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9/5/08

Detector Construction

   4 chambers are built.   
TGEM:
Foils have been mounted on the TGEM comparison chamber.  Both charge collectors are mounted on the TGEM test detectors.  One TGEM test detector has the Thick PC board GEM foils which need much higher HV than the regular GEM foils.  The second TGEM test chamber has 3 GEM foils from CERN.

Need a min of 32 1 Meg Ohm resistors to complete the output termination connectors. Need 32 more termination connectors made from 16 wires.

Need to grind down 16, M3 bolts for mounting the GEM foils and TGEM PCboards.

Need 24 washers for GEM foils. Check mounting of the TGEM boards. Look up spacing and HV for the TGEM boards[1], Media:01352098.pdf .

Need to etch 2 cathodes for the TGEm boards.


Qweak:

  a.) Need to do final outer footprint machining so there is no interference with the Electron profile of the other octant.
  b.)  Need to machining back of the chamber for the Charge collector
 c.) Need to machine thick frames for the cathode and maybe GEM foils.
 d.) Apply electrical insulation to HV distribution boards
 e.) Need to mount GEM foils on the Qweak chambers.

SIS3610 I/O software

Objectives: a.) The first step will be to read 16 of the I/O input channel into a CODA data file.

b.) Display the 16 input channels on a GUI. Unfortunately, only 2 of the 16 will be used to read in the GEM output. The GEM output will transfer 128 hit/no hit signals to a single I/O channel in a serial fashion. The data from one I/O channel needs to be decoded according to the data structure described in Figure 8 and 9 of the VFAT manual.

c.) The final task will be to write a multiple trigger function so the I/O can be triggered by several different interrupt trigger signals and label those trigger signals.


Tasks:

Inject a signal into the I/O board input connector and use a Read function from the ROC to determine if the signal is high or low.

9/19/08

Detector work

TGEM assembled and ready for testing.

Need to assemble GEM comparison detector.

Made 2 thick frames for Qweak Cathode.

Get Fe source from TSO on loan for many months.(done)
Machine hole punch for Qweak charge collector holes(done)
Drill holes in Qweak chamber for Charge collector mounting
 Measure sag of Qweak foils and cathode.  Try using a string stretched across the frame

SIS3610 I/O software

Tasks:

Inject a signal into the I/O board input connector and use a Read function from the ROC to determine if the signal is high or low.


The SIS module latches input when a VME read is initiated

The command below sets a low constant output level on the SIS output which is then conencted to one of the SIS input line directly.

-> s3610WriteOutput(0,12288)
value = 0 = 0x0

I initiated a read function and saw the following bits set

-> s3610ReadInput(0)        
value = 18464 = 0x4820

Now I zero the output and read call the read function

-> s3610WriteOutput(0,0)    
value = 0 = 0x0
-> s3610ReadInput(0)    
value = 2080 = 0x820


I am clearly turning bits on and off but there is some randomness to other channels. Perhaps terminationg the other channels in 100 Ohms will solve this problem.

Check


created subroutine in SIS3610 library to generate a single pulse according to an given bit pattern passed as a decimal number

void TDpulse(int id, unsigned int val) {

 if((id<0) || (s3610p[id] == NULL)) {
   logMsg("s3610WriteOutput: ERROR : SIS3610 id %d not initialized \n",id,0,0,0,0,0);
   return;
 }
 s3610p[id]->d_out = val;
 s3610p[id]->d_out = 0;
 return;

}

-> TDpulse(0,12288) value = 0 = 0x0


Now we tried to use

-> TDpulse(0,12288) value = 0 = 0x0 -> s3610ReadInput(0) value = 2080 = 0x820

2080 d = 100011000 b => channel 4,5 and 9 were high

The input did not change

I think we need to Latch it.

18464 d = 100100000100000 b

Read manual to see how to latch the input.

9/26/08

Detector Construction

Both GEM and TGEM proto type detectors have been assembled.


TGEM draws 200 [math]\mu[/math] A at 800 Volts Need to see why.


