418 



V. M. Zaporozhetz and E. M. Filippov 



the well neutron generators it is known that currents of charged particles 

 in such generators cannot exceed 10 ^A, which corresponds to -^10^* protons 

 per sec. Knowing the relative output of gamma quanta per proton it 

 is easy to obtain the power of the gamma quanta per second. Knowing the 

 relative output of gamma quanta per proton it is easy to obtain the power 

 of the gamma quanta source. From the Table 5 it is evident that from the 

 point of view of a maximum output of gamma quanta and of obtaining the 

 necessary energy for this the best targets are of Uthium and fluor. The use 

 of the former target allows obtaining gamma quanta energy up to 17.6 MeV; 

 while the use of the latter up to 6.3 MeV. Let us consider whether these 

 sources are sufficiently powerful for GGL and GNL. 



For GGL with scintillation counters of gamma quanta it is necessary 

 to have the activity of the gamma quanta source in the proximity of the 

 counter of not less than 10~^Cu. The distribution of the scattered gamma 

 radiation in a homogeneous medium is expressed by the formula 



/- 



Qe- 



47ll^ 



where : Q is the power of the gamma quanta source; t is the average coefficient 

 of gamma radiation weakening in the rock. 

 I is the sonde length. 

 6 is a coefficient which is a function of the rock density. 



Table 6. The source-power necessary for GGK in curies 



Table 6 shows the power of the gamma quanta source wth energies of 

 10 and 17 MeV calculated for different lengths of the sonde according to 

 the above mentioned formula. In the table the quantities of t^^ and b are 

 adopted from(^). Comparing the data of this table with the data of the 

 Table 5 it is evident that the gamma quanta generator with an acceleration 

 tube can be used only with GGL probe of no more than 40 cms. 



As has been shown already, to carry out GNL gamma radiation sources 

 with a power of lO^^^-lO^^ gamma quanta per second (1-10 Cu) are necessary. 

 This exceeds the permitted power of a gamma quanta generator with an 

 acceleration tvibe. 



