NEUTRON ErFECTS ON ANIMALS 



23 



reasons. The Roentgen refers only to X (Roentgen) radiation. The bio- 

 logical effect of an n unit of neutrons is different from that of an r unit of 

 X-raj's even though both give the same reading when measured with a 

 Victoreen 100 r chamber. 



The dosages were controlled by a Victoreen Integron. This instrument 

 consists of ionization chamber, amplifier, and meter. The meter indicates 

 the chamber charge in r units and may be set at any dosage value. The 



z 

 u, 



< 



< lao 



q: 



D 

 O 



z 



160 



O 



z 



< 



UJ 



a. 



14 



z 



< 



UJ 



cr 



UJ 

 CD 



< 



X 



o 



z 

 o 



120 



100 



^ 



n 



12 3 4 5 



INCHES OF PARAFFIN 



Fig. 5. Neutron intensity previous to the installation of the cadmium shielding. 

 = Position ;^-4. O = Position #2. 



reading decreases as the ionization chamber is exposed to radiation until 

 the reading becomes zero. Thus, if the chamber is to receive 10 r, the 

 meter is set at 10 r and the chamber is exposed. When the chamber has 

 received the 10 r, the meter reads zero and closes a relay which rings a bell 

 and lights a light. This relay is connected to the cyclotron oscillator in 

 such a way that it turns off the oscillator and hence stops radiation when 

 the exposure is completed and the meter reads zero. 



It was impractical to mount the Integron ion chamber in the cages, 

 so it w^as placed in the position indicated in Fig. 1. Like the cages, it was 



