gamma radiation absorption study on cryogenic multilayer insulation

Sorin Gherghinescu^*

National Research and Development Institute for Cryogenics and Isotopic Technologies - ICIT Rm. Valcea, code 240050 - Rm. Valcea, Uzinei 4, CP7 Riureni, Valcea, Romania, phone:0040 250  736979, fax:0040 250 732746

ABSTRACT

Photon radiation is a high energy flow, resulting from the radioactive decay of nuclei. When passing through a substance, γ radiation interacts with atomic nuclei, with free electrons and bound electrons. Phenomena that can occur from these interactions are:

- Photoelectric effect

- Compton effect

- Generation of electron-positron pairs.

They have the effect of initial γ radiation attenuation. The degree of attenuation of radiation intensity depends on the nature of the γ radiation and crossed the absorbent layer. Law of variation of γ radiation intensity is thick substance:

I = I₀e^-mx

where: I - intensity of initial radiation, I - intensity of radiation that passed through the layer of substance, x - thickness of the absorbing substance, μ- radiation absorption coefficient of the substance.

Paper aims to determine the half-value layer (HVL) of the few materials that can be used in multilayer insulation, compared with other material properties for effective application in different temperature conditions.

KEYWORDS: Photon radiation, half-value layer, multilayer insulation