 2 - 3 0.08700 3 - 4 0.09600 5 - * 5 0.13000 4 - 6 0.15800 6 - * 7 0.18600 5 - 8 0.21300 2 + 9 0.23300 7 - * 10 0.25200 6 - 11 0.28100 5 - 12 0.31600 8 - 13 0.32900 7 - 14 0.34600 1 - 15 0.39800 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 -------------------------------------------------------- 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 Am-238 18.3685 0.0000 1.3698 0.2894 -0.6819 1.0000 Am-237 18.3022 0.7795 1.5929 0.2878 0.0989 1.7795 -------------------------------------------------------- Table 4. Fission barrier parameters ---------------------------------------- Nuclide V_A hw_A V_B hw_B MeV MeV MeV MeV ---------------------------------------- Am-241 6.200 0.800 5.750 0.520 Am-240 6.100 0.650 6.000 0.450 Am-239 6.000 0.800 5.400 0.520 Am-238 5.700 0.650 2.100 0.450 Am-237 5.100 0.800 2.000 0.520 ---------------------------------------- Table 5. Level density above inner saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Am-241 21.3526 0.9018 2.6000 0.2826 -0.9589 2.4018 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 Am-238 21.1238 0.0000 2.6000 0.3231 -2.3946 2.0000 Am-237 21.0475 0.9094 2.6000 0.3238 -1.4852 2.9094 -------------------------------------------------------- Table 6. Level density above outer saddle -------------------------------------------------------- Nuclide a* Pair Eshell T E0 Ematch 1/MeV MeV MeV MeV MeV MeV -------------------------------------------------------- Am-241 23.2093 0.9018 0.5200 0.3009 -0.3647 2.4018 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 Am-238 21.1238 0.0000 0.4000 0.3591 -1.6968 2.0000 Am-237 21.0475 0.9094 0.3600 0.3603 -0.7868 2.9094 -------------------------------------------------------- Table 7. Gamma-ray strength function for Am-241 -------------------------------------------------------- * E1: ER = 11.55 (MeV) EG = 2.78 (MeV) SIG = 315.97 (mb) ER = 14.33 (MeV) EG = 4.20 (MeV) SIG = 418.60 (mb) * M1: ER = 6.59 (MeV) EG = 4.00 (MeV) SIG = 1.38 (mb) * E2: ER = 10.12 (MeV) EG = 3.22 (MeV) SIG = 6.93 (mb) -------------------------------------------------------- References 1) O.Iwamoto et al.: J. Nucl. Sci. Technol., 46, 510 (2009). 2) R.J.Tuttle: INDC(NDS)-107/G+Special, p.29 (1979). 3) G.Benedetti et al.: Nucl. Sci. Eng., 80, 379 (1982). 4) R.Waldo et al.: Phys. Rev., C23, 1113 (1981). 5) R.J.Howerton: Nucl. Sci. Eng., 62, 438 (1977). 6) O.Iwamoto: J. Nucl. Sci. Technol., 44, 687 (2007). 7) E.Sh.Soukhovitskii et al.: Phys. Rev. C72, 024604 (2005). 8) H.C.Britt, J.B.Wilhelmy: Nucl. Sci. Eng., 72, 222 (1979). 9) V.V.Verbinski et al.: Phys. Rev., C7, 1173 (1973). 10) T.Kawano, K.Shibata, JAERI-Data/Code 97-037 (1997) in Japanese. 11) C.Kalbach: Phys. Rev. C33, 818 (1986). 12) A.J.Koning, M.C.Duijvestijn: Nucl. Phys. A744, 15 (2004). 13) J.M.Akkermans, H.Gruppelaar: Phys. Lett. 157B, 95 (1985). 14) P.A.Moldauer: Nucl. Phys. A344, 185 (1980). 15) D.L.Hill, J.A.Wheeler: Phys. Rev. 89, 1102 (1953). 16) J.Kopecky, M.Uhl: Phys. Rev. C41, 1941 (1990). 17) J.Kopecky, M.Uhl, R.E.Chrien: Phys. Rev. C47, 312 (1990).