Ionising radiation gamma-rays

In terms of atomic spectrometry, NAA is a method combining excitation by nuclear reaction with delayed de-excitation of the radioactive atoms produced by emission of ionising radiation (fi, y, X-ray). Measurement of delayed particles or radiations from the decay of a radioactive product of a neutron-induced nuclear reaction is known as simple or delayed-gamma NAA, and may be purely instrumental (INAA). The y-ray energies are characteristic of specific indicator radionuclides, and their intensities are proportional to the amounts of the various target nuclides in the sample. NAA can thus... 

Gamma rays are completely different from neutrons for their action on the matter. Electromagnetic radiation as gamma rays knock electrons off atoms or molecules causing primary ionisation. This damage process was assessed in all tested organisms (Table 4). 

When ionising radiation is used as source of initiation for grafting instead of UV (10-14), analogous additive effects to those previously discussed, have been found. Thus Inclusion of sulfuric acid in methanollc solutions of styrene leads to an enhancement in copolymerisation to a polyolefin, such as polyethylene, when Irradiated by cobalt - 60 gamma rays (Table VI). 

Ionising radiation. Radiation that produces ionisation in matter. Examples are alpha and beta particles, gamma and X-rays, and, indirectly, neutrons. 

Radiation. Radiation (implying ionising radiation) describes both electromagnetic emission (X-rays and gamma rays) and particulate emission (alphas, betas and neutrons). 

Another way of achieving polymerisation at low temperatures is by using ionising radiation from gamma rays emitted by cobalt-60. The radiation energy absorbed by the monomer results in the production of free radicals. The radiation method does not require initiators or promoters. On the other hand, the cost of radiation source is high and polymerisation rate may be low [11]. 

Ionising radiation means atomic and nuclear particles, i.e., gamma rays, electrons neutrons, etc. The intensity of ionising radiation at the earth s surface is not high enough to significantly affect mbbers and hence radiation exposure is only a consideration in connection with apphcations in nuclear plant and possibly where radiation is used to induce crosslinking or for sterilisation. 

Interest in the use of ionising radiation in the food industry was aroused in the mid-fifties with the availability of large isotope sources and the development of suitable electrical machines such as the linear accelerator. In particular, attention focused on the radioisotope cobalt 60 as a source of gamma rays. During the past 25 years it would be a reasonable estimate that some 50 million curies have been installed in plants situated in various parts of the world. However, the majority of these are employed for the sterilisation of disposable medical products, pharmaceuticals, cosmetic preparations, and laboratory animal diets. Only a few commercial fecilities have been constructed for the processing of human foods. 

The standard sources have been designed in order to allow the calibration of all the classical detectors of a, p, e, y, n, X radiation (ionisation chambers, Geiger-Miiller or proportional counters, scintillation or solid-state counters, etc.). They are classified as alpha sources, electron sources, beta sources, gamma sources, neutron sources. X-ray sources, heat flux sources, and sources for radiation protection dose meters. 

The description is based on reports from the Swedish National Institute of Radiation Protection (SSI, 1986a and 1986b). Since the end of the 1950s, 25 stations equipped with ionisation chambers 2.5 m above ground have been in operation by the Swedish National Institute of Radiation Protection (SSI). They register continuously the gamma radiation from both ground and cosmic rays. Only three stations transmit data automatically via telephone to a computer at SSI. 

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