278 Applied Biophysics 



1. Protection against gamma radiation from the radium paint 

 issued to each operator and against gamma radiation from 

 the main stock of luminous compound possessed by the 

 firm. 



2. Protection of the exposed parts of the body against beta 

 radiation. Each operator is to work behind a lead-glass 

 screen, thus preventing beta radiation from the luminized 

 object from reaching the face. 



3. Local ventilation on each working bench, so as to remove 

 radon and radium dust from the vicinity of the operator. 



4. General ventilation of the workroom to remove radon and 

 radium dust. 



5. Provision of special clothing for use in the workroom. 



6. Periodical cleaning of bench tops and equipment. 



7. Personal hygiene. 



Similar proposals were put forward in America in the Bureau 

 of Standards' Handbook H.27. 



Reference has already been made to the fact that neutrons 

 can be decelerated in hydrogenous materials and are ultimately 

 reduced to thermal velocities. The "thermal neutrons" are easily 

 absorbed, in capture processes, by elements such as cadmium 

 and boron which, in turn, become temporarily radioactive. In 

 this phenomenon, we hnd a method of protecting personnel 

 against neutrons, produced by heavy particles accelerated by 

 apparatus such as the cyclotron. Tanks of water up to 1 meter 

 thick, or stacks of paraffin wax blocks up to about 70 centimeters 

 thick, are placed round the neutron source, most of the slow 

 neutrons being absorbed by salts of cadmium or boron intro- 

 duced into the water or wax. Any gamma radiation which is 

 liberated is absorbed in a final .sheet of lead. 



Tests on Radiation Workers and Inspections of 

 Radiological Departments 



Since the introduction of the first report of the British X-ray 

 and Radium Protection Committee, the National Physical Lab- 



