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BELL SYSTEM TECHNICAL JOURNAL 



muting which increases smoothly from zero (though this suggestion 

 might not occur to anyone not having foreknowledge of the current 

 theory!). The least energy at which transmutation is observable 

 should then depend entirely on the strength of the proton-stream and 

 the sensitiveness of the apparatus; von Traubenberg, with a stream 



>0 80 100 120 140 160 



ENERGY IN EUECTRON-KILOVOLTS 



180 200 220 



Fig. 16 — Disintegration-functions of thin films of lithium and boron. (Oliphant 



& Rutherford) 



perhaps as strong as that of Oliphant and Rutherford, observed one 

 to three fragments per minute at 13,000 volts. 



The curve of Fig. 17 extends very much further — all the way to 

 1.125 MEV — but was obtained with so thick a target of lithium 

 (lithium fluoride, to be precise) that the protons came to a stop in the 



