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BELL SYSTEM TECHNICAL JOURNAL 



These are curves in which the abscissa stands for the thickness of a 

 special kind of matter (air of a standard density) interposed in the 

 path of the fragments, and the ordinate for the number of fragments 

 detected on the far side of that matter; I will call them "integral 

 distribution-in-range" curves representing the number /(x) of particles 

 able to traverse thickness x. Were one to differentiate them, one 

 would get the "differential distribution-in-range" curves, representing 

 a function f'{x) such that f'{x)dx stands for the number of particles 

 able to traverse thickness x but not additional thickness dx — the 

 particles which are said to have "ranges" between x and x + dx. 



» ■ * * 4 « " n ■ i i r^ ^ 



I I I 1 1 1 •*- 



1.5 2 3 4 5 



AIR EQUIVALENT IN CENTIMETERS 



Fig. 8 — Integral distribution-in-range curve of the fragments resulting from bombard- 

 ment of lithium by protons. (Oiiphant Kinsey & Rutherford) 



These, however, are usually not plotted,''^ and one must accustom 

 himself to draw the proper inferences from the integral curves. 



The clearest of these to read are those which are shaped like a 

 staircase, with steep rises connecting horizontal parts called paliers or 

 plateaux. A steep rise extending over a narrow interval of x signifies 

 a "group" of fragments all having ranges close together. A plateau 

 extending over a broad interval of x signifies that no particle has a 

 range comprised anywhere in this interval. An integral curve in the 

 form of a staircase therefore implies the analogue of a line-spectrum, 



" One of the rare examples is reproduced in "Transmutation," B. S. T. J., \'o\. X, 

 p. 650 (Oct. 1931), from the work of Bothe and P>anz. 



