93-Np-236

 93-Np-236 JAEA+      EVAL-FEB10 O.Iwamoto,T.Nakagawa,K.Furutaka,+
                      DIST-MAY10                       20100318   
----JENDL-4.0         MATERIAL 9343                               
-----INCIDENT NEUTRON DATA                                        
------ENDF-6 FORMAT                                               
                                                                  
History                                                           
07-07 New theoretical calculation was made with CCONE code.       
07-09 Resolved resonance parameters were replaced.                
07-10 Theoretical calculation was made with CCONE code.           
      Data were compiled as JENDL/AC-2008/1/.                     
09-02 (3,102) below 0.2 eV, (1,452), (1,455) and (1,456) 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 systematics by Tuttle/2/, Benedetti et al./3/ 
    and Waldo et al./4/, and partial fission cross sections       
    calculated with CCONE code /5/.                               
                                                                  
  MT=456 Number of prompt neutrons per fission                    
    Based on the data measured by Lindner and Seegmiller/6/ and   
    Ohsawa's systematics/7/.                                      
                                                                  
                                                                  
MF= 2 Resonance parameters                                        
  MT=151                                                          
  Resolved resonance parameters (MLBW: 1.0e-5 - 21.5 eV)          
    Evaluated by Furutaka /8/ with SAMMY-7 code/9/.               
    Experimental data used are fission cross-section data measured
    by Danon et al./10/ Their data were normalized to 2815 b at   
    0.0253 eV. The capture width was fixed to 40 meV.             
    Doppler as well as resolution broadenings were taken into     
    account in the analysis: temperature was assumed to be 298 K. 
    For resolution broadening, parameters of SAMMY's original     
    resolution-broadening function were chosen to approximately   
    reproduce the experimental resolution function described by   
    equation (11) of ref./10/.                                    
                                                                  
    The 8 fictitious resonances in the energy range 24 to 33 eV   
    were adopted from ENDF/B-VII.0/11/                            
                                                                  
  Un-resolved resonance parameters (21.5 eV - 10 keV)             
    Parameters (URP) were determined with ASREP code/12/ 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           2938.9                                        
    elastic            9.657                                      
    fission         2808.0          1170                          
    capture          121.3           100                          
    -------------------------------------------------------       
         (*) In the energy range from 0.5 eV to 10 MeV.           
                                                                  
                                                                  
MF= 3 Neutron cross sections                                      
  All the cross-section data above 21.5 eV were calculated with   
  CCONE code/5/.                                                  
                                                                  
  MT= 1 Total cross section                                       
    The cross section was calculated with CC OMP of Soukhovitskii 
    et al./13/.                                                   
                                                                  
  MT=18 Fission cross section                                     
    Calculated with CCONE code. The simulated (n,f) cross section 
    of Britt and Wilhelmy/14/ and the experimental data of        
    Danon et al./10/ and Val'skiy et al./15/ 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 Prompt neutrons                                           
    Calculated with CCONE code/5/.                                
                                                                  
                                                                  
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 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 30% which was  
    estimated from the experimental data of Lindner and           
    Seegmiller/6/.                                                
                                                                  
                                                                  
MF=32 Covariances of resonance parameters                         
  MT=151 Resolved resonance parameterss                           
    Format of LCOMP=1 was adopted.                                
                                                                  
    Covariances of parameters were taken from the results of SAMMY
    analysis/8/. The covariances were multiplied by a factor      
    of 10 because they were too small.                            
                                                                  
                                                                  
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.                         
                                                                  
  Covariances of the fission cross section were determined by     
  considering the experimental data (see MF=3).                   
                                                                  
  In the resolved resonance region, the following standard        
  deviations were added to the contributions from resonance       
  parameters:                                                     
       Elastic scattering  20 %                                   
       Capture             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/5/ 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 = 0,1,5 (see Table 2)                          
  * optical potential parameters /13/                             
    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= 0.90e-4 S1= 2.70e-4 R'=  9.46 fm (En=1 keV)               
  --------------------------------------------------              
                                                                  
