Pixel Layout Options

1
Pixel Layout Options

• E. Anderssen, D. Bintinger, M. Gilchriese
• LBNL
• and
• W. Miller
• Hytec, Inc

2
Current Layout and the Issues

• At a meeting on July 8, 1998 to identify issues
  related to the SCT-pixel interference, the pixel
  group was requested to examine alternative
  layouts to
• see if the outer radius of the pixel
  structure(disk space frame) could be reduced to
  reduce the interference with the forward SCT.
• see if the complete pixel system could be made to
  fit within z lt78 cm, which would reduce, if not
  eliminate, the interference and possibly simplify
  the interface with the beam pipe support.
• The purpose of this presentation is present
  preliminary results for evaluation by the pixel
  group.
• The region of interference is sketched below.

3
Considerations(for zlt78 cm)

• Maintain ability to get 3 detector tiles from a
  4 wafer
• We assume a usable radius of 45.3mm on the wafer
• This implies that the total width of the three
  sensorsscribe alleys cannot exceed 64 mm
• Minimum active inner radius of disks must be gt
  101 mm
• This is set by tooling for B-layer insertion
• Maintain rapidity coverage to about 2.5 and at
  least 3 hits
• Maintain(as best we can tell) structural
  properties and ability to route services
• We have considered options that
• keep barrel and disk modules the same, including
  the existing module dimensions
• have different barrel and disk modules. This
  implies two different chip sizes, two different
  sensor layouts and two different flex
  hybrids/MCM-D layouts
• Electronics
• Mixing two chip sizes is considered feasible
• Having up to about 192 rows is considered
  feasible
• If yield is linear as one increases chip size
  from 160 to 192 rows, no significant impact on
  cost
• Need to evaluate possible impact on schedule from
  change to larger(or smaller) number of rows
• Flex hybrid option
• Smaller chip size for some portion of disk module
  is judged acceptable. Can be done.
• MCM-D option
• Wider MCM-D sensors limits options. Having same
  barrel and disk module seems not possible

4
Current Layout Parameters

• Barrel
• Radius Staves Modules Chips Channels Active
  Area(m2) Tilt
• B-layer 4.3 cm 18 234 3744 1.4 x
  107 0.23 -15o
• Layer 1 10.1 42 546 8736 3.4 x 107
  0.54 -(11-16)o
• Layer 2 13.2 56 728 11648 4.5 x 107
  0.72 -(11-16)o
• Subtotal 118 1508 24128 9.3 x 107 1.49
• Disks
• Inner Outer
• Z(cm) Radius Radius Modules Chips Channels
  Active Area(m2)
• 49.5 12.6 18.7 72 1152 4.4 x 106 0.07
• 61.2 12.6 18.7 72 1152 4.4 x 106 0.07
• 67.0 12.6 18.7 72 1152 4.4 x 106 0.07
• 84.1 12.6 18.7 72 1152 4.4 x 106 0.07
• 92.6 12.6 18.7 72 1152 4.4 x 106 0.07
• Subtotal(Both Sides) 720 11520 4.4 x 107
  0.70
• GRAND TOTALS 2228 35648 1.4 x 108 2.2

5
Overview of Layout Options

• TDR is the layout in the TDR
• 160 and 120
• 2x5 identical disks with 64 modules 16
  chips/module. 12 chips with 160 rows, 4 chips
  with 120 rows
• 160, 160 and 120
• First disk as in TDR. Other disks like 160 and
  120 layout.
• 192 rows(2.5 mm)
• 2x3 disks same(56 modules), and 2x2 disks same(50
  modules). 2.5 mm end-of-column. 16 chips/module.
  All chips 192 rows. Assume barrel layout can be
  done with this also(to be confirmed)
• 192 rows(3.0 mm)
• 2x3 disks with 60 modules, 2x2 disks with 50
  modules but with 3.0 mm end-of-column logic
• 18 chips
• This has 18 chips per module. 12 chips with 160
  rows. 6 with 120. Only 4 disks. 66 modules per
  disk
• TDR module(zlt78)
• TDR module. Same barrel and disk. 160 rows. Two
  different disk types2x3 of 72 modules, 2x2 of 60
  modules. This is our proposed solution for zlt78
  cm.

6
Comparison of Current Layout and Proposed for
zlt78 cm
800
7
Parameters of Zlt78 Layout

• Disks(Zlt78)
• Inner Outer
• Z(cm) Radius Radius Modules Chips Channels
  Active Area(m2)
• 49.5 12.6 18.7 72 1152 4.4 x 106 0.07
• 61.2 12.6 18.7 72 1152 4.4 x 106 0.07
• 67.0 12.6 18.7 72 1152 4.4 x 106 0.07
• 71.8 10.5 16.5 60 960 3.7 x 106 0.06
• 77.0 10.5 16.5 60 960 3.7 x 106 0.06
• Subtotal(Both Sides) 672 10752 4.1 x 107 0.66

Disks(TDR) Inner Outer Z(cm) Radius Radius Modul
es Chips Channels Active Area(m2) 49.5 12.6 18
.7 72 1152 4.4 x 106 0.07 61.2 12.6 18.7
72 1152 4.4 x 106 0.07 67.0 12.6 18.7
72 1152 4.4 x 106 0.07 84.1 12.6 18.7
72 1152 4.4 x 106 0.07 92.6 12.6 18.7
72 1152 4.4 x 106 0.07 Subtotal(Both Sides)
720 11520 4.4 x 107 0.70
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Comments/Issues on Zlt78 Layout

• First 3 disks remain as in current layout
• Disks 4 and 5 are different, smaller
• Lifetime of inner parts of disks 4 and 5 become
  like Layer 1
• More radial space in region of disk 4 and 5
  possible for services routing.
• Total active area is less than current area
• Deflection of support frame will increase
  somewhat since supports now at ends gt
  some(small) increase in mass of outer support
  frame.
• Stability(vibration) of disks 4 and 5 might be
  worse, unless small increase in mass
• Different tooling and maybe mounts for disks 4
  and 5. Increased cost of this likely offset by
  reduced area.

9
Conclusions

• Since early July, SCT appears to have found
  layout that resolves interference with current
  layout - see http//hep.ph.liv.ac.uk/jonest/Layou
  t.html
• But no mechanical reasons not to implement Zlt78
  cm layout
• Lifetime decrease for part of smaller disks no
  worse than barrel Layer 1.
• Likely to be at least cost neutral, although
  different tooling sets will be required.
• Outstanding issue is pattern recognition - does
  closer spacing significantly degrade performance?

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