Connexion beticeen ft and 7 Ray Spectra. 311 



appear in the form of a swift ft ray. There is now strong 

 evidence from a variety of directions that the energy emitted 

 by a source of radiation of frequency vis in definite quanta E 

 when E — hv, h being Planck's constant. The general idea 

 that the energy of the 7 rays is emitted in definite units or 

 quanta appears to be necessary to explain the origin of homo- 

 geneous groups of ft rays expelled from radioactive matter. 

 We shall first assume that the energy in a single 7 ray of 

 frequency v is given by Planck's formula, and then discuss 

 how far this particular relation is supported by the experi- 

 mental evidence. 



We shall suppose certain regions in the atom are set in 

 vibration by the escape of the ft particle during the atomic 

 explosion. If v l9 v 2 ... are the frequencies of vibration, the 

 energy emitted in the form of y rays is phv x , qliv 2 . ... where 

 p and q may have any integral values. For example, one 

 atom may emit one 7 ray of frequency v and energy liv, 

 another may emit a train of two 7 rays of the same frequency 

 but of energy 2/tv, another three, and so on. There is no 

 method at present of deciding the most probable value of p 

 for a single atom, nor to fix an upper limit to its value. This 

 may depend on the intensity of the disturbance communicated 

 to a vibrating system by the escaping ft particle. The energy 

 of these 7 rays is supposed to be partially or wholly con- 

 verted into the ft ray form in their escape from the radio- 

 active atom. Unfortunately there is no evidence available 

 at present of how this conversion occurs or whether any 

 energy is ^absorbed in the process. If the conversion takes 

 place without loss of energy, a train of 7 rays of frequency Vj 

 will give rise to a ft particle of energy given by J&ssphv^ 



It is possible the conversion may occur in one of the 

 regions of the atom which give rise to characteristic radiations, 

 and is accompanied by the appearance of a new type of 

 7 rays of frequency v 2 etc. In such a case, we should 

 anticipate that the energy of the escaping ft particle is given 

 by E=p/iV]— qhv 2 , where p and q are whole numbers which 

 may have all possible values consistent with pv x being greater 

 than qv 2 . 



The value of E here refers to the energy of the ft particle 

 at the point in the atom where the conversion of energy 

 occurs. It seems possible that there may be a further change 

 of the energy of the ft particle in escaping from the atom. 

 In this case, the energy of the ft particle after it has escaped 

 from the atom is given by phv 1 — qhv 3 — A, where A may 

 have a negative value and is at present indeterminate. 



It will bo seen that the present theory of the origin of the 