Ramp voltage at 1 V/sec. Saw discharges on scope when increasing HV at rate of 5 V/s.


Ramping up the voltage on TGEM and GEM at 2 V/sec.

GEM Drift HV (Volts) GEM Drift current [math]\mu[/math] A GEM foil HV (Volts) GEM foil current [math]\mu[/math] A
3800 0 3500 845



GEMDetector Noise Level DriftHV 3800Volts.png


GEM Detector HV settings and Pulses

GEM Drift HV (Volts) GEM Drift current [math]\mu[/math] A GEM foil HV (Volts) GEM foil current [math]\mu[/math] A Scope Picture
3950 3650 882 GEMDetector Pulse ScopePicture HV 3950V.png
3900 3600 870 GEMDetector Pulse ScopePicture HV 3900V.png
3850 3550 859 GEMDetector Pulse ScopePicture HV 3850V.png


TGEM Drift HV (Volts) TGEM Drift current [math]\mu[/math] A TGEM foil HV (Volts) TGEM foil current [math]\mu[/math] A
3600 3300



TGEMDetector output 3600V.pngTGEMDetector output 3600V 1.pngTGEMDetector output 3600V 2.png

SIS310

1.) Get 100 Ohm resistors

2.) Get Bread board


10/3/08

The high current draw (> 1mA) of the TGEM on the power supply has forced us to switch to powering each PCboard GEM individually. We now have 4 HV channels hooked up with the ground floating on the top 2 GEM PCboards.

GEM Detector

Vdrift = 3800, VGem = 3500, IDrift = 0, IGem = 842 [math]\mu[/math] A. Channel 1 is the output of 16 strips tied together. The remaining output strips have a 1 M Ohm resister to ground. Channel 2 is the Trigger output (the output from the last foil). Notice the sign difference between the 2 outputs.

GEM Output 10-3-08 Vdrift-3800 VGEm-3500 IGEM-840.png

Noise Level GEM Noise 10-3-08 Vdrift-3800 VGEm-3500 IGEM-840.png


Vdrift = 3850, VGem = 3550, IDrift = 0, IGem = 858 [math]\mu[/math] A

GEM Output 10-3-08 Vdrift-3850 VGEm-3550 IGEM-858.png

Output from the GEM detector strips and from TrigOut after signal goes through the Timing Filter Amp(amplifier was set to "x10").
GEM TrigOut 1channel TFAmpl and 2channel from strips.pngGEM TrigOut 1channel TFAmpl and 2channel from strips positive.png


The output from GEM detector strips and TrigOut(after it goes through electronics):

Pulse from GEMD strips and CFD HV3900Volts 10-9-08.png300px

Positive Pulse GEMD strips and pulse from CFD HV3900Volts 10-9-08.pngRing from GEMD strips and pulse from CFDisc HV3900Volts 10-9-08.png

Noise from GEMD strips and pulse from CFD HV3900Volts 10-9-08.pngNoise from GEMD strips and no pulse CFD HV3900Volts 10-9-08.png


Noise level will be documented.

The GEM detector is working!
GEM DETECTOR IS READY WITH ELECTRONICS

THGEM Detector

Lets check the TGEM detector

Media:TheTHGEM_MasterThesis_Chen_Ken_Shalem.pdf

The distance between the THGEM foils is 2 mm(before it was ~1.5 mm) and the distance between the last THGEM foil and cathode is about ~5 mm. I have not changed the distance between the PCB(Charge collector) and the first THGEM foil.(might do it)
THGEM detector is not working still at high voltages. For now HVSettings are following(I still have sparks, but they are very few, and I think they come from THGEM foils)

HVsettings


Cathode HV (Volts) First THGEM foil(Volts) Second THGEM foil(Volts) Third THGEM foil(Volts) Third THGEM foil current [math]\mu[/math]A
3000 1650 1500 1500 1181


THGEMDetector output HVSettingsarelistedontheabovetable.png
THGEMDetector NoiseLevel HVSettingsarelistedontheabovetable.png

11/21/08

a.)ship out Qweak GEM

Rectangular GEM detector works after replacing all 3 GEM preamp foils!!!!!!!!

