Physics - 133 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 Calculation and Study of Gamma ray Attenuation Coefficients for Different Composites K.H.Mahdi, Z.S.Ahmed*, A.F.Mkhaiber Department of Physics , College of Education Ibn Al-Haithem, University of Baghdad *Ministry of Science and Technology. Received in :18 Sptember 2011, Accepted in: 12 February 2012 Abstract In this work, the total linear attenuation coefficients µ (cm-1 ) were calculated and studied for particulate reinforced polymer-based composites. Unsaturated polyester (UP) resin was used as a matrix filled with different concentrations of Al, Fe, and Pb metal powders as reinforcements. The effect of the metal powders addition at different weight percentages in the range of (10,20,30,40,50)wt % and gamma energy on attenuation coefficients was studied. The results show, as the metallic particulates content increase, the attenuation coefficients will increase too, while it, were exhibited a decrease in their values when the gamma energy increase.The total linear attenuation coefficients of gamma ray for 15 composites have been calculated using the XCOM program (version 3.1) in the energy range of 0.1-20 MeV. Key words: linear attenuation coefficients, composite materials, gamma ray. Introduction Shielding is one of the most effective radiation protection methods; others include time and distance. With shielding, radiation dose can be lowered to a desired level [1].Furthermore; different types of radiation can be shielded by different types of materials [2]. For shield designs, gamma ray was one of the main types of nuclear radiation, which have to be considered; since any shield attenuates the gamma rays will be more effective for attenuating other radiations [3]. Recently, there was a continuous demand for improved polymers for use as shielding materials [4]. Therefore, composite materials used for this purpose. Composites is a material brought about by combining materials differing in composition or form on a macroscale for the purpose of obtaining specific characteristics and properties. Composites consist from two components: matrix and reinforcement [5] . Reinforcement materials played the important role to improve the matrix properties. Since polymeric materials are on their own hydrocarbonic substances we would expect good neutron moderation then, with the good choice of metallic fillers, gamma rays and X-rays could be also shielded [6,7].Therefore, in this study, we attempted to prepare and characterize the polymer based composite radiation shields using unsaturated polyester resin as a matrix and Al, Fe, and Pb as filler with different concentrations (10,20,30,40,50)wt%. Then, the effect of gamma energy and filler concentrations on attenuation coefficients was studied. Physics - 134 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 Linear attenuation coefficient ( µ ) : In the design shielding materials , the linear attenuation coefficient ( µ ) which is defined as the probability of a radiation interacting with a material per unit path length, is important quantity and its magnitude depends on the incident photon energy and on the atomic number of the material, as well as, on the density ( ρ ) of the shielding material [8].Also,the mass attenuation coefficient ( ρµ / ) (cm2.g-1) directly measures the effectiveness of a shielding material based upon unit mass of material. Generally, calculations of the mass attenuation coefficient at high energies are widely needed and used as a radiation shielding design database for radiation sources, reactors and particle accelerators.[9]. Calculation of the total linear attenuation coefficients ( µ ): In shielding calculations, materials made of homogeneous mixture of elements are frequently encountered. For a mixture of known composition, the total mass attenuation coefficient μ/ρ (cm2 g -1) can be determined from basic data by relationships [10]: (1) (2) Where µ : the total linear attenuation coefficient, cm-1. Ni: number of atoms, cm-3. iσ : Microscopic cross section, cm 2 . iρ : Density of the i th constituent, g .cm-3. iw : Proportion by weight of i th constituent. The total linear attenuation coefficients ( µ ) were calculated for the 15 (unsaturated polyester / metal ) composite samples using a computer program called XCOM (version 3.1). The used XCOM program and database cross sections for elements ranging from Z=1 to 100 have been recently modified to calculate the total mass attenuation coefficients )/( ρµ for