Track heavy charged particles

Figure 17.1 Trails of ionization left by heavy charged particles (initial energy of 10 MeV/ nucleon) as they penetrate through a photographic plate (nuclear emulsion). The ions interact with the atomic electrons in the emulsion creating ion pairs to expose the emulsion and the hacks become visible after the Him is developed. Notice the straight-line tracks. (From Knoll, 2000.)...

As in the case of fast electrons, the main contribution to energy losses of heavy charged particles (ions) comes from ionization losses (see Section V), which are responsible for most of the radiation-chemical effects. Therefore, we consider here only the structure of that part of an ion s track where the ionization losses are dominating. The role of elastic interaction between ions and atoms of the medium, which becomes essential only at the end of the ion s track, is not considered in this section. 

Fig. 20. Schematic diagram of the changes in the characteristics of the track of heavy charged particles with retardation (a) the alpha particle (b) a multicharged ion.

Electrons tracks are less dense than the tracks of heavy charged particles and the spurs are more widely spaced (Chapter 4). The induced physical processes are comparable in many regards to the effect of exposure to heavy particles or ions. X- and gamma rays actually are indirect methods of producing fast electrons in matter. As a consequence, chemical effects can be considered very similar in nature. Some specific features may nevertheless arise from the significantly different dose rates i.e. amount of absorbed energy per unit time) as a consequence of different LET values. 

Jakupi B, Bytyci M, Todorovid Z, Antanasijcvid R, Perelygin VP, Stetsenko SG (1989) Tracks of heavy charged particles in some natural minerals. Nucl Tracks Radial Meas 17 55-57... 

The radiation effect produced by heavy ions can be simulated with electrons if the ions have high velocities. It is in this case that the spatial distribution of active particles in the track is close to the one in tracks of fast electrons. At small velocities of heavy ions the tracks of delta electrons overlap each other to a considerable extent, which results in the concentration of charged particles in a microvolume of the ion s track being very high. With development of powerful pulsed electron accelerators it became possible to create high concentrations of active particles in a medium. According to Ref. 372, with such accelerators one is able to reproduce and study the processes occurring in tracks of heavy ions. 

Henk RP, Benton EV (1967) Charged particle tracks in polymers No.5. A computer code for the computation of heavy ion range-energy relationships in any stopping material. U S Naval Radiological Defense Laboratory TechnRep 67-122... 

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