Ionization fraction nuclei

The primary effect of any ionizing radiation is based on its ability to excite and ionize molecules, and this leads to the formation of free radicals, which fhen initiate reactions such as polymerization and cross-linking or degradation. Accelerated electron beams have energy sufficient to affect the electrons in the atom shell, but not its nucleus, and can therefore only initiate chemical reactions. Typically, the reactions initiated by electron beam are extremely fast and are completed in fractions of a second. 

Effect of carbon recoils. Neutrons detected by methane-filled counters collide not only with hydrogen nuclei but also with carbon atoms. The ionization produced by carbon recoils is indistinguishable from that produced by protons. However, carbon recoils produce pulses that are smaller than those from protons because of differences in both kinematics and ionization ability. The maximum fraction of neutron energy that can be imparted to a carbon nucleus in one collision is 0.28 (versus 1 for a hydrogen nucleus), and the relative ionization efficiency of a carbon to a proton recoil is about 0.5. Thus, the effect of carbon recoils is to add pulses at the low-energy region of the response... 

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