elements, compounds and mixtures from1 keV to 100 GeV [11], and provides total cross section as well as partial cross sections for various interaction processes. With a known ∑ ∑∑     = == i i i ii iii w N ρ µ ρ µ σµµ Physics - 135 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 density ( ρ ) of shield materials, the total linear attenuation coefficients ( µ ) were extracted from calculated results of XCOM. The density of composite materials was calculated using the rule of mixtures formula given by the following equation [12]: ( ) mfffc VV ρρρ −+= 1 (3) Where :,, mfc ρρρ Density of composite body, reinforcement and the matrix materials respectively. :fV Fractional volume for reinforcement material which could be calculated from the equation:             − += m f fV ρ ρ ψ ψ . 1 1/1 (4) : Fractional weight for reinforcement materials: ψ Where %100×= c f W W ψ (5) mfc WWW += (6) mfc WWW ,, : Weight of composite, reinforcement and matrix materials respectively [13]. Results and Discussion In fig (1) , the linear attenuation coefficient ( µ ) was displayed as a function of the applied energy, it was clear that linear attenuation coefficient ( µ ) sharply decreased with the increase of the photon energy in the range (0.1-1) MeV for all composites .Such a behavior could be ascribed to the photoelectric and Compton scattering which were the main predominant interactions in this region. This sharp decrease was considered to be an indication that the ( µ ) was very sensitive to the photon energy. In the range (1-5) MeV the total linear attenuation coefficients ( µ ) were noticed to decrease with the increase of the photon energy for all composites. In this region, the Physics - 136 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 dominant interaction is pair production [14]. This slight decrease indicates that the ( µ ) is not very sensitive to the variations in the photon energy in this region. In the region (E>5) MeV , there was no significant decrease in the values of total linear attenuation coefficient ( µ ) with increase of the photon energy for all composite samples and this could be attributed to the successive collisions, due to several Compton scatterings. There is an agreement with the results of [14,15]. In fig (2), the total linear attenuation coefficient ( µ ) displayed as a function of concentration of metal powders (Al, Fe and Pb) at the different energies. From this figure one may notice that the total linear attenuation coefficient ( µ ) increased with the increase of metal concentration, especially within low photon energy, but at higher energies there was no clear change in the ( µ ) .This could explain that as the concentration of metal powders increased, the absorption process will also increase and this mean an increase in the ( µ ) values. From table (1), the total linear attenuation coefficients ( µ ) calculated for the unsaturated polyester (UP) had the minimum values and reached a maximum values for composite samples containing 50% of different powder metals. The improved shielding capability of (UP) metal powder composites could be explained on the fact that, unsaturated polyester (UP) matrix is a bad shielding material, but when some filling metals powders add to it, it was modified and become a good shielding material. In other word, an increase in the probability of interaction between the incident gamma radiation and the shield atoms was happened. Thus, one may conclude that, the total linear attenuation coefficient of the composites was increased with increased filler content in the composites samples prepared. References 1- Stewart,D.C.(1985) ,Data for radioactive waste management and nuclear applications, John Wiley Sons Inc, New York. 2- Chilton,A.B.;Shultis,J.K.andFaw,R.E.(1984)"Principles of radiation shielding", Prentice- Hall Inc, New Jersey. 3- Goldstein,H.(1959) Fundamental Aspects of Reactor Shielding, Addison-Wesley, Reading, MA. 4- Milewski, J.V. ( 1987),Handbook of Fillers for Plastics", Van Nostrand Reinhold. 5- Brian, S. M.( 2004) ,An Introduction To Materials Engineering And Science For Chemical And Materials Engineers", John Wiley & Sons, New Jersey. 6- Allen,R.T.and Edwards, S.C.( 1987) ,The Repair of Concrete Structures, Blackies, Glasgow and London. 7- Mukherjee, P.K.and Deans, J.J. ( 1988) ,Service performance of nucl containment concrete, Concrete International 10, 75–79. 8-Wood,J.(1982),Computational Methods in Reactor Shielding", Pergamon Press, Inc., New York. 9- Kaplan, M.F.