The photons of gamma rays emitted from radioactive sources (124Am, 137Cs, 226Ra) at energies (60, 662, 186, 242, 295, 352, 609, 1120, 1765) keV respectively have been used to determination attenuation coefficients, mean free path   and scattering cross section for two different specimen of organic compound (paraffin wax) and sodium chloride structures were measured by using measurement system of gamma ray Integrated Computer Spectrometer (ICS) has been used and the system is operated by computer according to program prepared for this purpose which is connected with sodium Iodide activated thallium detector (NaI(Tl)) with dimensions (1.5"×1.5"). the specimen was located between the source radioactive and the detector. Accumulation time was 900 seconds. The photo peak, net area and full width at half maximum (FWHM) of photo peak were measured with (USX PCI) software. The results measured and ICRU Report 44 value were compared. The variance between experimental results and human tissue of mass attenuation coefficients for organic compound and sodium chloride combination are lower than 6%.

In this paper x-ray mass attenuation coefficients of nickel were measured with precision between 0.2% and 0.5% for four characteristic wavelengths: copper and molybdenum K lines. The mass photoelectric absorption coefficients were determined by subtracting the calculated coherent and incoherent scattering from the total scattering and the values of measured attenuation coefficients. The values of the imaginary component of atomic scattering factor for x-ray in nickel were determined from the difference between the values of measured attenuation coefficients and theoretical calculations, it is shown that In the low energy at ω ≪ ωe, and the high energy at ω ≫ ωe, the imaginary component approximately is zero, and the electrons are so tightly bound to the atom. In the region ω ˜ ωe where the imaginary component of the scattering is dominate and the electron become highly absorbing. There was good agreement between the values of the imaginary component of atomic scattering factor has been found and the theoretical FFAST (Chantler, 1995) tabulated values..

In this study the coherent scattering function ƒ(k) has been calculated for x-ray in Copper using the Wave function involving Slater’s roles approximation for the values 0 ≤ k ≤ 1.6 A0-1, The Rayleigh scattering cross section, has been calculated. The Rayleigh scattering cross section was found to be dominate at low energy, where the scattering cross section starting from very small energy and less than 1KeV, Also the increasing of angular distribution for Rayleigh scattering cross section is principle dependent on the value of atomic scattering factor f(k), and observed Rayleigh scattering decreasing at high energies, while it is more distinct at low energies, for this reason the Rayleigh scattering is very important at low energies, because the scattering angle is large.