Rontgen Radiation and Corpuscular Radiation. 449 



of this energy converted per second into energy of corpuscular 

 radiation is I'kSx. 



The corpuscular energy entering the ionization-chamber I 

 from a layer of thickness Bx and of area S (the area of R 3 

 upon which the secondary radiation falls) situated at a depth 

 x below the surface of R 3 



= £-BkI'8*e-Px*, (2) 



47T V J 



where & is the absorption coefficient of the corpuscular 

 radiation by the material of the tertiary radiator, and w is 

 the mean solid angle subtended by the ionization-chamber 

 at a point in the layer at which a corpuscle originates (the 

 value of (o will not appreciably alter with changes in value 



of A). 



But I' = I e~ x v v , where I is the energy of the homogeneous 

 Rontgen radiation incident per sec. upon unit area at the 

 surface of the radiator R 3 , and \i the coefficient of absorption 

 of the incident radiation by the material of the tertiary 

 radiator. 



The whole energy passing into the ionization-chamber is 

 then given by 



— ifelS 8* e-CM-M* (3) 



On integration this becomes 



ft) 81 k 



sa+v (4) 



or since we have I = T <?~ X 2, this expression for the energy 

 entering the ionization-chamber per sec. may be written 



I 



to SI &£- 



4tt j3 x + \ Y 



(5) 



Since none of the corpuscles can travel more than a few 

 mm. in air it may be assumed that the ionization which 

 they produce in the space between R 3 and B will be pro- 

 portional to the total energy of the corpuscles emerging from 

 the^ radiator R 3 . We may, therefore, write for°the total 

 ionization produced by the corpuscles 



-q w S I n k 



4tt & + A,j 

 where D is a constant. 



(6) 