Table 2. Level Scheme of Np-236                                   
  -------------------                                             
  No.  Ex(MeV)   J PI                                             
  -------------------                                             
   0  0.00000   6  -  *                                           
   1  0.05600   7  -  *                                           
   2  0.06000   1  +                                              
   3  0.07600   2  +                                              
   4  0.10000   3  +                                              
   5  0.12000   8  -  *                                           
   6  0.13200   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         
  --------------------------------------------------------        
   Np-237 18.3022  0.7795  2.4371  0.3963 -0.9739  3.1569         
   Np-236 18.2358  0.0000  2.1332  0.2999 -0.7994  1.1664         
   Np-235 18.1694  0.7828  2.2924  0.3973 -0.9417  3.1303         
   Np-234 18.1029  0.0000  2.1332  0.2844 -0.6773  1.0000         
   Np-233 18.0364  0.7861  2.3620  0.4163 -1.1454  3.3864         
  --------------------------------------------------------        
                                                                  
Table 4. Fission barrier parameters                               
  ----------------------------------------                        
  Nuclide     V_A    hw_A     V_B    hw_B                         
              MeV     MeV     MeV     MeV                         
  ----------------------------------------                        
   Np-237   6.000   0.950   5.570   0.600                         
   Np-236   6.100   0.600   6.080   0.600                         
   Np-235   6.250   0.950   5.630   0.600                         
   Np-234   6.200   0.460   5.850   0.370                         
   Np-233   4.300   0.800   3.300   0.520                         
  ----------------------------------------                        
                                                                  
Table 5. Level density above inner saddle                         
  --------------------------------------------------------        
  Nuclide      a*    Pair  Eshell       T      E0  Ematch         
            1/MeV     MeV     MeV     MeV     MeV     MeV         
  --------------------------------------------------------        
   Np-237 21.9626  0.9094  2.6000  0.3162 -1.4591  2.9094         
   Np-236 22.2477  0.0000  2.6000  0.3139 -2.3586  2.0000         
   Np-235 20.3497  0.9133  2.6000  0.3299 -1.4981  2.9133         
   Np-234 20.2753  0.0000  2.6000  0.3306 -2.4114  2.0000         
   Np-233 20.2008  0.9172  2.6000  0.3312 -1.4942  2.9172         
  --------------------------------------------------------        
                                                                  
Table 6. Level density above outer saddle                         
  --------------------------------------------------------        
  Nuclide      a*    Pair  Eshell       T      E0  Ematch         
            1/MeV     MeV     MeV     MeV     MeV     MeV         
  --------------------------------------------------------        
   Np-237 22.3287  0.9094  0.2400  0.3268 -0.5253  2.6094         
   Np-236 22.2477  0.0000  0.2000  0.3977 -2.2734  2.7000         
   Np-235 22.1666  0.9133  0.1600  0.3517 -0.7691  2.9133         
   Np-234 20.2753  0.0000  0.1200  0.3712 -1.6997  2.0000         
   Np-233 20.2008  0.9172  0.0800  0.3724 -0.7819  2.9172         
  --------------------------------------------------------        
                                                                  
Table 7. Gamma-ray strength function for Np-237                   
  --------------------------------------------------------        
  K0 = 1.300   E0 = 4.500 (MeV)                                   
  * E1: ER = 10.98 (MeV) EG = 2.17 (MeV) SIG = 311.00 (mb)        
        ER = 14.08 (MeV) EG = 4.66 (MeV) SIG = 540.00 (mb)        
  * M1: ER =  6.63 (MeV) EG = 4.00 (MeV) SIG =   2.08 (mb)        
  * E2: ER = 10.18 (MeV) EG = 3.27 (MeV) SIG =   6.65 (mb)        
  --------------------------------------------------------        
                                                                  
                                                                  
References                                                        
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 7) T.Ohsawa: J.Nucl. Radiochem. Sci., 9, 19 (2008).              
 8) K.Furutaka: Private communication (2007).                     
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10) Y.Danon et al.: Nucl. Sci. Eng., 124, 482 (1996).             
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    Japanese.                                                     
18) C.Kalbach: Phys. Rev. C33, 818 (1986).                        
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20) J.M.Akkermans, H.Gruppelaar: Phys. Lett. 157B, 95 (1985).     
21) P.A.Moldauer: Nucl. Phys. A344, 185 (1980).                   
22) D.L.Hill, J.A.Wheeler: Phys. Rev. 89, 1102 (1953).            
23) J.Kopecky, M.Uhl: Phys. Rev. C41, 1941 (1990).                
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