78 



THE PHYSICS OF VIRUSES 



Deuterons of different energy are obtained l)y putting foils 

 over the samples. The whole unit is evacuated to the cyclotron 

 vacuum of about 10""'' mm mercury. 



Insulated 

 Diaphragm 



Fig. 3.3. Use of a deuteron beam from a cyclotron to bombard viruses. The 

 upper drawing shows the side view, and the lower is an enlarged view of the 

 end with the sample holder and shutter indicated schematically. 



Results of deuteron bombardment of T-1 bacteriophage are 

 shown in Fig. 3.4. The data are due to Pollard and Forro (1951). 

 It can be seen that a semilogarithinic relation between the per- 

 cent of infectivity surviving and number of deuterons per square 

 centimeter employed in bombardment holds. This is the charac- 



