34-Se- 76

 34-SE- 76 JNDC       EVAL-MAR90 JNDC FP NUCLEAR DATA W.G.        
                      DIST-NOV90                                  
----JENDL-3.2         MATERIAL 3431                               
-----INCIDENT NEUTRON DATA                                        
------ENDF-6 FORMAT                                               
HISTORY                                                           
90-03 NEW EVALUATION FOR JENDL-3 WAS COMPLETED BY JNDC FPND       
      W.G./1/                                                     
                                                                  
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 9 KEV          
    RESONANCE PARAMETERS WERE BASED ON MUGHABGHAB ET AL./2/       
    AVERAGE RADIATION WIDTH GIVEN BY MUGHABGHAB ET AL. WAS        
    SLIGHTLY MODIFIED AND WAS ADOPTED FOR THE 16 RESONANCE LEVELS 
    WHOSE RADIATION WIDTH WAS UNKNOWN.  NEUTRON ORBITAL ANGULAR   
    MOMENTUM L OF SOME RESONANCES WAS ESTIMATED WITH A METHOD OF  
    BOLLINGER AND THOMAS/3/.  SCATTERING RADIUS WAS ALSO TAKEN    
    FROM MUGHABGHAB ET AL.  A NEGATIVE RESONANCE WAS ADDED SO AS  
    TO REPRODUCE THE THERMAL CAPTURE AND SCATTERING CROSS SECTIONS
    GIVEN BY MUGHABGHAB ET AL.                                    
                                                                  
  UNRESOLVED RESONANCE REGION : 9 KEV - 100 KEV                   
    THE NEUTRON STRENGTH FUNCTIONS, S0 AND S1 WERE BASED ON THE   
    COMPILATION OF MUGHABGHAB ET AL., AND S2 WAS CALCULATED WITH  
    OPTICAL MODEL CODE CASTHY/4/.  THE OBSERVED LEVEL SPACING WAS 
    DETERMINED TO REPRODUCE THE CAPTURE CROSS SECTION CALCULATED  
    WITH CASTHY.  THE EFFECTIVE SCATTERING RADIUS WAS OBTAINED    
    FROM FITTING TO THE CALCULATED TOTAL CROSS SECTION AT 100 KEV.
    THE RADIATION WIDTH GG WAS BASED ON THE COMPILATION OF        
    MUGHABGHAB ET AL.                                             
                                                                  
  TYPICAL VALUES OF THE PARAMETERS AT 70 KEV:                     
    S0 = 1.640E-4, S1 = 0.939E-4, S2 = 0.760E-4, SG = 1.90E-4,    
    GG = 0.230 EV, R  = 7.363 FM.                                 
                                                                  
  CALCULATED 2200-M/S CROSS SECTIONS AND RES. INTEGRALS (BARNS)   
                     2200 M/S               RES. INTEG.           
      TOTAL         103.4                      -                  
      ELASTIC        18.40                     -                  
      CAPTURE        85.00                     41.1               
                                                                  
MF = 3  NEUTRON CROSS SECTIONS                                    
  BELOW 100 KEV, RESONANCE PARAMETERS WERE GIVEN.                 
  ABOVE 100 KEV, THE SPHERICAL OPTICAL AND STATISTICAL MODEL      
  CALCULATION WAS PERFORMED WITH CASTHY, BY TAKING ACCOUNT OF     
  COMPETING REACTIONS, OF WHICH CROSS SECTIONS WERE CALCULATED    
  WITH PEGASUS/5/ STANDING ON A PREEQUILIBRIUM AND MULTI-STEP     
  EVAPORATION MODEL.  THE OMP'S FOR NEUTRON GIVEN IN TABLE 1 WERE 
  DETERMINED TO REPRODUCE A SYSTEMATIC TREND OF THE TOTAL CROSS   
  SECTION BY CHANGING R0, RS AND RSO OF IIJIMA-KAWAI POTENTIAL/6/.
  THE OMP'S FOR CHARGED PARTICLES ARE AS FOLLOWS:                 
     PROTON   = PEREY/7/                                          
     ALPHA    = HUIZENGA AND IGO/8/                               
     DEUTERON = LOHR AND HAEBERLI/9/                              
     HELIUM-3 AND TRITON = BECCHETTI AND GREENLEES/10/            
  PARAMETERS FOR THE COMPOSITE LEVEL DENSITY FORMULA OF GILBERT   
  AND CAMERON/11/ WERE EVALUATED BY IIJIMA ET AL./12/  MORE       
  EXTENSIVE DETERMINATION AND MODIFICATION WERE MADE IN THE       
  PRESENT WORK.  TABLE 2 SHOWS THE LEVEL DENSITY PARAMETERS USED  
  IN THE PRESENT CALCULATION.  ENERGY DEPENDENCE OF SPIN CUT-OFF  
  PARAMETER IN THE ENERGY RANGE BELOW E-JOINT IS DUE TO GRUPPELAAR
  /13/.                                                           
                                                                  
