WheelocJc — Nature of Ionization Produced hy a Rays. '2iZ7 



This cbambei" was used in the same containing vessel as that 

 shown in fig. 1, so that tlie radio-active material being below, 

 the field was perpendicnlar to the trajectory of the a particle. 



I. (a) Comparison of Curves obtained with the Field parallel 

 and perpendicular to the Path of the a particle. 



"When a gas is ionized by a rays, if the ions are formed in 

 colnmns along the path of the a particle the saturation value 

 of the current would be obtained for a much smaller potential 

 gradient applied between the plates, when the field is perpen- 

 dicular, than when it is applied along the path of the a particle. 



The following data show this to be true and agree with the 

 results obtained by Moulin: 



Perpendicidar Field. 

 Source 2-6'^'" from the middle 

 of the chamber. 



Parallel Field. 

 Soui-ce 2-6°'" from the middle 

 of the chamber. 



Volts/cm. 



Current 



% lack sat. 



Volts/cm. 



Current 



% lack sat. 



5 



12-77 



33-9 



2 



11-98 



59-0 



10 



13-67 



29-3 (1) 



4 



15-95 



45-4 



20 



15-1 



21-8 (2) 



10 



20-76 



29-3 (1) 



40 



15-95 



17-4 (3) 



20 



23-80 



18-5 (2) 



100 



17-45 



9-7 



40 



26-40 



9-6 (3) 



200 



18-35 



5-0 (4) 



80 



27-85 



4-6 



400 



19-15 



1-9 



120 



28-65 



1-9 



800 



19-32 



0-0 



200 



29-08 



0-4 (4) 









400 ' 



29-18 



0-07 









1000 



29-20 



0-00 



Note. — For a direct comparison, see (1), (3), (3), (4), above, or fig. 3. 



The saturation curves are practically the same when a posi- 

 tive charge is applied to the gauze of the ionization chamber 

 as they are for a negative charge. This is true when the field 

 is applied parallel or perpendicular to the path of the a 

 particle. 



{b) "When a weak source of yS and 7 rays is used as the 

 ionizing agent, saturation is practically obtained for a very 

 small potential gradient applied between the plates. 



Parallel Field. Perpendicular Field. 



Soui'ce 5-1"=" from the middle of Source 2-7'^"' from the middle of 

 the chamber. the chamber. 



Volts /cm. 



Current 



% lack sat. 



Volts /cm. 



Current 



% lack sat 



5-0 



6-95 



6-0 



2-0 



2-75 



5-2 



40-0 



7-0 



5-4 



4-0 



2-84 



2-1 



200-0 



7-2 



2-7 



8-0 



2-87 



1-0 



800-0 



7-4 



0-0 



40-0 



2-9 



0-0 



1200-0 



7.4 



0-0 



200-0 



2-9 



0-0 









1000-0 



2-9 



0-0 







Note. — For cu 



rves see fig. 3. 







