Table 1. Fractional standard uncertainty in desmeared calibrated USAXS intensity for one measurement of one coupon for a USAXS setup at a specific X-ray energy.

X-ray energy (keV)	Number of coupons measured	Standard uncertainty (%)
10.5	4	2.19
11.5	4	2.16
11.5	16	2.09
12.0	4	1.81
12.0	16	1.71
16.8	4	2.24

The same four glassy carbon coupons, each cut from the center of a plate, were measured at all four X-ray energies. At 11.5 and 12.0 keV, 12 additional coupons were measured, cut from the edge, corner and intermediate locations.