132 BELL SYSTEM TECHNICAL JOURNAL 



,W + zW +To = 22He^ + Ti, (1) 



iH2 + sLis + To = 22He^ + Tr, (2) 



of which the first has already appeared in Part I. of this article. 



These are to be regarded as equations for mass and energy, owing 

 to the equivalence of these two entities. Attached to the symbol of 

 each atom are its mass-number as superscript and its atomic number 

 as subscript (and, incidentally, every such equation must balance 

 when considered as an ordinary equation in either the mass-numbers 

 or the atomic numbers). The symbols To and Ti stand for the total 

 kinetic energy of the particles before and the particles after the trans- 

 mutation, expressed in mass-units. (I recall from Part I. that a 

 mass-unit is one-sixteenth the mass of an sO^^ atom, and that one 

 million electron-volts is equal to 0.00107 of one mass-unit.) The other 

 symbols then stand for the rest-masses of the nuclei of the atoms in 

 question. It would be proper, and in accordance with the spirit of 

 relativity, to leave out the symbols T^o and Ti and consider each of the 

 other symbols as standing for the total mass of the nucleus, viz. the 

 sum of its rest-mass and the extra mass resulting from its speed. 

 When hereinafter the symbols Tq and Ti are absent from such an 

 equation, the others are thus to be interpreted. 



The suggestion thus is, that when a proton meets with a sLV nucleus 

 or a deuton with a sLi^ nucleus, either process ends in the formation 

 of two helium nuclei — alpha-particles — out of the substance of the 

 original bodies. It is further suggested that these nuclei share kinetic 

 energy amounting to Ti; and if they are emitted in directions making 

 equal angles with that of the impinging particles — the "symmetrical 

 case" which (as we shall see) is most commonly observed — they must 

 share Ti equally in order to assure conservation of momentum. Now 

 the rest-masses of all the nuclei figuring in equations (1) and (2) are 

 accurately known through the work of Aston and of Bainbiidge. 

 Taking them from Table I and substituting them into the equations, 

 and using the electron-volt for our unit, we get : 



Ti = To -f 16.8- 10«, ■ (3) 



Ti = To + 22.2- 10«, (4) 



in the two cases, ^' and therefore expect alpha-particles paired with 

 one another, their kinetic energies amounting altogether to these values. 



^^ For these numerical values and their uncertainties, see K. T. Bainbridge, Phys. 

 Rev. (2). 44, 123 (July 15, 1933). 



