70-Yb-176

 70-Yb-176 JAEA       EVAL-FEB10 S.Kunieda, A.Ichihara, K.Shibata+
                      DIST-MAY10                       20100222   
----JENDL-4.0         MATERIAL 7049                               
-----INCIDENT NEUTRON DATA                                        
------ENDF-6 FORMAT                                               
                                                                  
History                                                           
10-02 New evaluation was done (compiled by S. Kunieda).           
                                                                  
MF= 1 General information                                         
                                                                  
  MT=451 Descriptive data and directory                           
                                                                  
                                                                  
MF= 2 Resonance parameters                                        
                                                                  
  MT=151 Resolved and unresolved resonance parameters             
                                                                  
    - Resolved resonance region: below 5.0 keV                    
      The parameters (MLBW formula) were taken from the           
      compilation of Mughabghab /1/.                              
                                                                  
    - Unresolved resonance region: 5.0 keV - 250 keV              
      The parameters were obtained by fitting to the total and    
      capture cross sections calculated by the POD code /2/.      
      The ASREP code /3/ was employed in this evaluation.         
      The unresolved parameters should be used only for           
      self-shielding calculation.                                 
                                                                  
   Thermal cross sections & resonance integrals at 300 K          
    ----------------------------------------------------------    
                     0.0253 eV           res. integ. (*)          
                      (barns)              (barns)                
    ----------------------------------------------------------    
     Total          1.16948E+01                                   
     Elastic        8.87143E+00                                   
     n,gamma        2.82339E+00           6.97643E+00             
    ----------------------------------------------------------    
    (*) Integrated from 0.5 eV to 10 MeV.                         
                                                                  
                                                                  
MF= 3 Neutron cross sections                                      
                                                                  
  MT=  1 Total cross section                                      
    Sum of partial cross sections.                                
                                                                  
  MT=  2 Elastic scattering cross section                         
    The OPTMAN /4/ & POD calculations /2/.                        
                                                                  
  MT=  3 Non-elastic cross section                                
    Sum of partial non-elastic cross sections.                    
                                                                  
  MT=  4,51-91 (n,n') cross section                               
    The OPTMAN /4/ & POD calculations /2/.                        
                                                                  
  MT= 16 (n,2n) cross section                                     
  MT= 17 (n,3n) cross section                                     
  MT= 22 (n,na) cross section                                     
  MT= 28 (n,np) cross section                                     
  MT= 32 (n,nd) cross section                                     
    Calculated by the POD code /2/.                               
                                                                  
  MT=102 Capture cross section                                    
    Calculated by the POD code /2/. Gamma-ray strength            
    function was normalized to fit the experimental cross         
    sections measured by Wisshak et al /5/.                       
                                                                  
  MT=103 (n,p) cross section                                      
  MT=104 (n,d) cross section                                      
  MT=105 (n,t) cross section                                      
  MT=106 (n,He3) cross section                                    
  MT=107 (n,a) cross section                                      
    Calculated by the POD code /2/.                               
                                                                  
  MT=203 (n,xp) cross section                                     
    Sum of (n,np) and (n,p)                                       
                                                                  
  MT=204 (n,xd) cross section                                     
    Sum of (n,nd) and (n,d)                                       
                                                                  
  MT=205 (n,xt) cross section                                     
  MT=206 (n,xHe3) cross section                                   
    Calculated by the POD code /2/.                               
                                                                  
  MT=207 (n,xa) cross section                                     
    Sum of (n,na) and (n,a)                                       
                                                                  
                                                                  
MF= 4 Angular distributions of emitted neutrons                   
                                                                  
  MT=  2 Elastic scattering                                       
    The OPTMAN /4/ & POD calculations /2/.                        
                                                                  
                                                                  
MF= 6 Energy-angle distributions of emitted particles             
                                                                  
  MT= 16 (n,2n) reaction                                          
  MT= 17 (n,3n) reaction                                          
  MT= 22 (n,na) reaction                                          
  MT= 28 (n,np) reaction                                          
  MT= 32 (n,nd) reaction                                          
    Neutron spectra calculated by the POD code /2/.               
                                                                  
  MT= 51-90 (n,n') reaction                                       
    Neutron angular distributions calculated by                   
    OPTMAN /4/ & POD /2/.                                         
                                                                  
  MT= 91 (n,n') reaction                                          
    Neutron spectra calculated by the POD code /2/.               
                                                                  
  MT= 203 (n,xp) reaction                                         
  MT= 204 (n,xd) reaction                                         
  MT= 205 (n,xt) reaction                                         
  MT= 206 (n,xHe3) reaction                                       
  MT= 207 (n,xa) reaction                                         
    Light-ion spectra calculated by the POD code /6/.             
                                                                  
                                                                  
MF=12 Gamma-ray multiplicities                                    
                                                                  
  MT=  3 Non-elastic gamma emission                               
    Calculated by the POD code /2/.                               
                                                                  
                                                                  
MF=14 Gamma-ray angular distributions                             
                                                                  
  MT=  3 Non-elastic gamma emission                               
    Assumed to be isotropic.                                      
                                                                  
                                                                  
MF=15 Gamma-ray spectra                                           
                                                                  
  MT=  3 Non-elastic gamma emission                               
    Calculated by the POD code /2/.                               
                                                                  
                                                                  
                                                        
