TABLE 2

Comparison of Some Calculated Characteristics and Measured Parameters at 140 keV with Pinhole Inserts

Material	Diameter (mm)	Calculated*			Measured
Material	Diameter (mm)			Effective diameter (mm)	% Normalized efficiency^†	% Sensitivity^‡	% Depleted uranium background
Tungsten	1.0	1.0035	6.28	10.8	—
	2.0	2.0032	25.1	28.9	—
	3.0	3.0029	56.3	60.8	—
	4.0	4.0027	100.0	99.2	—
Depleted uranium	1.0	1.0021	6.27	12.3	11.8
	2.0	2.0019	25.0	31.1	7.3
	3.0	3.0017	56.2	59.9	1.5
	4.0	4.0016	99.9	100.0	0.74

↵* Calculated from data in (31).
↵^† Geometric efficiency calculated along central ray and normalized to 4-mm-diameter tungsten pinhole aperture.
↵^‡ Values are normalized to 4-mm depleted uranium pinhole value.