Media:thesis-2004-006-1.pdf

Need to replace foils one at a time to see which one is bad and then determine why it is bad. Short?

Distance between the GEM foils are 2 mm. Distance between the last GEM foil and PCB is also 2 mm. The first GEM foil and cathode are separated by 3 mm.

Ramp Up = 2 Volts/sec.

Can go up to [math]V_{Drift} = 3850[/math] Volts without even one spark and [math]V_{GEM} = 3550[/math] Volts.


Noise level on GEMDetector HVOFF 11-22-08.pngNoise level on GEMDetector HVON 3850Volts 11-22-08.png

Pulse TrigOut and Strip GEMDetector HVON 3850Volts 11-22-08.pngPulse TrigOut and Strip GEMDetector HVON 3850Volts 11-22-08 1.png
Pulse TrigOut and Strip GEMDetector HVON 3850Volts 11-22-08 2.pngPulse TrigOut and Strip GEMDetector HVON 3850Volts 11-22-08 3.png

[math]V_{Drift} = 3900[/math] Volts and [math]V_{GEM} = 3600[/math] Volts.
Pulse TrigOut and Strip GEMDetector HVON 3900Volts 11-22-08.png

11-25-08

1.) One GEM foil is bad.

Used first GEMFoil 11-25-08 top.jpgUsed first GEMFoil 11-25-08 bottom.jpg


2.) Second GEM foil works:

High Voltage on Drift was 3800Volts and on GEM 3500 Volts.

proof:Used second GEMFoil works 3800Volts 11-25-08.png

Used second GEMFoil 11-25-08 top.jpgUsed second GEMFoil 11-25-08 bottom.jpg

3.) Third GEM foil works:

High Voltage on Drift was 3800Volts and on GEM 3500 Volts(Sparks).

proof:Used third GEMFoil works 3800Volts 11-25-08.png

Used third GEMFoil 11-25-08 top.jpgUsed third GEMFoil 11-25-08 bottom.jpg


I see spots on the above "working" GEM foils.  Let's leave them out and keep the three new ones in.
 
DONE
Why is the "1" GEM foil not working?
Do not know yet.

Testing DC

HV Settings:

HV settings
Wire Volts
Sense 1700
Field -850
Guard 850


Gas type: ArCO2 (90/10).

Below are shown the scope images of the signal from the DC(direct output from the sense wires):


Metalica

Sense wire 1 1700Volts testing DC Metalica.pngSense wire 2 1700Volts testing DC Metalica.pngSense wire 3 1700Volts testing DC Metalica.png
Sense wire 4 1700Volts testing DC Metalica.pngSense wire 5 1700Volts testing DC Metalica.pngSense wire 6 1700Volts testing DC Metalica.png
Sense wire 7 1700Volts testing DC Metalica.png

Plastika

Sense wire 1 1700Volts testing DC Plastika.pngSense wire 2 1700Volts testing DC Plastika.pngSense wire 3 1700Volts testing DC Plastika.png
Sense wire 4 1700Volts testing DC Plastika.pngSense wire 5 1700Volts testing DC Plastika.pngSense wire 6 1700Volts testing DC Plastika.png
Sense wire 7 1700Volts testing DC Plastika.png


Need UVA 122B Signal Splitter

PreAmp should be set to 6.5 Volts, otherwise we get the ring(noise level is high).


PreAmp, Chamber Amp && VPIPostAmp

Gas type: ArCO2 (90/10).
The voltage on PreAmp is set to 6.5 Volts.
HV Settings:

HV settings
Wire Volts
Sense 1500
Field -750
Guard 750


The signal outputs from the PreAmp and ChamberAmp compared for Metalica && Plastika.