                                                                  
***************************************************************   
*        Nuclear Model Calculations with POD Code /2/     *       
***************************************************************   
1. Theoretical models                                             
 The POD code is based on the spherical optical model, the        
distorted-wave Born approximaiton (DWBA), one-component exciton   
preequilibrium model, and the Hauser-Feshbach-Moldauer statis-    
tical model.  With the preequilibrium model, semi-empirical       
pickup and knockout process can be taken into account for         
composite-particle emission.  The gamma-ray emission from the     
compound nucleus can be calculated within the framework of the    
exciton model.  The code is capable of reading in particle        
transmission coefficients calculated by separate spherical or     
coupled-channel optical model code. In this evaluation, the OPTMAN
/4/ code was employed for neutrons, while the ECIS code           
/6/ was adopted for charged particles.                            
                                                                  
2. Optical model & parameters                                     
  Neutrons:                                                       
    Model: Coupled-channel model based on the rigid-rotor model   
    OMP  : Coupled-channel optical potential /7/                  
           Deformation parameters were taken from FRDM /8/.       
  Protons:                                                        
    Model: Spherical                                              
    OMP  : Koning and Delaroche /9/                               
  Deuterons:                                                      
    Model: Spherical                                              
    OMP  : Bojowald et al. /10/                                   
  Tritons:                                                        
    Mode: Spherical                                               
    OMP : Becchetti and Greenlees /11/                            
  He-3:                                                           
    Model: Spherical                                              
    OMP  : Becchetti and Greenlees /11/                           
  Alphas:                                                         
    Model: Spherical                                              
    OMP  : A simplified folding model potential /12/              
           (The nucleon OMP was taken form Ref./7/.)              
                                                                  
3. Level scheme of Yb-176                                         
  ------------------------------------                            
   No.   Ex(MeV)     J  PI      CC                                
  ------------------------------------                            
    0    0.00000     0   +       *                                
    1    0.08213     2   +       *                                
    2    0.27170     4   +       *                                
    3    0.56470     6   +       *                                
    4    0.95400     8   +       *                                
    5    1.05000     8   -                                        
    6    1.08820     0   +                                        
    7    1.13200     3   +                                        
    8    1.19340     3   -                                        
    9    1.26090     2   +                                        
   10    1.28340     2   +                                        
   11    1.34110     2   +                                        
   12    1.43100    10   +                                        
   13    1.43170     4   -                                        
  -------------------------                                       
  Levels above  1.44170 MeV are assumed to be continuous.         
                                                                  
4. Level density parameters                                       
 Energy-dependent parameters of Mengoni-Nakajima /13/ were used   
  ----------------------------------------------------------      
  Nuclei    a*    Pair    Esh     T     E0    Ematch Elv_max      
          1/MeV   MeV     MeV    MeV    MeV    MeV    MeV         
  ----------------------------------------------------------      
  Yb-177  20.576  0.902  1.393  0.514 -0.787  5.416  0.526        
  Yb-176  20.767  1.809  1.620  0.504  0.128  6.258  1.432        
  Yb-175  19.992  0.907  1.317  0.517 -0.669  5.299  0.872        
  Yb-174  20.061  1.819  1.463  0.541 -0.106  6.753  1.926        
  Tm-176  20.617  0.000  1.514  0.541 -2.085  5.130    -          
  Tm-175  19.828  0.907  1.572  0.490 -0.388  4.810  0.532        
  Tm-174  20.417  0.000  1.186  0.574 -2.400  5.682    -          
  Er-174  20.564  1.819  1.826  0.508  0.071  6.367    -          
  Er-173  21.018  0.912  1.560  0.495 -0.711  5.236    -          
  Er-172  20.361  1.830  1.668  0.479  0.504  5.706  0.961        
  ----------------------------------------------------------      
                                                                  
5. Gamma-ray strength functions                                   
   M1, E2: Standard Lorentzian (SLO)                              
   E1    : Generalized Lorentzian (GLO) /14/                      
                                                                  
6. Preequilibrium process                                         
   Preequilibrium is on for n, p, d, t, He-3, and alpha.          
   Preequilibrium capture is on.                                  
                                                                  
                                                                  
References                                                        
 1) S.F.Mughabghab, "Atlas of Neutron Resonances",                
    Elsevier (2006).                                              
 2) A.Ichihara et al., JAEA-Data/Code 2007-012 (2007).            
 3) Y.Kikuchi et al., JAERI-Data/Code 99-025 (1999)               
    [in Japanese].                                                
 4) E.Soukhovitski et al., JAERI-Data/Code 2005-002 (2005).       
 5) K.Wisshak et al., Phys. Rev. C61, 065801 (2000).              
 6) J.Raynal, CEA Saclay report, CEA-N-2772 (1994).               
 7) S.Kunieda et al., J. Nucl. Sci. Technol. 44, 838 (2007).      
 8) P.Moller et al., At. Data and Nucl. Data Tables 59, 185       
    (1995).                                                       
 9) A.J.Koning, J.P.Delaroche, Nucl. Phys. A713, 231 (2003).      
10) Bojowald et al., Phys. Rev. C 38, 1153 (1988).                
11) F.D.Becchetti,Jr., G.W.Greenlees, "Polarization               
    Phenomena in Nuclear Reactions," p.682, The University        
    of Wisconsin Press (1971).                                    
12) D.G.Madland, NEANDC-245 (1988), p. 103.                       
13) A.Mengoni, Y.Nakajima, J. Nucl. Sci. Technol. 31, 151         
     (1994).                                                      
14) M.Brink, Ph.D thesis, Oxford University, 1955.