242 Wheelock — Nature of Ionization Produced hy a Rays. 



Tlie cnirrent obtained with the beam A is much larger than 

 that with either J^ or C. The ratios A/J3 and A/C are not 

 constant. This looks as if, with beam A, enough columns do 

 exist to give interference of the ions between columns and 

 consequently more recombination occurs. 



{d) A further test for columnar ionization was made as 

 follows: the radio-active source was covered by hollow cylin- 

 ders of different diametei-s and heigh is. The source was kept 

 at a fixed distance (2"6"") from the chamber and the internal 

 dimensions of the hollow cylinders were varied so that the 

 area of the plate receiving ions was constant in all cases, as 

 shown in fig. 5. 



Fig. 5. 



The internal dimensions of the cylinders are given below. 



A 

 B 

 C 

 D 



Diameter 



Height 



5""" 



V-S""" 



4 



6-0 



3 



4-5 



2 



3-0 



The following data were obtained : 



Parallel Field. 



Source 2*6*=" from the middle of the chamber. 



Volts/cm 



Cylinder 

 5 X 7-5'""> 



Cylinder 

 4x6-""' 



of 

 Currents 



5-4 



8-33 



6-68 



1-25 



21-5 



9-78 



7-87 



1-24 



107-5 



11-4 



9-12 



1-25 



427-5 



12-38 



9-8 



1-26 



1252-5 



12-62 



10-03 



1-26 



Volts/cm 



Cylinder 

 3 X 4-5™"' 



Cylinder 

 3x4"'"' 



Eatio 



5-43 



9-02 



3-87 



2-3 



22-5 



10-68 



4-37 



2-4 



109-5 



12-63 



5-25 



2-4 



432-5 



13-6 



5-63 



2-4 



1297-5 



13-83 



5-77 



2-4 



