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Home  >  Volume 22 (2012)

Application of Penelope Code in The Investigation of The Major Types of Gamma Ray Interaction in Lead And Aluminum Slabs by Ngadda, Y. H. and 2Ewa, I. O. B. Volume 22 (November, 2012), pp 63 – 72
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PENELOPE as a Monte Carlo code has been applied by running its main program on the plat form of G77 FORTRAN compiler. Material slabs of lead and aluminum of the same thickness of 4.237cm and for an aluminum end-cap of detector housing, 0.127cm thick and photon sources of 60Co (1332.502keV), 60Co(1173.238keV), 137Cs(661.66keV and 241Am(59.537keV) have been used. The simulation of photons has revealed the cross section capabilities of the major gamma ray interaction mechanism with matter, namely, Rayleigh, Compton, photoelectric absorption and pair production cross sections. Simulated results reveal that pair production is possible only with photon sources which have threshold energy of 1.02MeV, in agreement with other works. Results show that both transmitted and backscattered particles are those that exhibit Rayleigh and Compton scattering. Most primary photons simulated by the high energy photon sources are transmitted through the aluminum end-cap. This is confirmed by the fractional transmission which is near unity. Thus the use of the Al (0.127cm) as a detector end-cap allows photon energies, which are not too small, to be transmitted. Due to the low scattering cross section of aluminum, the end-cap of a detector does not alter the photon count in an experiment, but provides a protective housing for the germanium crystal.

Keywords: PENELOPE, Monte Carlo, gamma ray or photon, lead slab, aluminum slab, HPGe pop top detector, FORTRAN G77, Rayleigh, Compton, photoelectric effect, pair production, transmitted backscattered, absorbed