compton: size and shape of electrons 9 



methods show, however, that if the electron is a rigid ring whose 

 plane is invariable, the scattered energy follows equation (2) 

 rather closely, and is symmetrical on the incident and the emer- 

 gent sides. If the electron is a flexible ring, or one capable of 

 rotation about any axis, the scattering is more nearly that given 

 by equation (4), but should be somewhat greater for large 

 values of a/\. The ratio of the incident to the emergent scat- 

 tered radiation should also be appreciably larger than that 

 given by expression (5). It seems probable, therefore, that the 

 scattering of 7-rays and X-rays may be completely explained on 

 the hypothesis that the electron is a ring of electricity of radius 

 about 2 X lO-'i" cm., if the ring is capable of rotation about any 

 axis. 



This hypothesis makes it possible to explain also the effect 

 noticed by A. H. Forman'* that the absorption coefficient of 

 iron for a beam of X-rays is greater when the iron is magnetized 

 parallel with the transmitted beam than when the iron is un- 

 magnetized or magnetized perpendicular to the X-ray beam. 

 Using an effective potential of 27,000 volts the effect was about 

 0.4 per cent, and with a potential of 81,000 volts it was 0.6 per 

 cent. From X-ray spectra obtained under similar circumstances 

 it can be shown that the effective wave-length used in the two 

 cases was about 1.0 X 10^^ and 0.5 X 10^^ cm. respectively. 

 If the ring electron acts as a tiny magnet, as suggested by 

 Parson,^^ it may be turned by the magnetic field until its plane 

 is perpendicular to the incident beam of X-rays This will 

 make the rays scattered by the different parts of the electron 

 more nearly in the same phase, so that the absorption due to 

 scattered radiation will be increased. Moreover, since the in- 

 cident rays can get a better hold on the electron in this posi- 

 tion, its displacement will be greater than when unorientated, 

 and absorption due to transformation of the X-rays into other 

 types of energy will be greater. For the relatively long waves 

 used bj^ Forman the ratio of the absorption coefficient when 



16 Forman. Phys. Rev. 7: 119. 1916. 



1' Parson, A. L. Smithsonian Misc. Collections, Nov. 191.5. Parson esti- 

 mates his "magneton," or ring electron, to have a radius of 1.5 X 10""' cm. 