( 1989),Concrete Radiation Shielding, John Wiley & Sons, New York. 10- Seltzer, M.S. ( 1993), Calculation of photon mass energy-transfer and mass energy absorption coefficients", Radiation Research, 136; 147–170. 11- Berger, M.J.and Hubbell, J.H. ( 1987), Photon Cross Sections on a Personal Computer.National Institute of Standards and Technology , NBSIR 87– 3597, XCOM, Gaithersburg, MD 20899, USA. Physics - 137 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 12- Schwartz, M.M. ( 1984) ,composite Materials ,Hand book Mc Graw- Hill co. 13- Hull, D. (1981) ,An introduction to composite materials" First eddition, Cambridge University press U. K. 14- Akkurt,I.(2011),Gamma ray attenuation coefficient of microalloyed stainless steel, Arab J Sci Eng,36 ;145-149. 15-Korkut,T. (2011) ,A new radiation shielding material, Annals of nuclear energy.38 ;56-59. Physics - 138 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 Table (1):Linear attenuation coefficient values at different energies for composite samples filled with( Al,Fe and Pb) powders at different weight percentages Al ENERGY (Mev) µ (cm-1) Al 10% wt Al 20% wt Al 30% wt Al 40% wt Al 50% wt 0.1 0.198768 0.2128434 0.2287365 0.247079 0.268441 0.5 0.1121637 0.11839905 0.1254903 0.1336029 0.1430604 1 0.0818565 0.08638091 0.09152258 0.09741972 0.10427838 5 0.0351657 0.03739813 0.03992746 0.04283704 0.04621078 10 0.0258423 0.02781625 0.03006451 0.03263846 0.03563534 15 0.0226689 0.02463538 0.02687479 0.0294392 0.03242378 20 0.0212175 0.02322166 0.02550377 0.02813246 0.03117484 Fe ENERGY (Mev) µ ( cm-1) Fe10% wt Fe20% wt Fe30% wt Fe40% wt Fe50% wt 0.1 0.2303956 0.2835144 0.3488362 0.431376 0.5382564 0.5 0.11559088 0.12635124 0.1395968 0.1563232 0.1780371 1 0.0841952 0.09182064 0.10122326 0.11308 0.12845766 5 0.0366452 0.04080762 0.04591426 0.0523776 0.06074088 10 0.02749024 0.0315948 0.03664416 0.0430144 0.0512577 15 0.02451044 0.02881278 0.0341202 0.0408144 0.04949856 20 0.02321708 0.0277503 0.0333412 0.040392 0.049539 Pb ENERGY (Mev) µ ( cm-1) Pb 10% wt Pb 20% wt Pb 30% wt Pb 40% wt Pb 50% wt 0.1 0.8910356 1.749294 2.820099 4.19196 6.00692 0.5 0.12597312 0.1494954 0.1790136 0.216657 0.2663664 1 0.08600774 0.0959427 0.10837623 0.1243108 0.14532328 5 0.03825822 0.04442472 0.05213295 0.0620106 0.07504968 10 0.03014284 0.03752928 0.04673715 0.0585535 0.07414496 15 0.02788786 0.03637062 0.0469752 0.0605445 0.07850024 20 0.02712346 0.03648366 0.04816545 0.0631328 0.08291864 Physics - 139 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 Al 0.01 0.1 1 0 5 10 15 20 Energy (Mev) Fe10% Fe20% Fe30% Fe40% Fe50% 0.01 0.1 1 10 0 2 4 6 8 10 12 14 16 18 20 Energy (Mev) Pb10% Pb20% Pb30% Pb40% Pb50% 0.01 0.1 1 0 5 10 15 20 Energy (Mev) Al 10% Al 20% Al 30% Al 40% Al 50% Fig .(1):Total linear attenuation coefficient ( µ ) as a function of energy (E) at different concentrations of (Al,Fe and Pb) (c m -1 ) µ (c m -1 ) µ (c m -1 ) µ Cu Pb Physics - 140 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 0 1 2 3 4 5 6 7 0 10 20 30 40 50 60 0.1 Mev 0.5Mev 1 Mev 5 Mev 10 Mev 15 Mev 20 Mev 0 0.1 0.2 0.3 0.4 0.5 0.6 0 10 20 30 40 50 60 0.1 Mev 0.5Mev 1 Mev 5 Mev 10 Mev 15 Mev 20 Mev µ (c m -1 ) µ (c m -1 ) Pb wt% Fe wt% Fig .(2):Total linear attenuation coefficient ( µ ) as a function of concentration of (Al,Fe and Pb) at different energies 0 0.05 0.1 0.15 0.2 0.25 0.3 0 10 20 30 40 50 60 0.1 Mev 0.5Mev 1 Mev 5 Mev 10 Mev 15 Mev 20 Mev µ (c m -1 ) Al wt% Physics - 141 مجلة إبن الهيثم للعلوم الصرفة و التطبيقية 2012 السنة 25 المجلد 3 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 3 Vol. 25 Year 2012 حساب ودراسة معامل توهين أشعة كاما لمتراكبات مختلفة ، احمد فاضل مخيبر*دخالد هادي مهدي، زياد شهاب احم جامعة بغداد ،كلية التربية ،قسم الفيزياء وزارة العلوم والتكنلوجيا * 2012شباط 12، قبل البحث في: 2011ايلول 18استلم البحث في: الخالصة ) لمتراكبات بوليميرية مدعمة بالدقائق µ) (cm-1رس معامل التوهين الخطي الكلي (سب ودُ حث ، حُ في هذا الب ،والحديد ،( كمادة أساس) مدعم بتراكيز مختلفة من (األلمنيوم ) UPمكونة من راتنج البولي استر غير المشبع ( )%، وكذلك طاقة أشعة 50،40،30،20،10اضافة المساحيق المعدنية عند تراكيز (رس تأثير والرصاص) (مواد تدعيم). دُ كاما على معامالت التوهين. أظهرت النتائج انه عندما يزداد تركيز المعدن فان معامل التوهين سوف يزداد ايضا، بينما 15ل و امالت التوهين الخطية الكليةفي قيم معامالت التوهين عندما تزداد طاقة اشعة كاما. ان مع اً ظهر ان هناك نقصان –) مليون إلكترون 20-0.1) ضمن المدى الطاقي ( version 3.1( (XCOM)متراكبة حسبت باستخدام البرنامج فولت. : معامل التوهين الخطي ، المواد المتراكبة ،أشعة كاما.الكلمات المفتاحية