3488

3294

كارشناسي ارشد

فيزيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1385

[هشت] ، 79،[II] ص: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

فيزيك

ID3294

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

AbstractIn this thesis the exposure buildup factors of gamma rays have been calculated in theenergy rang from 40keV to 10MeV for point isotropic sources placed in the center of aspherical two layer shield consisting of 5mfp water 8mfp lead using the MCNP codeand the effects of coherent scattering and bremsstrahlung radiation on these factors havebeen investigated The results obtained show the effect of coherent scattering is significantup to gamma ray energies of about 200keV in the water layer and up to about 2MeV in thelead layer The bremsstrahlung radiation which is considerable above 5MeV in the leadlayer is quite significant at 10MeV and increases with shield thickness such that at 10mfpthe bremsstrahlung radiation causes an increase of more than 30 per cent in the buildupfactor These results show good agreement with previous works in which different methodsof calculations have been used In this thesis exposure buildup factors have also beencalculated by taking into account all kinds of interactions of gamma rays with matter forshields of various thicknesses of water and lead from 0mfp water 13mfp lead to 10mfpwater 3mfp lead in the energy rang from 3 to 10MeV These factors can be used fordesigning stratified shields of water lead in this energy rang

احمد شيراني

محمد حسن علامت ساز