Metalica Sense Wire 1 PreAmp && ChAmp outputs.pngPlastika Sense Wire 1 PreAmp && ChAmp outputs.png

The signal outputs and noise level from the PreAmp and VPIPostAmp(TDC output) compared for Metalica && Plastika.

Metalica Sense Wire 1 PreAmp && VPIPostAmp outputs.pngPlastika Sense Wire 1 PreAmp && VPIPostAmp outputs.png

Metalica Sense Wire 1 PreAmp && VPIPostAmp Noise level.pngPlastika Sense Wire 1 PreAmp && VPIPostAmp Noise level.png

GEM 29-11-08

The strip output signal is used as a trigger and as a pulse too. Gas type ArCO2 (90/10).

HV Settings: [math]V_{Drift} = 3550[/math] Volts and [math]V_{GEM} = 3250[/math] Volts.

Data: r564 and r571.


CAEN V775 TDC

From the results shown below one can make conclusions that the time interval between the end of the pulses effects the data.

The table below shows the TDC measurement made using the Stanford pulse generator to generate 2 ECL input pulses. The first pulse is defined to rise at point "A" in time and fall at point "B" in time. The second pulse rises at point "C" in time and falls at point "B" in time. Comparing the time intervals between the pulses to the TDC output indicates that the TDC measures the time interval [math]\Delta[/math] BD.

A B C D TDC [math]\Delta[/math] AC [math]\Delta[/math] AD [math]\Delta[/math] BC [math]\Delta[/math] BD
0 60 150 200 2526 150 200 90 140
0 90 150 200 1942 150 200 60 110
0 90 150 230 2504 150 230 60 140
30 60 150 200 1927 120 170 90 140
30 60 130 200 2501 100 170 70 140


First case

A=T+0

B=A+60ns

C=T+150ns

D=T+200ns


Scope picture of pulses first example.png

-> c775Reset     
value = 0 = 0x0
-> c775Status(0) 
STATUS for TDC id 0 at base address 0x90610000 
---------------------------------------------- 
Interrupts Disabled
Last Interrupt Count    : 0 
            --1--  --2--
 S-> c775Reset     
value = 0 = 0x0
-> c775Status(0) 
STATUS for TDC id 0 at base address 0x90610000 
---------------------------------------------- 
 Interrupts Disabled
 Last Interrupt Count    : 0 
            --1--  --2--
  Status  = 0x0053 0x0000  (Data Ready)
  BitSet  = 0x0000 0x4880
  Control = 0x0000
  FSR     = 440 nsec
  Event Count     = 1
  Last Event Read = (No Events Read)
 value = 37 = 0x25 = '%'
-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa000100   nWords = 1 
     0xf80249de
 Trailer: 0xfc000000   Event Count = 0 
value = 3 = 0x3
->

TDC bits 100111011110 b = 2526 d

Second case

A=T+0

B=A+90ns

C=T+150ns

D=T+200ns


Scope picture of pulses second example.png


-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa000100   nWords = 1 
     0xf8024796
 Trailer: 0xfc000003   Event Count = 3 
value = 3 = 0x3
-> c775Status(0) 
STATUS for TDC id 0 at base address 0x90610000 
---------------------------------------------- 
Interrupts Disabled
Last Interrupt Count    : 0 
            --1--  --2--
 Status  = 0x005f 0x0004  (Buffer Full)
 BitSet  = 0x0000 0x4880
 Control = 0x0000
 FSR     = 440 nsec
 Event Count     = 217
 Last Event Read = 3
value = 22 = 0x16
-> 

The TDC Bits 011110010110 b = 1942 d


Third case

A=T+0

B=A+90ns

C=T+150ns

D=T+230ns


Scope picture of pulses third example.png

-> c775Status(0) 
STATUS for TDC id 0 at base address 0x90610000 
---------------------------------------------- 
Interrupts Disabled
Last Interrupt Count    : 0 
            --1--  --2--
 Status  = 0x0053 0x0000  (Data Ready)
 BitSet  = 0x0000 0x4880
 Control = 0x0000
 FSR     = 440 nsec
 Event Count     = 5
 Last Event Read = (No Events Read)
value = 37 = 0x25 = '%'
-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa000100   nWords = 1 
     0xf80249c8
 Trailer: 0xfc000000   Event Count = 0 
value = 3 = 0x3
-> 

