TABLE 3.

Summary of the calibration points, current, and time used for each electrometer.

Electrometer	Range					Calibration points
RT521R	–	Input charge [nC]	+200	+20	+5	−5	−20	−200
		Current [nA]	+20	+2	+0.2	−0.2	−2	−20
		Time [s]	10	10	25	25	10	10
Model 35040	–	Input charge [nC]	+200	+20	+5	−5	−20	−200
		Current [nA]	+20	+2	+0.2	−0.2	−2	−20
		Time [s]	10	10	25	25	10	10
RAMTEC Duo	L	Input charge [nC]	+10	+5	+1	−1	−5	−10
		Current [nA]	+0.2	+0.2	+0.2	−0.2	−0.2	−0.2
		Time [s]	50	25	5	5	25	50
	M	Input charge [nC]	+500	+250	+100	+50	+5	−5	−50	−100	−250	−500
		Current [nA]	+10	+10	+10	+10	+0.2	−0.2	−10	−10	−10	−10
		Time [s]	50	25	10	5	25	25	5	10	25	50
UNIDOS‐E	L	Input charge [nC]	+10	+5	+1	−1	−5	−10
		Current [nA]	+0.2	+0.2	+0.2	−0.2	−0.2	−0.2
		Time [s]	50	25	5	5	25	50
	M	Input charge [nC]	+500	+250	+100	+50	+5	−5	−50	−100	−250	−500
		Current [nA]	+10	+10	+10	+10	+0.2	−0.2	−10	−10	−10	−10
		Time [s]	50	25	10	5	25	25	5	10	25	50