GEM and Mini Prototype DC Cosmics Run
Experimental Setup for efficiency tests
Connector Tables
For Metalica
Metalica Sense Wire # | VPI PostAmplifier Output(ADC && TDC) | ADC Channel# (VME) | TDC Channel# (VME) |
1 | 16 | 17 | 1 |
2 | 14 | 19 | 3 |
3 | 12 | 21 | 5 |
4 | 10 | 23 | 7 |
5 | 8 | 25 | 9 |
6 | 6 | 27 | 11 |
7 | 4 | 29 | 13(no cable) |
For Plastika
Plastika Sense Wire # | VPI PostAmplifier Output(ADC && TDC) | ADC Channel# (VME) | TDC Channel# (VME) |
1 | 15 | 18 | 2 |
2 | 13 | 20 | 4 |
3 | 11 | 22 | 6 |
4 | 9 | 24 | 8 |
5 | 7 | 26 | 10 |
6 | 5 | 28 | 12 |
7 | 3 | 30 | 14(not connected) |
Setting Electronics
Using The Stanford Pulse Generator, Model DG535, four identical pulses were injected into the GEM(I mean output),, two PMTs and DC(first Metalica and then Plastika).
Data taking
(12/23/08)
Mini DCs and GEM detectors are sandwiched between the two PMTs. The top scintillator is operated at 1050 Volts and bottom one-1000 Volts.
HV settings on GEM detector:
HV settings on DCs: Sense=1450 Volts, Field=-725 Volts && Guard=724 Volts.
The coincidence pulse from two PMTs is used as a trigger and gate for GEM and DCs.
The PreAmp voltage on DCs is set to 6.4 Volts, the pulse form DC is amplified using PostAmplifier(amplification is on maximum). The TDC output of the amplified pulse is discriminated using the Leading Edge Discriminator and putted to the NIM-ECL converter, which than goes to the TDC(VME). The ADC output of the PostAmp was used for ADC(VME).
Run Number is r685
(1/5/08)
The GEM ADC measurements from the last cosmic run do not show a GEM signal while the DC has a clear ADC signal. Is the GEM output in time with the ADC gate?
I only saw one GEM signal from Trig out when triggering the scope on the bottom scintillator. It looked like
Some drift chamber signals start hat before the gate suggesting there is too much delay on the gate line.
I observed more DC signals from channel 7 than GEM trigger signals when I triggered the scope on the bottom scintilator. Could the GEM gain/efficiency be substantially lower than the DC?
- When running with HRRL electrons we should probably set the HV for each detector so they have the same rate.
Changed integrate gate from 150 ns to 300ns
Increased GEM HV 25 volts from 3325/2925 to 3350/2950
(1/6/09)
starting cosmic run # 686 on Jan 6 17:54.
- Next week let's do plateau measurements, change HV and measurements cosmics for 1 day to plot rate -vs- voltage
- Mac will double check his calculations for the correct sense wire HV.
Plateau measurement when S:F:G=2:-1:1
Voltage is changing only on Metalica. The HV setting for Plastika are set to the fixed values:
The Sense, Field, and Guard (S:F:G) wire HV ratios are 2:-1:1
HV settings on Sense Wire (Volts) | Run Number | Run Period (minutes) | ADC23 Signal Counts/scint trigger (bin 70:4000)" | ADC24 Signal Counts/scint trigger (bin 70:4000)" | Cosmic Coincidence Rate (Counts/min) | ADC23 Rate (Counts/min) | ADC24 Rate (Counts/min) |
1600 | r695 | 1774 | 1376/1842 = 0.747 | 1404/1842 = 0.762 | 1.028185 | 0.775648253 | 0.791431793 |
r708 | 1034.69 | 1099/1103=0.996 | 1099/1103=0.996 | 1.06602 | 1.0621538 | 1.0621538 | |
1550 | r693 | 635.3 | 557/746 = 0.747 | 562/746 = 0.753 | 1.174248 | 0.876751141 | 0.884621439 |
1500 | r691 | 1459.7 | 1201/1502 = 0.800 | 1168/1502 = 0.778 | 1.028978 | 0.822771802 | 0.800164417 |
1450 | r692 | 1007.85 | 796/1049 = 0.759 | 793/1049 = 0.756 | 1.040829 | 0.789800069 | 0.786823436 |
1400 | r696 | 2874.25 | 2124/2867 = 0.741 | 2146/2867 = 0.749 | 0.997477 | 0.738975385 | 0.746629556 |
1350 | r710 | 872.25 | 668/791=0.8445 | 653/791=0.825 | 0.9068 | 0.765835 | 0.764835483 |
The efficiency for Plastika (ADC24) seemed to track with Metalik's efficiency even though the HV on Metalika was changing while Plastica's HV stayed constant. We believe we are still in the plateau region and should make measurements with a sense wire voltage less than 1350 Volts.
- Histograms for Each ADC
(1/14/09)
Comparison of two runs: r685_vsr691
The HV for Sense wire in run 685 was set to 1450 Volts and for 691 - 1500 Volts
Plateau Measurements when S:F:G=1:-0.5:0.7
The previous efficiency measurements seems to all be still on the plateau. We need to change the Guard voltage to be 70% of the Sense wire voltage instead of 50%.
Mac's prediction is that the BABY chamber voltages need to be (sense,field,guard) = 1340,-670,940 for the BABY chamber to have a gas gain similar to the present CLAS chambers (which I think is about 1.7*10^4).
