Finding ST Sensors that cause CMN: A Follow up to TSC Meeting N. 215

Prof. J. Incandela

UC Santa Barbara

US CMS Tracker Project Leader

Tracker Steering Committee Meeting Number 216

March 4, 2004

These slides were prepared with the help of Tony Affolder and are based upon

work done this past week by the dedicated efforts of the UCSB production group

TSC No.216 March 4, 2004 - J. Incandela 2

Is Increased Bias Current and CMN Correlated?

• As of TSC #215 held on Feb. 27 2004, UCSB had in stock 22 sensors which upon reprobing showed a current change of

I > 1.5 A

• These sensors were probed both at UCSB and U Rochester with uniform results (like many of those reported on this last tracker week)• We ordered these sensors by increasing I• We built 8 modules with 9 of these sensors

• We picked every other sensor in the ordered list starting with the one with the lowest I

• The sensor with large I was always placed in position furthest from hybrid in module construction

• 1 module was built with 2 “bad” sensors

•6 of 8 modules have common mode noise

•Of the two modules without common mode noise:

• The “bad” sensor had < 2 A of increased current

• Increased noise is seen around a known, and hence unbonded, pinhole

• The other module now has current consistent with QTC measurement after construction

•We expect ~11 of the 13 sensors remaining from the original 22 will cause CMN in modules

TSC No.216 March 4, 2004 - J. Incandela 3

5104

•Sensors• 20275912

• 21738507

•Channels• 442 at 80V

• Increased bias current seen at 60V in sensor reprobing

30200020005104

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Voltage

Bia

s C

urr

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t (n

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Current(DB)

Current(probing)

Current(Bonded)

TSC No.216 March 4, 2004 - J. Incandela 4

5110

•Sensors• 31215014

• 14308304

•Channels• 203 at 70V

• Increased bias current seen at 30V in sensor reprobing

• 251 at 130V

• Increased bias current seen at 130V in sensor reprobing

30200020005110

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TSC No.216 March 4, 2004 - J. Incandela 5

5124

•Sensors• 24104717

• 31830607

•Channels• 160-162 at 150V

• Increased bias current seen at 250V in sensor reprobing

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TSC No.216 March 4, 2004 - J. Incandela 6

5160

•Sensors• 15061422

• 21174105

•Channels• 86-90 at 200V

• Increased bias current seen at 220V in sensor reprobing

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TSC No.216 March 4, 2004 - J. Incandela 7

5232

•Sensors• 14842724

• 14842701

•Channels• 505,506 at 350V

• Increased bias current seen at 400V in sensor reprobing

30200020005232

01000200030004000500060007000

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TSC No.216 March 4, 2004 - J. Incandela 8

5294

•Sensors• 20825319

• 20833807

•Channels• 280, 281 at 250V

• Increased bias current seen at 250V in sensor reprobing

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TSC No.216 March 4, 2004 - J. Incandela 9

Updated Correlation Plot

% of reprobed sensors leading to modules with CMN

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

-7000

-5000

-4000

-3000

-2000

-1000

0 1000

3000

4000

6000

7000

8000

>10000

I(Reprobed-QTC)(nA)

•All CMN modules built at UCSB to date:• 12 of 13 sensors with I >3 A caused common mode noise

• 2 of 9 modules with I between 2-3 A caused common mode noise

TSC No.216 March 4, 2004 - J. Incandela 10

Conclusions

• The correlation is strong and it is at the same level first seen last summer. It is no fluke.

• It is therefore not at all difficult to identify affected sensors.