TDC bits 100111001000 b = 2504 d

Fourth case

A=T+30ns

B=A+60ns

C=T+150ns

D=T+200ns


Scope picture of pulses fourth example.png

-> c775Status(0)
STATUS for TDC id 0 at base address 0x90610000  
---------------------------------------------- 
Interrupts Disabled
Last Interrupt Count    : 0 
            --1--  --2--
 Status  = 0x0053 0x0000  (Data Ready)
 BitSet  = 0x0000 0x4880
 Control = 0x0000
 FSR     = 440 nsec
 Event Count     = 5
 Last Event Read = (No Events Read)
value = 37 = 0x25 = '%'
-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa000100   nWords = 1 
     0xf8014787
 Trailer: 0xfc000003   Event Count = 3 
value = 3 = 0x3
-> 

TDC : 011110000111 b = 1927 d


Fifth case

A=T+30ns

B=A+60ns

C=T+130ns

D=T+200ns


Scope picture of pulses fifth example.png


-> c775Status(0) 
STATUS for TDC id 0 at base address 0x90610000 
---------------------------------------------- 
Interrupts Disabled
Last Interrupt Count    : 0 
            --1--  --2--
 Status  = 0x0053 0x0000  (Data Ready)
 BitSet  = 0x0000 0x4880
 Control = 0x0000
 FSR     = 440 nsec
 Event Count     = 3
 Last Event Read = 0
value = 22 = 0x16
-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa000100   nWords = 1 
     0xf80149c5
 Trailer: 0xfc000000   Event Count = 0 
value = 3 = 0x3
-> 


TDC bits 100111000101 b = 2501 d


TDC AND DC

-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa000200   nWords = 2 
     0xf80040e8  0xf80f415f
  Trailer: 0xfc000004   Event Count = 4 
value = 4 = 0x4

Checking PMT

Amplified pulse from PMT 11013Volts 2-12-08.pngAmplified pulse from PMT and Discriminator 1013Volts 2-12-08.png


-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa001000   nWords = 16 
     0xf8004252  0xf80140e9  0xf80240d3  0xf80340e5  0xf80440e5
     0xf80540f4  0xf80640ef  0xf807418a  0xf8084195  0xf80942d9
     0xf80a418b  0xf80b4184  0xf80c4140  0xf80d413d  0xf80e4152
     0xf80f414d
 Trailer: 0xfc000000   Event Count = 0 
value = 18 = 0x12
-> c775PrintEvent
 TDC DATA for Module 0
 Header: 0xfa001000   nWords = 16 
     0xf8004214  0xf8014172  0xf802415a  0xf80340af  0xf804416e
     0xf805417a  0xf806424a  0xf80740b5  0xf80841a5  0xf809419a
     0xf80a40b9  0xf80b4195  0xf80c418e  0xf80d40b2  0xf80e4193
     0xf80f4184
 Trailer: 0xfc000001   Event Count = 1 
value = 18 = 0x12


Pulse from Bottom PMT 1000Volts 3-12-08.pngPulse from Top PMT 1110Volts 3-12-08.png

1/29/09

Checking TDC

Sense Wire Run Number
# 1 r722
#2 r723



TDCSenseWire2 NoPulseSenseWire PGPulse.png

ADC20 19.gif


ADC20 19 1.gif


1/30/09

1.) decrease DC HV well below 1000 Volts

2.) unplug postamp outputs and do a channel by channel test of DAQ DC ADC and TDC readout

3.) calculate gas consumption rate Liters/hr

The Volume of 1 mole of an Ideal gas

24.47 litres (24.47L) at S.L.C
[Standard Laboratory Conditions, 25oC (298K) and 101.3kPa (1atm)]


Amount of ArCO2 in Liters[math]= \frac{18000kPa}{101.3kPa} \times 24.47 L = 4348.075025 L[/math]

[math]Rate=\frac{4348.075025L}{336 hours} = 12.9407 \frac{L}{hr}[/math]

4.)Develop apparatus to measure gas chamber leaks.

