Cathode Voltage Effect on the Peak sensing Spectrum

All the measurements have the same GEM voltage 2.87 kV, just cathode voltage changes.

the figure below shows the the spectrum when the cathode at 3.735 kV (865V higher than the top GEM's voltage), which reaches to the maxmum rate that DAQ can measure.

Date	CATH. Voltage (kV)	[math]\displaystyle{ \Delta }[/math] V	Shutter	source	run number	Notes
10/23	2.870	0	Open	off	7916	3h 45min
10/23	2.870	0	Closed	off	7917	12h 12min
10/23	2.995	125	Open	off	7912
10/23	2.995	125	Closed	off	7913
10/25	3.050		Open	off	7920	5min
10/25	3.050		Closed	off	7926	5min
10/25	3.030		Open	off	7921	6min
10/25	3.030		Closed	off	7925	5min
10/25	3.000		Open	off	7923
10/25	3.000		Closed	off	7924
10/23	3.120	250	Open	off	7899
10/23	3.120	250	Closed	off	7900
10/23	3.245 (redo)	375	Open	off	7904
10/23	3.245	375	Closed	off	7905
10/23	3.245	375	Open	off	7928	21min
10/23	3.245	375	Closed	off	7927
10/23	3.370	500	Open	off	7908 (22')
10/23	3.370	500	Closed	off	7909
10/26	3.735	865	Open	off	7933	2k Hz 3 min. rate
10/26	3.735	865	Closed	off	7932	0.5-1k Hz 3 min.
10/26	3.585		Open	off	7934	1k Hz 123" rate
10/26	3.585		Closed	off	7935	0.5k Hz 118".

GEM-2.87 kV CATH-3.435 kV

Date	Shutter	source	run number	Scaler counts (Hz)	pedestal	Integral in ADC full spectrum (Hz)	Integral in ADC spectrum beyond pedestal (Hz)	notes
10/16	Open	off	7847	150+_7	1429/60	7915/60	5810/60
10/16	Closed	off	7846	72+_3	1070/60	4029/60	2817/60
10/16	Open	off	7848	137+_16	19	129	111
10/16	Closed	off	7862	53+_1	7	47	41
10 /16	Open	On	7863	147+_12	30	129	101
10/16	Closed	On	7864	67+_4	15	59	45
10/17	Open	off	7865	132+_14	28	121	97
10/17	Closed	off	7866	95+_7	11	59	49
10 /17	Open	On	7868	150+_6	32	128	100
10/17	Closed	On	7867	74+_4	13	63	52
10/18	Open	off	7872	136+_10	9	124	115
10/18	Closed	off	7871	51+_3	4	48	44
10 /18	Open	On	7869	140+_10	10	123	115
10/18	Closed	On	7870	53+_2	4	49	44
10/19	Open	off	7873	124+_14	10	114	104
10/19	Closed	off	7874	59+_4	5	54	49
10 /19	Open	On	7876	141+_8	10	117	108
10/19	Closed	On	7875	60+_4	6	55	50
10/20	Open	off	7879	129+_16	8	116	108
10/20	Closed	off	7880	49+_2	2	45	42
10 /20	Open	On	7882	142+_3	8	108	99
10/20	Closed	On	7881	53+_2	5	49	44

Test runs

Date	Shutter	source	run number	Notes
10/21	open	off	7884	5 min separate pedestal from signal
10/20	Closed	off	7885	5 min shows a difference.
10/22	open	off	7891	5 min CATH 2930 V
10/22	Closed	off	7892	5 min CATH 2930 V
10/22	open	off	7893	2 min CATH 3435 V
10/22	Closed	off	7894	2 min CATH 2435 V
10/23	open	off	7898	5 min CATH 3435 V low shutter close rate
10/23	Closed	off	7897	5 min CATH 2435 V
10/23	open	off	7902	min CATH 3435 V
10/23	Closed	off	7901	2 min CATH 2435 V
10/23	open	off	7907	2 min CATH 3435 V
10/23	Closed	off	7906	2 min CATH 2435 V
10/23	open	off	7911	2 min CATH 3435 V
10/23	Closed	off	7910	2 min CATH 2435 V
10/23	open	off	7915	2 min CATH 3435 V
10/23	Closed	off	7914	2 min CATH 2435 V
10/25	open	off	7919	3 min CATH 3435 V
10/25	Closed	off	7918	3 min CATH 2435 V
10/26	open	off	7929	2 min CATH 3435 V
10/26	Closed	off	7931	2 min CATH 2435 V
10/26	open	off	7937	2 min CATH 3435 V
10/26	Closed	off	7936	2 min CATH 2435 V