50 



NEUTRONS AND THEIR SPECIAL EFFECTS 



ever, in the specific case of P^^, Sherwin (18) has carried out experiments 

 which show that the neutrino probably enters the same hemisphere as 

 the electron. In general, three limiting cases can be considered: the 

 neutrino and the electron can be emitted in the same direction, they can 

 be emitted in opposite directions, or there can be no correlation at all. 

 The recoil effect is maximum in the first case, minimum in the second, 

 and intermediate in the third. The relative probabilities of recoil 



0.20 



^" 



0.10 



En, ev 



(21.5) 



(32.4) 



Fig. 1. Recoil spectra for varying angular correlations of electron and neutrino, for 



hypothetical nucleus of 100 atomic mass units with maximum beta-ray energy of 



2.0 mev. [From Edwards and Davies (17).] 



energies for a hypothetical nucleus of mass 100, giving off a 2-mev beta 

 particle, have been calculated by Edwards and Davies (17) and are 

 shown in Fig. 1. The maximum recoil energy for C^^ is 6.9 ev; for P^" 

 it reaches the sizable amount of 76.6 ev. The amount of this recoil 

 energy {Er in electron volts) available for bond strain or rupture is 

 given by Ei = m/{M + m)Er, where Ei is the bond strain energy in 

 electron volts and M and m are the masses of the recoiling atom and the 

 rest of the molecule, respectively. Thus, the energy available for bond 

 rupture following beta decay is large except when the rest of the mole- 

 cule has a mass small compared with that of the recoiling atom. 



It is not entirely clear whether orbital electrons are lost after beta 

 emission. If they are not, the increase in nuclear charge should corre- 

 spond to a chemical oxidation of one unit. Gest, Edwards, and Davies 