Let's set Plastika to those voltages as a control and change Metalika's voltage maintaining the S:F:G=1:-0.5:0.7. Let's try going to lower voltage first.
Plastika is set to the following voltages: (Sense,Field,Guard) = 1340,-670,940
HV settings on Sense:Field:Guard (Volts) | Run Number | Run Length (minutes) | Metalica Sense Wire 4 (ADC23) Signal Counts/scint trigger (bin 70:4000)" | Plastika Sense Wire 4 (ADC24) Signal Counts/scint trigger (bin 70:4000)" | Cosmic Coincidence Rate (Counts/min) | Metalica Sense Wire 4 Rate (Counts/min) | Plastika Sense Wire 4 Rate (Counts/min) |
1500:-750:1050 | r715 | ||||||
1300:-650:910 | r716 | 1844.37 | 1525/1907=0.799685 | 1544/1907=0.809649 | 1.033957 | 0.8268406 | 0.83714222 |
1250:-625:875 | r718 | 984.79 | 824/1031=0.79922405 | 830/1031=0.80504365 | 1.04692371 | 0.8367266 | 0.84281928 |
1200:-600:840 | r719 | 1271.3 | 1067/1331=0.8016529 | 1075/1331=0.8076634 | 1.0469598 | 0.839298 | 0.84559113 |
1150:-575:805 | r734 | 1257.3 | 845/1145=0.7379913 | 867/1145=0.75720524 | 0.91068165 | 0.672075082 | 0.68957289 |
1050:-525:735 | r735 | 462.97 | 277/378=0.7328042 | 279/378=0.738095 | 0.81646759 | 0.5983109 | 0.60263084 |
HV settings on Sense:Field:Guard (Volts) | Metalica Sense Wire 4 ADC23(bin 70:4000) | Plastika Sense Wire 4 ADC24(bin 70:4000) | Metalica Sense Wire 4 (ADC23) Gaussian fit | Plastika Sense Wire 4 (ADC24) Gaussian fit |
1500:-750:1050 | 150px | 150px | ||
1300:-650:910 | ||||
1250:-625:875 | ||||
1200:-600:840 | ||||
1150:-575:805 | ||||
1050:-525:735 |
HV settings on Sense:Field:Guard (Volts) | Run Number | Metalica Sense Wire 4 ADC Mean Value | Plastika Sense Wire 4 ADC Mean Value |
1300:-650:910 | r716 | 277 +/- 3.1 | 276.1 +/- 2.7 |
1250:-625:875 | r718 | 277.2 +/- 6.8 | 278.9 +/- 6.7 |
1200:-600:840 | r719 | 281.6 +/- 5.1 | 274.5 +/- 4.2 |
1150:-575:805 | r734 | 283.9 +/- 14.5 | 285.4 +/- 14.1 |
1050:-525:735 | r735 | 272.5 +/- 44.9 | 286 +/- 58.8 |
Plateau Measurements of Wire 4 using scaler
S:F:G=1:-0.5:0.7
HV Settings S:F:G=1400:-700:980
Discriminator Threshold On Metalica | Run Length(sec) | Metalica Sense Wire 4 # of events | M4 events/hr | P4 events/hr |
130 mV | 10 | 110 | ||
11 | 109 | |||
12 | 117 | 36791 | 2000||
150 mV | 879 | 1626 | ||
193 | 304 | |||
87 | 158 | 6289 | 440399 | 81|
250 mV | 338 | 316 | ||
88 | 91 | |||
178 | 171 | 3516 | 151433 | 44|
350 mV | 203 | 152 | ||
185 | 118 | |||
182 | 154 | 2679 | 306394 | 71|
450 mV | 245 | 133 | ||
733 | 405 | |||
360 | 181 | 1918 | 76470 | 89|
550 mV | 238 | 102 | ||
184 | 91 | |||
175 | 89 | 1718 | 126382 | 75|
650 mV | 409 | 108 | ||
578 | 150 | |||
313 | 95 | 993 | 71300 | 81|
750 mV | 497 | 100 | ||
588 | 135 | |||
394 | 82 | 767 | 43285 | 24
HV Settings S:F:G=1300:-650:910
Discriminator Threshold On Metalica | Run Length(sec) | Metalica Sense Wire 4 # of events | M4 events/hr | P4 events/hr |
100 mV | 1 | 16150 | ||
1 | 17979 | |||
1 | 11604 | 54879600 | 9648774.75||
150 mV | 51 | 162 | ||
45 | 108 | |||
466 | 1034 | 9354 | 1495291 | 153|
250 mV | 3375 | 112 | ||
2745 | 66 | |||
4315 | 123 | 103 | 13396 | 14|
350 mV | 8812 | 84 | ||
13023 | 115 | |||
13706 | 112 | 32 | 2393 | 12
HV Settings S:F:G=1200:-600:840
Discriminator Threshold On Metalica | Run Length(sec) | Metalica Sense Wire 4 # of events | M4 events/hr |
100 mV | 2 | 546 | |
1 | 339 | ||
1 | 221 | 1010400 | 161381|
150 mV | 652 | 820 | |
99 | 258 | ||
136 | 230 | 6666 | 2023|
250 mV |
HV Settings S:F:G=1100:-550:770
Discriminator Threshold On Metalica | Run Length(sec) | Metalica Sense Wire 4 # of events | M4 events/hr | P4 events/hr |
150 mV | 91588 | 981 | 39 | 245 |
200 mV | 69663 | 375 | ||
129673 | 705 | 20 | 1292 | 12
Experimental Setup for tracking tests
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Mini-prototype