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: [math]V_{Drift}=3300[/math] Volts and [math]V_{GEM}=3000[/math] 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: [math]V_Sense=1450[/math] V, [math]V_F=725[/math] V and [math]V_G=725[/math] 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.

• Histograms for Each ADC

HV settings on Sense Wire (Volts)

Run Number

ADC17_tot

ADC17_peak

ADC17_gaussian_fit

ADC18_tot

ADC18_peak

ADC18_gaussian_fit

ADC19_tot

ADC19_peak

ADC19_gaussian_fit

ADC20_tot

ADC20_peak

ADC20_gaussian_fit

ADC21_tot

ADC21_peak

ADC21_gaussian_fit

ADC22_tot

ADC22_peak

ADC22_gaussian_fit

ADC23_tot

ADC23_peak

ADC23_gaussian_fit

ADC24_tot

ADC24_peak

ADC24_gaussian_fit

ADC25_tot

ADC25_peak

ADC25_gaussian_fit

ADC26_tot

ADC26_peak

ADC26_gaussian_fit

ADC27_tot

ADC27_peak

ADC27_gaussian_fit

ADC28_tot

ADC28_peak

ADC28_gaussian_fit

ADC29_tot

ADC29_peak

ADC29_gaussian_fit

ADC30_tot

ADC30_peak

ADC30_gaussian_fit

1600

r695

1550

r693

1500

r691

1450

r692

1400

r696

1089/1477 = 0.737

(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 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)
1500:750:1050	r715

Experimental Setup for tracking tests

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