CESIUM-OX YGEN-SILVER PHOTOELECTRIC CELL 



345 



in the neighborhood of the 20 ratio. Also, the maximum activity is 

 significantly higher for the 30-minute heat treatment than for either 

 15 or 60 minutes. The second series of cells was made with pellets 

 containing 3 milligrams of caesium chromate. The oxygen-casium 

 ratio was varied from 10 to 30 and three groups baked for 7.5, 15 and 

 30 minutes, respectively. In this series the maximum activity occurs 



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OXYGEN TO CAESIUM RATIO 



Fig- 3 — -Integral sensitivity as a function of oxygen-caesium ratio for 5 mg. pellets. 



at a ratio of 17 and with a heat treatment of 15 minutes as shown in 

 Fig. 4. One additional point of interest is that with the light pellets 

 the cells have still fair activities at the high ratios for the short heat 

 treatments but are destroyed by the 30-minute heating. This is 

 most probably due to the oxidation of free caesium by residual silver 

 oxide. 



