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)

Electronics

VPI postamp range

The VPI postamp has an adjustable gain on the TDC output. The peak to peak pulse amplification ranges approximately from x2 to x10. The ratio of the area under the pulse in case of minimum amplification is about 8.96 and in case of maximum it is ~ 650.

 The VPI PostAmp is set to minimum gain The VPI PostAmp is set to maximum gain

Timing

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: Volts and Volts
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: V, V and V.

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.

(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

For these measurements, the high voltage on Plastika was fixed to (S:F:G=1400:-700:980) and the HV on Metalica was changed preserving the HV ratio (S:F:G=1:-0.5:0.7). The output from sense wire 4 was measured for these plateau measurements. The signal from the DCs(Plastika and Metalica Sense Wire 4) was sent to the UVA 122B Signal Splitter on channels 2(Metalica) and 15(Plastika), after that the output is sent to the VPI PostAmp. The Amplified pulse(amplification for Plastika and Metalica is about x10), from channel # 16 for Metalica and channel # 3 for Plastika, is discriminated using LeCroy Octal Discriminator Model 623B. The discriminator threshold was changed only for Metalica, for Plastika it was set to 300 mV, for whole run.

We would expect to see a plateau curve which looks like

We had the following observations for the Baby chambers

Does this mean we have not entered the Geiger Muller region or is noise impacting the low HV measurements?

on different scales:

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 Noise + 10 mV =170 mV 108 107 3566.7 102 121 4270.6 91 106 4193.4 130 mV 10 110 11 109 12 117 3.68e+4 2000 150 mV 879 1626 193 304 87 158 6.3e+3 440 399 81 250 mV 338 316 88 91 178 171 3.5e+3 151 433 44 350 mV 203 152 185 118 182 154 2.7e+3 306 394 71 450 mV 245 133 733 405 360 181 1.9e+3 76 470 89 550 mV 238 102 184 91 175 89 1.7e+3 126 382 75 650 mV 409 108 578 150 313 95 9.9e+2 71 300 81 750 mV 497 100 588 135 394 82 7.7e+2 43 285 24
 Discriminator Threshold On Metalica Run Length(sec) Metalica Sense Wire 4 # of events M4 events/hr P4 events/hr Noise + 10 mV =170 mV 108 107 3566.7 102 121 4270.6 91 106 4193.4 130 mV 10 110 11 109 12 117 3.68e+4 2000 150 mV 879 1626 193 304 87 158 6.3e+3 440 399 81 250 mV 338 316 88 91 178 171 3.5e+3 151 433 44 350 mV 203 152 185 118 182 154 2.7e+3 306 394 71 450 mV 245 133 733 405 360 181 1.9e+3 76 470 89 550 mV 238 102 184 91 175 89 1.7e+3 126 382 75 650 mV 409 108 578 150 313 95 9.9e+2 71 300 81 750 mV 497 100 588 135 394 82 7.7e+2 43 285 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 Noise + 10 mV = 180 mV 4351 233 192.8 608 2611 155 213.7 360 1671 109 234.8 213 150 mV 51 162 45 108 466 1034 9.4e+3 1495 291 153 200 mV 9422 1566 7396 1477 658 60 286 6 250 mV 3375 112 2745 66 4315 123 103 13 396 14 300 mV 19605 242 22791 294 45 1 379 11 350 mV 8812 84 13023 115 13706 112 32 2 393 12 450 mV 50365 263 19 330 550 mV 8868 12 5 545 650 mV 43949 48 6620

HV Settings S:F:G=1200:-600:840

 Discriminator Threshold On Metalica Run Length(sec) Metalica Sense Wire 4 # of events M4 events/hr P4 events/hr Noise + 10 mv = 180 mV 25492 206 3170 120 mV 58 129 121 247 7.7e+3 329 130 mV 1422 166 1645 62 278 142 150 mV 16426 138 23339 227 33 2 200 mV 15686 122 28 300 mV 58303 137 12373 400 mV 79553 42