  MT = 1  TOTAL                                                   
    SPHERICAL OPTICAL MODEL CALCULATION WAS ADOPTED.              
                                                                  
  MT = 2  ELASTIC SCATTERING                                      
    CALCULATED AS (TOTAL - SUM OF PARTIAL CROSS SECTIONS).        
                                                                  
  MT = 4, 51 - 91  INELASTIC SCATTERING                           
    SPHERICAL OPTICAL AND STATISTICAL MODEL CALCULATION WAS       
    ADOPTED. THE LEVEL SCHEME WAS BASED ON EVALUATED NUCLEAR      
    STRUCTURE DATA FILE (1987 VERSION)/14/ AND NUCLEAR DATA       
    SHEETS/15/.                                                   
                                                                  
           NO.      ENERGY(MEV)    SPIN-PARITY                    
           GR.       0.0             0  +                         
            1        0.5591          2  +                         
            2        1.1223          0  +                         
            3        1.2161          2  +                         
            4        1.3309          4  +                         
            5        1.6890          3  +                         
            6        1.7876          2  +                         
            7        2.0260          4  +                         
            8        2.1272          2  +                         
            9        2.1705          0  +                         
           10        2.2623          6  +                         
           11        2.3629          2  +                         
           12        2.4291          3  -                         
           13        2.4886          5  +                         
           14        2.5147          2  +                         
           15        2.5700          4  +                         
           16        2.6057          4  +                         
           17        2.6184          4  +                         
           18        2.6309          1  -                         
           19        2.6553          1  -                         
           20        2.6699          2  -                         
           21        2.8045          2  +                         
           22        2.8125          4  +                         
           23        2.8167          2  +                         
           24        2.8248          5  -                         
           25        2.8597          4  -                         
           26        2.8698          4  +                         
           27        2.9110          4  -                         
           28        2.9200          4  +                         
           29        2.9506          1  +                         
      LEVELS ABOVE 2.968 MEV WERE ASSUMED TO BE OVERLAPPING.      
                                                                  
  MT = 102  CAPTURE                                               
    SPHERICAL OPTICAL AND STATISTICAL MODEL CALCULATION WITH      
    CASTHY WAS ADOPTED.  DIRECT AND SEMI-DIRECT CAPTURE CROSS     
    SECTIONS WERE ESTIMATED ACCORDING TO THE PROCEDURE OF BENZI   
    AND REFFO/16/ AND NORMALIZED TO 1 MILLI-BARN AT 14 MEV.       
                                                                  
    THE GAMMA-RAY STRENGTH FUNCTION (1.59E-04) WAS ASSUMED.       
                                                                  
  MT = 16  (N,2N) CROSS SECTION                                   
  MT = 17  (N,3N) CROSS SECTION                                   
  MT = 22  (N,N'A) CROSS SECTION                                  
  MT = 28  (N,N'P) CROSS SECTION                                  
  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,ALPHA) CROSS SECTION                                
  MT =111  (N,2P) CROSS SECTION                                   
    THESE REACTION CROSS SECTIONS WERE CALCULATED WITH THE        
    PREEQUILIBRIUM AND MULTI-STEP EVAPORATION MODEL CODE PEGASUS. 
                                                                  
    THE KALBACH'S CONSTANT K (=  68.3) WAS ESTIMATED BY THE       
    FORMULA DERIVED FROM KIKUCHI-KAWAI'S FORMALISM/17/ AND LEVEL  
    DENSITY PARAMETERS.                                           
                                                                  
    FINALLY, THE (N,2N) (N,P) AND (N,ALPHA) CROSS SECTIONS WERE   
    NORMALIZED TO THE FOLLOWING VALUES AT 14.5 MEV:               
      (N,2N)       900.00  MB (RECOMMENDED BY BYCHKOV+/18/)       
      (N,P)         70.00  MB (RECOMMENDED BY FORREST/19/)        
      (N,ALPHA)     15.60  MB (SYSTEMATICS OF FORREST/19/)        
                                                                  
  MT = 251  MU-BAR                                                
    CALCULATED WITH CASTHY.                                       
                                                                  
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, ISOTROPIC DISTRI- 
  BUTIONS IN THE LABORATORY SYSTEM WERE ASSUMED.                  
                                                                  
MF = 5  ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS                
  ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS WERE CALCULATED WITH 
  PEGASUS FOR INELASTIC SCATTERING TO OVERLAPPING LEVELS AND FOR  
  OTHER NEUTRON EMITTING REACTIONS.                               
                                                                  
TABLE 1  NEUTRON OPTICAL POTENTIAL PARAMETERS                     
                                                                  
                DEPTH (MEV)       RADIUS(FM)    DIFFUSENESS(FM)   
         ----------------------   ------------  ---------------   
        V  = 46.0-0.25E           R0 = 5.7      A0 = 0.62         
        WS = 7.0                  RS = 6.2      AS = 0.35         
        VSO= 7.0                  RSO= 5.7      ASO= 0.62         
  THE FORM OF SURFACE ABSORPTION PART IS DER. WOODS-SAXON TYPE.   
                                                                  
