63-Eu-151

 63-EU-151 JAERI,JNDC EVAL-MAR89 T.ASAMI, JNDC FP ND W.G.         
                      DIST-MAR02 REV2-SEP01            20010907   
----JENDL-3.3         MATERIAL 6325                               
-----INCIDENT NEUTRON DATA                                        
------ENDF-6 FORMAT                                               
                                                                  
HISTORY                                                           
84-10 Evaluation for JENDL-2 was made by JNDC FPND W.G./1/        
89-03 Evaluation for JENDL-3 was made by T.Asami(jaeri) and JNDC  
      FP NUCLEAR DATA W.G.                                        
                                                                  
------------------------------------------------------------------
Data are the same as mat=3631 of JENDL-3 general purpose file/2/. 
------------------------------------------------------------------
01-07 Compiled by K.Shibata for JENDL-3.3                         
      *****  modified parts for JENDL-3.3  ***********************
      (1,451)          Updated.                                   
      (3,251)          Deleted.                                   
      (4,2)            Transformation matrix deleted.             
      (5,16-91)        INT=22                                     
      (12,16-107)      Added.                                     
      (14,16-107)      Added.                                     
      (15,16-107)      Added.                                     
      ************************************************************
                                                                  
mf = 1  General information                                       
  mt=451 Comments and dictionary                                  
                                                                  
mf = 2  Resonance parameters                                      
  mt=151 Resolved and unresolved resonance parameters             
  Resolved resonance region (MLBW formula) : Below 0.0982 keV     
       For JENDL-2, resonance parameters were evaluated by Kikuchi
    et al./3/ The parameters were adopted mainly from the data    
    measured by Rahn et al./4/  for the lowest 2 levels, the data 
    of Tassan et al./5/ were adopted.  The average radiation width
    of 0.093 eV/4/ was assumed for the levels whose radiation     
    width was not measured.  A negative resonance was added at    
    -0.00361 eV so as to reproduce the capture cross section of   
    9200+-100 barns at 0.0253 eV/6/.                              
       For JENDL-3, total spin J of some levels was estimated     
    with a random number method.                                  
                                                                  
  Unresolved resonance region : 0.0982 keV - 100 keV              
    The neutron strength functions S0, S1, S2 were based on the   
    compilation of Mughabghab/7/.  The observed level spacing was 
    adjusted to reproduce the capture cross section measured by   
    Macklin and Young/8/.  The effective scattering radius was    
    obtained from fitting to the calculated total cross section at
    100 keV.                                                      
                                                                  
  Typical values of the parameters at 70 keV:                     
    S0 = 3.699e-4, S1 = 0.100e-4, S2 = 3.000e-4, Sg = 2230.e-4,   
    Gg = 0.091 eV, R  = 6.870 fm.                                 
                                                                  
  calculated 2200-m/s cross sections and res. integrals (barns)   
                     2200 m/s               res. integ.           
      total        9201                        -                  
      elastic         3.207                    -                  
      capture      9198                      3070                 
     (n,alpha)        8.806e-06                                   
                                                                  
mf = 3  Neutron cross sections                                    
  Below 100 keV, resonance parameters were given.                 
  Above 100 keV, theoretical calculation was made by using the    
  optical and statistical model code casthy/9/ and the preequili- 
  brium and statistical model code gnash/10/.  The omp's for      
  neutron are given in tables 1 and 2, which were determined so as
  to reproduce the total cross section of natural Eu measured by  
  Foster and glasgow/11/.  Those for charged particles are adopted
  from Menet et al./12/ for proton and from Huizenga and Igo/13/  
  for alpha particle.                                             
                                                                  
  mt = 1  Total                                                   
    Below 10 MeV, calculation with casthy was adopted.  The       
    optical potential parameters listed in Table 1 were used.     
    Above 10 mev, the cross section was determined by eye-guiding 
    to the data of Foster and Glasgow/11/ for natural Eu.         
                                                                  
  mt = 2  Elastic scattering                                      
    Calculated as (total - sum of partial cross sections).        
                                                                  
  mt = 4, 51-60, 91  Inelastic scattering                         
    Calculated with the casthy code.  The level scheme used in the
    calculations was taken from ref./14/                          
                                                                  
         no   level energy(MeV)   spin-parity                     
        g.s      0.0                 5/2+                         
         1       0.02150             7/2+                         
         2       0.19620            11/2-                         
         3       0.19650             3/2+                         
         4       0.2432              7/2-                         
         5       0.2604              5/2+                         
         6       0.3070              7/2+                         
         7       0.3075              5/2+                         
         8       0.3498              9/2-                         
         9       0.3536              7/2-                         
        10       0.4160              7/2+                         
        Levels above 0.420 MeV were assumed to be overlapping.    
                                                                  
  mt = 102  Capture                                               
    Below 2 MeV, cross section was determined by eye-guiding the  
    data measured by Macklin and Young/8/.  Above 2 MeV, JENDL-2  
    data calculated with casthy was normalized to Macklin and     
    Young at 2 MeV.  Direct and semi-direct capture cross sections
    were added, which were estimated according to the procedure of
    Benzi and Reffo/15/ and normalized to 1 milli-barn at 14 MeV. 
                                                                  
