She asp eiarllittitoe Gov a AH EXPOSURE RATE X 100 3s a B38 6 7 8 = Bree noe meen me emcees oeetee ten Ro At pny Fege pe (MeV/gm~sec) pane Fe HEIGHT (METERS) Figure l. Total ara scattered exposure rates versus height for uniformly distributed scurces with energies cf .364, 1.0 and 2.5 MeV and the single rormalized curve of exposure rates for natural emitters.