Dan Levin, Yiftah Silver 1

UM lab activity

Status report Nov. 9Work from the last two weeks

11/9/2010

Dan Levin, Yiftah Silver 2

Objectives & procedure

• Search for traces of discharge spreading between neighboring pixels1. Check that all the pixels (in our work area) are

working – all of the pixels show the same behavior.

2. Trigger on one pixel and check the signal induced on it’s neighboring pixels

3. Repeat for different configurations of trigger and neighbors.

11/9/2010

Dan Levin, Yiftah Silver 3

Measurement setup• PV1-99%Ar-1%CF4 @700 Torr• Large part of the panel is covered with tape to minimize the

noise induced by light.• Trigger threshold: -1V• Collimator ~20cm lead with square aperture ~4mm^2

RO-26

RO-27

RO-28

RO-29

RO-30

VP1

HV lines– 93-96

20 pixels were tested.

26

27

28

29

30

96

HV

93 94 95

11/9/2010

Dan Levin, Yiftah Silver 4

Electrical Setup

HVRq=10MOhm

Rout=100[Ohm]

20 dB atten

Discriminator @ 100 mV

SnO2

Ni

11/9/2010

Up to 6 different read out channels

Up to 8 separately quenched HV channels

Dan Levin, Yiftah Silver 511/9/2010

23cm

2.8 mCi

Pb filled collimatorthe “zayin”

1/8” x 1/8” square aperture

handle

The panel

Dan Levin, Yiftah Silver 6

Single pixel (26x96) 880V • Amplitude 10-12V• Leading fall time:2-4ns– 10%-90%

• Full recovery time 150-200 ns.

• All pixels show same characteristics.

•

2V

2V

5ns

50ns

Effective capacitance of one pixel:8±2 [pF]

26

27

28

29

30

96

HV

11/9/2010

Dan Levin, Yiftah Silver 7

Signal from 20 (single) pixelsPixel Ni\SnO2 93 [#/min] 94 [#/min] 95 [#/min] 96 [#/min]

26 Bkg -21/5Src – 29/3

Bkg -10/3 Src – 24/3

Bkg -16/3 Src – 33/3

Bkg -16/3 Src – 31/3

27 Bkg – 15/5Src – 45/5

Bkg – 10/3Src – 24/3

Bkg – 11/3Src – 33/3

Bkg – 11/3Src – 20/3

28 Bkg – 11/3Src – 20/3

Bkg – 74/3Src – 163/3

Bkg – 43/3Src – 101/3

Bkg – 12/3Src – 28/3

29 Bkg – 13/3Src – 27/3

Bkg – 8/3Src – 36/3

Bkg – 8/3Src – 25/3

Bkg – 13/3Src – 35/3

30 Bkg – 12/3Src – 30/3

Bkg – 29/3Src – 69/3

Bkg – 24/3Src – 31/3

Bkg – 30/3Src – 50/3

All the measurements above were done at a voltage of 880V

11/9/2010

Dan Levin, Yiftah Silver 8

Search for discharge spreading

• New connectors allow measurement of 6 separate (or ganged) lines.

• Each HV line is terminated separately with a 10MOhm resistor.

• The idea is to trigger on the center pixel and to check the signal induced on the neighboring pixels

11/9/2010

Dan Levin, Yiftah Silver 9

Search for discharge spreading single HV line

• Green – pixel (28x96)• Red- 2 pixels on each side

(26,27,29,30x96 ) all ganged together.

• Same signal shape for the triggered pixel.

• A positive pulse on the neighboring pixels.

• All positive pulses show the same “double peak” behavior.

50ns1V

5V

Bkg- 10/3 [#/min]Src- 21/3 [#/min]

Rate measurements26

27

28

29

30

96

HV

11/9/2010

Dan Levin, Yiftah Silver 10

Search for discharge spreading single HV line

• Green – pixel (28x96)• Red- 1 pixels on each side

(27,29x96 ) ganged together.• Same signal shape for the

triggered pixel.• A positive pulse on the

neighboring pixels.• All positive pulses show the

same “double peak” behavior.

•

5V

1V 50ns

Rate measurements:Bkg - 6/3 [#/min]Src - 22/3 [#/min]

26

27

28

29

30

96

HV

11/9/2010

Dan Levin, Yiftah Silver 11

Search for discharge spreading single HV line

• Green – pixel (28x96)• Red- pixel (27x96)• Same signal shape for the

triggered pixel.• A positive pulse on the

neighboring pixel.• Rate measurement:

• Bkg – 8/3 [#/min]• Src – 17/3[#/min]

•

5V

1V 50ns

26

27

28

29

30

96

HV

11/9/2010

Dan Levin, Yiftah Silver 12

Search for discharge spreading single HV line

• Green – pixel (27x96)• Red- pixel (28x96)• Same signal shape for the

triggered pixel.• Same positive pulse on the

neighboring pixel.• Rate measurement:

• Bkg – 7/3 [#/min]• Src – 22/3 [#/min]

•

5V

1V 50ns

Different pixel – same signal… 26

27

28

29

30

96

HV

11/9/2010

Dan Levin, Yiftah Silver 13

Test for discharge spreading – Two HV lines

• HV lines 95,96 separately quenched with 10MOhm

• Green- RO line 28 (triggered)• Red – RO line 27• Rate measurements:

– Bkg 8/3 [#/min]– Src 40/3 [#/min]

•

5V

1V 50ns

26

27

28

29

30

96

HV

95

11/9/2010

Dan Levin, Yiftah Silver 14

Test for discharge spreading 4 HV lines

• HV lines 93-96 separately quenched with 10MOhm

• Green- RO line 28 (triggered)• Red – RO line 26,27,29,30 all

ganged together.• Rate measurements:

– Bkg: 38/3 [#/min]– Src: 74/3 [#/min]

•

26

27

28

29

30

96

HV

93 94 95

5V

1V50ns

880V gave rise to many “after-pulses”. this measurement was done at 870VMost signals looks like this but not all…11/9/2010

Dan Levin, Yiftah Silver 15

Different signals shapes – 4 HV lines

5V

1V50ns

Possible discharge spreading???

11/9/2010

Dan Levin, Yiftah Silver 16

Conclusions

• Results from measurements of one and two HV line shows no trace of discharge spreading!!! (along the SnO2 electrodes)

• It “looks like” most of the time there is no discharge spreading between pixels on the Ni electrodes.

• We will be able to give a better conclusion when readout is available on the HV lines as well.

11/9/2010