58 



some of the OH's are formed along the tracks of delta rays. • 



MAGEE: We have one primary event which forms, say, three OH's. Take 

 the three as shown in figure 2d. The primarily affected molecule is not neces- 

 sarily in the center of the sphere. The ionizations take place rather quickly and 

 leave the OH's close together. The H's are in the vicinity as shown. 



H.OH 



H 



^H 



y 



H 



Fig. 2. (a) Distribution of radicals around track as envisaged by Lea. (b) Dis- 

 tribution of radicals around track as envisaged by Samuel and Magee. (c) Typi- 

 cal spur according to Lea-Gray model. (d) Typical spur according to Samuel- 

 Magee model. 



1 - from D.E. Lea, Brit. J. Radio. Supplement 1, 59 (1947) 



We were influenced by the considerations which I have told you about, and 

 we said what actually happens is, of course, that the electron gets back. A 

 highly excited H2O molecule is formed by the electron capture and then it dis- 

 sociates. The H atom, haying a considerable amount of kinetic energy, will get 

 several molecular diameters away, and so the H atoms are formed more or less 

 randomly. We decided to take all radicals formed, completely at random, in 

 such a small volume as shown in figure 2d. That is the picture we have been 

 working with: all H and OH radicals are distributed completely at random 

 within some kind of a volume. It should be understood that all of the previous 

 discussion about the radical formation from excited H^O molecules just provides 



