408 V. M. Zaporozhetz and E. M. Filippov 



of deuterium in an acceleration tube. The following factors were considered 

 in this calculation. 



(a) The average molecular free path in a deuterium or hydrogen atmosphere 

 is equal to 11.77 X 10~^ cm at 760 mm Hg pressure. 



(b) There are 6 x 10^^ diatomic molecules in 22 htres of deuterium at 

 temperature and 760 mm Hg pressure. 



(c) The volume of an acceleration tube in a well neutron generator equals 

 1000 cm^; the volume of an ion source is 500 cm^ and the operational 

 temperature 40 °C, while the duration of an uninterrupted run of the mecha- 

 nism (until it is filled with gas) is 10 hours. The neutron emission is lO^n/sec, 

 namely 100 times more than is normally obtained in logging with Po +Be 

 sources. 



As is evident from the Table 2 the expenditure of deuterium in a nuclear 

 reaction of the type H^(i, ra)He* is very small. Even if the source produces 

 lO^n/sec in a sealed acceleration tube which is shoAvn diagrammatically in 

 Figs. 5 and 6, the expenditure of deuterium, with the gas pressure at the 

 ion source being not less than 10~^-10'* mm Hg, does not exceed 1 per cent 

 per eighteen working hours. Thus, the tube is capable of working for 

 a long time without renewal of the gas that fills it. 



GAMMA QUANTA GENERATOR 



Well accelerators are used as sources of gamma particles. 



First let us consider what new^ data can be obtained by using these accelera- 

 tors in gamma -gamma logging. 



The contemporary demands of safety in Avorking on bore-holes do not al- 

 low the use of natural uninterrupted radiating sources stronger than 30 m Cu. 

 The relative safety of working with an accelerator allows the use of much 

 more powerful gamma quanta in gamma-gamma logging. This makes it 

 possible to increase the velocity of running GGL without lowering its accuracy 

 and to conduct investigations involving considerable distances (provided 

 the distance between the mid -points of the source and the indicator is large). 



A source of gamma quanta no stronger than 30 mCu allows us to conduct 

 the GGL method of bore-hole investigations with the aid of the standard 

 apparatus RARK (containing one discharge counter of the type VS-9) 

 with an additional device which screens the counter from the radiation 

 scattered by the drilling fluid. In such a case the deflection of the registered 

 GGL curve from statistical fluctuations wiU be no more than 1 % if the device 

 is raised at a velocity no higher than 500 m/hr. 



The use of powerful accelerators of gamma quanta presents a possibihty 



