ENTRY            A0452   20021218
SUBENT        A0452001   20021218                                 
BIB                 10         66                                 
TITLE      Preequilibrium emission in alpha induced reactions on  
           bromine and thallium                                   
AUTHOR     (N.P.M.Sathik, M.Afzal Ansari, B.P.Singh, M.Ismail,    
           M.H.Rashid)                                            
REFERENCE  (J,PR/C,66,014602,2002)                                
INSTITUTE  (3INDMUA) Department of physics                        
           (3INDVEC)                                              
SAMPLE     Targets of KBr and TlCl of thicknesses 1.5 and 3.52    
           mg/cm**2 , respectively, were prepared by a special    
           vacuum evaporation technique because of the hygroscopic
           nature of these compounds.  These targets were         
           deposited on aluminum backings of uniform thickness of 
           6.75 mg/cm**2 , placed over a rectangular masking      
           plate. A thin aluminum layer of thickness 25 mg/cm**2  
           was further deposited by vacuum evaporation onto the   
           upper surface of the prepared targets, so that the     
           moisture would not affect the surface of these targets.
METHOD     (STTA) See sample                                      
           aluminum foils of different thicknesses were also      
           interspersed as energy degraders in order to get the   
           desired alpha-particle energy on different targets.    
           (ACTIV) A stack of KBr and TlCl comprised of eight     
           targets each was irradiated at 50 MeV for 3 hours.     
           Moreover, stacks of KBr comprised of six foils and of  
            TlCl  having two foils were irradiated at 30 and 25   
           MeV, respectively, for 3 hours each.                   
           (BCINT)                                                
           (GSPEC)                                                
DETECTOR   (GELI)                                                 
FACILITY   (ISOCY,3INDVEC)                                        
HISTORY    (20021202C)                                            
           (20021218R) Corrected data table is received from m.   
           Afzal ansari.                                          
           (20021218U) Last checking has been done.               
ERR-ANALYS (ERR-T)  The uncertainty in the detector efficiency due
           to the statistical errors of counting, is estimated  to
           be <1%.  Since the irradiated targets were not point   
           sources, the uncertainties due to a solid angle are    
           estimated and is found to be <5%.  The total           
           uncertainty in the efficiency is estimated to be <6.5%.
           The uncertainty due to flux variation is estimated to  
           be <4%.  In order to minimize the errors due to the    
           dead time, particularly for the cases where the        
           activity in the irradiated samples was large, the      
           sample-detector distance was suitably adjusted to keep 
           the dead time <10%.  However, the corrections were     
           applied in the counting rates accordingly.  The errors 
           in the estimation of number of target nuclei were      
           analyzed and are estimated to be <1%.  To avoid the    
           uncertainty due to the recoiling of nuclei out of the  
           sample, the targets were placed perpendicular to the   
           incident beam such that sample deposition faced the    
           incident beam.  As such, the recoiling nuclei are      
           likely to be trapped in the aluminum backing;  hence,  
           no correction is applied for that.  As the beam        
           traverses the stack materials, low-energy neutrons may 
           be released which in turn may disturb the yield.       
           However, it was indicated that such disturbing yields  
           are negligible.  The overall error due to all these    
           factors mentioned above is expected to be <12%. The    
           overall errors including the statistical errors in     
           counting and are generally <20% except for few  points.
           These errors do not include the uncertainty of the     
           nuclear data such as the branching ratio, the decay    
           constants, etc                                         
           (EN-ERR) Noany information is presented.               
ENDBIB              66                                            
NOCOMMON                                                          
ENDSUBENT           69