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 Noise + 10 mv = 70 mV 2006 46 82.6 1368 7245 139 69.1 4901 7245 96 47.7 2536 120 mV 551 237 589 280 1630 81 130 mV 1019 45 1429 48 140 19 140 mV 10719 108 36 150 mV 91588 981 39 245 200 mV 69663 375 129673 705 20 1 292 12 300 mV 47273 41 6112 400 mV 46857 37 4034

HV Settings S:F:G=1000:-500:700

 Discriminator Threshold On Metalica Run Length(sec) Metalica Sense Wire 4 # of events M4 events/hr P4 events/hr Noise + 10 mv = 150 mV 33285 240 26 440 200 mV 52659 441 30 365 250 mV 8390 48 21 962 350 mV 147583 198 95232 450 mV 73359 15 59700

HV Settings S:F:G=700:-350:490

 Discriminator Threshold On Metalica Run Length(sec) Metalica Sense Wire 4 # of events M4 events/hr P4 events/hr Noise + 10 mv =80 mV(can be 70) 3995 2 3787 4359 5 3946 581 0 516 200 mV 15201 98 23 614 300 mV 48725 235 17 580 400 mV 3850 4 4 635 5373 4 3 1 639 4 300 mV(3/03/2009) 51701 14 43904 200 mV (4/03/2009) 44469 153 38953

HV Settings S:F:G=500:-250:350

 Discriminator Threshold On Metalica Run Length(sec) Metalica Sense Wire 4 # of events M4 events/hr P4 events/hr Noise + 10 mv = 140 mV 3809 48 45 651 200 mV 11713 33 10 680 250 mV 56322 181 11 727 300 mV 4225 0 0 694

Plateau measurement when VPI gain = x10 and Disc thresh = 80 mV

The above plateau measurements were done using the UVA splitter. In addition to cross talk, the splitter also increased the noise level. About 70 mV out of 140 mV of noise is due to the splitter. If the DC output goes directly into the VPI post amp the noise level goes down to about 70 mV. A grounding strap to the DC preamp power supply will decrease this noise to below 40 mV.

HV settings on Metalica are following S:F:G = 1300:-650:910

 HV Settings S:F:G Run Length(sec) (ch # 01) Plastika Sense Wire 4 # of events(ch # 09) P4 events/hr M4 (ch # 15) events/hr ratio X 1400:-700:980 95 289 100 2890 30 92 31 2967 34 99 10825 245 32 3096 1300:-650:910 110 100 108 925 140 109 170 641 145 102 2869 306 139 774 1200:-600:840 929 121 972 124 722 114 819 139 950 102 475 74 967 106 1100:-550:770 2142 29 49 0.2 2252 13 700:-350:490 73329 1572 77 0.02 74782 21 500:-250:350 217503 4231 70 0.02 467034 9

 I am confident that below 1200 Volts there is just noise,
If there is a pulse the rate cant be approximately 7 events/hr.


Scint coinc Plateau measurement using 1 DC

Now that we may have our cross talk problems gone and the noise reduced lets try to measure the plateaus again using 2 scintillators in coincidence .

Connector Tables

For Metalica

 Metalica Sense Wire # VPI PostAmplifier Output(ADC && TDC) ADC Channel# (VME) TDC Channel# (VME) 1 8 12 14 2 7 8 3 6 9 4 5 1 10 5 4 12 6 3 11(not used) 7 1 13

For Plastika

 Plastika Sense Wire # VPI PostAmplifier Output(ADC && TDC) ADC Channel# (VME) ???? TDC Channel# (VME) 1 16 18 1 2 15 20 2 3 14 22 3 4 13 24 4 5 12 26 5 6 11 28 7(not used) 7 10 30 6

24-04-2009

The HV settings on Metalica and Plastika are following: S:F:G=1350:-675:945. Metalica is placed between two scintillators. As a trigger and gate the coincidence pulse from PMTs is used. Only sense wire # 1 and # 4 of metalica are connected to the ADC and TDC of VME crator.

Experimental Setup for tracking tests

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