Cases of Ionization by X-Rays. 

 its face of incidence 



m ffrflSV** ; 



:;< i 



r 



Jo 



/l* 



x + x'* 



Similarly the intensity of corpuscular radiation from a 

 thick layer of gas proceeding from the face of emergence of 

 the primary beam is 



M X'-V 



where / 2 is the fraction directed towards the emergent face, 

 and I is here the intensity of primary radiation emerging 

 from the thick layer. 



Each thin layer of gas is thus exposed to corpuscular 

 radiation of total intensity 



^.oJVtx+xAJ- 



In the cases we are considering X is negligible in com- 

 parison with X'. 



Therefore each layer of gas is exposed to corpuscular 

 radiation of intensity 



.'. Intensity of corpuscular radiation producing ions _ ,k r 

 Intensity of primary X-radiation producing ions V * 



If ihe coefficients of ionization ,of the two types of radiation 

 (primary X and secondary corpuscular) in tjie gas jitself are 

 i r and ?'/, as denned by the equations 



dn = i r IdcV and da =i !Vdx, 



where dn and dm! are the numbers of ions produced in a layer 

 of gas of thickness dx by primary aiid secondary corpuscular 

 radiations of intensities I and P, 



then dn' k'ij . . . . 



-y- = T77-, which theretore 

 an X i r 



_ Ionization by secondary corpuscular radiation 



Ionization by primary X-radiation 



Phil. Mag. S. 6. Vol. 20. No. 116. Aug. 1910. 2 C 



