6 .A7 It is shown on Figure 6.A4, with the accompanying equations for the fit in Table 6.A2. Figure 6.A4 also shows a comparison between solar particle event spectra and the galactic background spectrum. Also from reference (6.Al) is Table 6.A3, which shows relative abundances of the most abundant nuclei in the primary cosmic ray. background. Nuclei are assumed to have the same energy spectrum as protons except for a constant reduction factor in intensity. Positrons and photons are assumed to have the same spectrum as electrons, with a factor of 10 reduction in flux. No data exists on neutrons in the galactic background. Presumably they cannnot be accelerated and do not exist in observable quantities. Likewise, anti-protons, anti-nuclei, and other particle types are assumed to be absent from the primary cosmic ray background. In general the problem in getting a good primary cosmic ray background spectrum is that statistics are very poor at higher energies due to low counting rates. The systematic effects due to latitude, sun cycle, and interpretation of a complex sequence of events involved in a cosmic prima~y•s interaction with the atmosphere also contribute a great amount of confusion. Probably the best way to get a really good primary spectrum is to use data only from satellite-borne experiments designed specifically for the job. VI.A.3: DOSIMETRY There are several different fields where particle radiation is hazardous to humans, such as nuclear reactors, medical X-rays, high energy accelerators and space. Units and methods of description and calculation of dosages vary correspondingly. For purposes here the basic unit of radiation absorption will be the rad, or ~oentgens ~sorbed Qose. This is defined as 100 ergs deposited in one gram of mass. The effects of a rad depend on how the energy is deposited, so for each separate energy deposition mechanism the dose in rads is multiplied by a factor called the rbe, or ~elative ~iological ~ffectiveness, to get a dose in rem, or ~oentgen ~quivalent per ~an, (6.A2).
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