182 



RADIATION BIOLOGY 



of the maximum. The variation in intensity with temperature is pri- 

 marily due to variation in 253.7-m^i resonance radiation in the mercury 

 discharge. Below 48°C the discharge is deficient in mercury ions; above 

 48°C the efficiency of production of resonance radiant energy is decreased. 

 Phosphor efficiency is influenced only slightly by temperature, the 

 efficiency being highest at low temperatures. These are very important 

 considerations when large banks of lamps are operated in enclosures. 



INTENSITY 



The fluorescent lamp is inherently a low-intensity low-brightness 

 source, the white lamps having brightness values ranging from 0.01 to 

 0.03 c mm~2 (Table 3-14). Low brightness is an asset for general irradi- 



Table 3-14. Comparative Total Radiation Characteristics of Sources 



Source 



Sun, air mass = 2 



Black body, 3000°K 



Incandescent lamp 



General service 



General service 



Projection 



Photoflood 



Tungsten arc, G.E. 



Photomicrographic 



Carbon arc 



Low intensity, 30 amp. . 



High intensity, 180 amp 



Flame, rare-earth, 40 amp 

 Zirconium arc 



0.085-mm-diam. source. . 



1.50-mm-diam. source... 

 Xenon arc, 3.5-mm gap. . . . 

 Mercury arc 



Low pressure, germicidal . 



H-4, 8 atm 



H-6, 110 atm, water- 

 cooled 



Fluorescent lamp 



Standard cool white, 60 in. 



Green, 48 in 



Sodium lamp 



Power, 

 w 



40 



500 



500 



1,000 



330 



1.650 



13,300 



1,500 



2 

 100 

 150 



30 

 100 



1,000 



85 



40 



180 



Bright- 

 ness, 

 c mm~^ 



1650 



28 



4. 



9 

 16 

 30 



48 



150 

 950 



96 



52 



170 



18 



300 



0.008 



0.01 



0.06 



Luminous 



efficiency, 

 lumens w~' 



Abso- 

 lute 



100 

 19 



17 

 23 

 30 

 40 



46 



110 

 150 



Elec- 

 trical 



11 

 20 

 26 

 36 



13 

 25 

 60 



18 



27 



65 



55 

 75 

 53 



Color 



temp., 



°K 



5000 

 3000 



2760 

 2960 

 3190 

 3360 



3700 



3600 

 6000 

 4700 



4000 



4500 



Wave 

 length 

 of maxi- 

 mum in- 

 tensity, 



500 

 1040 



1020 



1000 



900 



850 



700 



1000 

 600 

 400 



1000 

 1000 

 1050 



254 

 365 



436 



590 



530 

 589 



