132 Prof. P. 0. Pedersen on the 



The total number of ionizations N ( o-y(*y) • dx in the 

 element of space (x, x + dx), which are due to electrons 

 the direct collisions of which occurred between x = and 

 x=l , is determined by : 



for x<l : N ( o-z )(V) = 0, 



for ^*<2J : N<p- W (*) = \%(x).dy^{A-e% 



and for ^>2Z : N (0 -z o) (^) = ^l{x).dy = ^{e-^r-e'l). 



The total number of ionizations 1ST (x) .dx in the element 

 of space (x, x-\-dx), which are due to electrons which either 

 come directly from A or the direct collisions of which took 

 place within the distance l from A, is thus determined by : 



f or x < l : N (x) = 0, ^ 



for k^2k : N(.,, = £.."&, I % 2> n (g) 



and for a > 2/ : N(a-) = ^° . e^. J 



It is obvious that the number N 1 (x)dx in the element of 

 space (x, x + dx), wmich are due to collisions with electrons 

 originally coming from A, is determined by : 



for^</ : ~N 1 {x) = 0, 1 



and for x>:l : -Ni(/u) = -p. e L . 



The total number of liberated electrons of that class 

 which we called Class 1, of which the collisions are due to 

 impacts between molecules and electrons originally coming 

 from A, is therefore 



ni=(a--Zo)j^E (10) 



It is also possible to realize the correctness of this result 

 directly, but the procedure followed above has the advantage 

 that it gives some information about the " geometry " of 

 ionization by collision, 



X7) 