TABLE 2  LEVEL DENSITY PARAMETERS                                 
                                                                  
 NUCLIDE  SYST A(1/MEV)  T(MEV)    C(1/MEV)  EX(MEV)   PAIRING    
 ---------------------------------------------------------------  
 32-GE- 72  *  1.350E+01 9.028E-01 3.062E+00 1.086E+01 2.790E+00  
 32-GE- 73  *  1.409E+01 8.904E-01 1.973E+01 9.644E+00 1.360E+00  
 32-GE- 74  *  1.384E+01 8.784E-01 1.667E+00 1.106E+01 3.240E+00  
 32-GE- 75  *  1.368E+01 8.667E-01 1.100E+01 8.810E+00 1.360E+00  
                                                                  
 33-AS- 73  *  1.369E+01 8.904E-01 1.364E+01 9.389E+00 1.430E+00  
 33-AS- 74     1.132E+01 9.475E-01 1.967E+01 7.033E+00 0.0        
 33-AS- 75     1.250E+01 9.510E-01 6.830E+00 1.008E+01 1.880E+00  
 33-AS- 76     1.330E+01 7.860E-01 1.900E+01 5.611E+00 0.0        
                                                                  
 34-SE- 74     1.290E+01 8.620E-01 1.070E+00 9.612E+00 2.860E+00  
 34-SE- 75     1.391E+01 8.500E-01 9.741E+00 8.707E+00 1.430E+00  
 34-SE- 76     1.315E+01 8.900E-01 1.097E+00 1.082E+01 3.310E+00  
 34-SE- 77     1.438E+01 8.000E-01 7.140E+00 8.015E+00 1.430E+00  
 ---------------------------------------------------------------  
  SYST:  * = LDP'S WERE DETERMINED FROM SYSTEMATICS.              
                                                                  
 SPIN CUTOFF PARAMETERS WERE CALCULATED AS 0.146*SQRT(A)*A**(2/3).
 IN THE CASTHY CALCULATION, SPIN CUTOFF FACTORS AT 0 MEV WERE     
 ASSUMED TO BE 6.780 FOR SE- 76 AND 6.517 FOR SE- 77.             
                                                                  
REFERENCES                                                        
 1) KAWAI, M. ET AL.: PROC. INT. CONF. ON NUCLEAR DATA FOR SCIENCE
    AND TECHNOLOGY, MITO, P. 569 (1988).                          
 2) MUGHABGHAB, S.F. ET AL.: "NEUTRON CROSS SECTIONS, VOL. I,     
    PART A", ACADEMIC PRESS (1981).                               
 3) BOLLINGER, L.M. AND THOMAS, G.E.: PHYS. REV., 171,1293(1968). 
 4) IGARASI, S.: J. NUCL. SCI. TECHNOL., 12, 67 (1975).           
 5) IIJIMA, S. ET AL.: JAERI-M 87-025, P. 337 (1987).             
 6) IIJIMA, S. AND KAWAI, M.: J. NUCL. SCI. TECHNOL., 20, 77      
    (1983).                                                       
 7) PEREY, F.G: PHYS. REV. 131, 745 (1963).                       
 8) HUIZENGA, J.R. AND IGO, G.: NUCL. PHYS. 29, 462 (1962).       
 9) LOHR, J.M. AND HAEBERLI, W.: NUCL. PHYS. A232, 381 (1974).    
10) BECCHETTI, F.D., JR. AND GREENLEES, G.W.: POLARIZATION        
    PHENOMENA IN NUCLEAR REACTIONS ((EDS) H.H. BARSHALL AND       
    W. HAEBERLI), P. 682, THE UNIVERSITY OF WISCONSIN PRESS.      
    (1971).                                                       
11) GILBERT, A. AND CAMERON, A.G.W.: CAN. J. PHYS., 43, 1446      
    (1965).                                                       
12) IIJIMA, S., ET AL.: J. NUCL. SCI. TECHNOL. 21, 10 (1984).     
13) GRUPPELAAR, H.: ECN-13 (1977).                                
14) ENSDF: EVALUATED NUCLEAR STRUCTURE DATA FILE (JUNE 1987).     
15) NUCLEAR DATA SHEETS, 42, 233 (1984).                          
16) BENZI, V. AND REFFO, G.: CCDN-NW/10 (1969).                   
17) KIKUCHI, K. AND KAWAI, M.: "NUCLEAR MATTER AND NUCLEAR        
    REACTIONS", NORTH HOLLAND (1968).                             
18) BYCHKOV, V.M. ET AL.: INDC(CCP)-146/LJ (1980).                
19) FORREST, R.A.: AERE-R 12419 (1986).