248 Wheelock — Nature of Ionization Produced hy a Kays. 



Per cent lack of saturation 



20 



18 



16 



14 



.2 12 



10 



3 



Volts/cm. 



Dist. 3-5"" 



. 2-6'^'" 



1-9""" 



5 



35-9 



33-9 



30-2 



10 



30-5 



29-2 



24-1 



20 



24-2 



21-8 



19-2 



100 



12-4 



9-7 



7-8 



400 



2-3 



1-9 



1-7 



Fig. 





























^ 



^ 



--- 





B 











/ 



^ 





. 



_-. 





C 

















/> 























1 









































































A 











r 























' 













































20 40 80 120 



Volts per cm. > 



160 



200 



Fig. 7.— a, Source at 3-5=". B, Source at 2-6'^'". C, Source at 1-9"". 



It will be noticed that with the polonium 3-5'='" from the 

 middle of the ionization chamber, that is, nearl_y out of range, 

 the percentage lack of saturation is greatest; at I'O'^'" it is least, 

 and at 2-6"" an intermediate value is obtained. 



Assuming Bragg's initial recombination hypothesis, this can 

 be explained as follows : The electrons emitted in the act of 

 ionization would be sent farther away from the parent mole- 

 cules when the source is 1-9"" from the ionization chamber 

 than when the distance is either 2-6™' or 3-5™. The electrons 

 would thus have a greater chance of getting out of the sphere 

 of influence of the remaining positive ions, with the ionizing 

 source at 1-9"^ from the chamber, than in either of the other 

 cases. 



