TABLE I DOSE RATE CALIBRATION OF SPECTROMETER Peak Energy (MeV) 0.5 ° Source Distribution Isotope Peak Counts/ur/hr pal40_1,140 Exponential 6000 Rul03-Rn103 Exponential 35000 RulO06_RA1l O06 Exponential 18000 2193 -Nb?5 Exponential 21000 x40 Uniform 59550 Bpi2zl4(y series) Uniform 700 7T1208(Th series) Uniform 750 - 14 - 20