Media:chamber_leak_cert.pdf

File:Chamber leak rate measurement 2002 03 13.pdf


5.) Enter Calorimeter cuts used for electron and pion cuts into wiki and put link to them in the Teleconference wiki area

6.) Prepare next items for EG1 teleconference : E/P graphs for electron and pions before and after cuts, try to use all of the data we use for asymemtries. Also put in table estimating number of events we expect after cuts.

2/6/09

1.) Plateau DC using singles counting

2.) Take picture of chamber and upload into wiki, Prep Qweak chamber for testing

shopping list for Norco: Gas flow valve, copper lines, shutoff valve, something to go from copper line to quick connect on Qweak chamber (compression fitting.

3.) write up procedure and part list to leak test CLAS12 R1 drift chambers

4.) pions

NPE -vs- EC/p for e- with cuts?

5.) Estimate of pion contamination

6.) difference W-spectrum for each run number add link to wiki location for teleconference.

7.) recheck the sign of all polarization for plots of semi-inclusive spectrum: a.) h>0 Pt>0 b.) h > 0 pt<0 c.)h<0 pt>0 d.)h<0 pt<0


2-06-09

Checking TDC Outputs

Real Signal From DCs

Using Drift Chambers

The scope images below describe the crosstalk which exists in the UVA splitter and the VPI postamp. For both DCs only Sense Wire 4 is used. The high voltage on Plastika is turned Off and Metalica's HV is set to (1425:-700:990). The PreAmp is set to 6.4 Volts and hooked up on both detectors. We are able to minimize the cross talk by maximizing the distance between the connector pins used to transport the sense wire #4 signal from the 2 DC to the DAQ.

The output signal from the DCs after PreAmp are sent to the UVA 122B Signal Splitter on channel # 8 an 9 for Metalica and Plastika respectevily. The scope image below shows that approximately 1/30 of Metalicas output signal appears on Plastika's channel, as a result of the two channels being next to each other.


The UVA 122B Signal Splitter used as a fan-in fan-out for Metalica and Plastika output signals.
Cross talk between channel 8 & 9 on the UVA 122B signal splitter. Metalicas output is sent on channel 8 and Plastica's output sent on channel 9. Even though Plastica's HV is off (preamp ON), about 1/30 of Metalicas output signal will appear on Plastica's as a result of occupying nearby channel in the UVA 122B splitter.


In order to decrease interference from occupying nearby channels in the UVA 122B signal splitter, the pulse output from the detectors are sent to the channel number 2 for Metalica and channel # 15 for Plastika. The cross talk caused by the UVA 122B signal splitter is far less then in first case, which was described above.

The UVA 122B Signal Splitter used as fan-in fan-out for Metalica and Plastika output signals
The cross talk on the UVA 122B splitter is far less when the 2 input signals occupy different ends of the connect.

The output signals from the UVA 122B signal splitter from channels 8 and 9 of Metlica and Plastika are sent through channels 10 and 9 of the VPI post amp. 1/4 of the signal from Metalica appears on channel 9, which is TDC output for Plastika. This kind of signal, which actually comes from the Metalica, can be misidentified as a real pulse from the Plastika.

The VPI Post Amp. The sense wire # 4 for Plastika and Metalica are sent through the VPI Post Amp channels 9 and 10 respectively.
Cross talk between VPI post amp channels 9 & 10. The middle sense wire (#4) from each DC is sent through a postamp. Although Plastika's HV is off 1/4 of the signal from Metalica sent through channel 10 of the VPI post amp will appear on channel 9 of the post amp. The cross talk amplitude of 340 mV excedes the detectors noise level of 20 mv possible being labeled as a hit if the descriminator is not set to account for this.

