Photon energy absorption buildup factors of gaseous mixtures used in radiation detectors

Gamma-ray energy absorption buildup factors of gaseous mixtures; neon (95%) + argon (5%), argon (95%) + acetylene (5%), argon (95%) + methane (5%), argon (95%) + carbon dioxide (5%), methane (70%) + pentane (30%) and argon (90%) + methane (10%) were studied by Geometrical Progression (G-P) fitting for the photon energy range 0.015-15 MeV. It was found that the equivalent atomic number, Zeq of the gaseous mixtures sharply reduces after 1 MeV photon energy. The Zeq for the mixture of methane (70%) + pentane (30%) is the minimum, whereas the maximum is for argon (95%) + carbon dioxide (5%) for the photon energies under investigation. The Energy Absorption Buildup Factor (EABF) for methane (70%) + pentane (30%) was found to be the highest among all the selected gaseous mixtures. The chemical composition of the gaseous mixtures has an impact on the EABF values for photon energy and penetration depth. The investigation of the EABF is useful for selection of gaseous mixtures in design consideration of gaseous radiation detectors for gamma radiation