NIST Calibration Conditions for X- and Gamma-Ray Measuring Instruments

Beam code		Added Filtration a					Half-value layer b (HVL)			Homogeneity coefficient (HC)			Effective energy (keV)
		Al (mm)	Cu (mm)	Sn (mm)	Pb (mm)		Al (mm)	Cu (mm)		Al	Cu
X-Ray Beam Qualities
L10							0.037			86
L15							0.059			70
L20							0.070			72
L30		0.30					0.23			60
L40		0.53					0.52			61
L50		0.71					0.79			63
L80		1.45					1.81			56
L100		1.98					2.80			58
M20		0.27					0.15			72
M30		0.5					0.36			65
M40		0.89					0.74			67
M50		1.07					1.04			68
M60		1.81					1.64	0.052		63	60
M80		2.86					2.98	0.10		68	61
M100		5.25					5.00	0.20		74	55
M120		7.12					6.72	0.31		77	53
M150		5.25	0.25				10.1	0.66		88	63
M200		4.35	1.12				14.7	1.64		94	68
M250		5.25	3.2				18.3	3.2		98	85
M300		4.25		6.5			21.7	5.3		100	97
H10		0.105					0.051			77
H15		0.5					0.16			87
H20		1.01					0.36			89
H30		4.50					1.20			86
H40		4.53	0.26				2.93			94
H50		4.0			0.1		4.2	0.14		93	93		38
H60		4.0	0.61				6.0	0.25		94	94		46
H100		4.0	5.2				13.4	1.15		97	92		80
H150		4.0	4.0	1.51			16.9	2.43		100	96		120
H200		4.0	0.6	4.16	0.77		19.7	4.10		99	99		166
H250		4.0	0.6	1.04	2.72		22	5.19		99	98		211
H300		4.1		3.0	5.0		23	6.19		99	98		252
S60		4.35					2.79	0.09		76	66
S75		1.50					1.81			58
Gamma-Ray Beam Qualities
137CS								10.8					662
60Co								14.9					1250
The additional filtration value does not include the inherent filtration. The inherent filtration is approximately 1.0 mm Be for beam codes L10-L100, M20-M50, H10-H40, and S75; and 3.0 mm Be for beam codes M60-M300, H50-H300, and S60.The HVL values were measured directly using the two new x-ray tubes installed in November of 2001 and May of 2002. The HVL values were measured directly using the two new x-ray tubes installed in November of 2001 and May of 2002.

Inquiries or comments: s.seltzer@nist.gov Online: September 1998   -   Last update: June 2003