Sense wire # 4 for Metalica and Plastika from the UVA 122B signa splitter channel numbers 2 and 15 are sent to the VPI post amp channels 16 and 3. One can see on the scope picture that the cross talk between the two detectors decreased considerably.

The VPI Post Amp. The sense wire # 4 for Plastika and Metalica are sent through the VPI Post Amp channels 3 and 16 respectively in order to decrease the cross talk.
moving wire 4 inputs to opposite sides of the UVA 122B splitter connector and on channel numbers of VPI post Amp decrease the cross talk considerably.
||
The sense wire # 4 for Plastika and Metalica are sent first through the UVA 122B Signal splitter and than are connected to the VPI Post Amp channels 9 and 10 respectively. 1/10 of the signal coming from the Metlica appears on the Plastika VPI output

Using The Stanford Pulse Generator

The Stanford Pulse Generator output pulse is going through the VPI PostAmp without using the UVA 122B Signal Splitter. The gain on the VPI PostAmp is set to maximum. Three channel outputs are observed on the scope. The signal is connected to channel # 15 on VPI PostAmp(the first scope image in the tabla below). The neighboring channels 14 and 16 are also shown below.

Gain settings
Channel # 14 - X3; channel # 15 - X10; channel # 16 - x10.
The VPI PostAmp signal output without using the UVA 122B Signal Splitter
The output pulse is connected to the channel # 15 of the VPI PostAmp and on the neighboring ch # 14 only ~1/250 appears(which is just a noise)
The output pulse is connected to the channel # 15 of the VPI PostAmp and on the neighboring ch # 16 only ~1/125 appears(which is just a noise again(i think))


The generated signal from the Stanford Pulse Generator is sent through the UVA 122B Signal Splitter and than is connected to the VPI PostAmp channel # 15. Below scope images show the cross-talk caused by using the UVA 122B signal splitter. When the gain of the neighboring ch #(14) is set to X3 1/50 of the signal appears on it, in other case when it is set to X10 - 1/10 of the pulse appears on the channel(16) output


The VPI PostAmp signal output using the UVA 122B Signal Splitter on Ch# 15
The VPI PostAmp signal output on channel # 14. 1/50 of the signal from the channel # 15 appears on neighboring channel # 14.
The VPI PostAmp signal output on channel # 16. 1/10 of the signal from the channel # 15 appears on neighboring channel # 16.


CONCLUSION
In order to run DCs without having the cross-talk problem we should not use the UVA 122B Signal Splitter.


Noise Problem on DCs

The output from DCs goes through the UVA 122B Signal Splitter and after is connected to the VPI PostAmp. The noise level for both chambers is measured and shown below on scope pictures before and after change using the grounded strip.


NoiseLevelOnChambers 1100Volts before.pngNoiseLevelOnChambers 1100Volts after.png


In this case, the output from the Metalica is connected directly to the VPI PostAmp. The noise level for minimum and maximum gains are shown below:


NoiseLevelOnChambers 1400Volts MinimumGain.pngNoiseLevelOnChambers 1400Volts MaximumGain.png


After connecting the grounded strip to the PreAmp box, the noise level was reduced.

NoiseLevelOnChamberMetalica 1400Volts MaximumGain PreAmpGround.png


The VPI PostAmp, PreAmp box are both grounded. My noise level is "perfect":

NoiseLevelOnChamberMetalicaandPlastika 1400Volts MaximumGain PreAmpGround.png

DCs

On Both chambers, Metalica and Plastika, the high voltage is applied(Settings S:F:G=1300:-650:910). The PreAmp is set to 6.4 Volts. The ArCO2(90/10) gas is flowing through the chambers. Metalika is placed between the two PMTs(only blue long PMTs are used). The cosmic coincidence event from the two PMTs is set as a trigger, ADC gate and start for the TDC.

Below on the scope picture are shown two pulses, coming out from the sense wire 1(ch 3) and 4 (ch 1) after going through the VPI PostAmp in gate. Gate width on image is approximately 400 ns. I thought it was narrow so i changed it to ~ 500 ns.

