Test on RO: PMT basis, mixer, amplifier

We started by calibrating the lead module, which had been centered in the beam using previous runs not listed here (see logbook), using an 80 GeV e- beam. We used CAEN ADCs to read out the signals and moved the table to point the beam to the center of the different towers. We then followed with a repeat of these measurements wit the beam centered in tower 3 only at different electron beam energies. The table gives the online analysis of these runs.

Tower Run ADC C ADC S
4 6928 817 773
3 6929 815 775
2 6930 817 833
1 6931 819 857

Moving back to tower 3 (note run 6929 matches these conditions), we took data at additonal energies:

e- Energy (GeV) Run ADC C ADC S
150 6933 1220 1660
125 6936 1117 1310
100 6934 1011 1068
50 6935 441 371
30 6932 207? 152?

These results show significant non-linearity in the ADC response. There followed an extensive set of runs in which HV variations, capacitive coupling, and different ADC's were tried. The results were not significantly different, so we switched to using oscilloscope readout for the remainder of the studies. Online results will not be repeated here, since they require more extensive analysis, but the settings for the oscilloscope scales are recorded here for convenience.

Energy scan with different PMT Bases

Electron beam, centered in tower 3
S3, C3 only low gain channel;

Tapered PMT bases

logbook pages 60-68

e- Energy (GeV) Run S3L S3L scope scale (V/div)   Run C3L C3L scope scale (V/div)
20 6962 0.05   6981 0.1
30 6956 0.1   6973 0.1
50 6957 0.1   6976 0.2
80 6954 0.2   6977 0.5
80 6955 0.1   --- ---
100 6959 0.2   6978 0.5
125 6960 0.2   6979 0.5
150 6961 0.2   6980 0.5

Standard PMT bases

HV settings: C3= 570 V ; S3 = 480 V logbook pages 69 - 71

e- Energy (GeV) Run C3L scope scale (V/div) S3L scope scale (V/div)
20 7001 0.05 0.05
30 7000 0.1 0.1
50 6999 0.1 0.1
80 6991 0.1 0.1
100 6997 0.1 0.2
125 6998 0.2 0.2
150 6993 0.2 0.2

Tapered PMT bases with independed last dynode

Configuration with polarization of last dynode which maximize the signal output
HV settings: C3 = 715 V ; S3 = 620 V; Dy_C3 = 35.5 V; Dy_S3 = 31 V

e- Energy (GeV) Run C3L scope scale (V/div) S3L scope scale (V/div)
20 7026 0.05 0.05
30 7018 0.05 0.05
50 7025 0.05 0.1
80 7012 0.1 0.2
100 7022 0.1 0.2
125 7021 0.2 0.2
150 7016 0.2 0.2

Configuration with polarization of last dynode which reproduce the tapered base
HV settings: C3 = 715 V ; S3 = 620 V; Dy_C3 = 77.5 V; Dy_S3 = 67 V

e- Energy (GeV) Run C3L scope scale (V/div) S3L scope scale (V/div)
20 7027 0.05 0.1
30 7019 0.05 0.05
50 7024 0.05 0.1
80 7013 0.1 0.2
100 7023 0.1 0.2
125 7020 0.2 0.2
150 7015 0.2 0.2

-- AlanSill - 21-Jul-2012

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