Recent TOB Developments

First LT failure andStereo Module Status

J. IncandelaWith slides provided by E. Chabalina, A. Affolder, Dean White

Report to TSC October 2, 2003 – Incandela 2

Module 705 before LT• After assembly module was tested (09/08) on ARCS at 400 V and graded “B” (6 faulty channels). No problems observed.

Report to TSC October 2, 2003 – Incandela 3

Module 705: LT data – Data was taken at 20°C on Sept.19 (10 days after the first test).

A group of high noise channels is seen around channel 219 and increased CMN is seen in chip #2

Report to TSC October 2, 2003 – Incandela 4

Module 705 after LT - I– Module was re-tested on ARCS on 09/23. High noise in channel

#219 and high CMN is observed at 400 V. At 200 V channel #219 has only slightly higher noise than the rest of the channels

Report to TSC October 2, 2003 – Incandela 5

Module 705 after LT - II– On ARCS kept module at 400 V for 30 minutes before testing (to

allow current settle down)– CMN did not go away, it became even higher

Report to TSC October 2, 2003 – Incandela 6

Comparison of IV curves – ”before” measurement is taken on 09/08 on ARCS before LT– “after” measurement is taken on 09/23 on ARCS after LT– green curve is a measurement done using Keithley on 09/24

with 1 minute interval between steps

0

5

10

15

20

50 150

250

350

450

applied voltage (V)

leak

age

curr

ent (

um)

ARC beforeARC afterkeithley

No visual defects are observed on the sensors around noisy channel #219

At this point we can’t conclude whether the effect we observe is due to thermocycling or if it is some other effect

Report to TSC October 2, 2003 – Incandela 7

Why be concerned• Several people have argued that this may not

be a real problem for several reasons:1. It is mainly occurring at high bias voltages2. It causes only a small amount of Common Mode Noise (CMN) 3. The noise is removed by CMN subtraction in the FED.

– In fact we see evidence that all of the above are false at significant levels.

– It may be that more sophisticated CMN removal algorithms are needed and hopefully the FED is capable of running them

– It may be that the new ST sensors have a drastic reduction in this problem– We will study 110 or so recent ST sensors sent to the US

(thanks Manfred et al.) as soon as they clear customs.

Report to TSC October 2, 2003 – Incandela 8

CMN Turn-on Voltage

CMN Turn-on Voltage

00.5

11.5

22.5

33.5

50 100 150 200 250 300 350 400 450

Voltage

Num

ber o

f Mod

ules

Report to TSC October 2, 2003 – Incandela 9

Common Mode Subtracted Noise25 ADC

869 881 1010 1011 1013 1014 1015 1016 1030 1031 1038 1042

6.5 ADC

Modules with CMN (micro-discharge problem)Common mode subtracted noise in blue

For majority of modules with problems, the CM subtraction is imperfect.7 of 12 have >2.0 ADC noise

3 of 12 have more than twice the usual noise

Report to TSC October 2, 2003 – Incandela 10

Common Mode Subtraction Variation

• Common mode subtraction results clearly vary– Answer differs mode-to-mode or test-to-test– Would yield varying signal efficiency/noise during data taking– Not clear how this will evolve with time/radiation

Module 1016 Module 1010

Report to TSC October 2, 2003 – Incandela 11

UCSB Stereo Module Production• UCSB Stereo plate

completed on schedule– Tested via dry runs and

produced results as good as the r-phi plates “right out of the box”

– We made a fixture to attach the cable stiffener on our hybrids.

• First hybrid retrofitted last week. Tested cable by making/unmaking connection 20 times by hand. No apparent problem with functionality and no signs of cracking.

Report to TSC October 2, 2003 – Incandela 12

First Stereo Module

• First Stereo TOB module made at USCB– Well within specs mechanically and functions very well

• Kapton circuit was missing a trace for bias. We made it by hand with Ag Epoxy. Otherwise this is a Grade A module!

• First TOB SS6 module to be made today.