Image 5.png


1200

HV settings on Metalica S:F:G=1200:-600:840

Below is shown the noise level and typical pulse at this voltage.

Noise 1.pngPulse 1.png

1150

HV settings on Metalica S:F:G=1150:-575:805

Below is shown the noise level and "pulse" caused by noise which is misidentified as a real pulse.


Noise 1150.pngPulseNoise 1150.pngPulseNoise 1150 1.png

1100

HV settings on Metalica S:F:G=1100:-550:770

Below is shown the noise level and "pulse" caused by noise which is misidentified as a real pulse.

Noise 1100.pngPulseNoise 1100.png

1.) HV Metalica 1300 Volts

Run number r751.dat

Strat: Mar 12 15:49:03


End: Mar 13 13:07:42


2.) HV Metalica 1300 Volts (only sense wire 4 in TDC)

Run number r754.dat

Strat: Mar 13 14:28:39


End: Mar 13 21:35:55


3.) HV Metalica 1300 Volts (only sense wire 4 and 1 in TDC)

Run number r755.dat

Strat: Mar 13 21:50:32


End: Mar 15 16:27:37

For 1, 2 and 3 runs discr. threshold is the same

4.) HV Metalica 1300 Volts (only sense wire 4 and 1 in TDC)

r756

Threshold doubled on Metalica

Start: mar 15 16:36:56

End: Mar 16 12:11:07

5.) HV Metalica 1200 Volts (only sense wire 4 and 1 in TDC)

r756

Threshold doubled on Metalica

Start: mar 16 12:14:30

End: Mar 17 08:30:11

5.) HV Metalica 1350 Volts

r772


Start: mar 17 13:01:27

End: Mar 17 16:47:58

5.) HV Metalica 1350 Volts (m4 and p4)

r775


Start: mar 17 19:47:57

End: Mar 18 10:38:07

Chamber Leak Rate Measurements

Media:TDC_V775.pdf

List of devices needed to measure chamber leaks
  • 2). The Leak Measuring Device (LMD).
  • 3). The Weather Monitoring Device(to measure the barometric pressure and ambient air temperature).


Using this devices, chamber leak rate is calculated in the following way:

[math]\frac{\Delta V}{\Delta t}(cc/min) \approx V_0 \left |- \frac{2 \Delta H + \Delta B}{B_0} \right | \frac{H_{initial}}{(H_{final} + H_{initial})/2} \frac{1}{\Delta t}[/math]

where

[math]V_0[/math] is the chamber volume
[math]\Delta H = H_{final} - H_{initial}[/math] is the change in the chamber overpressure
[math]\Delta B = B_{final} - B_{initial}[/math] is the change in the atmospheric(barometric) pressure
[math]\Delta t[/math] is the time between the final and initial measurements of the overpressure(recommended time interval is ~ 24 hours)
In other paper, for the chamber gas leak measurements a mass spectrometer was used

Qweak GEM Foil

Qweak GEM Foil useless.jpg


Testing Qweak GEM Detector

The cathode was taken out from the chamber, and only GEM foils were tested. On GEM i went up to 3500 volts, without seeing any "sparks".

2/20/09

1.) VPI post amp cross talk measurement

Need to get rid of UVA splitter. Lets make a cable to connect 2 DC into 1 VPI input connector

2.) Do Inclusive Histograms and then do helicity difference histograms

3.) Change Qweak bottom foil, connector from Walter coming soon will use to terminate detector output

4.) Continue Plateau measurements, prepare plateau measurement run plan for April.


27-04-09

Drift Velocity Calculation

HV Settings S:F:G=1350:-675:945

Cell size d=0.86 cm

[math]\Delta V = 1350 + 675 = 2025 Volts[/math]

[math]E = \frac{\Delta V}{d} = \frac{2025 Volts }{0.86 cm} \frac{100 cm}{m} = 235465\frac{Volts}{m}[/math]


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