collision analysis svd meeting markus friedl (hephy vienna) 18 june 2015

Collision Analysis

SVD Meeting

Markus Friedl (HEPHY Vienna)

18 June 2015


Distance Between Ladders

• (Not really) collision analysis: looking at various spots where neighboring objects are close to each other

• Generally: 1mm minimum gap (with exceptions)

• Some cases look like a problem (in a 2D projection) but in fact aren’t (when looking at different angle in 3D model)

218 June 2015


Barrel Cross Section

318 June 2015

1

5

3

4

2

6

Symmetry:Same occurrences in left and right halves

7

8

Proximity issues (all between L4 and L5)

DSSD distance of neighboring ladders

Markus Friedl (HEPHY Vienna) 418 June 2015

1

3 4

0.33 mm

0.84 mm 1.32 mm

0.46 mm

2


6

7 8

2.59 mm

2.74 mm4.27 mm

5

1.88 mm

No wirebonds near edge

Minus wirebondHeight ~2.0 mm

Minus wirebondHeight ~2.0 mm Minus wirebond

Height ~3.5 mm

UPDATE

BondsMeasured height ~0.5 mm


Barrel Near L4 Knee

618 June 2015

1

2

Same occurrences on the other half (L4, L5, L6 are symmetric)

UPDATE


1 2

0.93 mm

Not an issue (looks like one only in 2D projection)

3.23 mm min distance

0.33 mm

0.46 mm

UPDATE


Barrel Near L5 Knee

818 June 2015

1

2


UPDATE


1 2

0.16 mm

0.33 mm

0.46 mm

0.16 mm

Possible remedy: local dent in L6 ribs similar to L5 ribsUnder investigation at HEPHY (where all the final L6 ribs are)

UPDATE


Forward Cross Section

1018 June 2015

1

2



1 2

1.13 mm

0.33 mm

0.46 mm

0.97 mm

This is the reason for the local dent in L5 ribs

UPDATE


Wide sensor edge

4.11 mm

2.78 mm

1.28 mm

4.38 mm

Narrow sensor edge

L6 FWD Gaps Between Ladders

Rib to PF1 Connectors

UPDATE


Backward Cross Section

1318 June 2015

3

1 & 2

1 & 2 occur between all L4 ladders


1 2

3

1.13 mm

0.63 mm

1.26 mm Not an issue (looks like one only in 2D projection)

Better to make the clamp a bit narrower (to achieve at

least 1mm gap)

15Markus Friedl (HEPHY Vienna)

BWD L4 Connectors

• That’s why we need to connect the BWD L4 cables before mounting the ladder (similar to the L3 case)

18 June 2015

0.95 mm

16Markus Friedl (HEPHY Vienna)

Comparison CAD – Reality

• Measured on L5.902 (class C)– 2 PA1 & 2 PA2, each measured on both sides– Good match of average and CAD

18 June 2015

CAD = 3.73 mmReality:Min = 3.25 mmAvg = 3.74 mmMax = 4.10 mm

CAD = 2.25 mmReality:Min = 2.06 mmAvg = 2.28 mmMax = 2.56 mm


Assessment

• Gap between adjacent DSSD sufficiently large to allow some sagging without collision– 1.88mm (L3) to 4.27mm (L6)

• Generally 1mm minimum gap except for cases mostly between L4 and L5 (and L5 to L6) with PA1/2 loop (flexible)

• Average PA1/2 bend in CAD matches well with reality, but 0.5mm tolerance in height (~0.3 length)

• Tolerances may lead to PA1/2 touching adjacent rib– No Ohmic issue because of PA coverlay– Maybe noise issue? (Capacitive coupling)– Maybe add Kapton tape around bottom of L5 & L6 ribs?

1718 June 2015


Action Items

• L6 rib to L5 FW clip: 0.16mm– Possible solution: make local dent in L6 ribs– Under investigation at HEPHY

• Adjacent CO2 clamps in L4: 0.63mm– Slightly reduce clamp thickness at end

1818 June 2015

UPDATE

collision analysis svd meeting markus friedl (hephy vienna) 18 june 2015

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