Wheelock — Nature of Ionization Produced hy a Hays. 245 



Since 



or 



2kX + oN f 

 Q- =7ra'e -— - log 2^^ ; l^=Tta' n^b 



where Q- = charge per column reachmg the electrode for 

 a field X. 



2k X 



Now let S = Tra" ^ cross section of a column and a = • 



^ a ' 



The above expression reduces to 



Q. = .^.log (l +^) (B) 



If columnar ionization is to explain completely the lack of 

 saturation obtained when a gas is ionized by a, particles, the 

 theoretical curve should fit the experimental curve. 



Comparison of the Experimental Curve with that given 

 by Equation (B). 



Volts /cm. 



Current obtained by 



experiment with the 



parallel field. 



Source 2-6"^" from 



chamber. 



Current calculated from 



Equation B, made to fit 



experimental curve at 



0-25 volts /cm. and 



at saturation. 



0-25 



1-70 





1-70 



0-75 ■ 



4-58 





3'44' 



2-02 



6-66 





5-73 



4-80 



7-79 





7-90 



1013 



8-28 





9-45 



20-75 



9-00 





10-48 



42-00 



9-49 





11-10 



105-75 



10-49 





11-46 



209-50 



10-91 





11-67 



419-50 



11-21 





11-72 



840-50 



11-43 





11-75 



1260-75 



11-80 





11-77 





For curve 



see fig 



6. 



It is seen from the data or from the curves, fig. 6, that 

 except for a potential gradient below 5 volts /cm., the theo- 

 retical curve lies above the experimental and approaches 

 saturation faster. Calculations were made for several curves 

 and the above was always found to be the case. 



In the ionization chamber used (the ordinary Bragg cham- 

 ber), the lines of electric force would not be strictly parallel to 

 the path of the a particle so that there would be the combined 



