Table 2.

Comparison of source calibrations referenced to “500” source, using the aluminum chamber, and open-air calibrations

Source	Working standard calibrations referenced to “500” source (mR · m2 · h−1)	$\text{Ratio}:\frac{\text{ open-air cal }}{"500"\text{ ref cal }}$
500	136.96	1.000
50	14.79	1.007
5	1.276	1.04
100	36.15	0.994
60	9.48
25	8.23