                                                                  
  mt=16, 17, 22, 28, 103, 107  (n,2n), (n,3n), (n,na), (n,np),    
     (n,p) and (n,a) cross sections                               
    Calculated with the gnash code using the optical model        
    parameters in Table 2.  The level scheme data were taken from 
    ref./14/.  the calculated (n,2n) and (n,3n) cross sections    
    were modified on the basis of the experimental data of Frehaut
    et al./16/ and Bayhurt/17/, respectively.                     
                                                                  
    The (n,alpha) cross section in the resonance region was       
    calculated from resonance parameters, by assuming a mean alpha
    width of 9.0e-11 ev so as to reproduce the thermal cross      
    section/7/.  The cross section was averaged in suitable energy
    intervals.  Above 98.2 eV, the cross section was connected    
    smoothly to the gnash calculation.                            
                                                                  
mf = 4  Angular distributions of secondary neutrons               
  Legendre polynomial coefficients for angular distributions are  
  given in the center-of-mass system for mt=2 and discrete inelas-
  tic levels, and in the laboratory system for mt=91.  They were  
  calculated with casthy.  For other reactions, the isotropic     
  distributions in the laboratory system were assumed.            
                                                                  
mf = 5  Energy distributions of secondary neutrons                
  Energy distributions of secondary neutrons were calculated with 
  gnash.                                                          
                                                                  
mf = 12  Photon production multiplicities                         
  mt=16, 17, 22, 28, 91, 103, 107                                 
    Calculated with gnash code /10/.                              
  mt=102                                                          
    Calculated with casthy code /9/.                              
  mt=51-60                                                        
    Transitioin probability arrays                                
                                                                  
mf = 14  Photon angular distributions                             
  mt=16, 17, 22, 28, 51-60, 91, 102, 103, 107                     
    Isotropic.                                                    
                                                                  
mf = 15  Continuous photon energy distributions                   
  mt=16, 17, 22, 28, 91, 103, 107                                 
    Calculated with egnash code /10/.                             
  mt=102                                                          
    Calculated with casthy code /9/.                              
                                                                  
                                                                  
Table 1  Neutron optical potential parameters (for casthy)        
                                                                  
         V  = 43.71 - 0.0566*En,     Vso = 7.9   (MeV)            
         Ws = 7.696,                  Wv = 0.0   (MeV)            
          r = 1.270,  rs = 1.440,  rso = 1.280   (fm)             
          a = 0.60,    b = 0.45,   aso = 0.60    (fm)             
                                                                  
Table 2  Neutron optical potential parameters (for gnash)         
                                                                  
         V  = 43.71 - 0.05655*En,    Vso = 0.0   (MeV)            
         Ws = 7.696,                  Wv = 0.0   (MeV)            
          r = 1.272,  rs = 1.440,  rso = 1.270   (fm)             
          a = 0.48,    b = 0.45,   aso = 0.48    (fm)             
                                                                  
References                                                        
 1) Aoki, T. et al.: Proc. Int. Conf. on Nuclear Data for Basic   
    and Applied Science, Santa Fe., Vol. 2, p.1627 (1985).        
 2) Shibata, K., et al.: JAERI 1319 (1990).                       
 3) Kikuchi, Y. et al.: JAERI-M 86-030 (1986).                    
 4) Rahn, F., et al.: Phys. Rev., C6, 251 (1972).                 
 5) Tassan, S., et al.: Nucl. Sci., Eng., 10, 169 (1961).         
 6) Mughabghab, S.F., Garber, D.I.: "Neutron Cross Sections,      
    Vol.1, Rresonance Parameters", BNL 325, 3rd ed., Vol. 1,      
    (1973).                                                       
 7) Mughabghab, S.F.: "Neutron Cross Sections, Vol. I, Part B",   
    Academic Press (1984).                                        
 8) Macklin, R.L. and Young, P.G.: Nucl. Sci. Eng., 95, 189(1987).
 9) Igarasi, S.: J. Nucl. Sci. Technol., 12, 67 (1975).           
10) Young, P.G. and Arthur, E.D.: LA-6947 (1977).                 
11) Foster Jr,.D.G. and Glasgow, D.W.: Phys. Rev., C3, 576 (1971).
12) Menet, J.J.H., et al.: Phys. Rev., C4, 1114 (1971).           
13) Huizenga, J.R. and Igo, G.: Nucl. Phys. 29, 462 (1962).       
14) ENSDF: Evaluated Nuclear Structure Data File (June 1987).     
15) Benzi, V. and Reffo, G.: CCDN-NW/10 (1969).                   
16) Frehaut, J. et al.: Data (1980) in the EXFOR file.            
17) Bayhurst, B.P. et al.: Phys. Rev., C12, 451 (1975).