Track length

Fig. 2 Fluorescence scan of the chromatogram tracks of the standard substances cephaeline (A) and emetine (B) and of the ipecacuanha extract (C). Amounts applied cephaeline 0.5 pg, emetine 0.7 pg per 10 mm track length.

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). 

The average energy loss per unit track length of a 1-MeV electron is about 0.2 eV/nm [64]. With an average energy loss per collision event of 60 eV the mean separation of spurs is 300 nm, which is much too far apart for interspur reactions. (It is assumed throughout... 

Track lengths slOmm shall be disregarded for T class rating... 

Gleadow A. J. W., Duddy I. R., Green P. F., and Lovering J. F. (1986) Confined fission track lengths in apatite a diagnostic tool for thermal history analysis. Contrib. Mineral. Petrol. 94, 405-415. 

The positioning scan is designed to accurately position every spot on a measuring track. The parameters for measuring, like track length, track distance, number of tracks and spots per track, mode of evaluation as well as step sizes for the search of spots and positioning, spot width and data per spot for the integration are entered into the computer. If a method is elaborated, these parameters can be stored and need not be repeatedly entered for each scan. 

The application of fission track length studies to the interpretation of fission track ages depends on three properties of spontaneous fission tracks. 

These factors combine to give a final distribution of track lengths which contains a complete record of the temperatures experienced, below about 120°C. Different length distributions result from different styles of thermal history, as illustrated in Figure 9. 

Figure 10. Representative track length distributions for spontaneous tracks in the various apatite length groups recognized by Gleadow et al. (1986). The top row represents measurements on horizontal confined tracks for which the differences between the different types are more distinctive than for the corresponding projected length distributions (bottom row). 100 confined tracks and 500 projected track lengths were measured in each case. After Gleadow et al. (1986).

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