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   Investigation of activation rate uniformity in a prompt-γ rays IVNAA facility  
   
نویسنده miri hakimabad h. ,rafat motavalli l.
منبع journal of radiation research - 2010 - دوره : 51 - شماره : 2 - صفحه:123 -130
چکیده    The preliminary design studies for developing a prompt-γ rays in vivo neutron activation analysis facility are in construction at neutron activation research centre of ferdowsi university of mashhad. in this work,activation rate distribution is studied in different bilateral configurations in order to reduce the cv of activation rate distribution throughout the body to less than 10%. it means that the maximum rms deviation from the mean value of distribution must be smaller than 0.5%. the best case includes two pairs of 241am-be neutron sources. each pair (with 70 cm distance between two sources) is positioned within up and down 40 × 110 cm2 area graphite collimators. also,four moderator/reflector objects are added to transversal body surfaces with 5 cm thick water and 3 cm thick graphite. the proper thickness of polyethylene pre-moderators is chosen 8 mm. the rms deviation of distribution is 0.3% with the mean activation rate of 1.85 × 10 -6 cm-3.
کلیدواژه Activation rate uniformity; Collimator aperture; IVNAA; MCNP; Moderator-reflector
آدرس physics department,school of sciences,ferdowsi university of mashhad,91775-1436,mashhad, ایران, physics department,school of sciences,ferdowsi university of mashhad,91775-1436,mashhad, ایران
 
     
   
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