Electrons track structure

It is clear from the present discussion that LET alone does not completely determine track structure. Track length (or particle velocity) is also a contributing factor. For example, at the same intermediate LET, high-energy heavy-ion tracks would be cylindrical while those for the KeV electrons would be better described as either spheroidal or as partially overlapped spurs (Samuel and Magee, 1953). 

Track structure simulation has found application in many areas of radiation research since the pioneering studies of Mozumder and Magee [35]. These studies all employ essentially the same type of approach, a collision-to-collision modeling of the trajectory of the primary radiation particle and of its daughter secondary electrons, with the most significant difference between different calculations being the interaction cross sections used to describe the... 

The simulation of a heavy ion track structure employs essentially the same methodology as described for energetic electrons except that... 

The IRT method was applied initially to the kinetics of isolated spurs. Such calculations were used to test the model and the validity of the independent pairs approximation upon which the technique is based. When applied to real radiation chemical systems, isolated spur calculations were found to predict physically unrealistic radii for the spurs, demonstrating that the concept of a distribution of isolated spurs is physically inappropriate [59]. Application of the IRT methodology to realistic electron radiation track structures has now been reported by several research groups [60-64], and the excellent agreement found between experimental data for scavenger and time-dependent yields and the predictions of IRT simulation shows that the important input parameter in determining the chemical kinetics is the initial configuration of the reactants, i.e., the use of a realistic radiation track structure. 

In contrast to liquid water, a detailed mechanistic understanding of the physical and chemical processes occurring in the evolution of the radiation chemical track in hydrocarbons is not available except on the most empirical level. Stochastic diffusion-kinetic calculations for low permittivity media have been limited to simple studies of cation-electron recombination in aliphatic hydrocarbons employing idealized track structures [56-58], and simplistic deterministic calculations have been used to model the radical and excited state chemistry [102]. While these calculations have been able to reproduce measured free ion yields and end product yields, respectively, the lack of a detailed mechanistic model makes it very difficult... 

For a given medium such as water, its density and the velocity of the incident heavy ion contribute to the formation of the columnar track structure. The spacing of the primary energy loss events must be within the delocalization of the secondary electrons for elfects attributed to high LET to occur. For this reason, typical LET effects will not be... 

The Monte Carlo track structure code kurbuc simulates electron tracks in water vapor for initial electron energies 10 eV-10 MeV [174]. The code kurbuc provides all coordinates of... 

Remember—the straight line in both versions represents two electrons, one from each atom. Thus we now have two types of electron pairs to keep track of. The term nonbondingpair refers to any pair that exists in the electron-dot structure of an individual atom, and the term bonding pair refers to any pair that results from formation of a covalent bond. In a nonbonding pair, both electrons come from the same atom in a bonding pair, one electron comes from one of the... 

The track structures considered in these papers were only those formed by primary electrons. Santar and Bednar have carried out the calculations of Ref. 309 in more detail and have taken into account the... 

Such a presentation of a fast electron track as a set of spurs, blobs, and short tracks is widely used in radiation chemistry for describing the processes that occur in a condensed medium exposed to electron or gamma radiation.7 However, this presentation is not the only one there is. Other possible approaches are discussed in Ref. 305, where, in particular, the authors note that the most general description of track structures is the one using correlation functions. 

At high velocities the track of an ion can be considered as consisting of separate track structures similar to those of a fast electron. However, the ions used in radiation chemistry usually have initial energies not exceeding 10 MeV per nucleon. At such energies, even in the case of protons,... 

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