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

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
3900	3600	870
3850	3550	859

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

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.

Noise Level

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

Output from the GEM detector strips and from TrigOut after signal goes through the Timing Filter Amp(amplifier was set to "x10").

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

300px

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

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.