Younis S. Selim

Analytical calculation of the efficiencies of gamma scintillators. Part I : Total efficiency for coaxial disk sources

Total efficiencies of clad right cylindrical NaI(Tl) scintillation detectors exposed to photons emitted by circular disk sources have been calculated by using rigid mathematical expressions. Results are tabulated for various gamma energies.

Analytical calculations of gamma scintillators efficiencies — II. Total efficiency for wide coaxial circular disk sources

Abstract A statistical integral formulation of the total efficiency for the general wide coaxial circular disk source–cylindrical NaI(Tl) detector arrangement (source radius S>detector radius R) is presented. Simple programming is possible and short computer time is needed.

Calculation of relative full-energy peak efficiencies of well-type detectors

A mathematical expression to calculate the full-energy peak efficiency of HPGe well-type detectors has been derived in an integral form. The attenuation of photons by the source itself (self-absorption), the source container and the detector end cap materials is also included. The calculated values of the efficiency are found to be in good agreement with the published experimental data.

Source-detector geometrical efficiency

Abstract By the use of simple analytical spherical-trigonometry a mathematical expression of a solid angle subtended by a point to a plane triangle is deduced. Generalizing, solid angles subtended by a non-axial point source to a circular disk detector and a circular disk source to a circular disk detector are deduced into rigid mathematical expressions very easily computed, for the first time. Results were compared with previous tabulations. By this method, with some mathematical manipulations, solid angles could be deduced for detectors of different geometrical shapes, e.g. rectangular, elliptical, spherical and cylindrical.

Direct calculation of the total efficiency of cylindrical scintillation detectors for extended circular sources

Abstract By the use of spherical coordinates, direct expressions for the total efficiency of a cylindrical NaI(Tl) detector arising from a non-axial point (ϱ > R) and coaxial-circular disk (S > R) of isotropic radiating sources, are deduced. Results are compared with previous treatments.

Spatial and energy distributions of fast monoenergetic neutrons in an infinite plane slab of material

Abstract The actual neutron energy and spatial distributions in a medium arising from unidirectional normally incident monoenergetic neutrons has been theoretically calculated using statistical techniques. The present medium of interest is an infinite plane slab of material. The nutron beam is incident isotropically on one face and the differential flux at different locations along the slabs thickness has been calculated. Effects of inelastic scattering have been also considered. Comparison with other calculations is given.